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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.
#ifndef PPAPI_SHARED_IMPL_PROXY_LOCK_H_
#define PPAPI_SHARED_IMPL_PROXY_LOCK_H_
#include "base/basictypes.h"
#include "base/bind.h"
#include "base/callback.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();
private:
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);
};
// A set of function template overloads for invoking a function pointer while
// the ProxyLock is unlocked. This assumes that the luck is held.
// CallWhileUnlocked unlocks the ProxyLock just before invoking the given
// function. The lock is immediately re-acquired when the invoked function
// function returns. CallWhileUnlocked returns whatever the given function
// returned.
//
// Example usage:
// *result = CallWhileUnlocked(ppp_input_event_impl_->HandleInputEvent,
// instance,
// resource->pp_resource());
template <class ReturnType>
ReturnType CallWhileUnlocked(ReturnType (*function)()) {
ProxyAutoUnlock unlock;
return function();
}
template <class ReturnType, class P1>
ReturnType CallWhileUnlocked(ReturnType (*function)(P1), const P1& p1) {
ProxyAutoUnlock unlock;
return function(p1);
}
template <class ReturnType, class P1, class P2>
ReturnType CallWhileUnlocked(ReturnType (*function)(P1, P2),
const P1& p1,
const P2& p2) {
ProxyAutoUnlock unlock;
return function(p1, p2);
}
template <class ReturnType, class P1, class P2, class P3>
ReturnType CallWhileUnlocked(ReturnType (*function)(P1, P2, P3),
const P1& p1,
const P2& p2,
const P3& p3) {
ProxyAutoUnlock unlock;
return function(p1, p2, p3);
}
template <class ReturnType, class P1, class P2, class P3, class P4>
ReturnType CallWhileUnlocked(ReturnType (*function)(P1, P2, P3, P4),
const P1& p1,
const P2& p2,
const P3& p3,
const P4& p4) {
ProxyAutoUnlock unlock;
return function(p1, p2, p3, p4);
}
template <class ReturnType, class P1, class P2, class P3, class P4, class P5>
ReturnType CallWhileUnlocked(ReturnType (*function)(P1, P2, P3, P4, P5),
const P1& p1,
const P2& p2,
const P3& p3,
const P4& p4,
const P5& p5) {
ProxyAutoUnlock unlock;
return function(p1, p2, p3, p4, p5);
}
void PPAPI_SHARED_EXPORT CallWhileUnlocked(const base::Closure& closure);
// CallWhileLocked locks the ProxyLock and runs the given closure immediately.
// The lock is released when CallWhileLocked returns. This function assumes the
// lock is not held. This is mostly for use in RunWhileLocked; see below.
void PPAPI_SHARED_EXPORT CallWhileLocked(const base::Closure& closure);
// RunWhileLocked binds the given closure with CallWhileLocked and returns the
// new Closure. This is for cases where you want to run a task, but you want to
// ensure that the ProxyLock is acquired for the duration of the task.
// Example usage:
// GetMainThreadMessageLoop()->PostDelayedTask(
// FROM_HERE,
// RunWhileLocked(base::Bind(&CallbackWrapper, callback, result)),
// delay_in_ms);
inline base::Closure RunWhileLocked(const base::Closure& closure) {
return base::Bind(CallWhileLocked, closure);
}
} // namespace ppapi
#endif // PPAPI_SHARED_IMPL_PROXY_LOCK_H_