michael@0: /* -*- Mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; tab-width: 40 -*- */
michael@0: /* This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #ifndef mozilla_dom_workers_queue_h__
michael@0: #define mozilla_dom_workers_queue_h__
michael@0: 
michael@0: #include "Workers.h"
michael@0: 
michael@0: #include "mozilla/Mutex.h"
michael@0: #include "nsTArray.h"
michael@0: 
michael@0: BEGIN_WORKERS_NAMESPACE
michael@0: 
michael@0: template <typename T, int TCount>
michael@0: struct StorageWithTArray
michael@0: {
michael@0:   typedef nsAutoTArray<T, TCount> StorageType;
michael@0: 
michael@0:   static void Reverse(StorageType& aStorage)
michael@0:   {
michael@0:     uint32_t length = aStorage.Length();
michael@0:     for (uint32_t index = 0; index < length / 2; index++) {
michael@0:       uint32_t reverseIndex = length - 1 - index;
michael@0: 
michael@0:       T t1 = aStorage.ElementAt(index);
michael@0:       T t2 = aStorage.ElementAt(reverseIndex);
michael@0: 
michael@0:       aStorage.ReplaceElementsAt(index, 1, t2);
michael@0:       aStorage.ReplaceElementsAt(reverseIndex, 1, t1);
michael@0:     }
michael@0:   }
michael@0: 
michael@0:   static bool IsEmpty(const StorageType& aStorage)
michael@0:   {
michael@0:     return !!aStorage.IsEmpty();
michael@0:   }
michael@0: 
michael@0:   static bool Push(StorageType& aStorage, const T& aEntry)
michael@0:   {
michael@0:     return !!aStorage.AppendElement(aEntry);
michael@0:   }
michael@0: 
michael@0:   static bool Pop(StorageType& aStorage, T& aEntry)
michael@0:   {
michael@0:     if (IsEmpty(aStorage)) {
michael@0:       return false;
michael@0:     }
michael@0: 
michael@0:     uint32_t index = aStorage.Length() - 1;
michael@0:     aEntry = aStorage.ElementAt(index);
michael@0:     aStorage.RemoveElementAt(index);
michael@0:     return true;
michael@0:   }
michael@0: 
michael@0:   static void Clear(StorageType& aStorage)
michael@0:   {
michael@0:     aStorage.Clear();
michael@0:   }
michael@0: 
michael@0:   static void Compact(StorageType& aStorage)
michael@0:   {
michael@0:     aStorage.Compact();
michael@0:   }
michael@0: };
michael@0: 
michael@0: class LockingWithMutex
michael@0: {
michael@0:   mozilla::Mutex mMutex;
michael@0: 
michael@0: protected:
michael@0:   LockingWithMutex()
michael@0:   : mMutex("LockingWithMutex::mMutex")
michael@0:   { }
michael@0: 
michael@0:   void Lock()
michael@0:   {
michael@0:     mMutex.Lock();
michael@0:   }
michael@0: 
michael@0:   void Unlock()
michael@0:   {
michael@0:     mMutex.Unlock();
michael@0:   }
michael@0: 
michael@0:   class AutoLock
michael@0:   {
michael@0:     LockingWithMutex& mHost;
michael@0: 
michael@0:   public:
michael@0:     AutoLock(LockingWithMutex& aHost)
michael@0:     : mHost(aHost)
michael@0:     {
michael@0:       mHost.Lock();
michael@0:     }
michael@0: 
michael@0:     ~AutoLock()
michael@0:     {
michael@0:       mHost.Unlock();
michael@0:     }
michael@0:   };
michael@0: 
michael@0:   friend class AutoLock;
michael@0: };
michael@0: 
michael@0: class NoLocking
michael@0: {
michael@0: protected:
michael@0:   void Lock()
michael@0:   { }
michael@0: 
michael@0:   void Unlock()
michael@0:   { }
michael@0: 
michael@0:   class AutoLock
michael@0:   {
michael@0:   public:
michael@0:     AutoLock(NoLocking& aHost)
michael@0:     { }
michael@0: 
michael@0:     ~AutoLock()
michael@0:     { }
michael@0:   };
michael@0: };
michael@0: 
michael@0: template <typename T,
michael@0:           int TCount = 256,
michael@0:           class LockingPolicy = NoLocking,
michael@0:           class StoragePolicy = StorageWithTArray<T, TCount % 2 ?
michael@0:                                                      TCount / 2 + 1 :
michael@0:                                                      TCount / 2> >
michael@0: class Queue : public LockingPolicy
michael@0: {
michael@0:   typedef typename StoragePolicy::StorageType StorageType;
michael@0:   typedef typename LockingPolicy::AutoLock AutoLock;
michael@0: 
michael@0:   StorageType mStorage1;
michael@0:   StorageType mStorage2;
michael@0: 
michael@0:   StorageType* mFront;
michael@0:   StorageType* mBack;
michael@0: 
michael@0: public:
michael@0:   Queue()
michael@0:   : mFront(&mStorage1), mBack(&mStorage2)
michael@0:   { }
michael@0: 
michael@0:   bool IsEmpty()
michael@0:   {
michael@0:     AutoLock lock(*this);
michael@0:     return StoragePolicy::IsEmpty(*mFront) &&
michael@0:            StoragePolicy::IsEmpty(*mBack);
michael@0:   }
michael@0: 
michael@0:   bool Push(const T& aEntry)
michael@0:   {
michael@0:     AutoLock lock(*this);
michael@0:     return StoragePolicy::Push(*mBack, aEntry);
michael@0:   }
michael@0: 
michael@0:   bool Pop(T& aEntry)
michael@0:   {
michael@0:     AutoLock lock(*this);
michael@0:     if (StoragePolicy::IsEmpty(*mFront)) {
michael@0:       StoragePolicy::Compact(*mFront);
michael@0:       StoragePolicy::Reverse(*mBack);
michael@0:       StorageType* tmp = mFront;
michael@0:       mFront = mBack;
michael@0:       mBack = tmp;
michael@0:     }
michael@0:     return StoragePolicy::Pop(*mFront, aEntry);
michael@0:   }
michael@0: 
michael@0:   void Clear()
michael@0:   {
michael@0:     AutoLock lock(*this);
michael@0:     StoragePolicy::Clear(*mFront);
michael@0:     StoragePolicy::Clear(*mBack);
michael@0:   }
michael@0: 
michael@0:   // XXX Do we need this?
michael@0:   void Lock()
michael@0:   {
michael@0:     LockingPolicy::Lock();
michael@0:   }
michael@0: 
michael@0:   // XXX Do we need this?
michael@0:   void Unlock()
michael@0:   {
michael@0:     LockingPolicy::Unlock();
michael@0:   }
michael@0: 
michael@0: private:
michael@0:   // Queue is not copyable.
michael@0:   Queue(const Queue&);
michael@0:   Queue & operator=(const Queue&);
michael@0: };
michael@0: 
michael@0: END_WORKERS_NAMESPACE
michael@0: 
michael@0: #endif /* mozilla_dom_workers_queue_h__ */