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//
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#include "base/at_exit.h"
#include "base/logging.h"

// Keep a stack of registered AtExitManagers.  We always operate on the most
// recent, and we should never have more than one outside of testing, when we
// use the shadow version of the constructor.  We don't protect this for
// thread-safe access, since it will only be modified in testing.
static std::stack<base::AtExitManager*> g_managers;

namespace base {

AtExitManager::AtExitManager() {
  DCHECK(g_managers.empty());
  g_managers.push(this);
}

AtExitManager::AtExitManager(bool shadow) {
  DCHECK(shadow || g_managers.empty());
  g_managers.push(this);
}

AtExitManager::~AtExitManager() {
  if (g_managers.empty()) {
    NOTREACHED() << "Tried to ~AtExitManager without a AtExitManager";
    return;
  }
  DCHECK(g_managers.top() == this);

  ProcessCallbacksNow();
  g_managers.pop();
}

// static
void AtExitManager::RegisterCallback(AtExitCallbackType func) {
  if (g_managers.empty()) {
    NOTREACHED() << "Tried to RegisterCallback without a AtExitManager";
    return;
  }

  AtExitManager* manager = g_managers.top();
  AutoLock lock(manager->lock_);
  manager->stack_.push(func);
}

// static
void AtExitManager::ProcessCallbacksNow() {
  if (g_managers.empty()) {
    NOTREACHED() << "Tried to RegisterCallback without a AtExitManager";
    return;
  }

  AtExitManager* manager = g_managers.top();
  AutoLock lock(manager->lock_);

  while (!manager->stack_.empty()) {
    base::AtExitCallbackType func = manager->stack_.top();
    manager->stack_.pop();
    if (func)
      func();
  }
}

}  // namespace base