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      1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "base/at_exit.h"
      6 
      7 #include <stddef.h>
      8 #include <ostream>
      9 
     10 #include "base/bind.h"
     11 #include "base/callback.h"
     12 #include "base/logging.h"
     13 
     14 namespace base {
     15 
     16 // Keep a stack of registered AtExitManagers.  We always operate on the most
     17 // recent, and we should never have more than one outside of testing (for a
     18 // statically linked version of this library).  Testing may use the shadow
     19 // version of the constructor, and if we are building a dynamic library we may
     20 // end up with multiple AtExitManagers on the same process.  We don't protect
     21 // this for thread-safe access, since it will only be modified in testing.
     22 static AtExitManager* g_top_manager = NULL;
     23 
     24 AtExitManager::AtExitManager() : next_manager_(g_top_manager) {
     25 // If multiple modules instantiate AtExitManagers they'll end up living in this
     26 // module... they have to coexist.
     27 #if !defined(COMPONENT_BUILD)
     28   DCHECK(!g_top_manager);
     29 #endif
     30   g_top_manager = this;
     31 }
     32 
     33 AtExitManager::~AtExitManager() {
     34   if (!g_top_manager) {
     35     NOTREACHED() << "Tried to ~AtExitManager without an AtExitManager";
     36     return;
     37   }
     38   DCHECK_EQ(this, g_top_manager);
     39 
     40   ProcessCallbacksNow();
     41   g_top_manager = next_manager_;
     42 }
     43 
     44 // static
     45 void AtExitManager::RegisterCallback(AtExitCallbackType func, void* param) {
     46   DCHECK(func);
     47   RegisterTask(base::Bind(func, param));
     48 }
     49 
     50 // static
     51 void AtExitManager::RegisterTask(base::Closure task) {
     52   if (!g_top_manager) {
     53     NOTREACHED() << "Tried to RegisterCallback without an AtExitManager";
     54     return;
     55   }
     56 
     57   AutoLock lock(g_top_manager->lock_);
     58   g_top_manager->stack_.push(task);
     59 }
     60 
     61 // static
     62 void AtExitManager::ProcessCallbacksNow() {
     63   if (!g_top_manager) {
     64     NOTREACHED() << "Tried to ProcessCallbacksNow without an AtExitManager";
     65     return;
     66   }
     67 
     68   AutoLock lock(g_top_manager->lock_);
     69 
     70   while (!g_top_manager->stack_.empty()) {
     71     base::Closure task = g_top_manager->stack_.top();
     72     task.Run();
     73     g_top_manager->stack_.pop();
     74   }
     75 }
     76 
     77 AtExitManager::AtExitManager(bool shadow) : next_manager_(g_top_manager) {
     78   DCHECK(shadow || !g_top_manager);
     79   g_top_manager = this;
     80 }
     81 
     82 }  // namespace base
     83