// 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 "butil/at_exit.h"

#include <stddef.h>

#include <ostream>

#include "butil/logging.h"

namespace butil {

// Keep a stack of registered AtExitManagers.  We always operate on the most

// recent, and we should never have more than one outside of testing (for a

// statically linked version of this library).  Testing may use the shadow

// version of the constructor, and if we are building a dynamic library we may

// end up with multiple AtExitManagers on the same process.  We don't protect

// this for thread-safe access, since it will only be modified in testing.

static AtExitManager* g_top_manager = NULL;

AtExitManager::AtExitManager() : next_manager_(g_top_manager) {

// If multiple modules instantiate AtExitManagers they'll end up living in this

// module... they have to coexist.

#if !defined(COMPONENT_BUILD)

  DCHECK(!g_top_manager);

#endif

  g_top_manager = this;

}

AtExitManager::~AtExitManager() {

  if (!g_top_manager) {

    NOTREACHED() << "Tried to ~AtExitManager without an AtExitManager";

    return;

  }

  DCHECK_EQ(this, g_top_manager);

  ProcessCallbacksNow();

  g_top_manager = next_manager_;

}

// static

void AtExitManager::RegisterCallback(AtExitCallbackType func, void* param) {

  DCHECK(func);

  if (!g_top_manager) {

    NOTREACHED() << "Tried to RegisterCallback without an AtExitManager";

    return;

  }

  AutoLock lock(g_top_manager->lock_);

  g_top_manager->stack_.push({func, param});

}

// static

void AtExitManager::ProcessCallbacksNow() {

  if (!g_top_manager) {

    NOTREACHED() << "Tried to ProcessCallbacksNow without an AtExitManager";

    return;

  }

  AutoLock lock(g_top_manager->lock_);

  while (!g_top_manager->stack_.empty()) {

    Callback task = g_top_manager->stack_.top();

    task.func(task.param);

    g_top_manager->stack_.pop();

  }

}

AtExitManager::AtExitManager(bool shadow) : next_manager_(g_top_manager) {

  DCHECK(shadow || !g_top_manager);

  g_top_manager = this;

}

}  // namespace butil