bug 532333: part 2: implement an alternate EnsureChildTerminated() that listens for SIGCHLD (with a timeout) on the IO thread, instead of spawning a cleanup thread

ipc/chromium/Makefile.in

@@ -201,7 +201,7 @@ CPPSRCS += \
   waitable_event_watcher_posix.cc \
   file_descriptor_set_posix.cc \
   ipc_channel_posix.cc \
-  process_watcher_posix.cc \
+  process_watcher_posix_sigchld.cc \
   $(NULL)
 
 endif # } OS_POSIX

ipc/chromium/src/chrome/common/process_watcher_posix_sigchld.cc

@@ -0,0 +1,166 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 et sw=2 tw=80: 
+ */
+/* ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is Mozilla IPC.
+ *
+ * The Initial Developer of the Original Code is
+ *   Mozilla Foundation
+ * Portions created by the Initial Developer are Copyright (C) 2009
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *   Chris Jones <jones.chris.g@gmail.com>
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either the GNU General Public License Version 2 or later (the "GPL"), or
+ * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+//-----------------------------------------------------------------------------
+//   XXXXXXXXXXXXXXXX
+//
+// How is this code supposed to be licensed?  I don't /think/ that
+// this code is doing anything different than, say,
+// GeckoChildProcess.h/cpp, so I /think/ this gets a MoFo copyright
+// and license.  Yes?
+//
+//   XXXXXXXXXXXXXXXX
+//-----------------------------------------------------------------------------
+
+#include <errno.h>
+#include <signal.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+#include "base/eintr_wrapper.h"
+#include "base/message_loop.h"
+#include "base/process_util.h"
+
+#include "chrome/common/process_watcher.h"
+
+// Maximum amount of time (in milliseconds) to wait for the process to exit.
+// XXX/cjones: fairly arbitrary, chosen to match process_watcher_win.cc
+static const int kMaxWaitMs = 2000;
+
+namespace {
+
+bool
+IsProcessDead(pid_t process)
+{
+  bool exited = false;
+  // don't care if the process crashed, just if it exited
+  base::DidProcessCrash(&exited, process);
+  return exited;
+}
+
+// Fear the reaper
+class ChildReaper : public Task,
+                    public base::MessagePumpLibevent::SignalEvent,
+                    public base::MessagePumpLibevent::SignalWatcher
+{
+public:
+  explicit ChildReaper(pid_t process) : process_(process)
+  {
+  } 
+
+  virtual ~ChildReaper()
+  {
+    if (process_)
+      KillProcess();
+    // StopCatching() is implicit
+  }
+
+  // @override
+  virtual void OnSignal(int sig)
+  {
+    DCHECK(SIGCHLD == sig);
+    DCHECK(process_);
+
+    // this may be the SIGCHLD for a process other than |process_|
+    if (IsProcessDead(process_)) {
+      process_ = 0;
+      StopCatching();
+    }
+  }
+
+  // @override
+  virtual void Run()
+  {
+    // we may have already been signaled by the time this runs
+    if (process_)
+      KillProcess();
+  }
+
+private:
+  void KillProcess()
+  {
+    DCHECK(process_);
+
+    if (IsProcessDead(process_)) {
+      process_ = 0;
+      return;
+    }
+
+    if (0 == kill(process_, SIGKILL)) {
+      // XXX this will block for whatever amount of time it takes the
+      // XXX OS to tear down the process's resources.  might need to
+      // XXX rethink this if it proves expensive
+      HANDLE_EINTR(waitpid(process_, NULL, 0));
+    }
+    else {
+      LOG(ERROR) << "Failed to deliver SIGKILL to " << process_ << "!"
+                 << "("<< errno << ").";
+    }
+    process_ = 0;
+  }
+
+  pid_t process_;
+
+  DISALLOW_EVIL_CONSTRUCTORS(ChildReaper);
+};
+
+}  // namespace <anon>
+
+
+void
+ProcessWatcher::EnsureProcessTerminated(base::ProcessHandle process)
+{
+  DCHECK(process != base::GetCurrentProcId());
+  DCHECK(process > 0);
+
+  if (IsProcessDead(process))
+    return;
+
+  MessageLoopForIO* loop = MessageLoopForIO::current();
+  ChildReaper* reaper = new ChildReaper(process);
+
+  // there are three ways |process| will be reaped:
+  //  (1) catch SIGCHLD after its death (common case)
+  //  (2) kMaxWaitMs timeout fires, |kill(SIGKILL)|
+  //  (3) shutdown before (1) or (2), |reaper| dtor does |kill(SIGKILL)|
+  loop->CatchSignal(SIGCHLD, reaper, reaper);
+  // |loop| takes ownership of |reaper|
+  loop->PostDelayedTask(FROM_HERE, reaper, kMaxWaitMs);
+}