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1 \chapter{Handling repository events with hooks}
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2 \label{chap:hook}
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3
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4 Mercurial offers a powerful mechanism to let you perform automated
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5 actions in response to events that occur in a repository. In some
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6 cases, you can even control Mercurial's response to those events.
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7
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8 The name Mercurial uses for one of these actions is a \emph{hook}.
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9 Hooks are called ``triggers'' in some revision control systems, but
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10 the two names refer to the same idea.
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11
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12 \section{An overview of hooks in Mercurial}
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13
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14 Here is a brief list of the hooks that Mercurial supports. We will
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15 revisit each of these hooks in more detail later, in
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16 section~\ref{sec:hook:ref}.
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17
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18 \begin{itemize}
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19 \item[\small\hook{changegroup}] This is run after a group of
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20 changesets has been brought into the repository from elsewhere.
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21 \item[\small\hook{commit}] This is run after a new changeset has been
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22 created in the local repository.
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23 \item[\small\hook{incoming}] This is run once for each new changeset
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24 that is brought into the repository from elsewhere. Notice the
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25 difference from \hook{changegroup}, which is run once per
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26 \emph{group} of changesets brought in.
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27 \item[\small\hook{outgoing}] This is run after a group of changesets
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28 has been transmitted from this repository.
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29 \item[\small\hook{prechangegroup}] This is run before starting to
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30 bring a group of changesets into the repository.
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31 \item[\small\hook{precommit}] Controlling. This is run before starting
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32 a commit.
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33 \item[\small\hook{preoutgoing}] Controlling. This is run before
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34 starting to transmit a group of changesets from this repository.
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35 \item[\small\hook{pretag}] Controlling. This is run before creating a tag.
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36 \item[\small\hook{pretxnchangegroup}] Controlling. This is run after a
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37 group of changesets has been brought into the local repository from
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38 another, but before the transaction completes that will make the
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39 changes permanent in the repository.
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40 \item[\small\hook{pretxncommit}] Controlling. This is run after a new
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41 changeset has been created in the local repository, but before the
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42 transaction completes that will make it permanent.
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43 \item[\small\hook{preupdate}] Controlling. This is run before starting
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44 an update or merge of the working directory.
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45 \item[\small\hook{tag}] This is run after a tag is created.
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46 \item[\small\hook{update}] This is run after an update or merge of the
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47 working directory has finished.
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48 \end{itemize}
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49 Each of the hooks whose description begins with the word
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50 ``Controlling'' has the ability to determine whether an activity can
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51 proceed. If the hook succeeds, the activity may proceed; if it fails,
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52 the activity is either not permitted or undone, depending on the hook.
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53
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54 \section{Hooks and security}
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55
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56 \subsection{Hooks are run with your privileges}
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57
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58 When you run a Mercurial command in a repository, and the command
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59 causes a hook to run, that hook runs on \emph{your} system, under
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60 \emph{your} user account, with \emph{your} privilege level. Since
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61 hooks are arbitrary pieces of executable code, you should treat them
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62 with an appropriate level of suspicion. Do not install a hook unless
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63 you are confident that you know who created it and what it does.
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64
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65 In some cases, you may be exposed to hooks that you did not install
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66 yourself. If you work with Mercurial on an unfamiliar system,
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67 Mercurial will run hooks defined in that system's global \hgrc\ file.
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68
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69 If you are working with a repository owned by another user, Mercurial
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70 can run hooks defined in that user's repository, but it will still run
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71 them as ``you''. For example, if you \hgcmd{pull} from that
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72 repository, and its \sfilename{.hg/hgrc} defines a local
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73 \hook{outgoing} hook, that hook will run under your user account, even
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74 though you don't own that repository.
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75
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76 \begin{note}
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77 This only applies if you are pulling from a repository on a local or
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78 network filesystem. If you're pulling over http or ssh, any
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79 \hook{outgoing} hook will run under whatever account is executing
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80 the server process, on the server.
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81 \end{note}
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82
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83 XXX To see what hooks are defined in a repository, use the
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84 \hgcmdargs{config}{hooks} command. If you are working in one
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85 repository, but talking to another that you do not own (e.g.~using
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86 \hgcmd{pull} or \hgcmd{incoming}), remember that it is the other
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87 repository's hooks you should be checking, not your own.
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88
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89 \subsection{Hooks do not propagate}
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90
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91 In Mercurial, hooks are not revision controlled, and do not propagate
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92 when you clone, or pull from, a repository. The reason for this is
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93 simple: a hook is a completely arbitrary piece of executable code. It
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94 runs under your user identity, with your privilege level, on your
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95 machine.
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96
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97 It would be extremely reckless for any distributed revision control
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98 system to implement revision-controlled hooks, as this would offer an
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99 easily exploitable way to subvert the accounts of users of the
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100 revision control system.
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101
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102 Since Mercurial does not propagate hooks, if you are collaborating
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103 with other people on a common project, you should not assume that they
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104 are using the same Mercurial hooks as you are, or that theirs are
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105 correctly configured. You should document the hooks you expect people
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106 to use.
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107
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108 In a corporate intranet, this is somewhat easier to control, as you
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109 can for example provide a ``standard'' installation of Mercurial on an
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110 NFS filesystem, and use a site-wide \hgrc\ file to define hooks that
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111 all users will see. However, this too has its limits; see below.
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112
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113 \subsection{Hooks can be overridden}
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114
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115 Mercurial allows you to override a hook definition by redefining the
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116 hook. You can disable it by setting its value to the empty string, or
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117 change its behaviour as you wish.
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118
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119 If you deploy a system-~or site-wide \hgrc\ file that defines some
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120 hooks, you should thus understand that your users can disable or
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121 override those hooks.
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122
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123 \subsection{Ensuring that critical hooks are run}
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124
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125 Sometimes you may want to enforce a policy that you do not want others
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126 to be able to work around. For example, you may have a requirement
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127 that every changeset must pass a rigorous set of tests. Defining this
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128 requirement via a hook in a site-wide \hgrc\ won't work for remote
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129 users on laptops, and of course local users can subvert it at will by
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130 overriding the hook.
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131
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132 Instead, you can set up your policies for use of Mercurial so that
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133 people are expected to propagate changes through a well-known
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134 ``canonical'' server that you have locked down and configured
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135 appropriately.
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136
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137 One way to do this is via a combination of social engineering and
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138 technology. Set up a restricted-access account; users can push
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139 changes over the network to repositories managed by this account, but
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140 they cannot log into the account and run normal shell commands. In
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141 this scenario, a user can commit a changeset that contains any old
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142 garbage they want.
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143
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144 When someone pushes a changeset to the server that everyone pulls
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145 from, the server will test the changeset before it accepts it as
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146 permanent, and reject it if it fails to pass the test suite. If
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147 people only pull changes from this filtering server, it will serve to
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148 ensure that all changes that people pull have been automatically
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149 vetted.
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150
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151 \section{Using hooks with shared access to a repository}
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152
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153 If you want to use hooks to so some automated work in a repository
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154 that a number of people have ahred access to, you need to be careful
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155 in how you do this.
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156
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157 Mercurial only locks a repository when it is writing to the
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158 repository, and only the parts of Mercurial that write to the
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159 repository pay attention to locks. Write locks are necessary to
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160 prevent multiple simultaneous writers from scribbling on each other's
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161 work, corrupting the repository.
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162
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163 Because Mercurial is careful with the order in which it reads and
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164 writes data, it does not need to acquire a lock when it wants to read
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165 data from the repository. The parts of Mercurial that read from the
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166 repository never pay attention to locks. This lockless reading scheme
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167 greatly increases performance and concurrency.
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168
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169 With great performance comes a trade-off, though, one which has the
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170 potential to cause you trouble unless you're aware of it. To describe
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171 this requires a little detail about how Mercurial adds changesets to a
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172 repository and reads those changes.
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173
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174 When Mercurial \emph{writes} metadata, it writes it straight into the
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175 destination file. It writes file data first, then manifest data
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176 (which contains pointers to the new file data), then changelog data
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177 (which contains pointers to the new manifest data). Before the first
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178 write to each file, it stores a record of where the end of the file
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179 was in its transaction log. If the transaction must be rolled back,
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180 Mercurial simply truncates each file back to te size it was before the
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181 transaction began.
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182
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183 When Mercurial \emph{reads} metadata, it reads the changelog first,
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184 then everything else. Since a reader will only access parts of the
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185 manifest or file metadata that it can see in the changelog, it can
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186 never see partially written data.
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187
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188 Some controlling hooks (\hook{pretxncommit} and
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189 \hook{pretxnchangegroup}) run when a transaction is almost complete.
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190 All of the metadata has been written, but Mercurial can still roll the
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191 transaction back and cause the newly-written data to disappear.
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192
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193 If one of these hooks runs for long, it opens a window in which a
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194 reader can see the metadata for changesets that are, strictly
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195 speaking, not yet permanent. The longer the hook runs, the bigger the
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196 window.
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197
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198 A good use for the \hook{pretxnchangegroup} hook would be to
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199 automatically build and test incoming changes before they are accepted
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200 into the repository, so that you can guarantee that nobody can push
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201 changes to this repository that ``break the build''. But if a client
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202 can pull changes while they're being tested, the usefulness of the
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203 test is zero; someone can pull untested changes.
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204
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205 The safest answer to this challenge is to set up such a ``gatekeeper''
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206 repository as \emph{unidirectional}. It can take changes pushed in
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207 from the outside, but nobody can pull changes from it. Use the
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208 \hook{preoutgoing} hook to lock it down. Configure a
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209 \hook{changegroup} hook so that if a build or test succeeds, the hook
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210 will push the new changes out to another repository that people
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211 \emph{can} pull from.
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212
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213 \section{A short tutorial on using hooks}
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214 \label{sec:hook:simple}
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215
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216 It is easy to write a Mercurial hook. Let's start with a hook that
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217 runs when you finish a \hgcmd{commit}, and simply prints the hash of
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218 the changeset you just created. The hook is called \hook{commit}.
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219
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220 \begin{figure}[ht]
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221 \interaction{hook.simple.init}
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222 \caption{A simple hook that runs when a changeset is committed}
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223 \label{ex:hook:init}
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224 \end{figure}
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225
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226 All hooks follow the pattern in example~\ref{ex:hook:init}. You add
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227 an entry to the \rcsection{hooks} section of your \hgrc\. On the left
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228 is the name of the event to trigger on; on the right is the action to
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229 take. As you can see, you can run an arbitrary shell command in a
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230 hook. Mercurial passes extra information to the hook using
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231 environment variables (look for \envar{HG\_NODE} in the example).
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232
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233 \subsection{Performing multiple actions per event}
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234
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235 Quite often, you will want to define more than one hook for a
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236 particular kind of event, as shown in example~\ref{ex:hook:ext}.
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237 Mercurial lets you do this by adding an \emph{extension} to the end of
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238 a hook's name. You extend a hook's name by giving the name of the
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239 hook, followed by a full stop (the ``\texttt{.}'' character), followed
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240 by some more text of your choosing. For example, Mercurial will run
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241 both \texttt{commit.foo} and \texttt{commit.bar} when the
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242 \texttt{commit} event occurs.
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243
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244 \begin{figure}[ht]
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245 \interaction{hook.simple.ext}
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246 \caption{Defining a second \hook{commit} hook}
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247 \label{ex:hook:ext}
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248 \end{figure}
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249
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250 To give a well-defined order of execution when there are multiple
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251 hooks defined for an event, Mercurial sorts hooks by extension, and
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252 executes the hook commands in this sorted order. In the above
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253 example, it will execute \texttt{commit.bar} before
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254 \texttt{commit.foo}, and \texttt{commit} before both.
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255
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256 It is a good idea to use a somewhat descriptive extension when you
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257 define a new hook. This will help you to remember what the hook was
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258 for. If the hook fails, you'll get an error message that contains the
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259 hook name and extension, so using a descriptive extension could give
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260 you an immediate hint as to why the hook failed (see
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261 section~\ref{sec:hook:perm} for an example).
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262
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263 \subsection{Controlling whether an activity can proceed}
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264 \label{sec:hook:perm}
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265
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266 In our earlier examples, we used the \hook{commit} hook, which is
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267 run after a commit has completed. This is one of several Mercurial
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268 hooks that run after an activity finishes. Such hooks have no way of
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269 influencing the activity itself.
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270
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271 Mercurial defines a number of events that occur before an activity
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272 starts; or after it starts, but before it finishes. Hooks that
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273 trigger on these events have the added ability to choose whether the
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274 activity can continue, or will abort.
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275
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276 The \hook{pretxncommit} hook runs after a commit has all but
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277 completed. In other words, the metadata representing the changeset
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278 has been written out to disk, but the transaction has not yet been
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279 allowed to complete. The \hook{pretxncommit} hook has the ability to
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280 decide whether the transaction can complete, or must be rolled back.
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281
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282 If the \hook{pretxncommit} hook exits with a status code of zero, the
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283 transaction is allowed to complete; the commit finishes; and the
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284 \hook{commit} hook is run. If the \hook{pretxncommit} hook exits with
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285 a non-zero status code, the transaction is rolled back; the metadata
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286 representing the changeset is erased; and the \hook{commit} hook is
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287 not run.
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288
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289 \begin{figure}[ht]
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290 \interaction{hook.simple.pretxncommit}
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291 \caption{Using the \hook{pretxncommit} hook to control commits}
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292 \label{ex:hook:pretxncommit}
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293 \end{figure}
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294
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295 The hook in example~\ref{ex:hook:pretxncommit} checks that a commit
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296 comment contains a bug ID. If it does, the commit can complete. If
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297 not, the commit is rolled back.
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298
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299 \section{Writing your own hooks}
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300
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301 When you are writing a hook, you might find it useful to run Mercurial
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302 either with the \hggopt{-v} option, or the \rcitem{ui}{verbose} config
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303 item set to ``true''. When you do so, Mercurial will print a message
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304 before it calls each hook.
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305
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306 \subsection{Choosing how your hook should run}
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307 \label{sec:hook:lang}
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308
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309 You can write a hook either as a normal program---typically a shell
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310 script---or as a Python function that is executed within the Mercurial
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311 process.
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312
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313 Writing a hook as an external program has the advantage that it
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314 requires no knowledge of Mercurial's internals. You can call normal
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315 Mercurial commands to get any added information you need. The
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316 trade-off is that external hooks are slower than in-process hooks.
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317
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318 An in-process Python hook has complete access to the Mercurial API,
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319 and does not ``shell out'' to another process, so it is inherently
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320 faster than an external hook. It is also easier to obtain much of the
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321 information that a hook requires by using the Mercurial API than by
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322 running Mercurial commands.
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323
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324 If you are comfortable with Python, or require high performance,
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325 writing your hooks in Python may be a good choice. However, when you
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326 have a straightforward hook to write and you don't need to care about
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327 performance (probably the majority of hooks), a shell script is
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328 perfectly fine.
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329
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330 \subsection{Hook parameters}
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331 \label{sec:hook:param}
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332
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333 Mercurial calls each hook with a set of well-defined parameters. In
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334 Python, a parameter is passed as a keyword argument to your hook
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335 function. For an external program, a parameter is passed as an
|
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336 environment variable.
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337
|
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338 Whether your hook is written in Python or as a shell script, the
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339 hook-specific parameter names and values will be the same. A boolean
|
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340 parameter will be represented as a boolean value in Python, but as the
|
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341 number 1 (for ``true'') or 0 (for ``false'') as an environment
|
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342 variable for an external hook. If a hook parameter is named
|
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343 \texttt{foo}, the keyword argument for a Python hook will also be
|
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344 named \texttt{foo} Python, while the environment variable for an
|
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345 external hook will be named \texttt{HG\_FOO}.
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346
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347 \subsection{Hook return values and activity control}
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348
|
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349 A hook that executes successfully must exit with a status of zero if
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350 external, or return boolean ``false'' if in-process. Failure is
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351 indicated with a non-zero exit status from an external hook, or an
|
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352 in-process hook returning boolean ``true''. If an in-process hook
|
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353 raises an exception, the hook is considered to have failed.
|
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354
|
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355 For a hook that controls whether an activity can proceed, zero/false
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356 means ``allow'', while non-zero/true/exception means ``deny''.
|
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357
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358 \subsection{Writing an external hook}
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359
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360 When you define an external hook in your \hgrc\ and the hook is run,
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361 its value is passed to your shell, which interprets it. This means
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362 that you can use normal shell constructs in the body of the hook.
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363
|
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364 An executable hook is always run with its current directory set to a
|
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365 repository's root directory.
|
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366
|
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367 Each hook parameter is passed in as an environment variable; the name
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368 is upper-cased, and prefixed with the string ``\texttt{HG\_}''.
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369
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370 With the exception of hook parameters, Mercurial does not set or
|
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371 modify any environment variables when running a hook. This is useful
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372 to remember if you are writing a site-wide hook that may be run by a
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373 number of different users with differing environment variables set.
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374 In multi-user situations, you should not rely on environment variables
|
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375 being set to the values you have in your environment when testing the
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376 hook.
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377
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378 \subsection{Telling Mercurial to use an in-process hook}
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379
|
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380 The \hgrc\ syntax for defining an in-process hook is slightly
|
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381 different than for an executable hook. The value of the hook must
|
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382 start with the text ``\texttt{python:}'', and continue with the
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383 fully-qualified name of a callable object to use as the hook's value.
|
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384
|
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385 The module in which a hook lives is automatically imported when a hook
|
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386 is run. So long as you have the module name and \envar{PYTHONPATH}
|
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387 right, it should ``just work''.
|
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388
|
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389 The following \hgrc\ example snippet illustrates the syntax and
|
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|
390 meaning of the notions we just described.
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391 \begin{codesample2}
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392 [hooks]
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393 commit.example = python:mymodule.submodule.myhook
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394 \end{codesample2}
|
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395 When Mercurial runs the \texttt{commit.example} hook, it imports
|
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|
396 \texttt{mymodule.submodule}, looks for the callable object named
|
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397 \texttt{myhook}, and calls it.
|
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398
|
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399 \subsection{Writing an in-process hook}
|
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|
400
|
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401 The simplest in-process hook does nothing, but illustrates the basic
|
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|
402 shape of the hook API:
|
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403 \begin{codesample2}
|
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|
404 def myhook(ui, repo, **kwargs):
|
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|
405 pass
|
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406 \end{codesample2}
|
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407 The first argument to a Python hook is always a
|
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|
408 \pymodclass{mercurial.ui}{ui} object. The second is a repository object;
|
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|
409 at the moment, it is always an instance of
|
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|
410 \pymodclass{mercurial.localrepo}{localrepository}. Following these two
|
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|
411 arguments are other keyword arguments. Which ones are passed in
|
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|
412 depends on the hook being called, but a hook can ignore arguments it
|
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|
413 doesn't care about by dropping them into a keyword argument dict, as
|
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|
414 with \texttt{**kwargs} above.
|
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415
|
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416 \section{Some hook examples}
|
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|
417
|
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|
418 \subsection{Enforcing coding guidelines in your own repository}
|
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|
419
|
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|
420 An interesting use of a commit-related hook is to help you to write
|
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|
421 cleaner code. A simple example of ``cleaner code'' is the dictum that
|
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422 a change should not add any new lines of text that contain ``trailing
|
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|
423 whitespace''. Trailing whitespace is a series of space and tab
|
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|
424 characters at the end of a line of text. In most cases, trailing
|
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|
425 whitespace is unnecessary, invisible noise, but it is occasionally
|
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|
426 problematic, and people tend to prefer to get rid of it.
|
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|
427
|
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|
428 You can use either the \hook{precommit} or \hook{pretxncommit} hook to
|
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|
429 tell whether you have a trailing whitespace problem. If you use the
|
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|
430 \hook{precommit} hook, the hook will not know which files you are
|
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|
431 committing, so it will have to check every modified file in the
|
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|
432 repository for trailing white space. If you want to commit a change
|
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|
433 to just the file \filename{foo}, but the file \filename{bar} contains
|
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|
434 trailing whitespace, doing a check in the \hook{precommit} hook will
|
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|
435 prevent you from committing \filename{foo} due to the problem with
|
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|
436 \filename{bar}. This doesn't seem right.
|
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|
437
|
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|
438 Should you choose the \hook{pretxncommit} hook, the check won't occur
|
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|
439 until just before the transaction for the commit completes. This will
|
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|
440 allow you to check for problems only the exact files that are being
|
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|
441 committed. However, if you entered the commit message interactively
|
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|
442 and the hook fails, the transaction will roll back; you'll have to
|
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|
443 re-enter the commit message after you fix the trailing whitespace and
|
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|
444 run \hgcmd{commit} again.
|
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|
445
|
bos@44
|
446 \begin{figure}[ht]
|
bos@44
|
447 \interaction{hook.ws.simple}
|
bos@44
|
448 \caption{A simple hook that checks for trailing whitespace}
|
bos@44
|
449 \label{ex:hook:ws.simple}
|
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|
450 \end{figure}
|
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|
451
|
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|
452 Figure~\ref{ex:hook:ws.simple} introduces a simple \hook{pretxncommit}
|
bos@44
|
453 hook that checks for trailing whitespace. This hook is short, but not
|
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|
454 very helpful. It exits with an error status if a change adds a line
|
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|
455 with trailing whitespace to any file, but does not print any
|
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|
456 information that might help us to identify the offending file or line.
|
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|
457
|
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|
458 \section{Hook reference}
|
bos@41
|
459 \label{sec:hook:ref}
|
bos@39
|
460
|
bos@39
|
461 \subsection{In-process hook execution}
|
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|
462
|
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|
463 An in-process hook is called with arguments of the following form:
|
bos@39
|
464 \begin{codesample2}
|
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|
465 def myhook(ui, repo, **kwargs):
|
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|
466 pass
|
bos@39
|
467 \end{codesample2}
|
bos@39
|
468 The \texttt{ui} parameter is a \pymodclass{mercurial.ui}{ui} object.
|
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|
469 The \texttt{repo} parameter is a
|
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|
470 \pymodclass{mercurial.localrepo}{localrepository} object. The
|
bos@39
|
471 names and values of the \texttt{**kwargs} parameters depend on the
|
bos@39
|
472 hook being invoked, with the following common features:
|
bos@39
|
473 \begin{itemize}
|
bos@39
|
474 \item If a parameter is named \texttt{node} or
|
bos@39
|
475 \texttt{parent\emph{N}}, it will contain a hexadecimal changeset ID.
|
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|
476 The empty string is used to represent ``null changeset ID'' instead
|
bos@39
|
477 of a string of zeroes.
|
bos@39
|
478 \item Boolean-valued parameters are represented as Python
|
bos@39
|
479 \texttt{bool} objects.
|
bos@39
|
480 \end{itemize}
|
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|
481
|
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|
482 An in-process hook is called without a change to the process's working
|
bos@39
|
483 directory (unlike external hooks, which are run in the root of the
|
bos@39
|
484 repository). It must not change the process's working directory. If
|
bos@39
|
485 it were to do so, it would probably cause calls to the Mercurial API,
|
bos@39
|
486 or operations after the hook finishes, to fail.
|
bos@39
|
487
|
bos@39
|
488 If a hook returns a boolean ``false'' value, it is considered to
|
bos@39
|
489 have succeeded. If it returns a boolean ``true'' value or raises an
|
bos@39
|
490 exception, it is considered to have failed.
|
bos@39
|
491
|
bos@39
|
492 \subsection{External hook execution}
|
bos@39
|
493
|
bos@39
|
494 An external hook is passed to the user's shell for execution, so
|
bos@39
|
495 features of that shell, such as variable substitution and command
|
bos@39
|
496 redirection, are available. The hook is run in the root directory of
|
bos@39
|
497 the repository.
|
bos@39
|
498
|
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|
499 Hook parameters are passed to the hook as environment variables. Each
|
bos@39
|
500 environment variable's name is converted in upper case and prefixed
|
bos@39
|
501 with the string ``\texttt{HG\_}''. For example, if the name of a
|
bos@39
|
502 parameter is ``\texttt{node}'', the name of the environment variable
|
bos@39
|
503 representing that parameter will be ``\texttt{HG\_NODE}''.
|
bos@39
|
504
|
bos@39
|
505 A boolean parameter is represented as the string ``\texttt{1}'' for
|
bos@39
|
506 ``true'', ``\texttt{0}'' for ``false''. If an environment variable is
|
bos@39
|
507 named \envar{HG\_NODE}, \envar{HG\_PARENT1} or \envar{HG\_PARENT2}, it
|
bos@39
|
508 contains a changeset ID represented as a hexadecimal string. The
|
bos@39
|
509 empty string is used to represent ``null changeset ID'' instead of a
|
bos@39
|
510 string of zeroes.
|
bos@39
|
511
|
bos@39
|
512 If a hook exits with a status of zero, it is considered to have
|
bos@39
|
513 succeeded. If it exits with a non-zero status, it is considered to
|
bos@39
|
514 have failed.
|
bos@39
|
515
|
bos@39
|
516 \subsection{The \hook{changegroup} hook}
|
bos@39
|
517 \label{sec:hook:changegroup}
|
bos@39
|
518
|
bos@40
|
519 This hook is run after a group of pre-existing changesets has been
|
bos@40
|
520 added to the repository, for example via a \hgcmd{pull} or
|
bos@40
|
521 \hgcmd{unbundle}. This hook is run once per operation that added one
|
bos@41
|
522 or more changesets. This is in contrast to the \hook{incoming} hook,
|
bos@41
|
523 which is run once per changeset, regardless of whether the changesets
|
bos@41
|
524 arrive in a group.
|
bos@41
|
525
|
bos@41
|
526 Some possible uses for this hook include kicking off an automated
|
bos@41
|
527 build or test of the added changesets, updating a bug database, or
|
bos@41
|
528 notifying subscribers that a repository contains new changes.
|
bos@40
|
529
|
bos@40
|
530 Parameters to this hook:
|
bos@40
|
531 \begin{itemize}
|
bos@40
|
532 \item[\texttt{node}] A changeset ID. The changeset ID of the first
|
bos@40
|
533 changeset in the group that was added. All changesets between this
|
bos@40
|
534 and \index{tags!\texttt{tip}}\texttt{tip}, inclusive, were added by
|
bos@40
|
535 a single \hgcmd{pull}, \hgcmd{push} or \hgcmd{unbundle}.
|
bos@40
|
536 \end{itemize}
|
bos@40
|
537
|
bos@40
|
538 See also: \hook{incoming} (section~\ref{sec:hook:incoming}),
|
bos@40
|
539 \hook{prechangegroup} (section~\ref{sec:hook:prechangegroup}),
|
bos@40
|
540 \hook{pretxnchangegroup} (section~\ref{sec:hook:pretxnchangegroup})
|
bos@39
|
541
|
bos@39
|
542 \subsection{The \hook{commit} hook}
|
bos@39
|
543 \label{sec:hook:commit}
|
bos@39
|
544
|
bos@40
|
545 This hook is run after a new changeset has been created.
|
bos@40
|
546
|
bos@40
|
547 Parameters to this hook:
|
bos@40
|
548 \begin{itemize}
|
bos@40
|
549 \item[\texttt{node}] A changeset ID. The changeset ID of the newly
|
bos@40
|
550 committed changeset.
|
bos@40
|
551 \item[\texttt{parent1}] A changeset ID. The changeset ID of the first
|
bos@40
|
552 parent of the newly committed changeset.
|
bos@40
|
553 \item[\texttt{parent2}] A changeset ID. The changeset ID of the second
|
bos@40
|
554 parent of the newly committed changeset.
|
bos@40
|
555 \end{itemize}
|
bos@40
|
556
|
bos@40
|
557 See also: \hook{precommit} (section~\ref{sec:hook:precommit}),
|
bos@40
|
558 \hook{pretxncommit} (section~\ref{sec:hook:pretxncommit})
|
bos@40
|
559
|
bos@40
|
560 \subsection{The \hook{incoming} hook}
|
bos@40
|
561 \label{sec:hook:incoming}
|
bos@40
|
562
|
bos@40
|
563 This hook is run after a pre-existing changeset has been added to the
|
bos@40
|
564 repository, for example via a \hgcmd{push}. If a group of changesets
|
bos@40
|
565 was added in a single operation, this hook is called once for each
|
bos@40
|
566 added changeset.
|
bos@40
|
567
|
bos@41
|
568 You can use this hook for the same purposes as the \hook{changegroup}
|
bos@41
|
569 hook (section~\ref{sec:hook:changegroup}); it's simply more convenient
|
bos@41
|
570 sometimes to run a hook once per group of changesets, while othher
|
bos@41
|
571 times it's handier once per changeset.
|
bos@41
|
572
|
bos@40
|
573 Parameters to this hook:
|
bos@40
|
574 \begin{itemize}
|
bos@40
|
575 \item[\texttt{node}] A changeset ID. The ID of the newly added
|
bos@39
|
576 changeset.
|
bos@40
|
577 \end{itemize}
|
bos@40
|
578
|
bos@40
|
579 See also: \hook{changegroup} (section~\ref{sec:hook:changegroup}) \hook{prechangegroup} (section~\ref{sec:hook:prechangegroup}), \hook{pretxnchangegroup} (section~\ref{sec:hook:pretxnchangegroup})
|
bos@40
|
580
|
bos@40
|
581 \subsection{The \hook{outgoing} hook}
|
bos@40
|
582 \label{sec:hook:outgoing}
|
bos@40
|
583
|
bos@40
|
584 This hook is run after a group of changesets has been propagated out
|
bos@40
|
585 of this repository, for example by a \hgcmd{push} or \hgcmd{bundle}
|
bos@40
|
586 command.
|
bos@40
|
587
|
bos@41
|
588 One possible use for this hook is to notify administrators that
|
bos@41
|
589 changes have been pulled.
|
bos@41
|
590
|
bos@40
|
591 Parameters to this hook:
|
bos@40
|
592 \begin{itemize}
|
bos@40
|
593 \item[\texttt{node}] A changeset ID. The changeset ID of the first
|
bos@40
|
594 changeset of the group that was sent.
|
bos@40
|
595 \item[\texttt{source}] A string. The source of the of the operation.
|
bos@40
|
596 If a remote client pulled changes from this repository,
|
bos@40
|
597 \texttt{source} will be \texttt{serve}. If the client that obtained
|
bos@40
|
598 changes from this repository was local, \texttt{source} will be
|
bos@40
|
599 \texttt{bundle}, \texttt{pull}, or \texttt{push}, depending on the
|
bos@40
|
600 operation the client performed.
|
bos@40
|
601 \end{itemize}
|
bos@40
|
602
|
bos@40
|
603 See also: \hook{preoutgoing} (section~\ref{sec:hook:preoutgoing})
|
bos@40
|
604
|
bos@40
|
605 \subsection{The \hook{prechangegroup} hook}
|
bos@40
|
606 \label{sec:hook:prechangegroup}
|
bos@40
|
607
|
bos@41
|
608 This controlling hook is run before Mercurial begins to add a group of
|
bos@41
|
609 changesets from another repository.
|
bos@41
|
610
|
bos@41
|
611 This hook does not have any information about the changesets to be
|
bos@41
|
612 added, because it is run before transmission of those changesets is
|
bos@41
|
613 allowed to begin. If this hook fails, the changesets will not be
|
bos@41
|
614 transmitted.
|
bos@41
|
615
|
bos@41
|
616 One use for this hook is to prevent external changes from being added
|
bos@41
|
617 to a repository, for example to ``freeze'' a server-hosted branch
|
bos@41
|
618 temporarily or permanently.
|
bos@41
|
619
|
bos@40
|
620 This hook is not passed any parameters.
|
bos@40
|
621
|
bos@40
|
622 See also: \hook{changegroup} (section~\ref{sec:hook:changegroup}),
|
bos@40
|
623 \hook{incoming} (section~\ref{sec:hook:incoming}), ,
|
bos@40
|
624 \hook{pretxnchangegroup} (section~\ref{sec:hook:pretxnchangegroup})
|
bos@40
|
625
|
bos@40
|
626 \subsection{The \hook{precommit} hook}
|
bos@40
|
627 \label{sec:hook:precommit}
|
bos@40
|
628
|
bos@41
|
629 This hook is run before Mercurial begins to commit a new changeset.
|
bos@41
|
630 It is run before Mercurial has any of the metadata for the commit,
|
bos@41
|
631 such as the files to be committed, the commit message, or the commit
|
bos@41
|
632 date.
|
bos@41
|
633
|
bos@41
|
634 One use for this hook is to disable the ability to commit new
|
bos@41
|
635 changesets, while still allowing incoming changesets. Another is to
|
bos@41
|
636 run a build or test, and only allow the commit to begin if the build
|
bos@41
|
637 or test succeeds.
|
bos@40
|
638
|
bos@40
|
639 Parameters to this hook:
|
bos@40
|
640 \begin{itemize}
|
bos@40
|
641 \item[\texttt{parent1}] A changeset ID. The changeset ID of the first
|
bos@40
|
642 parent of the working directory.
|
bos@40
|
643 \item[\texttt{parent2}] A changeset ID. The changeset ID of the second
|
bos@40
|
644 parent of the working directory.
|
bos@40
|
645 \end{itemize}
|
bos@40
|
646 If the commit proceeds, the parents of the working directory will
|
bos@40
|
647 become the parents of the new changeset.
|
bos@40
|
648
|
bos@40
|
649 See also: \hook{commit} (section~\ref{sec:hook:commit}),
|
bos@40
|
650 \hook{pretxncommit} (section~\ref{sec:hook:pretxncommit})
|
bos@40
|
651
|
bos@40
|
652 \subsection{The \hook{preoutgoing} hook}
|
bos@40
|
653 \label{sec:hook:preoutgoing}
|
bos@40
|
654
|
bos@40
|
655 This hook is invoked before Mercurial knows the identities of the
|
bos@40
|
656 changesets to be transmitted.
|
bos@40
|
657
|
bos@41
|
658 One use for this hook is to prevent changes from being transmitted to
|
bos@41
|
659 another repository.
|
bos@41
|
660
|
bos@40
|
661 Parameters to this hook:
|
bos@40
|
662 \begin{itemize}
|
bos@40
|
663 \item[\texttt{source}] A string. The source of the operation that is
|
bos@40
|
664 attempting to obtain changes from this repository. See the
|
bos@40
|
665 documentation for the \texttt{source} parameter to the
|
bos@40
|
666 \hook{outgoing} hook, in section~\ref{sec:hook:outgoing}, for
|
bos@40
|
667 possible values of this parameter..
|
bos@40
|
668 \end{itemize}
|
bos@40
|
669
|
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|
670 See also: \hook{outgoing} (section~\ref{sec:hook:outgoing})
|
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|
671
|
bos@40
|
672 \subsection{The \hook{pretag} hook}
|
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|
673 \label{sec:hook:pretag}
|
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|
674
|
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|
675 This controlling hook is run before a tag is created. If the hook
|
bos@41
|
676 succeeds, creation of the tag proceeds. If the hook fails, the tag is
|
bos@41
|
677 not created.
|
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|
678
|
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|
679 Parameters to this hook:
|
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|
680 \begin{itemize}
|
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|
681 \item[\texttt{local}] A boolean. Whether the tag is local to this
|
bos@40
|
682 repository instance (i.e.~stored in \sfilename{.hg/tags}) or managed
|
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|
683 by Mercurial (stored in \sfilename{.hgtags}).
|
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|
684 \item[\texttt{node}] A changeset ID. The ID of the changeset to be tagged.
|
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|
685 \item[\texttt{tag}] A string. The name of the tag to be created.
|
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|
686 \end{itemize}
|
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|
687
|
bos@40
|
688 If the tag to be created is revision-controlled, the \hook{precommit}
|
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|
689 and \hook{pretxncommit} hooks (sections~\ref{sec:hook:commit}
|
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|
690 and~\ref{sec:hook:pretxncommit}) will also be run.
|
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|
691
|
bos@40
|
692 See also: \hook{tag} (section~\ref{sec:hook:tag})
|
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|
693
|
bos@40
|
694 \subsection{The \hook{pretxnchangegroup} hook}
|
bos@40
|
695 \label{sec:hook:pretxnchangegroup}
|
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|
696
|
bos@41
|
697 This controlling hook is run before a transaction---that manages the
|
bos@41
|
698 addition of a group of new changesets from outside the
|
bos@41
|
699 repository---completes. If the hook succeeds, the transaction
|
bos@41
|
700 completes, and all of the changesets become permanent within this
|
bos@41
|
701 repository. If the hook fails, the transaction is rolled back, and
|
bos@41
|
702 the data for the changesets is erased.
|
bos@41
|
703
|
bos@41
|
704 This hook can access the metadata associated with the almost-added
|
bos@41
|
705 changesets, but it should not do anything permanent with this data.
|
bos@41
|
706 It must also not modify the working directory.
|
bos@41
|
707
|
bos@41
|
708 While this hook is running, if other Mercurial processes access this
|
bos@41
|
709 repository, they will be able to see the almost-added changesets as if
|
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|
710 they are permanent. This may lead to race conditions if you do not
|
bos@41
|
711 take steps to avoid them.
|
bos@41
|
712
|
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|
713 This hook can be used to automatically vet a group of changesets. If
|
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|
714 the hook fails, all of the changesets are ``rejected'' when the
|
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|
715 transaction rolls back.
|
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|
716
|
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|
717 Parameters to this hook are the same as for the \hook{changegroup}
|
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|
718 hook; see section~\ref{sec:hook:changegroup} for details.
|
bos@40
|
719
|
bos@40
|
720 See also: \hook{changegroup} (section~\ref{sec:hook:changegroup}),
|
bos@40
|
721 \hook{incoming} (section~\ref{sec:hook:incoming}),
|
bos@40
|
722 \hook{prechangegroup} (section~\ref{sec:hook:prechangegroup})
|
bos@40
|
723
|
bos@40
|
724 \subsection{The \hook{pretxncommit} hook}
|
bos@40
|
725 \label{sec:hook:pretxncommit}
|
bos@40
|
726
|
bos@41
|
727 This controlling hook is run before a transaction---that manages a new
|
bos@41
|
728 commit---completes. If the hook succeeds, the transaction completes
|
bos@41
|
729 and the changeset becomes permanent within this repository. If the
|
bos@41
|
730 hook fails, the transaction is rolled back, and the commit data is
|
bos@41
|
731 erased.
|
bos@41
|
732
|
bos@41
|
733 This hook can access the metadata associated with the almost-new
|
bos@41
|
734 changeset, but it should not do anything permanent with this data. It
|
bos@41
|
735 must also not modify the working directory.
|
bos@41
|
736
|
bos@41
|
737 While this hook is running, if other Mercurial processes access this
|
bos@41
|
738 repository, they will be able to see the almost-new changeset as if it
|
bos@41
|
739 is permanent. This may lead to race conditions if you do not take
|
bos@41
|
740 steps to avoid them.
|
bos@41
|
741
|
bos@40
|
742 Parameters to this hook are the same as for the \hook{commit} hook;
|
bos@40
|
743 see section~\ref{sec:hook:commit} for details.
|
bos@40
|
744
|
bos@40
|
745 See also: \hook{precommit} (section~\ref{sec:hook:precommit})
|
bos@40
|
746
|
bos@40
|
747 \subsection{The \hook{preupdate} hook}
|
bos@40
|
748 \label{sec:hook:preupdate}
|
bos@40
|
749
|
bos@41
|
750 This controlling hook is run before an update or merge of the working
|
bos@41
|
751 directory begins. It is run only if Mercurial's normal pre-update
|
bos@41
|
752 checks determine that the update or merge can proceed. If the hook
|
bos@41
|
753 succeeds, the update or merge may proceed; if it fails, the update or
|
bos@41
|
754 merge does not start.
|
bos@41
|
755
|
bos@40
|
756 Parameters to this hook:
|
bos@40
|
757 \begin{itemize}
|
bos@40
|
758 \item[\texttt{parent1}] A changeset ID. The ID of the parent that the
|
bos@40
|
759 working directory is to be updated to. If the working directory is
|
bos@40
|
760 being merged, it will not change this parent.
|
bos@40
|
761 \item[\texttt{parent2}] A changeset ID. Only set if the working
|
bos@40
|
762 directory is being merged. The ID of the revision that the working
|
bos@40
|
763 directory is being merged with.
|
bos@40
|
764 \end{itemize}
|
bos@40
|
765
|
bos@40
|
766 See also: \hook{update} (section~\ref{sec:hook:update})
|
bos@40
|
767
|
bos@40
|
768 \subsection{The \hook{tag} hook}
|
bos@40
|
769 \label{sec:hook:tag}
|
bos@40
|
770
|
bos@41
|
771 This hook is run after a tag has been created.
|
bos@41
|
772
|
bos@40
|
773 Parameters to this hook are the same as for the \hook{pretag} hook;
|
bos@40
|
774 see section~\ref{sec:hook:pretag} for details.
|
bos@40
|
775
|
bos@40
|
776 If the created tag is revision-controlled, the \hook{commit} hook
|
bos@41
|
777 (section~\ref{sec:hook:commit}) is run before this hook.
|
bos@40
|
778
|
bos@40
|
779 See also: \hook{pretag} (section~\ref{sec:hook:pretag})
|
bos@40
|
780
|
bos@40
|
781 \subsection{The \hook{update} hook}
|
bos@40
|
782 \label{sec:hook:update}
|
bos@40
|
783
|
bos@41
|
784 This hook is run after an update or merge of the working directory
|
bos@41
|
785 completes. Since a merge can fail (if the external \command{hgmerge}
|
bos@41
|
786 command fails to resolve conflicts in a file), this hook communicates
|
bos@41
|
787 whether the update or merge completed cleanly.
|
bos@41
|
788
|
bos@40
|
789 \begin{itemize}
|
bos@40
|
790 \item[\texttt{error}] A boolean. Indicates whether the update or
|
bos@40
|
791 merge completed successfully.
|
bos@40
|
792 \item[\texttt{parent1}] A changeset ID. The ID of the parent that the
|
bos@40
|
793 working directory was updated to. If the working directory was
|
bos@40
|
794 merged, it will not have changed this parent.
|
bos@40
|
795 \item[\texttt{parent2}] A changeset ID. Only set if the working
|
bos@40
|
796 directory was merged. The ID of the revision that the working
|
bos@40
|
797 directory was merged with.
|
bos@40
|
798 \end{itemize}
|
bos@40
|
799
|
bos@40
|
800 See also: \hook{preupdate} (section~\ref{sec:hook:preupdate})
|
bos@34
|
801
|
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|
802 %%% Local Variables:
|
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|
803 %%% mode: latex
|
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|
804 %%% TeX-master: "00book"
|
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|
805 %%% End:
|