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1 \chapter{Managing change with Mercurial Queues}
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2 \label{chap:mq}
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3
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4 \section{The patch management problem}
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5 \label{sec:mq:patch-mgmt}
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6
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7 Here is a common scenario: you need to install a software package from
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8 source, but you find a bug that you must fix in the source before you
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9 can start using the package. You make your changes, forget about the
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10 package for a while, and a few months later you need to upgrade to a
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11 newer version of the package. If the newer version of the package
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12 still has the bug, you must extract your fix from the older source
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13 tree and apply it against the newer version. This is a tedious task,
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14 and it's easy to make mistakes.
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15
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16 This is a simple case of the ``patch management'' problem. You have
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17 an ``upstream'' source tree that you can't change; you need to make
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18 some local changes on top of the upstream tree; and you'd like to be
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19 able to keep those changes separate, so that you can apply them to
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20 newer versions of the upstream source.
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21
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22 The patch management problem arises in many situations. Probably the
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23 most visible is that a user of an open source software project will
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24 contribute a bug fix or new feature to the project's maintainers in the
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25 form of a patch.
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26
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27 Distributors of operating systems that include open source software
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28 often need to make changes to the packages they distribute so that
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29 they will build properly in their environments.
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30
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31 When you have few changes to maintain, it is easy to manage a single
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32 patch using the standard \texttt{diff} and \texttt{patch} programs
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33 (see section~\ref{sec:mq:patch} for a discussion of these tools).
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34 Once the number of changes grows, it starts to makes sense to maintain
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35 patches as discrete ``chunks of work,'' so that for example a single
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36 patch will contain only one bug fix (the patch might modify several
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37 files, but it's doing ``only one thing''), and you may have a number
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38 of such patches for different bugs you need fixed and local changes
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39 you require. In this situation, if you submit a bug fix patch to the
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40 upstream maintainers of a package and they include your fix in a
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41 subsequent release, you can simply drop that single patch when you're
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42 updating to the newer release.
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43
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44 Maintaining a single patch against an upstream tree is a little
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45 tedious and error-prone, but not difficult. However, the complexity
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46 of the problem grows rapidly as the number of patches you have to
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47 maintain increases. With more than a tiny number of patches in hand,
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48 understanding which ones you have applied and maintaining them moves
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49 from messy to overwhelming.
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50
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51 Fortunately, Mercurial includes a powerful extension, Mercurial Queues
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52 (or simply ``MQ''), that massively simplifies the patch management
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53 problem.
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54
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55 \section{The prehistory of Mercurial Queues}
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56 \label{sec:mq:history}
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57
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58 During the late 1990s, several Linux kernel developers started to
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59 maintain ``patch series'' that modified the behaviour of the Linux
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60 kernel. Some of these series were focused on stability, some on
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61 feature coverage, and others were more speculative.
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62
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63 The sizes of these patch series grew rapidly. In 2002, Andrew Morton
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64 published some shell scripts he had been using to automate the task of
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65 managing his patch queues. Andrew was successfully using these
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66 scripts to manage hundreds (sometimes thousands) of patches on top of
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67 the Linux kernel.
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68
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69 \subsection{A patchwork quilt}
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70 \label{sec:mq:quilt}
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71
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72
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73 In early 2003, Andreas Gruenbacher and Martin Quinson borrowed the
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74 approach of Andrew's scripts and published a tool called ``patchwork
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75 quilt''~\cite{web:quilt}, or simply ``quilt''
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76 (see~\cite{gruenbacher:2005} for a paper describing it). Because
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77 quilt substantially automated patch management, it rapidly gained a
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78 large following among open source software developers.
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79
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80 Quilt manages a \emph{stack of patches} on top of a directory tree.
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81 To begin, you tell quilt to manage a directory tree, and tell it which
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82 files you want to manage; it stores away the names and contents of
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83 those files. To fix a bug, you create a new patch (using a single
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84 command), edit the files you need to fix, then ``refresh'' the patch.
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85
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86 The refresh step causes quilt to scan the directory tree; it updates
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87 the patch with all of the changes you have made. You can create
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88 another patch on top of the first, which will track the changes
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89 required to modify the tree from ``tree with one patch applied'' to
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90 ``tree with two patches applied''.
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91
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92 You can \emph{change} which patches are applied to the tree. If you
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93 ``pop'' a patch, the changes made by that patch will vanish from the
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94 directory tree. Quilt remembers which patches you have popped,
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95 though, so you can ``push'' a popped patch again, and the directory
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96 tree will be restored to contain the modifications in the patch. Most
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97 importantly, you can run the ``refresh'' command at any time, and the
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98 topmost applied patch will be updated. This means that you can, at
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99 any time, change both which patches are applied and what
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100 modifications those patches make.
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101
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102 Quilt knows nothing about revision control tools, so it works equally
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103 well on top of an unpacked tarball or a Subversion repository.
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104
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105 \subsection{From patchwork quilt to Mercurial Queues}
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106 \label{sec:mq:quilt-mq}
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107
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108 In mid-2005, Chris Mason took the features of quilt and wrote an
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109 extension that he called Mercurial Queues, which added quilt-like
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110 behaviour to Mercurial.
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111
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112 The key difference between quilt and MQ is that quilt knows nothing
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113 about revision control systems, while MQ is \emph{integrated} into
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114 Mercurial. Each patch that you push is represented as a Mercurial
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115 changeset. Pop a patch, and the changeset goes away.
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116
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117 This integration makes understanding patches and debugging their
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118 effects \emph{enormously} easier. Since every applied patch has an
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119 associated changeset, you can use \hgcmdargs{log}{\emph{filename}} to
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120 see which changesets and patches affected a file. You can use the
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121 \hgext{bisect} extension to binary-search through all changesets and
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122 applied patches to see where a bug got introduced or fixed. You can
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123 use the \hgcmd{annotate} command to see which changeset or patch
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124 modified a particular line of a source file. And so on.
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125
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126 Because quilt does not care about revision control tools, it is still
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127 a tremendously useful piece of software to know about for situations
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128 where you cannot use Mercurial and MQ.
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129
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130 \section{Understanding patches}
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131 \label{sec:mq:patch}
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132
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133 Because MQ doesn't hide its patch-oriented nature, it is helpful to
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134 understand what patches are, and a little about the tools that work
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135 with them.
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136
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137 The traditional Unix \command{diff} command compares two files, and
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138 prints a list of differences between them. The \command{patch} command
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139 understands these differences as \emph{modifications} to make to a
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140 file. Take a look at figure~\ref{ex:mq:diff} for a simple example of
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141 these commands in action.
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142
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143 \begin{figure}[ht]
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144 \interaction{mq.diff.diff}
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145 \caption{Simple uses of the \command{diff} and \command{patch} commands}
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146 \label{ex:mq:diff}
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147 \end{figure}
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148
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149 The type of file that \command{diff} generates (and \command{patch}
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150 takes as input) is called a ``patch'' or a ``diff''; there is no
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151 difference between a patch and a diff. (We'll use the term ``patch'',
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152 since it's more commonly used.)
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153
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154 A patch file can start with arbitrary text; the \command{patch}
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155 command ignores this text, but MQ uses it as the commit message when
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156 creating changesets. To find the beginning of the patch content,
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157 \command{patch} searches for the first line that starts with the
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158 string ``\texttt{diff~-}''.
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159
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160 MQ works with \emph{unified} diffs (\command{patch} can accept several
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161 other diff formats, but MQ doesn't). A unified diff contains two
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162 kinds of header. The \emph{file header} describes the file being
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163 modified; it contains the name of the file to modify. When
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164 \command{patch} sees a new file header, it looks for a file with that
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165 name to start modifying.
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166
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167 After the file header comes a series of \emph{hunks}. Each hunk
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168 starts with a header; this identifies the range of line numbers within
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169 the file that the hunk should modify. Following the header, a hunk
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170 starts and ends with a few (usually three) lines of text from the
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171 unmodified file; these are called the \emph{context} for the hunk. If
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172 there's only a small amount of context between successive hunks,
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173 \command{diff} doesn't print a new hunk header; it just runs the hunks
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174 together, with a few lines of context between modifications.
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175
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176 Each line of context begins with a space character. Within the hunk,
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177 a line that begins with ``\texttt{-}'' means ``remove this line,''
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178 while a line that begins with ``\texttt{+}'' means ``insert this
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179 line.'' For example, a line that is modified is represented by one
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180 deletion and one insertion.
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181
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182 We will return to ome of the more subtle aspects of patches later (in
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183 section~\ref{sec:mq:adv-patch}), but you should have enough information
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184 now to use MQ.
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185
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186 \section{Getting started with Mercurial Queues}
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187 \label{sec:mq:start}
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188
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189 Because MQ is implemented as an extension, you must explicitly enable
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190 before you can use it. (You don't need to download anything; MQ ships
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191 with the standard Mercurial distribution.) To enable MQ, edit your
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192 \tildefile{.hgrc} file, and add the lines in figure~\ref{ex:mq:config}.
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193
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194 \begin{figure}[ht]
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195 \begin{codesample4}
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196 [extensions]
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197 hgext.mq =
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198 \end{codesample4}
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199 \label{ex:mq:config}
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200 \caption{Contents to add to \tildefile{.hgrc} to enable the MQ extension}
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201 \end{figure}
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202
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203 Once the extension is enabled, it will make a number of new commands
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204 available. To verify that the extension is working, you can use
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205 \hgcmd{help} to see if the \hgcmd{qinit} command is now available; see
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206 the example in figure~\ref{ex:mq:enabled}.
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207
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208 \begin{figure}[ht]
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209 \interaction{mq.qinit-help.help}
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210 \caption{How to verify that MQ is enabled}
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211 \label{ex:mq:enabled}
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212 \end{figure}
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213
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214 You can use MQ with \emph{any} Mercurial repository, and its commands
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215 only operate within that repository. To get started, simply prepare
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216 the repository using the \hgcmd{qinit} command (see
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217 figure~\ref{ex:mq:qinit}). This command creates an empty directory
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218 called \sdirname{.hg/patches}, where MQ will keep its metadata. As
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219 with many Mercurial commands, the \hgcmd{qinit} command prints nothing
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220 if it succeeds.
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221
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222 \begin{figure}[ht]
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223 \interaction{mq.tutorial.qinit}
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224 \caption{Preparing a repository for use with MQ}
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225 \label{ex:mq:qinit}
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226 \end{figure}
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227
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228 \begin{figure}[ht]
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229 \interaction{mq.tutorial.qnew}
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230 \caption{Creating a new patch}
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231 \label{ex:mq:qnew}
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232 \end{figure}
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233
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234 \subsection{Creating a new patch}
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235
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236 To begin work on a new patch, use the \hgcmd{qnew} command. This
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237 command takes one argument, the name of the patch to create. MQ will
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238 use this as the name of an actual file in the \sdirname{.hg/patches}
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239 directory, as you can see in figure~\ref{ex:mq:qnew}.
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240
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241 Also newly present in the \sdirname{.hg/patches} directory are two
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242 other files, \sfilename{series} and \sfilename{status}. The
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243 \sfilename{series} file lists all of the patches that MQ knows about
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244 for this repository, with one patch per line. Mercurial uses the
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245 \sfilename{status} file for internal book-keeping; it tracks all of the
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246 patches that MQ has \emph{applied} in this repository.
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247
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248 \begin{note}
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249 You may sometimes want to edit the \sfilename{series} file by hand;
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250 for example, to change the sequence in which some patches are
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251 applied. However, manually editing the \sfilename{status} file is
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252 almost always a bad idea, as it's easy to corrupt MQ's idea of what
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253 is happening.
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254 \end{note}
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255
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256 Once you have created your new patch, you can edit files in the
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257 working directory as you usually would. All of the normal Mercurial
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258 commands, such as \hgcmd{diff} and \hgcmd{annotate}, work exactly as
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259 they did before.
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260
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261 \subsection{Refreshing a patch}
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262
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263 When you reach a point where you want to save your work, use the
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264 \hgcmd{qrefresh} command (figure~\ref{ex:mq:qnew}) to update the patch
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265 you are working on. This command folds the changes you have made in
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266 the working directory into your patch, and updates its corresponding
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267 changeset to contain those changes.
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268
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269 \begin{figure}[ht]
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270 \interaction{mq.tutorial.qrefresh}
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271 \caption{Refreshing a patch}
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272 \label{ex:mq:qrefresh}
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273 \end{figure}
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274
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275 You can run \hgcmd{qrefresh} as often as you like, so it's a good way
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276 to ``checkpoint'' your work. Refresh your patch at an opportune
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277 time; try an experiment; and if the experiment doesn't work out,
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278 \hgcmd{revert} your modifications back to the last time you refreshed.
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279
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280 \begin{figure}[ht]
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281 \interaction{mq.tutorial.qrefresh2}
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282 \caption{Refresh a patch many times to accumulate changes}
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283 \label{ex:mq:qrefresh2}
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284 \end{figure}
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285
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286 \subsection{Stacking and tracking patches}
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287
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288 Once you have finished working on a patch, or need to work on another,
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289 you can use the \hgcmd{qnew} command again to create a new patch.
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290 Mercurial will apply this patch on top of your existing patch. See
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291 figure~\ref{ex:mq:qnew2} for an example. Notice that the patch
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292 contains the changes in our prior patch as part of its context (you
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293 can see this more clearly in the output of \hgcmd{annotate}).
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294
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295 \begin{figure}[ht]
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296 \interaction{mq.tutorial.qnew2}
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297 \caption{Stacking a second patch on top of the first}
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bos@8
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298 \label{ex:mq:qnew2}
|
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bos@8
|
299 \end{figure}
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bos@8
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300
|
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bos@8
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301 So far, with the exception of \hgcmd{qnew} and \hgcmd{qrefresh}, we've
|
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bos@27
|
302 been careful to only use regular Mercurial commands. However, MQ
|
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bos@27
|
303 provides many commands that are easier to use when you are thinking
|
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bos@27
|
304 about patches, as illustrated in figure~\ref{ex:mq:qseries}:
|
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bos@8
|
305
|
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bos@8
|
306 \begin{itemize}
|
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bos@8
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307 \item The \hgcmd{qseries} command lists every patch that MQ knows
|
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bos@8
|
308 about in this repository, from oldest to newest (most recently
|
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bos@8
|
309 \emph{created}).
|
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bos@8
|
310 \item The \hgcmd{qapplied} command lists every patch that MQ has
|
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bos@8
|
311 \emph{applied} in this repository, again from oldest to newest (most
|
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bos@8
|
312 recently applied).
|
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bos@8
|
313 \end{itemize}
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bos@8
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314
|
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bos@12
|
315 \begin{figure}[ht]
|
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bos@8
|
316 \interaction{mq.tutorial.qseries}
|
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bos@8
|
317 \caption{Understanding the patch stack with \hgcmd{qseries} and
|
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bos@8
|
318 \hgcmd{qapplied}}
|
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bos@8
|
319 \label{ex:mq:qseries}
|
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bos@8
|
320 \end{figure}
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bos@8
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321
|
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bos@8
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322 \subsection{Manipulating the patch stack}
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bos@8
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323
|
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bos@8
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324 The previous discussion implied that there must be a difference
|
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bos@11
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325 between ``known'' and ``applied'' patches, and there is. MQ can
|
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bos@11
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326 manage a patch without it being applied in the repository.
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bos@8
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327
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bos@8
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328 An \emph{applied} patch has a corresponding changeset in the
|
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bos@8
|
329 repository, and the effects of the patch and changeset are visible in
|
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bos@8
|
330 the working directory. You can undo the application of a patch using
|
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bos@12
|
331 the \hgcmd{qpop} command. MQ still \emph{knows about}, or manages, a
|
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bos@12
|
332 popped patch, but the patch no longer has a corresponding changeset in
|
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bos@12
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333 the repository, and the working directory does not contain the changes
|
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bos@12
|
334 made by the patch. Figure~\ref{fig:mq:stack} illustrates the
|
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bos@12
|
335 difference between applied and tracked patches.
|
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bos@12
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336
|
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bos@12
|
337 \begin{figure}[ht]
|
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bos@12
|
338 \centering
|
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bos@12
|
339 \grafix{mq-stack}
|
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bos@12
|
340 \caption{Applied and unapplied patches in the MQ patch stack}
|
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bos@12
|
341 \label{fig:mq:stack}
|
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bos@8
|
342 \end{figure}
|
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bos@8
|
343
|
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bos@8
|
344 You can reapply an unapplied, or popped, patch using the \hgcmd{qpush}
|
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bos@8
|
345 command. This creates a new changeset to correspond to the patch, and
|
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bos@8
|
346 the patch's changes once again become present in the working
|
|
bos@8
|
347 directory. See figure~\ref{ex:mq:qpop} for examples of \hgcmd{qpop}
|
|
bos@8
|
348 and \hgcmd{qpush} in action. Notice that once we have popped a patch
|
|
bos@8
|
349 or two patches, the output of \hgcmd{qseries} remains the same, while
|
|
bos@8
|
350 that of \hgcmd{qapplied} has changed.
|
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bos@8
|
351
|
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bos@12
|
352 \begin{figure}[ht]
|
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bos@12
|
353 \interaction{mq.tutorial.qpop}
|
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bos@12
|
354 \caption{Modifying the stack of applied patches}
|
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bos@12
|
355 \label{ex:mq:qpop}
|
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bos@11
|
356 \end{figure}
|
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bos@11
|
357
|
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bos@27
|
358 \subsection{Pushing and popping many patches}
|
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bos@27
|
359
|
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bos@27
|
360 While \hgcmd{qpush} and \hgcmd{qpop} each operate on a single patch at
|
|
bos@27
|
361 a time by default, you can push and pop many patches in one go. The
|
|
bos@27
|
362 \hgopt{qpush}{-a} option to \hgcmd{qpush} causes it to push all
|
|
bos@27
|
363 unapplied patches, while the \hgopt{qpop}{-a} option to \hgcmd{qpop}
|
|
bos@27
|
364 causes it to pop all applied patches. (For some more ways to push and
|
|
bos@27
|
365 pop many patches, see section~\ref{sec:mq:perf} below.)
|
|
bos@27
|
366
|
|
bos@27
|
367 \begin{figure}[ht]
|
|
bos@27
|
368 \interaction{mq.tutorial.qpush-a}
|
|
bos@27
|
369 \caption{Pushing all unapplied patches}
|
|
bos@27
|
370 \label{ex:mq:qpush-a}
|
|
bos@27
|
371 \end{figure}
|
|
bos@27
|
372
|
|
bos@27
|
373 \subsection{Safety checks, and overriding them}
|
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bos@27
|
374
|
|
bos@27
|
375 Several MQ commands check the working directory before they do
|
|
bos@27
|
376 anything, and fail if they find any modifications. They do this to
|
|
bos@27
|
377 ensure that you won't lose any changes that you have made, but not yet
|
|
bos@27
|
378 incorporated into a patch. Figure~\ref{ex:mq:add} illustrates this;
|
|
bos@27
|
379 the \hgcmd{qnew} command will not create a new patch if there are
|
|
bos@27
|
380 outstanding changes, caused in this case by the \hgcmd{add} of
|
|
bos@27
|
381 \filename{file3}.
|
|
bos@27
|
382
|
|
bos@27
|
383 \begin{figure}[ht]
|
|
bos@27
|
384 \interaction{mq.tutorial.add}
|
|
bos@27
|
385 \caption{Forcibly creating a patch}
|
|
bos@27
|
386 \label{ex:mq:add}
|
|
bos@27
|
387 \end{figure}
|
|
bos@27
|
388
|
|
bos@27
|
389 Commands that check the working directory all take an ``I know what
|
|
bos@27
|
390 I'm doing'' option, which is always named \option{-f}. The exact
|
|
bos@27
|
391 meaning of \option{-f} depends on the command. For example,
|
|
bos@27
|
392 \hgcmdargs{qnew}{\hgopt{qnew}{-f}} will incorporate any outstanding
|
|
bos@27
|
393 changes into the new patch it creates, but
|
|
bos@27
|
394 \hgcmdargs{qpop}{\hgopt{qpop}{-f}} will revert modifications to any
|
|
bos@27
|
395 files affected by the patch that it is popping. Be sure to read the
|
|
bos@27
|
396 documentation for a command's \option{-f} option before you use it!
|
|
bos@8
|
397
|
|
bos@13
|
398 \subsection{Working on several patches at once}
|
|
bos@13
|
399
|
|
bos@13
|
400 The \hgcmd{qrefresh} command always refreshes the \emph{topmost}
|
|
bos@13
|
401 applied patch. This means that you can suspend work on one patch (by
|
|
bos@13
|
402 refreshing it), pop or push to make a different patch the top, and
|
|
bos@13
|
403 work on \emph{that} patch for a while.
|
|
bos@13
|
404
|
|
bos@13
|
405 Here's an example that illustrates how you can use this ability.
|
|
bos@13
|
406 Let's say you're developing a new feature as two patches. The first
|
|
bos@18
|
407 is a change to the core of your software, and the second---layered on
|
|
bos@18
|
408 top of the first---changes the user interface to use the code you just
|
|
bos@13
|
409 added to the core. If you notice a bug in the core while you're
|
|
bos@13
|
410 working on the UI patch, it's easy to fix the core. Simply
|
|
bos@13
|
411 \hgcmd{qrefresh} the UI patch to save your in-progress changes, and
|
|
bos@13
|
412 \hgcmd{qpop} down to the core patch. Fix the core bug,
|
|
bos@13
|
413 \hgcmd{qrefresh} the core patch, and \hgcmd{qpush} back to the UI
|
|
bos@13
|
414 patch to continue where you left off.
|
|
bos@13
|
415
|
|
bos@19
|
416 \section{More about patches}
|
|
bos@19
|
417 \label{sec:mq:adv-patch}
|
|
bos@19
|
418
|
|
bos@19
|
419 MQ uses the GNU \command{patch} command to apply patches, so it's
|
|
bos@26
|
420 helpful to know a few more detailed aspects of how \command{patch}
|
|
bos@26
|
421 works, and about patches themselves.
|
|
bos@26
|
422
|
|
bos@26
|
423 \subsection{The strip count}
|
|
bos@26
|
424
|
|
bos@26
|
425 If you look at the file headers in a patch, you will notice that the
|
|
bos@26
|
426 pathnames usually have an extra component on the front that isn't
|
|
bos@26
|
427 present in the actual path name. This is a holdover from the way that
|
|
bos@26
|
428 people used to generate patches (people still do this, but it's
|
|
bos@26
|
429 somewhat rare with modern revision control tools).
|
|
bos@26
|
430
|
|
bos@26
|
431 Alice would unpack a tarball, edit her files, then decide that she
|
|
bos@26
|
432 wanted to create a patch. So she'd rename her working directory,
|
|
bos@26
|
433 unpack the tarball again (hence the need for the rename), and use the
|
|
bos@26
|
434 \cmdopt{diff}{-r} and \cmdopt{diff}{-N} options to \command{diff} to
|
|
bos@26
|
435 recursively generate a patch between the unmodified directory and the
|
|
bos@26
|
436 modified one. The result would be that the name of the unmodified
|
|
bos@26
|
437 directory would be at the front of the left-hand path in every file
|
|
bos@26
|
438 header, and the name of the modified directory would be at the front
|
|
bos@26
|
439 of the right-hand path.
|
|
bos@26
|
440
|
|
bos@26
|
441 Since someone receiving a patch from the Alices of the net would be
|
|
bos@26
|
442 unlikely to have unmodified and modified directories with exactly the
|
|
bos@26
|
443 same names, the \command{patch} command has a \cmdopt{patch}{-p}
|
|
bos@26
|
444 option that indicates the number of leading path name components to
|
|
bos@26
|
445 strip when trying to apply a patch. This number is called the
|
|
bos@26
|
446 \emph{strip count}.
|
|
bos@26
|
447
|
|
bos@26
|
448 An option of ``\texttt{-p1}'' means ``use a strip count of one''. If
|
|
bos@26
|
449 \command{patch} sees a file name \filename{foo/bar/baz} in a file
|
|
bos@26
|
450 header, it will strip \filename{foo} and try to patch a file named
|
|
bos@26
|
451 \filename{bar/baz}. (Strictly speaking, the strip count refers to the
|
|
bos@26
|
452 number of \emph{path separators} (and the components that go with them
|
|
bos@26
|
453 ) to strip. A strip count of one will turn \filename{foo/bar} into
|
|
bos@26
|
454 \filename{bar}, but \filename{/foo/bar} (notice the extra leading
|
|
bos@26
|
455 slash) into \filename{foo/bar}.)
|
|
bos@26
|
456
|
|
bos@26
|
457 The ``standard'' strip count for patches is one; almost all patches
|
|
bos@26
|
458 contain one leading path name component that needs to be stripped.
|
|
bos@26
|
459 Mercurial's \hgcmd{diff} command generates path names in this form,
|
|
bos@26
|
460 and the \hgcmd{import} command and MQ expect patches to have a strip
|
|
bos@26
|
461 count of one.
|
|
bos@26
|
462
|
|
bos@26
|
463 If you receive a patch from someone that you want to add to your patch
|
|
bos@26
|
464 queue, and the patch needs a strip count other than one, you cannot
|
|
bos@26
|
465 just \hgcmd{qimport} the patch, because \hgcmd{qimport} does not yet
|
|
bos@26
|
466 have a \texttt{-p} option (see~\bug{311}). Your best bet is to
|
|
bos@26
|
467 \hgcmd{qnew} a patch of your own, then use \cmdargs{patch}{-p\emph{N}}
|
|
bos@26
|
468 to apply their patch, followed by \hgcmd{addremove} to pick up any
|
|
bos@26
|
469 files added or removed by the patch, followed by \hgcmd{qrefresh}.
|
|
bos@26
|
470 This complexity may become unnecessary; see~\bug{311} for details.
|
|
bos@26
|
471 \subsection{Strategies for applying a patch}
|
|
bos@14
|
472
|
|
bos@14
|
473 When \command{patch} applies a hunk, it tries a handful of
|
|
bos@14
|
474 successively less accurate strategies to try to make the hunk apply.
|
|
bos@14
|
475 This falling-back technique often makes it possible to take a patch
|
|
bos@14
|
476 that was generated against an old version of a file, and apply it
|
|
bos@14
|
477 against a newer version of that file.
|
|
bos@14
|
478
|
|
bos@14
|
479 First, \command{patch} tries an exact match, where the line numbers,
|
|
bos@14
|
480 the context, and the text to be modified must apply exactly. If it
|
|
bos@14
|
481 cannot make an exact match, it tries to find an exact match for the
|
|
bos@14
|
482 context, without honouring the line numbering information. If this
|
|
bos@14
|
483 succeeds, it prints a line of output saying that the hunk was applied,
|
|
bos@14
|
484 but at some \emph{offset} from the original line number.
|
|
bos@14
|
485
|
|
bos@14
|
486 If a context-only match fails, \command{patch} removes the first and
|
|
bos@14
|
487 last lines of the context, and tries a \emph{reduced} context-only
|
|
bos@14
|
488 match. If the hunk with reduced context succeeds, it prints a message
|
|
bos@14
|
489 saying that it applied the hunk with a \emph{fuzz factor} (the number
|
|
bos@14
|
490 after the fuzz factor indicates how many lines of context
|
|
bos@14
|
491 \command{patch} had to trim before the patch applied).
|
|
bos@14
|
492
|
|
bos@14
|
493 When neither of these techniques works, \command{patch} prints a
|
|
bos@14
|
494 message saying that the hunk in question was rejected. It saves
|
|
bos@17
|
495 rejected hunks (also simply called ``rejects'') to a file with the
|
|
bos@17
|
496 same name, and an added \sfilename{.rej} extension. It also saves an
|
|
bos@17
|
497 unmodified copy of the file with a \sfilename{.orig} extension; the
|
|
bos@17
|
498 copy of the file without any extensions will contain any changes made
|
|
bos@17
|
499 by hunks that \emph{did} apply cleanly. If you have a patch that
|
|
bos@17
|
500 modifies \filename{foo} with six hunks, and one of them fails to
|
|
bos@17
|
501 apply, you will have: an unmodified \filename{foo.orig}, a
|
|
bos@17
|
502 \filename{foo.rej} containing one hunk, and \filename{foo}, containing
|
|
bos@17
|
503 the changes made by the five successful five hunks.
|
|
bos@14
|
504
|
|
bos@25
|
505 \subsection{Some quirks of patch representation}
|
|
bos@25
|
506
|
|
bos@25
|
507 There are a few useful things to know about how \command{patch} works
|
|
bos@25
|
508 with files.
|
|
bos@25
|
509 \begin{itemize}
|
|
bos@25
|
510 \item This should already be obvious, but \command{patch} cannot
|
|
bos@25
|
511 handle binary files.
|
|
bos@25
|
512 \item Neither does it care about the executable bit; it creates new
|
|
bos@25
|
513 files as readable, but not executable.
|
|
bos@25
|
514 \item \command{patch} treats the removal of a file as a diff between
|
|
bos@25
|
515 the file to be removed and the empty file. So your idea of ``I
|
|
bos@25
|
516 deleted this file'' looks like ``every line of this file was
|
|
bos@25
|
517 deleted'' in a patch.
|
|
bos@25
|
518 \item It treats the addition of a file as a diff between the empty
|
|
bos@25
|
519 file and the file to be added. So in a patch, your idea of ``I
|
|
bos@25
|
520 added this file'' looks like ``every line of this file was added''.
|
|
bos@25
|
521 \item It treats a renamed file as the removal of the old name, and the
|
|
bos@25
|
522 addition of the new name. This means that renamed files have a big
|
|
bos@25
|
523 footprint in patches. (Note also that Mercurial does not currently
|
|
bos@25
|
524 try to infer when files have been renamed or copied in a patch.)
|
|
bos@25
|
525 \item \command{patch} cannot represent empty files, so you cannot use
|
|
bos@25
|
526 a patch to represent the notion ``I added this empty file to the
|
|
bos@25
|
527 tree''.
|
|
bos@25
|
528 \end{itemize}
|
|
bos@14
|
529 \subsection{Beware the fuzz}
|
|
bos@14
|
530
|
|
bos@14
|
531 While applying a hunk at an offset, or with a fuzz factor, will often
|
|
bos@14
|
532 be completely successful, these inexact techniques naturally leave
|
|
bos@14
|
533 open the possibility of corrupting the patched file. The most common
|
|
bos@14
|
534 cases typically involve applying a patch twice, or at an incorrect
|
|
bos@14
|
535 location in the file. If \command{patch} or \hgcmd{qpush} ever
|
|
bos@14
|
536 mentions an offset or fuzz factor, you should make sure that the
|
|
bos@14
|
537 modified files are correct afterwards.
|
|
bos@14
|
538
|
|
bos@14
|
539 It's often a good idea to refresh a patch that has applied with an
|
|
bos@14
|
540 offset or fuzz factor; refreshing the patch generates new context
|
|
bos@14
|
541 information that will make it apply cleanly. I say ``often,'' not
|
|
bos@14
|
542 ``always,'' because sometimes refreshing a patch will make it fail to
|
|
bos@14
|
543 apply against a different revision of the underlying files. In some
|
|
bos@14
|
544 cases, such as when you're maintaining a patch that must sit on top of
|
|
bos@14
|
545 multiple versions of a source tree, it's acceptable to have a patch
|
|
bos@14
|
546 apply with some fuzz, provided you've verified the results of the
|
|
bos@14
|
547 patching process in such cases.
|
|
bos@14
|
548
|
|
bos@15
|
549 \subsection{Handling rejection}
|
|
bos@15
|
550
|
|
bos@15
|
551 If \hgcmd{qpush} fails to apply a patch, it will print an error
|
|
bos@16
|
552 message and exit. If it has left \sfilename{.rej} files behind, it is
|
|
bos@15
|
553 usually best to fix up the rejected hunks before you push more patches
|
|
bos@15
|
554 or do any further work.
|
|
bos@15
|
555
|
|
bos@15
|
556 If your patch \emph{used to} apply cleanly, and no longer does because
|
|
bos@15
|
557 you've changed the underlying code that your patches are based on,
|
|
bos@17
|
558 Mercurial Queues can help; see section~\ref{sec:mq:merge} for details.
|
|
bos@15
|
559
|
|
bos@15
|
560 Unfortunately, there aren't any great techniques for dealing with
|
|
bos@16
|
561 rejected hunks. Most often, you'll need to view the \sfilename{.rej}
|
|
bos@15
|
562 file and edit the target file, applying the rejected hunks by hand.
|
|
bos@15
|
563
|
|
bos@16
|
564 If you're feeling adventurous, Neil Brown, a Linux kernel hacker,
|
|
bos@16
|
565 wrote a tool called \command{wiggle}~\cite{web:wiggle}, which is more
|
|
bos@16
|
566 vigorous than \command{patch} in its attempts to make a patch apply.
|
|
bos@15
|
567
|
|
bos@15
|
568 Another Linux kernel hacker, Chris Mason (the author of Mercurial
|
|
bos@15
|
569 Queues), wrote a similar tool called \command{rej}~\cite{web:rej},
|
|
bos@15
|
570 which takes a simple approach to automating the application of hunks
|
|
bos@15
|
571 rejected by \command{patch}. \command{rej} can help with four common
|
|
bos@15
|
572 reasons that a hunk may be rejected:
|
|
bos@15
|
573
|
|
bos@15
|
574 \begin{itemize}
|
|
bos@15
|
575 \item The context in the middle of a hunk has changed.
|
|
bos@15
|
576 \item A hunk is missing some context at the beginning or end.
|
|
bos@18
|
577 \item A large hunk might apply better---either entirely or in
|
|
bos@18
|
578 part---if it was broken up into smaller hunks.
|
|
bos@15
|
579 \item A hunk removes lines with slightly different content than those
|
|
bos@15
|
580 currently present in the file.
|
|
bos@15
|
581 \end{itemize}
|
|
bos@15
|
582
|
|
bos@15
|
583 If you use \command{wiggle} or \command{rej}, you should be doubly
|
|
bos@15
|
584 careful to check your results when you're done.
|
|
bos@15
|
585
|
|
bos@17
|
586 \section{Getting the best performance out of MQ}
|
|
bos@27
|
587 \label{sec:mq:perf}
|
|
bos@17
|
588
|
|
bos@17
|
589 MQ is very efficient at handling a large number of patches. I ran
|
|
bos@17
|
590 some performance experiments in mid-2006 for a talk that I gave at the
|
|
bos@17
|
591 2006 EuroPython conference~\cite{web:europython}. I used as my data
|
|
bos@17
|
592 set the Linux 2.6.17-mm1 patch series, which consists of 1,738
|
|
bos@17
|
593 patches. I applied thes on top of a Linux kernel repository
|
|
bos@17
|
594 containing all 27,472 revisions between Linux 2.6.12-rc2 and Linux
|
|
bos@17
|
595 2.6.17.
|
|
bos@17
|
596
|
|
bos@17
|
597 On my old, slow laptop, I was able to
|
|
bos@17
|
598 \hgcmdargs{qpush}{\hgopt{qpush}{-a}} all 1,738 patches in 3.5 minutes,
|
|
bos@17
|
599 and \hgcmdargs{qpop}{\hgopt{qpop}{-a}} them all in 30 seconds. I
|
|
bos@17
|
600 could \hgcmd{qrefresh} one of the biggest patches (which made 22,779
|
|
bos@17
|
601 lines of changes to 287 files) in 6.6 seconds.
|
|
bos@17
|
602
|
|
bos@17
|
603 Clearly, MQ is well suited to working in large trees, but there are a
|
|
bos@17
|
604 few tricks you can use to get the best performance of it.
|
|
bos@17
|
605
|
|
bos@17
|
606 First of all, try to ``batch'' operations together. Every time you
|
|
bos@17
|
607 run \hgcmd{qpush} or \hgcmd{qpop}, these commands scan the working
|
|
bos@17
|
608 directory once to make sure you haven't made some changes and then
|
|
bos@17
|
609 forgotten to run \hgcmd{qrefresh}. On a small tree, the time that
|
|
bos@17
|
610 this scan takes is unnoticeable. However, on a medium-sized tree
|
|
bos@17
|
611 (containing tens of thousands of files), it can take a second or more.
|
|
bos@17
|
612
|
|
bos@17
|
613 The \hgcmd{qpush} and \hgcmd{qpop} commands allow you to push and pop
|
|
bos@17
|
614 multiple patches at a time. You can identify the ``destination
|
|
bos@17
|
615 patch'' that you want to end up at. When you \hgcmd{qpush} with a
|
|
bos@17
|
616 destination specified, it will push patches until that patch is at the
|
|
bos@17
|
617 top of the applied stack. When you \hgcmd{qpop} to a destination, MQ
|
|
bos@17
|
618 will pop patches until the destination patch \emph{is no longer}
|
|
bos@17
|
619 applied.
|
|
bos@17
|
620
|
|
bos@17
|
621 You can identify a destination patch using either the name of the
|
|
bos@17
|
622 patch, or by number. If you use numeric addressing, patches are
|
|
bos@17
|
623 counted from zero; this means that the first patch is zero, the second
|
|
bos@17
|
624 is one, and so on.
|
|
bos@17
|
625
|
|
bos@15
|
626 \section{Updating your patches when the underlying code changes}
|
|
bos@15
|
627 \label{sec:mq:merge}
|
|
bos@15
|
628
|
|
bos@17
|
629 It's common to have a stack of patches on top of an underlying
|
|
bos@17
|
630 repository that you don't modify directly. If you're working on
|
|
bos@17
|
631 changes to third-party code, or on a feature that is taking longer to
|
|
bos@17
|
632 develop than the rate of change of the code beneath, you will often
|
|
bos@17
|
633 need to sync up with the underlying code, and fix up any hunks in your
|
|
bos@17
|
634 patches that no longer apply. This is called \emph{rebasing} your
|
|
bos@17
|
635 patch series.
|
|
bos@17
|
636
|
|
bos@17
|
637 The simplest way to do this is to \hgcmdargs{qpop}{\hgopt{qpop}{-a}}
|
|
bos@17
|
638 your patches, then \hgcmd{pull} changes into the underlying
|
|
bos@17
|
639 repository, and finally \hgcmdargs{qpush}{\hgopt{qpop}{-a}} your
|
|
bos@17
|
640 patches again. MQ will stop pushing any time it runs across a patch
|
|
bos@17
|
641 that fails to apply during conflicts, allowing you to fix your
|
|
bos@17
|
642 conflicts, \hgcmd{qrefresh} the affected patch, and continue pushing
|
|
bos@17
|
643 until you have fixed your entire stack.
|
|
bos@17
|
644
|
|
bos@17
|
645 This approach is easy to use and works well if you don't expect
|
|
bos@17
|
646 changes to the underlying code to affect how well your patches apply.
|
|
bos@17
|
647 If your patch stack touches code that is modified frequently or
|
|
bos@17
|
648 invasively in the underlying repository, however, fixing up rejected
|
|
bos@17
|
649 hunks by hand quickly becomes tiresome.
|
|
bos@17
|
650
|
|
bos@17
|
651 It's possible to partially automate the rebasing process. If your
|
|
bos@17
|
652 patches apply cleanly against some revision of the underlying repo, MQ
|
|
bos@17
|
653 can use this information to help you to resolve conflicts between your
|
|
bos@17
|
654 patches and a different revision.
|
|
bos@17
|
655
|
|
bos@17
|
656 The process is a little involved.
|
|
bos@17
|
657 \begin{enumerate}
|
|
bos@17
|
658 \item To begin, \hgcmdargs{qpush}{-a} all of your patches on top of
|
|
bos@17
|
659 the revision where you know that they apply cleanly.
|
|
bos@17
|
660 \item Save a backup copy of your patch directory using
|
|
bos@17
|
661 \hgcmdargs{qsave}{\hgopt{qsave}{-e} \hgopt{qsave}{-c}}. This prints
|
|
bos@17
|
662 the name of the directory that it has saved the patches in. It will
|
|
bos@17
|
663 save the patches to a directory called
|
|
bos@17
|
664 \sdirname{.hg/patches.\emph{N}}, where \texttt{\emph{N}} is a small
|
|
bos@17
|
665 integer. It also commits a ``save changeset'' on top of your
|
|
bos@17
|
666 applied patches; this is for internal book-keeping, and records the
|
|
bos@17
|
667 states of the \sfilename{series} and \sfilename{status} files.
|
|
bos@17
|
668 \item Use \hgcmd{pull} to bring new changes into the underlying
|
|
bos@17
|
669 repository. (Don't run \hgcmdargs{pull}{-u}; see below for why.)
|
|
bos@17
|
670 \item Update to the new tip revision, using
|
|
bos@17
|
671 \hgcmdargs{update}{\hgopt{update}{-C}} to override the patches you
|
|
bos@17
|
672 have pushed.
|
|
bos@17
|
673 \item Merge all patches using \hgcmdargs{qpush}{\hgopt{qpush}{-m}
|
|
bos@17
|
674 \hgopt{qpush}{-a}}. The \hgopt{qpush}{-m} option to \hgcmd{qpush}
|
|
bos@17
|
675 tells MQ to perform a three-way merge if the patch fails to apply.
|
|
bos@17
|
676 \end{enumerate}
|
|
bos@17
|
677
|
|
bos@17
|
678 During the \hgcmdargs{qpush}{\hgopt{qpush}{-m}}, each patch in the
|
|
bos@17
|
679 \sfilename{series} file is applied normally. If a patch applies with
|
|
bos@17
|
680 fuzz or rejects, MQ looks at the queue you \hgcmd{qsave}d, and
|
|
bos@17
|
681 performs a three-way merge with the corresponding changeset. This
|
|
bos@17
|
682 merge uses Mercurial's normal merge machinery, so it may pop up a GUI
|
|
bos@17
|
683 merge tool to help you to resolve problems.
|
|
bos@17
|
684
|
|
bos@17
|
685 When you finish resolving the effects of a patch, MQ refreshes your
|
|
bos@17
|
686 patch based on the result of the merge.
|
|
bos@17
|
687
|
|
bos@17
|
688 At the end of this process, your repository will have one extra head
|
|
bos@17
|
689 from the old patch queue, and a copy of the old patch queue will be in
|
|
bos@17
|
690 \sdirname{.hg/patches.\emph{N}}. You can remove the extra head using
|
|
bos@17
|
691 \hgcmdargs{qpop}{\hgopt{qpop}{-a} \hgopt{qpop}{-n} patches.\emph{N}}
|
|
bos@17
|
692 or \hgcmd{strip}. You can delete \sdirname{.hg/patches.\emph{N}} once
|
|
bos@17
|
693 you are sure that you no longer need it as a backup.
|
|
bos@13
|
694
|
|
bos@26
|
695 \section{Useful things to know about}
|
|
bos@26
|
696
|
|
bos@26
|
697 There are a number of aspects of MQ usage that don't fit tidily into
|
|
bos@26
|
698 sections of their own, but that are good to know. Here they are, in
|
|
bos@26
|
699 one place.
|
|
bos@26
|
700
|
|
bos@26
|
701 \begin{itemize}
|
|
bos@26
|
702 \item Normally, when you \hgcmd{qpop} a patch and \hgcmd{qpush} it
|
|
bos@26
|
703 again, the changeset that represents the patch after the pop/push
|
|
bos@26
|
704 will have a \emph{different identity} than the changeset that
|
|
bos@26
|
705 represented the hash beforehand. See section~\ref{sec:mq:cmd:qpush}
|
|
bos@26
|
706 for information as to why this is.
|
|
bos@26
|
707 \item It's not a good idea to \hgcmd{merge} changes from another
|
|
bos@26
|
708 branch with a patch changeset, at least if you want to maintain the
|
|
bos@26
|
709 ``patchiness'' of that changeset and changesets below it on the
|
|
bos@26
|
710 patch stack. If you try to do this, it will appear to succeed, but
|
|
bos@26
|
711 MQ will become confused.
|
|
bos@26
|
712 \end{itemize}
|
|
bos@16
|
713 \section{Managing patches in a repository}
|
|
bos@16
|
714
|
|
bos@16
|
715 Because MQ's \sdirname{.hg/patches} directory resides outside a
|
|
bos@16
|
716 Mercurial repository's working directory, the ``underlying'' Mercurial
|
|
bos@16
|
717 repository knows nothing about the management or presence of patches.
|
|
bos@16
|
718
|
|
bos@16
|
719 This presents the interesting possibility of managing the contents of
|
|
bos@16
|
720 the patch directory as a Mercurial repository in its own right. This
|
|
bos@16
|
721 can be a useful way to work. For example, you can work on a patch for
|
|
bos@16
|
722 a while, \hgcmd{qrefresh} it, then \hgcmd{commit} the current state of
|
|
bos@16
|
723 the patch. This lets you ``roll back'' to that version of the patch
|
|
bos@16
|
724 later on.
|
|
bos@16
|
725
|
|
bos@26
|
726 You can then share different versions of the same patch stack among
|
|
bos@26
|
727 multiple underlying repositories. I use this when I am developing a
|
|
bos@26
|
728 Linux kernel feature. I have a pristine copy of my kernel sources for
|
|
bos@26
|
729 each of several CPU architectures, and a cloned repository under each
|
|
bos@26
|
730 that contains the patches I am working on. When I want to test a
|
|
bos@26
|
731 change on a different architecture, I push my current patches to the
|
|
bos@26
|
732 patch repository associated with that kernel tree, pop and push all of
|
|
bos@26
|
733 my patches, and build and test that kernel.
|
|
bos@16
|
734
|
|
bos@16
|
735 Managing patches in a repository makes it possible for multiple
|
|
bos@16
|
736 developers to work on the same patch series without colliding with
|
|
bos@16
|
737 each other, all on top of an underlying source base that they may or
|
|
bos@16
|
738 may not control.
|
|
bos@16
|
739
|
|
bos@17
|
740 \subsection{MQ support for patch repositories}
|
|
bos@16
|
741
|
|
bos@16
|
742 MQ helps you to work with the \sdirname{.hg/patches} directory as a
|
|
bos@16
|
743 repository; when you prepare a repository for working with patches
|
|
bos@17
|
744 using \hgcmd{qinit}, you can pass the \hgopt{qinit}{-c} option to
|
|
bos@16
|
745 create the \sdirname{.hg/patches} directory as a Mercurial repository.
|
|
bos@16
|
746
|
|
bos@16
|
747 \begin{note}
|
|
bos@16
|
748 If you forget to use the \hgopt{qinit}{-c} option, you can simply go
|
|
bos@16
|
749 into the \sdirname{.hg/patches} directory at any time and run
|
|
bos@16
|
750 \hgcmd{init}. Don't forget to add an entry for the
|
|
bos@17
|
751 \sfilename{status} file to the \sfilename{.hgignore} file, though
|
|
bos@17
|
752 (\hgcmdargs{qinit}{\hgopt{qinit}{-c}} does this for you
|
|
bos@17
|
753 automatically); you \emph{really} don't want to manage the
|
|
bos@17
|
754 \sfilename{status} file.
|
|
bos@16
|
755 \end{note}
|
|
bos@16
|
756
|
|
bos@16
|
757 As a convenience, if MQ notices that the \dirname{.hg/patches}
|
|
bos@16
|
758 directory is a repository, it will automatically \hgcmd{add} every
|
|
bos@16
|
759 patch that you create and import.
|
|
bos@16
|
760
|
|
bos@16
|
761 Finally, MQ provides a shortcut command, \hgcmd{qcommit}, that runs
|
|
bos@16
|
762 \hgcmd{commit} in the \sdirname{.hg/patches} directory. This saves
|
|
bos@16
|
763 some cumbersome typing.
|
|
bos@16
|
764
|
|
bos@16
|
765 \subsection{A few things to watch out for}
|
|
bos@16
|
766
|
|
bos@16
|
767 MQ's support for working with a repository full of patches is limited
|
|
bos@16
|
768 in a few small respects.
|
|
bos@16
|
769
|
|
bos@16
|
770 MQ cannot automatically detect changes that you make to the patch
|
|
bos@16
|
771 directory. If you \hgcmd{pull}, manually edit, or \hgcmd{update}
|
|
bos@16
|
772 changes to patches or the \sfilename{series} file, you will have to
|
|
bos@17
|
773 \hgcmdargs{qpop}{\hgopt{qpop}{-a}} and then
|
|
bos@17
|
774 \hgcmdargs{qpush}{\hgopt{qpush}{-a}} in the underlying repository to
|
|
bos@17
|
775 see those changes show up there. If you forget to do this, you can
|
|
bos@17
|
776 confuse MQ's idea of which patches are applied.
|
|
bos@16
|
777
|
|
bos@26
|
778 \section{Third party tools for working with patches}
|
|
bos@19
|
779 \label{sec:mq:tools}
|
|
bos@16
|
780
|
|
bos@16
|
781 Once you've been working with patches for a while, you'll find
|
|
bos@16
|
782 yourself hungry for tools that will help you to understand and
|
|
bos@16
|
783 manipulate the patches you're dealing with.
|
|
bos@16
|
784
|
|
bos@16
|
785 The \command{diffstat} command~\cite{web:diffstat} generates a
|
|
bos@16
|
786 histogram of the modifications made to each file in a patch. It
|
|
bos@18
|
787 provides a good way to ``get a sense of'' a patch---which files it
|
|
bos@16
|
788 affects, and how much change it introduces to each file and as a
|
|
bos@16
|
789 whole. (I find that it's a good idea to use \command{diffstat}'s
|
|
bos@16
|
790 \texttt{-p} option as a matter of course, as otherwise it will try to
|
|
bos@16
|
791 do clever things with prefixes of file names that inevitably confuse
|
|
bos@16
|
792 at least me.)
|
|
bos@16
|
793
|
|
bos@19
|
794 \begin{figure}[ht]
|
|
bos@19
|
795 \interaction{mq.tools.tools}
|
|
bos@19
|
796 \caption{The \command{diffstat}, \command{filterdiff}, and \command{lsdiff} commands}
|
|
bos@19
|
797 \label{ex:mq:tools}
|
|
bos@19
|
798 \end{figure}
|
|
bos@19
|
799
|
|
bos@16
|
800 The \package{patchutils} package~\cite{web:patchutils} is invaluable.
|
|
bos@16
|
801 It provides a set of small utilities that follow the ``Unix
|
|
bos@16
|
802 philosophy;'' each does one useful thing with a patch. The
|
|
bos@16
|
803 \package{patchutils} command I use most is \command{filterdiff}, which
|
|
bos@16
|
804 extracts subsets from a patch file. For example, given a patch that
|
|
bos@16
|
805 modifies hundreds of files across dozens of directories, a single
|
|
bos@16
|
806 invocation of \command{filterdiff} can generate a smaller patch that
|
|
bos@16
|
807 only touches files whose names match a particular glob pattern.
|
|
bos@16
|
808
|
|
bos@19
|
809 \section{Good ways to work with patches}
|
|
bos@19
|
810
|
|
bos@19
|
811 Whether you are working on a patch series to submit to a free software
|
|
bos@19
|
812 or open source project, or a series that you intend to treat as a
|
|
bos@19
|
813 sequence of regular changesets when you're done, you can use some
|
|
bos@19
|
814 simple techniques to keep your work well organised.
|
|
bos@19
|
815
|
|
bos@19
|
816 Give your patches descriptive names. A good name for a patch might be
|
|
bos@19
|
817 \filename{rework-device-alloc.patch}, because it will immediately give
|
|
bos@19
|
818 you a hint what the purpose of the patch is. Long names shouldn't be
|
|
bos@19
|
819 a problem; you won't be typing the names often, but you \emph{will} be
|
|
bos@19
|
820 running commands like \hgcmd{qapplied} and \hgcmd{qtop} over and over.
|
|
bos@19
|
821 Good naming becomes especially important when you have a number of
|
|
bos@19
|
822 patches to work with, or if you are juggling a number of different
|
|
bos@19
|
823 tasks and your patches only get a fraction of your attention.
|
|
bos@19
|
824
|
|
bos@19
|
825 Be aware of what patch you're working on. Use the \hgcmd{qtop}
|
|
bos@19
|
826 command and skim over the text of your patches frequently---for
|
|
bos@19
|
827 example, using \hgcmdargs{tip}{\hgopt{tip}{-p}})---to be sure of where
|
|
bos@19
|
828 you stand. I have several times worked on and \hgcmd{qrefresh}ed a
|
|
bos@19
|
829 patch other than the one I intended, and it's often tricky to migrate
|
|
bos@19
|
830 changes into the right patch after making them in the wrong one.
|
|
bos@19
|
831
|
|
bos@19
|
832 For this reason, it is very much worth investing a little time to
|
|
bos@19
|
833 learn how to use some of the third-party tools I described in
|
|
bos@19
|
834 section~\ref{sec:mq:tools}, particularly \command{diffstat} and
|
|
bos@19
|
835 \command{filterdiff}. The former will give you a quick idea of what
|
|
bos@19
|
836 changes your patch is making, while the latter makes it easy to splice
|
|
bos@19
|
837 hunks selectively out of one patch and into another.
|
|
bos@19
|
838
|
|
bos@19
|
839 \section{MQ cookbook}
|
|
bos@19
|
840
|
|
bos@19
|
841 \subsection{Manage ``trivial'' patches}
|
|
bos@19
|
842
|
|
bos@19
|
843 Because the overhead of dropping files into a new Mercurial repository
|
|
bos@19
|
844 is so low, it makes a lot of sense to manage patches this way even if
|
|
bos@19
|
845 you simply want to make a few changes to a source tarball that you
|
|
bos@19
|
846 downloaded.
|
|
bos@19
|
847
|
|
bos@19
|
848 Begin by downloading and unpacking the source tarball,
|
|
bos@19
|
849 and turning it into a Mercurial repository.
|
|
bos@19
|
850 \interaction{mq.tarball.download}
|
|
bos@19
|
851
|
|
bos@19
|
852 Continue by creating a patch stack and making your changes.
|
|
bos@19
|
853 \interaction{mq.tarball.qinit}
|
|
bos@19
|
854
|
|
bos@19
|
855 Let's say a few weeks or months pass, and your package author releases
|
|
bos@19
|
856 a new version. First, bring their changes into the repository.
|
|
bos@19
|
857 \interaction{mq.tarball.newsource}
|
|
bos@19
|
858 The pipeline starting with \hgcmd{locate} above deletes all files in
|
|
bos@19
|
859 the working directory, so that \hgcmd{commit}'s
|
|
bos@19
|
860 \hgopt{commit}{--addremove} option can actually tell which files have
|
|
bos@19
|
861 really been removed in the newer version of the source.
|
|
bos@19
|
862
|
|
bos@19
|
863 Finally, you can apply your patches on top of the new tree.
|
|
bos@19
|
864 \interaction{mq.tarball.repush}
|
|
bos@19
|
865
|
|
bos@19
|
866 \subsection{Combining entire patches}
|
|
bos@19
|
867 \label{sec:mq:combine}
|
|
bos@19
|
868
|
|
bos@19
|
869 It's easy to combine entire patches.
|
|
bos@19
|
870
|
|
bos@19
|
871 \begin{enumerate}
|
|
bos@19
|
872 \item \hgcmd{qpop} your applied patches until neither patch is
|
|
bos@19
|
873 applied.
|
|
bos@19
|
874 \item Concatenate the patches that you want to combine together:
|
|
bos@19
|
875 \begin{codesample4}
|
|
bos@19
|
876 cat patch-to-drop.patch >> patch-to-augment.patch
|
|
bos@19
|
877 \end{codesample4}
|
|
bos@19
|
878 The description from the first patch (if you have one) will be used
|
|
bos@19
|
879 as the commit comment when you \hgcmd{qpush} the combined patch.
|
|
bos@19
|
880 Edit the patch description if you need to.
|
|
bos@19
|
881 \item Use the \hgcmd{qdel} command to delete the patch you're dropping
|
|
bos@19
|
882 from the \sfilename{series} file.
|
|
bos@19
|
883 \item \hgcmd{qpush} the combined patch. Fix up any rejects.
|
|
bos@19
|
884 \item \hgcmd{qrefresh} the combined patch to tidy it up.
|
|
bos@19
|
885 \end{enumerate}
|
|
bos@19
|
886
|
|
bos@19
|
887 \subsection{Merging part of one patch into another}
|
|
bos@19
|
888
|
|
bos@19
|
889 Merging \emph{part} of one patch into another is more difficult than
|
|
bos@19
|
890 combining entire patches.
|
|
bos@19
|
891
|
|
bos@19
|
892 If you want to move changes to entire files, you can use
|
|
bos@19
|
893 \command{filterdiff}'s \cmdopt{filterdiff}{-i} and
|
|
bos@19
|
894 \cmdopt{filterdiff}{-x} options to choose the modifications to snip
|
|
bos@19
|
895 out of one patch, concatenating its output onto the end of the patch
|
|
bos@19
|
896 you want to merge into. You usually won't need to modify the patch
|
|
bos@19
|
897 you've merged the changes from. Instead, MQ will report some rejected
|
|
bos@19
|
898 hunks when you \hgcmd{qpush} it (from the hunks you moved into the
|
|
bos@19
|
899 other patch), and you can simply \hgcmd{qrefresh} the patch to drop
|
|
bos@19
|
900 the duplicate hunks.
|
|
bos@19
|
901
|
|
bos@19
|
902 If you have a patch that has multiple hunks modifying a file, and you
|
|
bos@19
|
903 only want to move a few of those hunks, the job becomes more messy,
|
|
bos@19
|
904 but you can still partly automate it. Use \cmdargs{lsdiff}{-nvv} to
|
|
bos@19
|
905 print some metadata about the patch.
|
|
bos@19
|
906 \interaction{mq.tools.lsdiff}
|
|
bos@19
|
907
|
|
bos@19
|
908 This command prints three different kinds of number:
|
|
bos@19
|
909 \begin{itemize}
|
|
bos@26
|
910 \item (in the first column) a \emph{file number} to identify each file
|
|
bos@26
|
911 modified in the patch;
|
|
bos@26
|
912 \item (on the next line, indented) the line number within a modified
|
|
bos@26
|
913 file where a hunk starts; and
|
|
bos@26
|
914 \item (on the same line) a \emph{hunk number} to identify that hunk.
|
|
bos@19
|
915 \end{itemize}
|
|
bos@19
|
916
|
|
bos@19
|
917 You'll have to use some visual inspection, and reading of the patch,
|
|
bos@19
|
918 to identify the file and hunk numbers you'll want, but you can then
|
|
bos@19
|
919 pass them to to \command{filterdiff}'s \cmdopt{filterdiff}{--files}
|
|
bos@19
|
920 and \cmdopt{filterdiff}{--hunks} options, to select exactly the file
|
|
bos@19
|
921 and hunk you want to extract.
|
|
bos@19
|
922
|
|
bos@19
|
923 Once you have this hunk, you can concatenate it onto the end of your
|
|
bos@19
|
924 destination patch and continue with the remainder of
|
|
bos@19
|
925 section~\ref{sec:mq:combine}.
|
|
bos@26
|
926
|
|
bos@26
|
927 \section{Differences between quilt and MQ}
|
|
bos@26
|
928
|
|
bos@26
|
929 If you are already familiar with quilt, MQ provides a similar command
|
|
bos@26
|
930 set. There are a few differences in the way that it works.
|
|
bos@26
|
931
|
|
bos@26
|
932 You will already have noticed that most quilt commands have MQ
|
|
bos@26
|
933 counterparts that simply begin with a ``\texttt{q}''. The exceptions
|
|
bos@26
|
934 are quilt's \texttt{add} and \texttt{remove} commands, the
|
|
bos@26
|
935 counterparts for which are the normal Mercurial \hgcmd{add} and
|
|
bos@26
|
936 \hgcmd{remove} commands. There is no MQ equivalent of the quilt
|
|
bos@26
|
937 \texttt{edit} command.
|
|
bos@25
|
938 \section{MQ command reference}
|
|
bos@25
|
939 \label{sec:mq:cmdref}
|
|
bos@25
|
940
|
|
bos@25
|
941 For an overview of the commands provided by MQ, use the command
|
|
bos@25
|
942 \hgcmdargs{help}{mq}.
|
|
bos@25
|
943
|
|
bos@25
|
944 \subsection{\hgcmd{qapplied}---print applied patches}
|
|
bos@25
|
945
|
|
bos@25
|
946 The \hgcmd{qapplied} command prints the current stack of applied
|
|
bos@25
|
947 patches. Patches are printed in oldest-to-newest order, so the last
|
|
bos@25
|
948 patch in the list is the ``top'' patch.
|
|
bos@25
|
949
|
|
bos@25
|
950 \subsection{\hgcmd{qcommit}---commit changes in the queue repository}
|
|
bos@25
|
951
|
|
bos@25
|
952 The \hgcmd{qcommit} command commits any outstanding changes in the
|
|
bos@25
|
953 \sdirname{.hg/patches} repository. This command only works if the
|
|
bos@25
|
954 \sdirname{.hg/patches} directory is a repository, i.e.~you created the
|
|
bos@25
|
955 directory using \hgcmdargs{qinit}{\hgopt{qinit}{-c}} or ran
|
|
bos@25
|
956 \hgcmd{init} in the directory after running \hgcmd{qinit}.
|
|
bos@25
|
957
|
|
bos@25
|
958 This command is shorthand for \hgcmdargs{commit}{--cwd .hg/patches}.
|
|
bos@25
|
959
|
|
bos@25
|
960 \subsection{\hgcmd{qdelete}---delete a patch from the
|
|
bos@25
|
961 \sfilename{series} file}
|
|
bos@25
|
962
|
|
bos@25
|
963 The \hgcmd{qdelete} command removes the entry for a patch from the
|
|
bos@25
|
964 \sfilename{series} file in the \sdirname{.hg/patches} directory. It
|
|
bos@25
|
965 does not delete the patch file, nor does it pop the patch if the patch
|
|
bos@25
|
966 is already applied.
|
|
bos@25
|
967
|
|
bos@25
|
968 \subsection{\hgcmd{qdiff}---print a diff of the topmost applied patch}
|
|
bos@25
|
969
|
|
bos@25
|
970 The \hgcmd{qdiff} command prints a diff of the topmost applied patch.
|
|
bos@25
|
971 It is equivalent to \hgcmdargs{diff}{-r-2:-1}.
|
|
bos@25
|
972
|
|
bos@25
|
973 \subsection{\hgcmd{qimport}---import a third-party patch into the queue}
|
|
bos@25
|
974
|
|
bos@25
|
975 The \hgcmd{qimport} command adds an entry for an external patch to the
|
|
bos@25
|
976 \sfilename{series} file, and copies the patch into the
|
|
bos@25
|
977 \sdirname{.hg/patches} directory. It adds the entry immediately after
|
|
bos@25
|
978 the topmost applied patch, but does not push the patch.
|
|
bos@25
|
979
|
|
bos@25
|
980 If the \sdirname{.hg/patches} directory is a repository,
|
|
bos@25
|
981 \hgcmd{qimport} automatically does an \hgcmd{add} of the imported
|
|
bos@25
|
982 patch.
|
|
bos@25
|
983
|
|
bos@25
|
984 \subsection{\hgcmd{qinit}---prepare a repository to work with MQ}
|
|
bos@25
|
985
|
|
bos@25
|
986 The \hgcmd{qinit} command prepares a repository to work with MQ. It
|
|
bos@25
|
987 creates a directory called \sdirname{.hg/patches}.
|
|
bos@25
|
988
|
|
bos@25
|
989 Options:
|
|
bos@25
|
990 \begin{itemize}
|
|
bos@25
|
991 \item[\hgopt{qinit}{-c}] Create \sdirname{.hg/patches} as a repository
|
|
bos@25
|
992 in its own right. Also creates a \sfilename{.hgignore} file that
|
|
bos@25
|
993 will ignore the \sfilename{status} file.
|
|
bos@25
|
994 \end{itemize}
|
|
bos@25
|
995
|
|
bos@25
|
996 When the \sdirname{.hg/patches} directory is a repository, the
|
|
bos@25
|
997 \hgcmd{qimport} and \hgcmd{qnew} commands automatically \hgcmd{add}
|
|
bos@25
|
998 new patches.
|
|
bos@25
|
999
|
|
bos@25
|
1000 \subsection{\hgcmd{qnew}---create a new patch}
|
|
bos@25
|
1001
|
|
bos@25
|
1002 The \hgcmd{qnew} command creates a new patch. It takes one mandatory
|
|
bos@25
|
1003 argument, the name to use for the patch file. The newly created patch
|
|
bos@25
|
1004 is created empty by default. It is added to the \sfilename{series}
|
|
bos@25
|
1005 file after the current topmost applied patch, and is immediately
|
|
bos@25
|
1006 pushed on top of that patch.
|
|
bos@25
|
1007
|
|
bos@25
|
1008 If \hgcmd{qnew} finds modified files in the working directory, it will
|
|
bos@25
|
1009 refuse to create a new patch unless the \hgopt{qnew}{-f} option is
|
|
bos@25
|
1010 used (see below). This behaviour allows you to \hgcmd{qrefresh} your
|
|
bos@25
|
1011 topmost applied patch before you apply a new patch on top of it.
|
|
bos@25
|
1012
|
|
bos@25
|
1013 Options:
|
|
bos@25
|
1014 \begin{itemize}
|
|
bos@25
|
1015 \item[\hgopt{qnew}{-f}] Create a new patch if the contents of the
|
|
bos@25
|
1016 working directory are modified. Any outstanding modifications are
|
|
bos@25
|
1017 added to the newly created patch, so after this command completes,
|
|
bos@25
|
1018 the working directory will no longer be modified.
|
|
bos@25
|
1019 \item[\hgopt{qnew}{-m}] Use the given text as the commit message.
|
|
bos@25
|
1020 This text will be stored at the beginning of the patch file, before
|
|
bos@25
|
1021 the patch data.
|
|
bos@25
|
1022 \end{itemize}
|
|
bos@25
|
1023
|
|
bos@25
|
1024 \subsection{\hgcmd{qnext}---print the name of the next patch}
|
|
bos@25
|
1025
|
|
bos@25
|
1026 The \hgcmd{qnext} command prints the name name of the next patch in
|
|
bos@25
|
1027 the \sfilename{series} file after the topmost applied patch. This
|
|
bos@25
|
1028 patch will become the topmost applied patch if you run \hgcmd{qpush}.
|
|
bos@25
|
1029
|
|
bos@25
|
1030 \subsection{\hgcmd{qpop}---pop patches off the stack}
|
|
bos@25
|
1031
|
|
bos@25
|
1032 The \hgcmd{qpop} command removes applied patches from the top of the
|
|
bos@25
|
1033 stack of applied patches. By default, it removes only one patch.
|
|
bos@25
|
1034
|
|
bos@25
|
1035 This command removes the changesets that represent the popped patches
|
|
bos@25
|
1036 from the repository, and updates the working directory to undo the
|
|
bos@25
|
1037 effects of the patches.
|
|
bos@25
|
1038
|
|
bos@25
|
1039 This command takes an optional argument, which it uses as the name or
|
|
bos@25
|
1040 index of the patch to pop to. If given a name, it will pop patches
|
|
bos@25
|
1041 until the named patch is no longer applied. If given a number,
|
|
bos@25
|
1042 \hgcmd{qpop} treats the number as an index into the entries in the
|
|
bos@25
|
1043 series file, counting from zero (empty lines and lines containing only
|
|
bos@25
|
1044 comments do not count). It pops patches until the patch identified by
|
|
bos@25
|
1045 the given index is no longer applied.
|
|
bos@25
|
1046
|
|
bos@25
|
1047 The \hgcmd{qpop} command does not read or write patches or the
|
|
bos@25
|
1048 \sfilename{series} file. It is thus safe to \hgcmd{qpop} a patch that
|
|
bos@25
|
1049 you have removed from the \sfilename{series} file, or a patch that you
|
|
bos@25
|
1050 have renamed or deleted entirely. In the latter two cases, use the
|
|
bos@25
|
1051 name of the patch as it was when you applied it.
|
|
bos@25
|
1052
|
|
bos@25
|
1053 By default, the \hgcmd{qpop} command will not pop any patches if the
|
|
bos@25
|
1054 working directory has been modified. You can override this behaviour
|
|
bos@25
|
1055 using the \hgopt{qpop}{-f} option, which reverts all modifications in
|
|
bos@25
|
1056 the working directory.
|
|
bos@25
|
1057
|
|
bos@25
|
1058 Options:
|
|
bos@25
|
1059 \begin{itemize}
|
|
bos@25
|
1060 \item[\hgopt{qpop}{-a}] Pop all applied patches. This returns the
|
|
bos@25
|
1061 repository to its state before you applied any patches.
|
|
bos@25
|
1062 \item[\hgopt{qpop}{-f}] Forcibly revert any modifications to the
|
|
bos@25
|
1063 working directory when popping.
|
|
bos@25
|
1064 \item[\hgopt{qpop}{-n}] Pop a patch from the named queue.
|
|
bos@25
|
1065 \end{itemize}
|
|
bos@25
|
1066
|
|
bos@25
|
1067 The \hgcmd{qpop} command removes one line from the end of the
|
|
bos@25
|
1068 \sfilename{status} file for each patch that it pops.
|
|
bos@25
|
1069 \subsection{\hgcmd{qprev}---print the name of the previous patch}
|
|
bos@25
|
1070
|
|
bos@25
|
1071 The \hgcmd{qprev} command prints the name of the patch in the
|
|
bos@25
|
1072 \sfilename{series} file that comes before the topmost applied patch.
|
|
bos@25
|
1073 This will become the topmost applied patch if you run \hgcmd{qpop}.
|
|
bos@25
|
1074
|
|
bos@25
|
1075 \subsection{\hgcmd{qpush}---push patches onto the stack}
|
|
bos@26
|
1076 \label{sec:mq:cmd:qpush}
|
|
bos@25
|
1077
|
|
bos@25
|
1078 The \hgcmd{qpush} command adds patches onto the applied stack. By
|
|
bos@25
|
1079 default, it adds only one patch.
|
|
bos@25
|
1080
|
|
bos@25
|
1081 This command creates a new changeset to represent each applied patch,
|
|
bos@25
|
1082 and updates the working directory to apply the effects of the patches.
|
|
bos@25
|
1083
|
|
bos@26
|
1084 The default data used when creating a changeset are as follows:
|
|
bos@25
|
1085 \begin{itemize}
|
|
bos@25
|
1086 \item The commit date and time zone are the current date and time
|
|
bos@25
|
1087 zone. Because these data are used to compute the identity of a
|
|
bos@25
|
1088 changeset, this means that if you \hgcmd{qpop} a patch and
|
|
bos@25
|
1089 \hgcmd{qpush} it again, the changeset that you push will have a
|
|
bos@25
|
1090 different identity than the changeset you popped.
|
|
bos@25
|
1091 \item The author is the same as the default used by the \hgcmd{commit}
|
|
bos@25
|
1092 command.
|
|
bos@25
|
1093 \item The commit message is any text from the patch file that comes
|
|
bos@25
|
1094 before the first diff header. If there is no such text, a default
|
|
bos@25
|
1095 commit message is used that identifies the name of the patch.
|
|
bos@25
|
1096 \end{itemize}
|
|
bos@26
|
1097 If a patch contains a Mercurial patch header (XXX add link), the
|
|
bos@26
|
1098 information in the patch header overrides these defaults.
|
|
bos@25
|
1099
|
|
bos@25
|
1100 Options:
|
|
bos@25
|
1101 \begin{itemize}
|
|
bos@25
|
1102 \item[\hgopt{qpush}{-a}] Push all unapplied patches from the
|
|
bos@25
|
1103 \sfilename{series} file until there are none left to push.
|
|
bos@25
|
1104 \item[\hgopt{qpush}{-l}] Add the name of the patch to the end
|
|
bos@25
|
1105 of the commit message.
|
|
bos@25
|
1106 \item[\hgopt{qpush}{-m}] If a patch fails to apply cleanly, use the
|
|
bos@25
|
1107 entry for the patch in another saved queue to compute the parameters
|
|
bos@25
|
1108 for a three-way merge, and perform a three-way merge using the
|
|
bos@25
|
1109 normal Mercurial merge machinery. Use the resolution of the merge
|
|
bos@25
|
1110 as the new patch content.
|
|
bos@25
|
1111 \item[\hgopt{qpush}{-n}] Use the named queue if merging while pushing.
|
|
bos@25
|
1112 \end{itemize}
|
|
bos@25
|
1113
|
|
bos@25
|
1114 The \hgcmd{qpush} command reads, but does not modify, the
|
|
bos@25
|
1115 \sfilename{series} file. It appends one line to the \hgcmd{status}
|
|
bos@25
|
1116 file for each patch that it pushes.
|
|
bos@25
|
1117
|
|
bos@25
|
1118 \subsection{\hgcmd{qrefresh}---update the topmost applied patch}
|
|
bos@25
|
1119
|
|
bos@25
|
1120 The \hgcmd{qrefresh} command updates the topmost applied patch. It
|
|
bos@25
|
1121 modifies the patch, removes the old changeset that represented the
|
|
bos@25
|
1122 patch, and creates a new changeset to represent the modified patch.
|
|
bos@25
|
1123
|
|
bos@25
|
1124 The \hgcmd{qrefresh} command looks for the following modifications:
|
|
bos@25
|
1125 \begin{itemize}
|
|
bos@25
|
1126 \item Changes to the commit message, i.e.~the text before the first
|
|
bos@25
|
1127 diff header in the patch file, are reflected in the new changeset
|
|
bos@25
|
1128 that represents the patch.
|
|
bos@25
|
1129 \item Modifications to tracked files in the working directory are
|
|
bos@25
|
1130 added to the patch.
|
|
bos@25
|
1131 \item Changes to the files tracked using \hgcmd{add}, \hgcmd{copy},
|
|
bos@25
|
1132 \hgcmd{remove}, or \hgcmd{rename}. Added files and copy and rename
|
|
bos@25
|
1133 destinations are added to the patch, while removed files and rename
|
|
bos@25
|
1134 sources are removed.
|
|
bos@25
|
1135 \end{itemize}
|
|
bos@25
|
1136
|
|
bos@25
|
1137 Even if \hgcmd{qrefresh} detects no changes, it still recreates the
|
|
bos@25
|
1138 changeset that represents the patch. This causes the identity of the
|
|
bos@25
|
1139 changeset to differ from the previous changeset that identified the
|
|
bos@25
|
1140 patch.
|
|
bos@25
|
1141
|
|
bos@26
|
1142 \subsection{\hgcmd{qrestore}---restore saved queue state}
|
|
bos@26
|
1143
|
|
bos@26
|
1144 XXX No idea what this does.
|
|
bos@26
|
1145
|
|
bos@26
|
1146 \subsection{\hgcmd{qsave}---save current queue state}
|
|
bos@26
|
1147
|
|
bos@26
|
1148 XXX Likewise.
|
|
bos@26
|
1149
|
|
bos@26
|
1150 \subsection{\hgcmd{qseries}---print the entire patch series}
|
|
bos@26
|
1151
|
|
bos@26
|
1152 The \hgcmd{qseries} command prints the entire patch series from the
|
|
bos@26
|
1153 \sfilename{series} file. It prints only patch names, not empty lines
|
|
bos@26
|
1154 or comments. It prints in order from first to be applied to last.
|
|
bos@26
|
1155
|
|
bos@26
|
1156 \subsection{\hgcmd{qtop}---print the name of the current patch}
|
|
bos@26
|
1157
|
|
bos@26
|
1158 The \hgcmd{qtop} prints the name of the topmost currently applied
|
|
bos@26
|
1159 patch.
|
|
bos@26
|
1160
|
|
bos@26
|
1161 \subsection{\hgcmd{qunapplied}---print patches not yet applied}
|
|
bos@26
|
1162
|
|
bos@26
|
1163 The \hgcmd{qunapplied} command prints the names of patches from the
|
|
bos@26
|
1164 \sfilename{series} file that are not yet applied. It prints them in
|
|
bos@26
|
1165 order from the next patch that will be pushed to the last.
|
|
bos@26
|
1166
|
|
bos@26
|
1167 \subsection{\hgcmd{qversion}}
|
|
bos@26
|
1168
|
|
bos@26
|
1169 The \hgcmd{qversion} command prints the version of MQ that is in use.
|
|
bos@26
|
1170
|
|
bos@26
|
1171 \subsection{\hgcmd{strip}---remove a revision and descendants}
|
|
bos@26
|
1172
|
|
bos@26
|
1173 The \hgcmd{strip} command removes a revision, and all of its
|
|
bos@26
|
1174 descendants, from the repository. It undoes the effects of the
|
|
bos@26
|
1175 removed revisions from the repository, and updates the working
|
|
bos@26
|
1176 directory to the first parent of the removed revision.
|
|
bos@26
|
1177
|
|
bos@26
|
1178 The \hgcmd{strip} command saves a backup of the removed changesets in
|
|
bos@26
|
1179 a bundle, so that they can be reapplied if removed in error.
|
|
bos@26
|
1180
|
|
bos@26
|
1181 Options:
|
|
bos@26
|
1182 \begin{itemize}
|
|
bos@26
|
1183 \item[\hgopt{strip}{-b}] Save unrelated changesets that are intermixed
|
|
bos@26
|
1184 with the stripped changesets in the backup bundle.
|
|
bos@26
|
1185 \item[\hgopt{strip}{-f}] If a branch has multiple heads, remove all
|
|
bos@26
|
1186 heads. XXX This should be renamed, and use \texttt{-f} to strip revs
|
|
bos@26
|
1187 when there are pending changes.
|
|
bos@26
|
1188 \item[\hgopt{strip}{-n}] Do not save a backup bundle.
|
|
bos@26
|
1189 \end{itemize}
|
|
bos@25
|
1190 \section{MQ file reference}
|
|
bos@25
|
1191
|
|
bos@25
|
1192
|
|
bos@25
|
1193 \subsection{The \sfilename{series} file}
|
|
bos@25
|
1194
|
|
bos@26
|
1195 The \sfilename{series} file contains a list of the names of all
|
|
bos@26
|
1196 patches that MQ can apply. It is represented as a list of names, with
|
|
bos@26
|
1197 one name saved per line. Leading and trailing white space in each
|
|
bos@26
|
1198 line are ignored.
|
|
bos@26
|
1199
|
|
bos@26
|
1200 Lines may contain comments. A comment begins with the ``\texttt{\#}''
|
|
bos@26
|
1201 character, and extends to the end of the line. Empty lines, and lines
|
|
bos@26
|
1202 that contain only comments, are ignored.
|
|
bos@26
|
1203
|
|
bos@26
|
1204 You will often need to edit the \sfilename{series} file by hand, hence
|
|
bos@26
|
1205 the support for comments and empty lines noted above. For example,
|
|
bos@26
|
1206 you can comment out a patch temporarily, and \hgcmd{qpush} will skip
|
|
bos@26
|
1207 over that patch when applying patches. You can also change the order
|
|
bos@26
|
1208 in which patches are applied by reordering their entries in the
|
|
bos@26
|
1209 \sfilename{series} file.
|
|
bos@26
|
1210
|
|
bos@26
|
1211 Placing the \sfilename{series} file under revision control is also
|
|
bos@26
|
1212 supported; it is a good idea to place all of the patches that it
|
|
bos@26
|
1213 refers to under revision control, as well. If you create a patch
|
|
bos@26
|
1214 directory using the \hgopt{qinit}{-c} option to \hgcmd{qinit}, this
|
|
bos@26
|
1215 will be done for you automatically.
|
|
bos@25
|
1216 \subsection{The \sfilename{status} file}
|
|
bos@25
|
1217
|
|
bos@26
|
1218 The \sfilename{status} file contains the names and changeset hashes of
|
|
bos@26
|
1219 all patches that MQ currently has applied. Unlike the
|
|
bos@26
|
1220 \sfilename{series} file, this file is not intended for editing. You
|
|
bos@26
|
1221 should not place this file under revision control, or modify it in any
|
|
bos@26
|
1222 way. It is used by MQ strictly for internal book-keeping.
|
|
bos@19
|
1223
|
|
bos@1
|
1224 %%% Local Variables:
|
|
bos@1
|
1225 %%% mode: latex
|
|
bos@1
|
1226 %%% TeX-master: "00book"
|
|
bos@1
|
1227 %%% End:
|
