Split toolchain update and install lookup to make generation faster

runhooks does toolchain update, saving relevant information to
build/win_toolchain.json, and during generation this is loaded
and used. This worked almost the same previously, however update
was called at generation time and the .json was deleted after
it was used. This speeds up generation time by a few seconds.

(In preference to https://codereview.chromium.org/228093002/)

R=dpranke@chromium.org
BUG=360878

Review URL: https://codereview.chromium.org/226643011

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@262590 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 64 insertions, 41 deletions

diff --git a/.gitignore b/.gitignore
index dc89e6f..efdfa0a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -50,6 +50,7 @@ v8.log
 /build/ipch/
 /build/Release
 /build/Release_x64
+/build/win_toolchain.json
 /build/util/LASTCHANGE*
 /build/util/support
 /build/x64/
diff --git a/DEPS b/DEPS
index dea74ed..e1bff70 100644
--- a/DEPS
+++ b/DEPS
@@ -637,6 +637,12 @@ hooks = [
     "action": ["python", "src/tools/clang/scripts/update.py", "--if-needed"],
   },
   {
+    # Update the Windows toolchain if necessary.
+    "name": "win_toolchain",
+    "pattern": ".",
+    "action": ["python", "src/build/vs_toolchain.py", "update"],
+  },
+  {
     # Update LASTCHANGE. This is also run by export_tarball.py in
     # src/tools/export_tarball - please keep them in sync.
     "name": "lastchange",
diff --git a/build/gyp_chromium b/build/gyp_chromium
index ca00a54..3ac81c0 100755
--- a/build/gyp_chromium
+++ b/build/gyp_chromium
@@ -265,7 +265,7 @@ if __name__ == '__main__':
       not 'OS=ios' in os.environ.get('GYP_DEFINES', []):
     os.environ['GYP_GENERATORS'] = 'ninja'
 
-  vs2013_runtime_dll_dirs = vs_toolchain.DownloadVsToolchain()
+  vs2013_runtime_dll_dirs = vs_toolchain.SetEnvironmentAndGetRuntimeDllDirs()
 
   # If CHROMIUM_GYP_SYNTAX_CHECK is set to 1, it will invoke gyp with --check
   # to enfore syntax checking.
diff --git a/build/vs_toolchain.py b/build/vs_toolchain.py
index 247703b8..4b925f0 100644
--- a/build/vs_toolchain.py
+++ b/build/vs_toolchain.py
@@ -8,7 +8,6 @@ import pipes
 import shutil
 import subprocess
 import sys
-import tempfile
 
 
 script_dir = os.path.dirname(os.path.realpath(__file__))
@@ -16,46 +15,23 @@ chrome_src = os.path.abspath(os.path.join(script_dir, os.pardir))
 SRC_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
 sys.path.insert(1, os.path.join(chrome_src, 'tools'))
 sys.path.insert(0, os.path.join(chrome_src, 'tools', 'gyp', 'pylib'))
+json_data_file = os.path.join(script_dir, 'win_toolchain.json')
 
 
 import gyp
 
 
-def GetDesiredVsToolchainHashes():
-  """Load a list of SHA1s corresponding to the toolchains that we want installed
-  to build with."""
-  sha1path = os.path.join(script_dir, 'toolchain_vs2013.hash')
-  with open(sha1path, 'rb') as f:
-    return f.read().strip().splitlines()
-
-
-def DownloadVsToolchain():
-  """Download the Visual Studio toolchain on Windows.
-
-  If on Windows, request that depot_tools install/update the automatic
-  toolchain, and then use it (unless opted-out) and return a tuple containing
-  the x64 and x86 paths. Otherwise return None.
+def SetEnvironmentAndGetRuntimeDllDirs():
+  """Sets up os.environ to use the depot_tools VS toolchain with gyp, and
+  returns the location of the VS runtime DLLs so they can be copied into
+  the output directory after gyp generation.
   """
   vs2013_runtime_dll_dirs = None
   depot_tools_win_toolchain = \
       bool(int(os.environ.get('DEPOT_TOOLS_WIN_TOOLCHAIN', '1')))
   if sys.platform in ('win32', 'cygwin') and depot_tools_win_toolchain:
-    import find_depot_tools
-    depot_tools_path = find_depot_tools.add_depot_tools_to_path()
-    temp_handle, data_file = tempfile.mkstemp(suffix='.json')
-    os.close(temp_handle)
-    get_toolchain_args = [
-        sys.executable,
-        os.path.join(depot_tools_path,
-                    'win_toolchain',
-                    'get_toolchain_if_necessary.py'),
-        '--output-json', data_file,
-      ] + GetDesiredVsToolchainHashes()
-    subprocess.check_call(get_toolchain_args)
-
-    with open(data_file, 'r') as tempf:
+    with open(json_data_file, 'r') as tempf:
       toolchain_data = json.load(tempf)
-    os.unlink(data_file)
 
     toolchain = toolchain_data['path']
     version = toolchain_data['version']
@@ -132,18 +108,58 @@ def CopyVsRuntimeDlls(output_dir, runtime_dirs):
   copy_runtime(out_release_nacl64, x64, 'msvc%s120.dll')
 
 
+def _GetDesiredVsToolchainHashes():
+  """Load a list of SHA1s corresponding to the toolchains that we want installed
+  to build with."""
+  sha1path = os.path.join(script_dir, 'toolchain_vs2013.hash')
+  with open(sha1path, 'rb') as f:
+    return f.read().strip().splitlines()
+
+
+def Update():
+  """Requests an update of the toolchain to the specific hashes we have at
+  this revision. The update outputs a .json of the various configuration
+  information required to pass to gyp which we use in |GetToolchainDir()|.
+  """
+  depot_tools_win_toolchain = \
+      bool(int(os.environ.get('DEPOT_TOOLS_WIN_TOOLCHAIN', '1')))
+  if sys.platform in ('win32', 'cygwin') and depot_tools_win_toolchain:
+    import find_depot_tools
+    depot_tools_path = find_depot_tools.add_depot_tools_to_path()
+    json_data_file = os.path.join(script_dir, 'win_toolchain.json')
+    get_toolchain_args = [
+        sys.executable,
+        os.path.join(depot_tools_path,
+                    'win_toolchain',
+                    'get_toolchain_if_necessary.py'),
+        '--output-json', json_data_file,
+      ] + _GetDesiredVsToolchainHashes()
+    subprocess.check_call(get_toolchain_args)
+
+  return 0
+
+
+def GetToolchainDir():
+  """Gets location information about the current toolchain (must have been
+  previously updated by 'update')."""
+  SetEnvironmentAndGetRuntimeDllDirs()
+  print '["%s", "%s"]' % (
+      os.environ['GYP_MSVS_OVERRIDE_PATH'], os.environ['WINDOWSSDKDIR'])
+
+
 def main():
-  if len(sys.argv) < 2:
-    print >>sys.stderr, 'Expected either "get_toolchain_dir" or "copy_dlls"'
+  if not sys.platform.startswith(('win32', 'cygwin')):
+    return 0
+  commands = {
+      'update': Update,
+      'get_toolchain_dir': GetToolchainDir,
+      # TODO(scottmg): Add copy_dlls for GN builds (gyp_chromium calls
+      # CopyVsRuntimeDlls via import, currently).
+  }
+  if len(sys.argv) < 2 or sys.argv[1] not in commands:
+    print >>sys.stderr, 'Expected one of: %s' % ', '.join(commands)
     return 1
-  if sys.argv[1] == 'get_toolchain_dir':
-    DownloadVsToolchain()
-    print '["%s", "%s"]' % (
-        os.environ['GYP_MSVS_OVERRIDE_PATH'], os.environ['WINDOWSSDKDIR'])
-  else:
-    print >>sys.stderr, 'TODO: not implemented "%s"' % sys.argv[1]
-    return 1
-  return 0
+  return commands[sys.argv[1]]()
 
 
 if __name__ == '__main__':