xref: /aosp_15_r20/external/libchrome/base/at_exit.cc (revision 635a864187cb8b6c713ff48b7e790a6b21769273)
1*635a8641SAndroid Build Coastguard Worker // Copyright (c) 2011 The Chromium Authors. All rights reserved.
2*635a8641SAndroid Build Coastguard Worker // Use of this source code is governed by a BSD-style license that can be
3*635a8641SAndroid Build Coastguard Worker // found in the LICENSE file.
4*635a8641SAndroid Build Coastguard Worker 
5*635a8641SAndroid Build Coastguard Worker #include "base/at_exit.h"
6*635a8641SAndroid Build Coastguard Worker 
7*635a8641SAndroid Build Coastguard Worker #include <stddef.h>
8*635a8641SAndroid Build Coastguard Worker #include <ostream>
9*635a8641SAndroid Build Coastguard Worker #include <utility>
10*635a8641SAndroid Build Coastguard Worker 
11*635a8641SAndroid Build Coastguard Worker #include "base/bind.h"
12*635a8641SAndroid Build Coastguard Worker #include "base/callback.h"
13*635a8641SAndroid Build Coastguard Worker #include "base/logging.h"
14*635a8641SAndroid Build Coastguard Worker 
15*635a8641SAndroid Build Coastguard Worker namespace base {
16*635a8641SAndroid Build Coastguard Worker 
17*635a8641SAndroid Build Coastguard Worker // Keep a stack of registered AtExitManagers.  We always operate on the most
18*635a8641SAndroid Build Coastguard Worker // recent, and we should never have more than one outside of testing (for a
19*635a8641SAndroid Build Coastguard Worker // statically linked version of this library).  Testing may use the shadow
20*635a8641SAndroid Build Coastguard Worker // version of the constructor, and if we are building a dynamic library we may
21*635a8641SAndroid Build Coastguard Worker // end up with multiple AtExitManagers on the same process.  We don't protect
22*635a8641SAndroid Build Coastguard Worker // this for thread-safe access, since it will only be modified in testing.
23*635a8641SAndroid Build Coastguard Worker static AtExitManager* g_top_manager = nullptr;
24*635a8641SAndroid Build Coastguard Worker 
25*635a8641SAndroid Build Coastguard Worker static bool g_disable_managers = false;
26*635a8641SAndroid Build Coastguard Worker 
AtExitManager()27*635a8641SAndroid Build Coastguard Worker AtExitManager::AtExitManager()
28*635a8641SAndroid Build Coastguard Worker     : processing_callbacks_(false), next_manager_(g_top_manager) {
29*635a8641SAndroid Build Coastguard Worker // If multiple modules instantiate AtExitManagers they'll end up living in this
30*635a8641SAndroid Build Coastguard Worker // module... they have to coexist.
31*635a8641SAndroid Build Coastguard Worker #if !defined(COMPONENT_BUILD)
32*635a8641SAndroid Build Coastguard Worker   DCHECK(!g_top_manager);
33*635a8641SAndroid Build Coastguard Worker #endif
34*635a8641SAndroid Build Coastguard Worker   g_top_manager = this;
35*635a8641SAndroid Build Coastguard Worker }
36*635a8641SAndroid Build Coastguard Worker 
~AtExitManager()37*635a8641SAndroid Build Coastguard Worker AtExitManager::~AtExitManager() {
38*635a8641SAndroid Build Coastguard Worker   if (!g_top_manager) {
39*635a8641SAndroid Build Coastguard Worker     NOTREACHED() << "Tried to ~AtExitManager without an AtExitManager";
40*635a8641SAndroid Build Coastguard Worker     return;
41*635a8641SAndroid Build Coastguard Worker   }
42*635a8641SAndroid Build Coastguard Worker   DCHECK_EQ(this, g_top_manager);
43*635a8641SAndroid Build Coastguard Worker 
44*635a8641SAndroid Build Coastguard Worker   if (!g_disable_managers)
45*635a8641SAndroid Build Coastguard Worker     ProcessCallbacksNow();
46*635a8641SAndroid Build Coastguard Worker   g_top_manager = next_manager_;
47*635a8641SAndroid Build Coastguard Worker }
48*635a8641SAndroid Build Coastguard Worker 
49*635a8641SAndroid Build Coastguard Worker // static
RegisterCallback(AtExitCallbackType func,void * param)50*635a8641SAndroid Build Coastguard Worker void AtExitManager::RegisterCallback(AtExitCallbackType func, void* param) {
51*635a8641SAndroid Build Coastguard Worker   DCHECK(func);
52*635a8641SAndroid Build Coastguard Worker   RegisterTask(base::Bind(func, param));
53*635a8641SAndroid Build Coastguard Worker }
54*635a8641SAndroid Build Coastguard Worker 
55*635a8641SAndroid Build Coastguard Worker // static
RegisterTask(base::Closure task)56*635a8641SAndroid Build Coastguard Worker void AtExitManager::RegisterTask(base::Closure task) {
57*635a8641SAndroid Build Coastguard Worker   if (!g_top_manager) {
58*635a8641SAndroid Build Coastguard Worker     NOTREACHED() << "Tried to RegisterCallback without an AtExitManager";
59*635a8641SAndroid Build Coastguard Worker     return;
60*635a8641SAndroid Build Coastguard Worker   }
61*635a8641SAndroid Build Coastguard Worker 
62*635a8641SAndroid Build Coastguard Worker   AutoLock lock(g_top_manager->lock_);
63*635a8641SAndroid Build Coastguard Worker   DCHECK(!g_top_manager->processing_callbacks_);
64*635a8641SAndroid Build Coastguard Worker   g_top_manager->stack_.push(std::move(task));
65*635a8641SAndroid Build Coastguard Worker }
66*635a8641SAndroid Build Coastguard Worker 
67*635a8641SAndroid Build Coastguard Worker // static
ProcessCallbacksNow()68*635a8641SAndroid Build Coastguard Worker void AtExitManager::ProcessCallbacksNow() {
69*635a8641SAndroid Build Coastguard Worker   if (!g_top_manager) {
70*635a8641SAndroid Build Coastguard Worker     NOTREACHED() << "Tried to ProcessCallbacksNow without an AtExitManager";
71*635a8641SAndroid Build Coastguard Worker     return;
72*635a8641SAndroid Build Coastguard Worker   }
73*635a8641SAndroid Build Coastguard Worker 
74*635a8641SAndroid Build Coastguard Worker   // Callbacks may try to add new callbacks, so run them without holding
75*635a8641SAndroid Build Coastguard Worker   // |lock_|. This is an error and caught by the DCHECK in RegisterTask(), but
76*635a8641SAndroid Build Coastguard Worker   // handle it gracefully in release builds so we don't deadlock.
77*635a8641SAndroid Build Coastguard Worker   base::stack<base::Closure> tasks;
78*635a8641SAndroid Build Coastguard Worker   {
79*635a8641SAndroid Build Coastguard Worker     AutoLock lock(g_top_manager->lock_);
80*635a8641SAndroid Build Coastguard Worker     tasks.swap(g_top_manager->stack_);
81*635a8641SAndroid Build Coastguard Worker     g_top_manager->processing_callbacks_ = true;
82*635a8641SAndroid Build Coastguard Worker   }
83*635a8641SAndroid Build Coastguard Worker 
84*635a8641SAndroid Build Coastguard Worker   // Relax the cross-thread access restriction to non-thread-safe RefCount.
85*635a8641SAndroid Build Coastguard Worker   // It's safe since all other threads should be terminated at this point.
86*635a8641SAndroid Build Coastguard Worker   ScopedAllowCrossThreadRefCountAccess allow_cross_thread_ref_count_access;
87*635a8641SAndroid Build Coastguard Worker 
88*635a8641SAndroid Build Coastguard Worker   while (!tasks.empty()) {
89*635a8641SAndroid Build Coastguard Worker     base::Closure task = tasks.top();
90*635a8641SAndroid Build Coastguard Worker     task.Run();
91*635a8641SAndroid Build Coastguard Worker     tasks.pop();
92*635a8641SAndroid Build Coastguard Worker   }
93*635a8641SAndroid Build Coastguard Worker 
94*635a8641SAndroid Build Coastguard Worker   // Expect that all callbacks have been run.
95*635a8641SAndroid Build Coastguard Worker   DCHECK(g_top_manager->stack_.empty());
96*635a8641SAndroid Build Coastguard Worker }
97*635a8641SAndroid Build Coastguard Worker 
DisableAllAtExitManagers()98*635a8641SAndroid Build Coastguard Worker void AtExitManager::DisableAllAtExitManagers() {
99*635a8641SAndroid Build Coastguard Worker   AutoLock lock(g_top_manager->lock_);
100*635a8641SAndroid Build Coastguard Worker   g_disable_managers = true;
101*635a8641SAndroid Build Coastguard Worker }
102*635a8641SAndroid Build Coastguard Worker 
AtExitManager(bool shadow)103*635a8641SAndroid Build Coastguard Worker AtExitManager::AtExitManager(bool shadow)
104*635a8641SAndroid Build Coastguard Worker     : processing_callbacks_(false), next_manager_(g_top_manager) {
105*635a8641SAndroid Build Coastguard Worker   DCHECK(shadow || !g_top_manager);
106*635a8641SAndroid Build Coastguard Worker   g_top_manager = this;
107*635a8641SAndroid Build Coastguard Worker }
108*635a8641SAndroid Build Coastguard Worker 
109*635a8641SAndroid Build Coastguard Worker }  // namespace base
110