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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef mozilla_dom_workers_queue_h__
#define mozilla_dom_workers_queue_h__
#include "Workers.h"
#include "mozilla/Mutex.h"
#include "nsTArray.h"
BEGIN_WORKERS_NAMESPACE
template <typename T, int TCount>
struct StorageWithTArray
{
typedef AutoTArray<T, TCount> StorageType;
static void Reverse(StorageType& aStorage)
{
uint32_t length = aStorage.Length();
for (uint32_t index = 0; index < length / 2; index++) {
uint32_t reverseIndex = length - 1 - index;
T t1 = aStorage.ElementAt(index);
T t2 = aStorage.ElementAt(reverseIndex);
aStorage.ReplaceElementsAt(index, 1, t2);
aStorage.ReplaceElementsAt(reverseIndex, 1, t1);
}
}
static bool IsEmpty(const StorageType& aStorage)
{
return !!aStorage.IsEmpty();
}
static bool Push(StorageType& aStorage, const T& aEntry)
{
return !!aStorage.AppendElement(aEntry);
}
static bool Pop(StorageType& aStorage, T& aEntry)
{
if (IsEmpty(aStorage)) {
return false;
}
uint32_t index = aStorage.Length() - 1;
aEntry = aStorage.ElementAt(index);
aStorage.RemoveElementAt(index);
return true;
}
static void Clear(StorageType& aStorage)
{
aStorage.Clear();
}
static void Compact(StorageType& aStorage)
{
aStorage.Compact();
}
};
class LockingWithMutex
{
mozilla::Mutex mMutex;
protected:
LockingWithMutex()
: mMutex("LockingWithMutex::mMutex")
{ }
void Lock()
{
mMutex.Lock();
}
void Unlock()
{
mMutex.Unlock();
}
class AutoLock
{
LockingWithMutex& mHost;
public:
explicit AutoLock(LockingWithMutex& aHost)
: mHost(aHost)
{
mHost.Lock();
}
~AutoLock()
{
mHost.Unlock();
}
};
friend class AutoLock;
};
class NoLocking
{
protected:
void Lock()
{ }
void Unlock()
{ }
class AutoLock
{
public:
explicit AutoLock(NoLocking& aHost)
{ }
~AutoLock()
{ }
};
};
template <typename T,
int TCount = 256,
class LockingPolicy = NoLocking,
class StoragePolicy = StorageWithTArray<T, TCount % 2 ?
TCount / 2 + 1 :
TCount / 2> >
class Queue : public LockingPolicy
{
typedef typename StoragePolicy::StorageType StorageType;
typedef typename LockingPolicy::AutoLock AutoLock;
StorageType mStorage1;
StorageType mStorage2;
StorageType* mFront;
StorageType* mBack;
public:
Queue()
: mFront(&mStorage1), mBack(&mStorage2)
{ }
bool IsEmpty()
{
AutoLock lock(*this);
return StoragePolicy::IsEmpty(*mFront) &&
StoragePolicy::IsEmpty(*mBack);
}
bool Push(const T& aEntry)
{
AutoLock lock(*this);
return StoragePolicy::Push(*mBack, aEntry);
}
bool Pop(T& aEntry)
{
AutoLock lock(*this);
if (StoragePolicy::IsEmpty(*mFront)) {
StoragePolicy::Compact(*mFront);
StoragePolicy::Reverse(*mBack);
StorageType* tmp = mFront;
mFront = mBack;
mBack = tmp;
}
return StoragePolicy::Pop(*mFront, aEntry);
}
void Clear()
{
AutoLock lock(*this);
StoragePolicy::Clear(*mFront);
StoragePolicy::Clear(*mBack);
}
// XXX Do we need this?
void Lock()
{
LockingPolicy::Lock();
}
// XXX Do we need this?
void Unlock()
{
LockingPolicy::Unlock();
}
private:
// Queue is not copyable.
Queue(const Queue&);
Queue & operator=(const Queue&);
};
END_WORKERS_NAMESPACE
#endif /* mozilla_dom_workers_queue_h__ */
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