From 32c1fbcb5b5e5eb8d2eafd1f1294bb5a4a70c178 Mon Sep 17 00:00:00 2001
From: Milo Casagrande <milo@ubuntu.com>
Date: Wed, 30 Jan 2013 13:48:55 +0100
Subject: Added simple mechanism for locking process.

---
 scripts/update-repos | 57 +++++++++++++++++++++++++++++++---------------------
 1 file changed, 34 insertions(+), 23 deletions(-)

(limited to 'scripts')

diff --git a/scripts/update-repos b/scripts/update-repos
index 73a6539..b31810b 100644
--- a/scripts/update-repos
+++ b/scripts/update-repos
@@ -5,10 +5,14 @@ import argparse
 import os
 import re
 import subprocess
+from tempfile import gettempdir
 
 
 # Match a directory that ends with .git, but not only .git
 GIT_DIRECTORY_ENDS = re.compile(".+\.git$")
+# Name for a lock file.
+LOCK_FILE_NAME = "update-repost.lock"
+LOCK_FILE = os.path.join(gettempdir(), LOCK_FILE_NAME)
 
 
 def args_parser():
@@ -26,26 +30,33 @@ if __name__ == '__main__':
     parser = args_parser()
     args = parser.parse_args()
 
-    for root, dirs, files in os.walk(os.path.abspath(args.repos_dir)):
-        if GIT_DIRECTORY_ENDS.match(root):
-            if files:
-                # We really are in a git repository.
-                cmd_args = []
-                if args.user:
-                    cmd_args = ["sudo", "-u", args.user, "-H"]
-                cmd_args += ["git", "fetch", "--all", "-q"]
-                repo_name = os.path.basename(root)
-                process = subprocess.Popen(cmd_args,
-                                           cwd=root,
-                                           stdout=subprocess.PIPE,
-                                           stderr=subprocess.PIPE)
-
-                print "Updating '%s' repository..." % repo_name
-                p_out, p_err = process.communicate()
-                if process.returncode != 0:
-                    print ("Error fetching updates for repository '%s'" % \
-                           repo_name)
-            else:
-                # git repositories always have a HEAD file, or it means they
-                # are empty.
-                continue
+    try:
+        if os.path.exists(LOCK_FILE):
+            print "Another process is still running: cannot acquire lock."
+        else:
+            with open(LOCK_FILE, 'w'):
+                for root, dirs, files in os.walk(os.path.abspath(args.repos_dir)):
+                    if GIT_DIRECTORY_ENDS.match(root):
+                        if files:
+                            # We really are in a git repository.
+                            cmd_args = []
+                            if args.user:
+                                cmd_args = ["sudo", "-u", args.user, "-H"]
+                            cmd_args += ["git", "fetch", "--all", "-q"]
+                            repo_name = os.path.basename(root)
+                            process = subprocess.Popen(cmd_args,
+                                                       cwd=root,
+                                                       stdout=subprocess.PIPE,
+                                                       stderr=subprocess.PIPE)
+
+                            print "Updating '%s' repository..." % repo_name
+                            p_out, p_err = process.communicate()
+                            if process.returncode != 0:
+                                print ("Error fetching updates for repository '%s'" % \
+                                       repo_name)
+                        else:
+                            # git repositories always have a HEAD file, or it means they
+                            # are empty.
+                            continue
+    finally:
+        os.unlink(LOCK_FILE)
-- 
cgit v1.2.3