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// Copyright (c) 2012 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 "ppapi/shared_impl/proxy_lock.h"
#include "base/lazy_instance.h"
#include "base/synchronization/lock.h"
#include "base/threading/thread_local.h"
#include "ppapi/shared_impl/ppapi_globals.h"
namespace ppapi {
base::LazyInstance<base::Lock>::Leaky g_proxy_lock = LAZY_INSTANCE_INITIALIZER;
bool g_disable_locking = false;
base::LazyInstance<base::ThreadLocalBoolean>::Leaky
g_disable_locking_for_thread = LAZY_INSTANCE_INITIALIZER;
// Simple single-thread deadlock detector for the proxy lock.
// |true| when the current thread has the lock.
base::LazyInstance<base::ThreadLocalBoolean>::Leaky g_proxy_locked_on_thread =
LAZY_INSTANCE_INITIALIZER;
// static
base::Lock* ProxyLock::Get() {
if (g_disable_locking || g_disable_locking_for_thread.Get().Get())
return NULL;
return &g_proxy_lock.Get();
}
// Functions below should only access the lock via Get to ensure that they don't
// try to use the lock on the host side of the proxy, where locking is
// unnecessary and wrong (because we haven't coded the host side to account for
// locking).
// static
void ProxyLock::Acquire() {
base::Lock* lock = Get();
if (lock) {
// This thread does not already hold the lock.
const bool deadlock = g_proxy_locked_on_thread.Get().Get();
CHECK(!deadlock);
lock->Acquire();
g_proxy_locked_on_thread.Get().Set(true);
}
}
// static
void ProxyLock::Release() {
base::Lock* lock = Get();
if (lock) {
// This thread currently holds the lock.
const bool locked = g_proxy_locked_on_thread.Get().Get();
CHECK(locked);
g_proxy_locked_on_thread.Get().Set(false);
lock->Release();
}
}
// static
void ProxyLock::AssertAcquired() {
base::Lock* lock = Get();
if (lock) {
// This thread currently holds the lock.
const bool locked = g_proxy_locked_on_thread.Get().Get();
CHECK(locked);
lock->AssertAcquired();
}
}
// static
void ProxyLock::DisableLocking() {
// Note, we don't DCHECK that this flag isn't already set, because multiple
// unit tests may run in succession and all set it.
g_disable_locking = true;
}
// static
void ProxyLock::DisableLockingOnThreadForTest() {
// Note, we don't DCHECK that this flag isn't already set, because multiple
// unit tests may run in succession and all set it.
g_disable_locking_for_thread.Get().Set(true);
}
// static
void ProxyLock::EnableLockingOnThreadForTest() {
g_disable_locking_for_thread.Get().Set(false);
}
void CallWhileUnlocked(const base::Closure& closure) {
ProxyAutoUnlock lock;
closure.Run();
}
} // namespace ppapi
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