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 
AtExitManager()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 
~AtExitManager()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
RegisterCallback(AtExitCallbackType func,void * param)45 void AtExitManager::RegisterCallback(AtExitCallbackType func, void* param) {
46   DCHECK(func);
47   RegisterTask(base::Bind(func, param));
48 }
49 
50 // static
RegisterTask(base::Closure task)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
ProcessCallbacksNow()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 
AtExitManager(bool shadow)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