Add Popen.start property.

R=dpranke@chromium.org
BUG=
TEST=


Review URL: http://codereview.chromium.org/8694006

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@112102 0039d316-1c4b-4281-b951-d872f2087c98

subprocess2.py

@@ -139,6 +139,7 @@ class Popen(subprocess.Popen):
   - Sets shell=True on windows by default. You can override this by forcing
     shell parameter to a value.
   - Adds support for VOID to not buffer when not needed.
+  - Adds self.start property.
 
   Note: Popen() can throw OSError when cwd or args[0] doesn't exist. Translate
   exceptions generated by cygwin when it fails trying to emulate fork().
@@ -180,6 +181,8 @@ class Popen(subprocess.Popen):
     fix('stdout')
     fix('stderr')
 
+    self.start = time.time()
+
     try:
       super(Popen, self).__init__(args, **kwargs)
     except OSError, e:
@@ -200,7 +203,7 @@ class Popen(subprocess.Popen):
 
 
 def communicate(args, timeout=None, **kwargs):
-  """Wraps subprocess.Popen().communicate().
+  """Wraps subprocess.Popen().communicate() and add timeout support.
 
   Returns ((stdout, stderr), returncode).
 
@@ -232,14 +235,13 @@ def communicate(args, timeout=None, **kwargs):
   # When the pipe fills up, it will deadlock this process. Using a real file
   # works around that issue.
   with tempfile.TemporaryFile() as buff:
-    start = time.time()
     kwargs['stdout'] = buff
     proc = Popen(args, **kwargs)
     if stdin is not None:
       proc.stdin.write(stdin)
     while proc.returncode is None:
       proc.poll()
-      if timeout and (time.time() - start) > timeout:
+      if timeout and (time.time() - proc.start) > timeout:
         proc.kill()
         proc.wait()
         # It's -9 on linux and 1 on Windows. Standardize to TIMED_OUT.