Fetch last change (revision) info in a separate action that can run

every build, instead of having it occur as a side effect of updating
some other target for which we want to use normal up-to-date checks.
BUG=none
TEST=none
Review URL: http://codereview.chromium.org/118192

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@17634 0039d316-1c4b-4281-b951-d872f2087c98

6 files changed, 181 insertions, 70 deletions

diff --git a/base/base.gyp b/base/base.gyp
index a294726..b73415a 100644
--- a/base/base.gyp
+++ b/base/base.gyp
@@ -362,11 +362,13 @@
               {
                 'action_name': 'linux_version',
                 'variables': {
+                  'lastchange_path':
+                    '<(SHARED_INTERMEDIATE_DIR)/build/LASTCHANGE',
                   'version_py_path': '../chrome/tools/build/version.py',
                   'version_path': '../chrome/VERSION',
                   'template_input_path': 'file_version_info_linux.h.version',
                   'template_output_path':
-                  '<(SHARED_INTERMEDIATE_DIR)/base/file_version_info_linux.h',
+                    '<(SHARED_INTERMEDIATE_DIR)/base/file_version_info_linux.h',
                 },
                 'conditions': [
                   [ 'branding == "Chrome"', {
@@ -385,22 +387,24 @@
                   '<(template_input_path)',
                   '<(version_path)',
                   '<(branding_path)',
+                  '<(lastchange_path)',
                 ],
                 'outputs': [
                   # Use a non-existant output so this action always runs and
                   # generates version information, e.g. to capture revision
                   # changes, which aren't captured by file dependencies.
-                  '<(SHARED_INTERMEDIATE_DIR)/base/file_version_info_linux.bogus',
+                  '<(SHARED_INTERMEDIATE_DIR)/base/file_version_info_linux.always',
 
                   # And this is the real output, so that the build system knows
                   # what action generates it.
-                  '<(SHARED_INTERMEDIATE_DIR)/base/file_version_info_linux.h',
+                  '<(template_output_path)',
                 ],
                 'action': [
                   'python',
                   '<(version_py_path)',
                   '-f', '<(version_path)',
                   '-f', '<(branding_path)',
+                  '-f', '<(lastchange_path)',
                   '<(template_input_path)',
                   '<(template_output_path)',
                 ],
@@ -419,6 +423,7 @@
               'idle_timer.cc',
             ],
             'dependencies': [
+              '../build/util/build_util.gyp:lastchange',
               '../build/linux/system.gyp:gtk',
               '../build/linux/system.gyp:nss',
             ],
diff --git a/build/all.gyp b/build/all.gyp
index 202c2038..ffe041e 100644
--- a/build/all.gyp
+++ b/build/all.gyp
@@ -37,6 +37,7 @@
         '../third_party/zlib/zlib.gyp:*',
         '../webkit/tools/test_shell/test_shell.gyp:*',
         '../webkit/webkit.gyp:*',
+        'util/build_util.gyp:*',
         'temp_gyp/googleurl.gyp:*',
       ],
       'conditions': [
diff --git a/build/util/build_util.gyp b/build/util/build_util.gyp
new file mode 100644
index 0000000..0624ab5
--- /dev/null
+++ b/build/util/build_util.gyp
@@ -0,0 +1,34 @@
+# Copyright (c) 2009 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+{
+  'includes': [
+    '../common.gypi',
+  ],
+  'targets': [
+    {
+      'target_name': 'lastchange',
+      'type': 'none',
+      'variables': {
+        'lastchange_out_path': '<(SHARED_INTERMEDIATE_DIR)/build/LASTCHANGE',
+      },
+      'actions': [
+        {
+          'action_name': 'lastchange',
+          'inputs': [
+            'lastchange.py',
+          ],
+          'outputs': [
+            '<(lastchange_out_path)',
+            '<(lastchange_out_path).always',
+          ],
+          'action': [
+            'python', '<@(_inputs)', '-o', '<(lastchange_out_path)',
+          ],
+          'message': 'Extracting last change to <(lastchange_out_path)'
+        },
+      ],
+    },
+  ]
+}
diff --git a/build/util/lastchange.py b/build/util/lastchange.py
new file mode 100644
index 0000000..3bac762
--- /dev/null
+++ b/build/util/lastchange.py
@@ -0,0 +1,121 @@
+#!/usr/bin/env python
+# Copyright (c) 2009 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""
+lastchange.py -- Chromium revision fetching utility.
+"""
+
+import optparse
+import os
+import re
+import subprocess
+import sys
+
+
+def svn_fetch_revision():
+  """
+  Fetch the Subversion revision for the local tree.
+
+  Errors are swallowed.
+  """
+  try:
+    p = subprocess.Popen(['svn', 'info'],
+                         stdout=subprocess.PIPE,
+                         stderr=subprocess.PIPE)
+  except OSError:
+    # 'svn' is apparently either not installed or not executable.
+    return None
+  revision = None
+  if p:
+    svn_re = re.compile('^Revision:\s+(\S+)$', re.M)
+    m = svn_re.search(p.stdout.read())
+    if m:
+      revision = m.group(1)
+  return revision
+
+
+def git_fetch_id():
+  """
+  Fetch the GIT identifier for the local tree.
+
+  Errors are swallowed.
+  """
+  try:
+    p = subprocess.Popen(['git', 'log', '-1'],
+                         stdout=subprocess.PIPE,
+                         stderr=subprocess.PIPE)
+  except OSError:
+    # 'git' is apparently either not installed or not executable.
+    return None
+  id = None
+  if p:
+    git_re = re.compile('^\s*git-svn-id:\s+(\S+)@(\d+)', re.M)
+    m = git_re.search(p.stdout.read())
+    if m:
+      id = m.group(1)
+  return id
+
+
+def fetch_change():
+  """
+  Returns the last change, from some appropriate revision control system.
+  """
+  change = svn_fetch_revision()
+  if not change and sys.platform in ('linux2',):
+    change = git_fetch_id()
+  if not change:
+    change = '0'
+  return change
+
+
+def write_if_changed(file_name, contents):
+  """
+  Writes the specified contents to the specified file_name
+  iff the contents are different than the current contents.
+  """
+  try:
+    old_contents = open(file_name, 'r').read()
+  except EnvironmentError:
+    pass
+  else:
+    if contents == old_contents:
+      return
+    os.unlink(file_name)
+  open(file_name, 'w').write(contents)
+
+
+def main(argv=None):
+  if argv is None:
+    argv = sys.argv
+
+  parser = optparse.OptionParser(usage="lastchange.py [-h] [[-o] FILE]")
+  parser.add_option("-o", "--output", metavar="FILE",
+                    help="write last change to FILE")
+  opts, args = parser.parse_args(argv[1:])
+
+  out_file = opts.output
+
+  while len(args) and out_file is None:
+    if out_file is None:
+      out_file = args.pop(0)
+  if args:
+    sys.stderr.write('Unexpected arguments: %r\n\n' % args)
+    parser.print_help()
+    sys.exit(2)
+
+  change = fetch_change()
+
+  contents = "LASTCHANGE=%s\n" % change
+
+  if out_file:
+    write_if_changed(out_file, contents)
+  else:
+    sys.stdout.write(contents)
+
+  return 0
+
+
+if __name__ == '__main__':
+  sys.exit(main())
diff --git a/chrome/chrome.gyp b/chrome/chrome.gyp
index 308f1e5..60e8f25 100644
--- a/chrome/chrome.gyp
+++ b/chrome/chrome.gyp
@@ -3677,6 +3677,7 @@
             'chrome_resources',
             'installer/installer.gyp:installer_util_strings',
             'worker',
+            '../build/util/build_util.gyp:lastchange',
             '../net/net.gyp:net_resources',
             '../views/views.gyp:views',
             '../webkit/webkit.gyp:webkit_resources',
@@ -3688,35 +3689,35 @@
               'rule_name': 'win_version',
               'extension': 'version',
               'variables': {
-                'version_py': '../chrome/tools/build/version.py',
-                'VERSION': '../chrome/VERSION',
+                'lastchange_path':
+                  '<(SHARED_INTERMEDIATE_DIR)/build/LASTCHANGE',
+                'version_py': 'tools/build/version.py',
+                'version_path': 'VERSION',
                 'template_input_path': 'app/chrome_dll_version.rc.version',
-                'template_output_path':
-                '<(grit_out_dir)/chrome_dll_version.rc',
+                'template_output_path': '<(grit_out_dir)/chrome_dll_version.rc',
               },
               'conditions': [
                 [ 'branding == "Chrome"', {
                   'variables': {
-                     'BRANDING':
-                       '../chrome/app/theme/google_chrome/BRANDING',
+                     'branding_path': 'app/theme/google_chrome/BRANDING',
                   },
                 }, { # else branding!="Chrome"
                   'variables': {
-                     'BRANDING':
-                       '../chrome/app/theme/chromium/BRANDING',
+                     'branding_path': 'app/theme/chromium/BRANDING',
                   },
                 }],
               ],
               'inputs': [
                 '<(template_input_path)',
-                '<(VERSION)',
-                '<(BRANDING)',
+                '<(version_path)',
+                '<(branding_path)',
+                '<(lastchange_path)',
               ],
               'outputs': [
                 # Use a non-existant output so this action always runs and
                 # generates version information, e.g. to capture revision
                 # changes, which aren't captured by file dependencies.
-                '<(grit_out_dir)/chrome_dll_version.bogus',
+                '<(grit_out_dir)/chrome_dll_version.always',
 
                 # And this is the real output, so that the build system knows
                 # what action generates it.
@@ -3725,13 +3726,14 @@
               'action': [
                 'python',
                 '<(version_py)',
-                '-f', '<(VERSION)',
-                '-f', '<(BRANDING)',
+                '-f', '<(version_path)',
+                '-f', '<(branding_path)',
+                '-f', '<(lastchange_path)',
                 '<(template_input_path)',
                 '<(template_output_path)',
               ],
               'process_outputs_as_sources': 1,
-              'message': 'Generating version information'
+              'message': 'Generating version information in <(template_output_path)'
             },
           ],
           'sources': [
diff --git a/chrome/tools/build/version.py b/chrome/tools/build/version.py
index 03abeb7..b6bb820 100755
--- a/chrome/tools/build/version.py
+++ b/chrome/tools/build/version.py
@@ -19,50 +19,6 @@ class Usage(Exception):
     self.msg = msg
 
 
-def svn_fetch_revision():
-  """
-  Fetch the Subversion revision for the local tree.
-
-  Errors are swallowed.
-  """
-  try:
-    p = subprocess.Popen(['svn', 'info'],
-                         stdout=subprocess.PIPE,
-                         stderr=subprocess.PIPE)
-  except OSError:
-    # 'svn' is apparently either not installed or not executable.
-    return None
-  revision = None
-  if p:
-    svn_re = re.compile('^Revision:\s+(\S+)$', re.M)
-    m = svn_re.search(p.stdout.read())
-    if m:
-      revision = m.group(1)
-  return revision
-
-
-def git_fetch_id():
-  """
-  Fetch the GIT identifier for the local tree.
-
-  Errors are swallowed.
-  """
-  try:
-    p = subprocess.Popen(['git', 'log', '-1'],
-                         stdout=subprocess.PIPE,
-                         stderr=subprocess.PIPE)
-  except OSError:
-    # 'git' is apparently either not installed or not executable.
-    return None
-  id = None
-  if p:
-    git_re = re.compile('^\s*git-svn-id:\s+(\S+)@(\d+)', re.M)
-    m = git_re.search(p.stdout.read())
-    if m:
-      id = m.group(1)
-  return id
-
-
 def fetch_values_from_file(values_dict, file_name):
   """
   Fetches KEYWORD=VALUE settings from the specified file.
@@ -83,17 +39,10 @@ def fetch_values(file_list):
   Returns a dictionary of values to be used for substitution, populating
   the dictionary with KEYWORD=VALUE settings from the files in 'file_list'.
 
-  Explicitly adds the following values from internal calculations:
+  Explicitly adds the following value from internal calculations:
 
-    LASTCHANGE  (the SVN revision, or GIT id of the local tree)
     OFFICIAL_BUILD
   """
-  change = svn_fetch_revision()
-  if not change and sys.platform in ('linux2',):
-    change = git_fetch_id()
-  if not change:
-    change = '0'
-
   CHROME_BUILD_TYPE = os.environ.get('CHROME_BUILD_TYPE')
   if CHROME_BUILD_TYPE == '_official':
     official_build = '1'
@@ -101,7 +50,6 @@ def fetch_values(file_list):
     official_build = '0'
 
   values = dict(
-    LASTCHANGE = change,
     OFFICIAL_BUILD = official_build,
   )