输出目录布局

报告问题 查看源代码

本页将介绍输出目录的要求和布局。

要求

输出目录布局的要求:

  • 如果多个用户在同一盒上进行构建,不会发生冲突。
  • 支持同时在多个工作区中进行构建。
  • 支持在同一工作区中针对多个目标配置进行构建。
  • 不会与任何其他工具冲突。
  • 易于访问。
  • 易于清理,甚至可以选择性地清理。
  • 明确,即使用户在切换到客户端目录时依靠符号链接,也是如此。
  • 每个用户的所有 build 状态都应位于一个目录下(“我想清除所有客户端中的所有 .o 文件。”)

当前布局

目前实现的解决方案:

  • 必须从包含代码库边界文件的目录或其子目录中调用 Bazel。换言之,必须从代码库内部调用 Bazel。否则,会报告错误。
  • outputRoot 目录在 Linux 上默认为 ${XDG_CACHE_HOME}/bazel(如果未设置 XDG_CACHE_HOME 环境变量,则默认为 ~/.cache/bazel)、在 macOS 上为 /private/var/tmp、在 Windows 上默认为 %HOME%(如果已设置),否则为 %USERPROFILE%(如果已设置),否则为设置了 FOLDERID_Profile 标志的调用 SHGetKnownFolderPath() 的结果。如果设置了环境变量 $TEST_TMPDIR(如对 Bazel 本身的测试),则该值会替换默认值。
  • Bazel 用户的构建状态位于 outputRoot/_bazel_$USER 下方。这称为 outputUserRoot 目录。
  • outputUserRoot 目录下面是 install 目录,而 installBase 目录的名称是 Bazel 安装清单的 MD5 哈希。
  • outputUserRoot 目录下,还会创建一个 outputBase 目录,其名称是工作区根目录的路径名称的 MD5 哈希值。例如,如果 Bazel 在工作区根目录 /home/user/src/my-project(或链接到该目录的符号链接)中运行,则会创建一个名为 /home/user/.cache/bazel/_bazel_user/7ffd56a6e4cb724ea575aba15733d113 的输出基本目录。您也可以在工作区根目录中运行 echo -n $(pwd) | md5sum 以获取 MD5。
  • 您可以使用 Bazel 的 --output_base 启动选项替换默认输出基本目录。例如 bazel --output_base=/tmp/bazel/output build x/y:z
  • 您还可以使用 Bazel 的 --output_user_root 启动选项来替换默认安装基准和输出基本目录。例如:bazel --output_user_root=/tmp/bazel build x/y:z

“bazel-<workspace-name>”“bazel-out”“bazel-testlogs”和“bazel-bin”的符号链接位于工作区目录中;这些符号链接指向输出目录中某个目标特定目录内的某些目录。这些符号链接只是为了方便用户,因为 Bazel 本身并不使用它们。此外,仅当工作区根目录可写入时,系统才会执行此操作。

布局图

目录布局如下:

<workspace-name>/                         <== The workspace root
  bazel-my-project => <..._main>          <== Symlink to execRoot
  bazel-out => <...bazel-out>             <== Convenience symlink to outputPath
  bazel-bin => <...bin>                   <== Convenience symlink to most recent written bin dir $(BINDIR)
  bazel-testlogs => <...testlogs>         <== Convenience symlink to the test logs directory

/home/user/.cache/bazel/                  <== Root for all Bazel output on a machine: outputRoot
  _bazel_$USER/                           <== Top level directory for a given user depends on the user name:
                                              outputUserRoot
    install/
      fba9a2c87ee9589d72889caf082f1029/   <== Hash of the Bazel install manifest: installBase
        _embedded_binaries/               <== Contains binaries and scripts unpacked from the data section of
                                              the bazel executable on first run (such as helper scripts and the
                                              main Java file BazelServer_deploy.jar)
    7ffd56a6e4cb724ea575aba15733d113/     <== Hash of the client's workspace root (such as
                                              /home/user/src/my-project): outputBase
      action_cache/                       <== Action cache directory hierarchy
                                              This contains the persistent record of the file
                                              metadata (timestamps, and perhaps eventually also MD5
                                              sums) used by the FilesystemValueChecker.
      command.log                         <== A copy of the stdout/stderr output from the most
                                              recent bazel command.
      external/                           <== The directory that remote repositories are
                                              downloaded/symlinked into.
      server/                             <== The Bazel server puts all server-related files (such
                                              as socket file, logs, etc) here.
        jvm.out                           <== The debugging output for the server.
      execroot/                           <== The working directory for all actions. For special
                                              cases such as sandboxing and remote execution, the
                                              actions run in a directory that mimics execroot.
                                              Implementation details, such as where the directories
                                              are created, are intentionally hidden from the action.
                                              Every action can access its inputs and outputs relative
                                              to the execroot directory.
        _main/                            <== Working tree for the Bazel build & root of symlink forest: execRoot
          _bin/                           <== Helper tools are linked from or copied to here.

          bazel-out/                      <== All actual output of the build is under here: outputPath
            _tmp/actions/                 <== Action output directory. This contains a file with the
                                              stdout/stderr for every action from the most recent
                                              bazel run that produced output.
            local_linux-fastbuild/        <== one subdirectory per unique target BuildConfiguration instance;
                                              this is currently encoded
              bin/                        <== Bazel outputs binaries for target configuration here: $(BINDIR)
                foo/bar/_objs/baz/        <== Object files for a cc_* rule named //foo/bar:baz
                  foo/bar/baz1.o          <== Object files from source //foo/bar:baz1.cc
                  other_package/other.o   <== Object files from source //other_package:other.cc
                foo/bar/baz               <== foo/bar/baz might be the artifact generated by a cc_binary named
                                              //foo/bar:baz
                foo/bar/baz.runfiles/     <== The runfiles symlink farm for the //foo/bar:baz executable.
                  MANIFEST
                  _main/
                    ...
              genfiles/                   <== Bazel puts generated source for the target configuration here:
                                              $(GENDIR)
                foo/bar.h                     such as foo/bar.h might be a headerfile generated by //foo:bargen
              testlogs/                   <== Bazel internal test runner puts test log files here
                foo/bartest.log               such as foo/bar.log might be an output of the //foo:bartest test with
                foo/bartest.status            foo/bartest.status containing exit status of the test (such as
                                              PASSED or FAILED (Exit 1), etc)
              include/                    <== a tree with include symlinks, generated as needed. The
                                              bazel-include symlinks point to here. This is used for
                                              linkstamp stuff, etc.
            host/                         <== BuildConfiguration for build host (user's workstation), for
                                              building prerequisite tools, that will be used in later stages
                                              of the build (ex: Protocol Compiler)
        <packages>/                       <== Packages referenced in the build appear as if under a regular workspace

RunfilesSupport 指向的位置更详细地记录了 *.runfiles 目录的布局。

bazel clean

bazel clean 会对 outputPathaction_cache 目录执行 rm -rf。它还会移除工作区符号链接。--expunge 选项将清理整个 outputBase。