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// 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.
#ifndef PPAPI_SHARED_IMPL_PROXY_LOCK_H_
#define PPAPI_SHARED_IMPL_PROXY_LOCK_H_
#include "base/basictypes.h"
#include "ppapi/shared_impl/ppapi_shared_export.h"
namespace base {
class Lock;
}
namespace ppapi {
// This is the one lock to rule them all for the ppapi proxy. All PPB interface
// functions that need to be synchronized should lock this lock on entry. This
// is normally accomplished by using an appropriate Enter RAII object at the
// beginning of each thunk function.
//
// TODO(dmichael): If this turns out to be too slow and contentious, we'll want
// to use multiple locks. E.g., one for the var tracker, one for the resource
// tracker, etc.
class PPAPI_SHARED_EXPORT ProxyLock {
public:
// Acquire the proxy lock. If it is currently held by another thread, block
// until it is available. If the lock has not been set using the 'Set' method,
// this operation does nothing. That is the normal case for the host side;
// see PluginResourceTracker for where the lock gets set for the out-of-
// process plugin case.
static void Acquire();
// Relinquish the proxy lock. If the lock has not been set, this does nothing.
static void Release();
// Set the lock that ProxyLock will use. The caller is responsible for
// ensuring that the lock stays valid so long as the ProxyLock may be in use.
static void Set(base::Lock* lock);
// Set the lock to NULL.
static void Reset();
private:
static base::Lock* lock_;
DISALLOW_IMPLICIT_CONSTRUCTORS(ProxyLock);
};
// A simple RAII class for locking the PPAPI proxy lock on entry and releasing
// on exit. This is for simple interfaces that don't use the 'thunk' system,
// such as PPB_Var and PPB_Core.
class ProxyAutoLock {
public:
ProxyAutoLock() {
ProxyLock::Acquire();
}
~ProxyAutoLock() {
ProxyLock::Release();
}
private:
DISALLOW_COPY_AND_ASSIGN(ProxyAutoLock);
};
// The inverse of the above; unlock on construction, lock on destruction. This
// is useful for calling out to the plugin, when we need to unlock but ensure
// that we re-acquire the lock when the plugin is returns or raises an
// exception.
class ProxyAutoUnlock {
public:
ProxyAutoUnlock() {
ProxyLock::Release();
}
~ProxyAutoUnlock() {
ProxyLock::Acquire();
}
private:
DISALLOW_COPY_AND_ASSIGN(ProxyAutoUnlock);
};
} // namespace ppapi
#endif // PPAPI_SHARED_IMPL_PROXY_LOCK_H_
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