rebaseline_server: clean up thread locks

tools/svn.py

 '''
 Copyright 2011 Google Inc.
 
 Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file.
 '''
 
 import fnmatch
 import os
 import re
 import subprocess
+import threading
 
 PROPERTY_MIMETYPE = 'svn:mime-type'
 
 # Status types for GetFilesWithStatus()
 STATUS_ADDED                 = 0x01
 STATUS_DELETED               = 0x02
 STATUS_MODIFIED              = 0x04
 STATUS_NOT_UNDER_SVN_CONTROL = 0x08
 
 
@@ skipping 16 matching lines @@
         raise Exception('Could not retrieve %s. Verify that the URL is valid '
                         'and check your connection.' % svn_url)
     return proc.communicate()[0]
 
 
 class Svn:
 
     def __init__(self, directory):
         """Set up to manipulate SVN control within the given directory.
 
+        The resulting object is thread-safe: access to all methods is
+        synchronized (if one thread is currently executing any of its methods,
+        all other threads must wait before executing any of its methods).
+
         @param directory
         """
         self._directory = directory
+        # This must be a reentrant lock, so that it can be held by both
+        # _RunCommand() and (some of) the methods that call it.
+        self._rlock = threading.RLock()
 
     def _RunCommand(self, args):
         """Run a command (from self._directory) and return stdout as a single
         string.
 
         @param args a list of arguments
         """
-        print 'RunCommand: %s' % args
-        proc = subprocess.Popen(args, cwd=self._directory,
-                                stdout=subprocess.PIPE, stderr=subprocess.PIPE)
-        (stdout, stderr) = proc.communicate()
-        if proc.returncode is not 0:
-            raise Exception('command "%s" failed in dir "%s": %s' %
-                            (args, self._directory, stderr))
-        return stdout
+        with self._rlock:
+            print 'RunCommand: %s' % args
+            proc = subprocess.Popen(args, cwd=self._directory,
+                                    stdout=subprocess.PIPE,
+                                    stderr=subprocess.PIPE)
+            (stdout, stderr) = proc.communicate()
+            if proc.returncode is not 0:
+              raise Exception('command "%s" failed in dir "%s": %s' %
+                              (args, self._directory, stderr))
+            return stdout
 
     def GetInfo(self):
         """Run "svn info" and return a dictionary containing its output.
         """
         output = self._RunCommand([SVN, 'info'])
         svn_info = {}
         for line in output.split('\n'):
           if ':' in line:
             (key, value) = line.split(':', 1)
             svn_info[key.strip()] = value.strip()
@@ skipping 84 matching lines @@
 
     def SetPropertyByFilenamePattern(self, filename_pattern,
                                      property_name, property_value):
         """Sets a svn property for all files matching filename_pattern.
 
         @param filename_pattern set the property for all files whose names match
                this Unix-style filename pattern (e.g., '*.jpg')
         @param property_name property_name to set for each file
         @param property_value what to set the property_name to
         """
-        all_files = os.listdir(self._directory)
-        matching_files = sorted(fnmatch.filter(all_files, filename_pattern))
-        self.SetProperty(matching_files, property_name, property_value)
+        with self._rlock:
+            all_files = os.listdir(self._directory)
+            matching_files = sorted(fnmatch.filter(all_files, filename_pattern))
+            self.SetProperty(matching_files, property_name, property_value)
 
     def ExportBaseVersionOfFile(self, file_within_repo, dest_path):
         """Retrieves a copy of the base version (what you would get if you ran
         'svn revert') of a file within the repository.
 
         @param file_within_repo path to the file within the repo whose base
                version you wish to obtain
         @param dest_path destination to which to write the base content
         """
         self._RunCommand([SVN, 'export', '--revision', 'BASE', '--force',
                           file_within_repo, dest_path])