Added code for renderer to cleanly exit.

base/process_util.cc

 // Copyright (c) 2011 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.
 
 #include "base/process_util.h"
 
 namespace base {
 
 #if defined(OS_POSIX)
 ProcessEntry::ProcessEntry() : pid_(0), ppid_(0), gid_(0) {}
@@ skipping 58 matching lines @@
   if (executable_name_.size() > 15) {
     executable_name_ = FilePath::StringType(executable_name_,
                                             executable_name_.size() - 15, 15);
   }
 #endif
 }
 
 NamedProcessIterator::~NamedProcessIterator() {
 }
 
+#if defined(RENDERER_CLEAN_EXIT)
+base::subtle::Atomic32 exit_counter;
+
+extern void clean_exit(int return_value)

[Markus (顧孟勤), 2012/03/28 23:07:56]

This function should be marked as __attribute__((noreturn))

+{
+  base::subtle::Atomic32 new_exit_counter;
+  new_exit_counter = base::subtle::
+      Barrier_AtomicIncrement(&exit_counter, (base::subtle::Atomic32)1);
+  if (new_exit_counter == 1)
+  {
+    fprintf(stderr, "Renderer process exiting.\n");

[Markus (顧孟勤), 2012/03/28 23:07:56]

If you plan on calling clean_exit() from a signal handler, then you cannot call
fprintf() here. You have to restrict yourself to functions that are
async-signal-safe.

See http://pubs.opengroup.org/onlinepubs/009695399/functions/xsh_chap02_04.html
for a list of suitable functions.

+    exit(return_value);
+  }
+  else
+  {
+    fprintf(stderr, "Another renderer thread already called exit!.\n");
+    fprintf(stderr, "Not calling exit() myself.\n");

[Markus (顧孟勤), 2012/03/28 23:07:56]

I don't think you ever want to return from this function. The calling code is
unlikely to be prepared for an exit-type function to return.

+  }
+}
+#endif // defined(RENDERER_CLEAN_EXIT)
+
 }  // namespace base