1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/dom/workers/Queue.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,202 @@
1.4 +/* -*- Mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; tab-width: 40 -*- */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +#ifndef mozilla_dom_workers_queue_h__
1.10 +#define mozilla_dom_workers_queue_h__
1.11 +
1.12 +#include "Workers.h"
1.13 +
1.14 +#include "mozilla/Mutex.h"
1.15 +#include "nsTArray.h"
1.16 +
1.17 +BEGIN_WORKERS_NAMESPACE
1.18 +
1.19 +template <typename T, int TCount>
1.20 +struct StorageWithTArray
1.21 +{
1.22 + typedef nsAutoTArray<T, TCount> StorageType;
1.23 +
1.24 + static void Reverse(StorageType& aStorage)
1.25 + {
1.26 + uint32_t length = aStorage.Length();
1.27 + for (uint32_t index = 0; index < length / 2; index++) {
1.28 + uint32_t reverseIndex = length - 1 - index;
1.29 +
1.30 + T t1 = aStorage.ElementAt(index);
1.31 + T t2 = aStorage.ElementAt(reverseIndex);
1.32 +
1.33 + aStorage.ReplaceElementsAt(index, 1, t2);
1.34 + aStorage.ReplaceElementsAt(reverseIndex, 1, t1);
1.35 + }
1.36 + }
1.37 +
1.38 + static bool IsEmpty(const StorageType& aStorage)
1.39 + {
1.40 + return !!aStorage.IsEmpty();
1.41 + }
1.42 +
1.43 + static bool Push(StorageType& aStorage, const T& aEntry)
1.44 + {
1.45 + return !!aStorage.AppendElement(aEntry);
1.46 + }
1.47 +
1.48 + static bool Pop(StorageType& aStorage, T& aEntry)
1.49 + {
1.50 + if (IsEmpty(aStorage)) {
1.51 + return false;
1.52 + }
1.53 +
1.54 + uint32_t index = aStorage.Length() - 1;
1.55 + aEntry = aStorage.ElementAt(index);
1.56 + aStorage.RemoveElementAt(index);
1.57 + return true;
1.58 + }
1.59 +
1.60 + static void Clear(StorageType& aStorage)
1.61 + {
1.62 + aStorage.Clear();
1.63 + }
1.64 +
1.65 + static void Compact(StorageType& aStorage)
1.66 + {
1.67 + aStorage.Compact();
1.68 + }
1.69 +};
1.70 +
1.71 +class LockingWithMutex
1.72 +{
1.73 + mozilla::Mutex mMutex;
1.74 +
1.75 +protected:
1.76 + LockingWithMutex()
1.77 + : mMutex("LockingWithMutex::mMutex")
1.78 + { }
1.79 +
1.80 + void Lock()
1.81 + {
1.82 + mMutex.Lock();
1.83 + }
1.84 +
1.85 + void Unlock()
1.86 + {
1.87 + mMutex.Unlock();
1.88 + }
1.89 +
1.90 + class AutoLock
1.91 + {
1.92 + LockingWithMutex& mHost;
1.93 +
1.94 + public:
1.95 + AutoLock(LockingWithMutex& aHost)
1.96 + : mHost(aHost)
1.97 + {
1.98 + mHost.Lock();
1.99 + }
1.100 +
1.101 + ~AutoLock()
1.102 + {
1.103 + mHost.Unlock();
1.104 + }
1.105 + };
1.106 +
1.107 + friend class AutoLock;
1.108 +};
1.109 +
1.110 +class NoLocking
1.111 +{
1.112 +protected:
1.113 + void Lock()
1.114 + { }
1.115 +
1.116 + void Unlock()
1.117 + { }
1.118 +
1.119 + class AutoLock
1.120 + {
1.121 + public:
1.122 + AutoLock(NoLocking& aHost)
1.123 + { }
1.124 +
1.125 + ~AutoLock()
1.126 + { }
1.127 + };
1.128 +};
1.129 +
1.130 +template <typename T,
1.131 + int TCount = 256,
1.132 + class LockingPolicy = NoLocking,
1.133 + class StoragePolicy = StorageWithTArray<T, TCount % 2 ?
1.134 + TCount / 2 + 1 :
1.135 + TCount / 2> >
1.136 +class Queue : public LockingPolicy
1.137 +{
1.138 + typedef typename StoragePolicy::StorageType StorageType;
1.139 + typedef typename LockingPolicy::AutoLock AutoLock;
1.140 +
1.141 + StorageType mStorage1;
1.142 + StorageType mStorage2;
1.143 +
1.144 + StorageType* mFront;
1.145 + StorageType* mBack;
1.146 +
1.147 +public:
1.148 + Queue()
1.149 + : mFront(&mStorage1), mBack(&mStorage2)
1.150 + { }
1.151 +
1.152 + bool IsEmpty()
1.153 + {
1.154 + AutoLock lock(*this);
1.155 + return StoragePolicy::IsEmpty(*mFront) &&
1.156 + StoragePolicy::IsEmpty(*mBack);
1.157 + }
1.158 +
1.159 + bool Push(const T& aEntry)
1.160 + {
1.161 + AutoLock lock(*this);
1.162 + return StoragePolicy::Push(*mBack, aEntry);
1.163 + }
1.164 +
1.165 + bool Pop(T& aEntry)
1.166 + {
1.167 + AutoLock lock(*this);
1.168 + if (StoragePolicy::IsEmpty(*mFront)) {
1.169 + StoragePolicy::Compact(*mFront);
1.170 + StoragePolicy::Reverse(*mBack);
1.171 + StorageType* tmp = mFront;
1.172 + mFront = mBack;
1.173 + mBack = tmp;
1.174 + }
1.175 + return StoragePolicy::Pop(*mFront, aEntry);
1.176 + }
1.177 +
1.178 + void Clear()
1.179 + {
1.180 + AutoLock lock(*this);
1.181 + StoragePolicy::Clear(*mFront);
1.182 + StoragePolicy::Clear(*mBack);
1.183 + }
1.184 +
1.185 + // XXX Do we need this?
1.186 + void Lock()
1.187 + {
1.188 + LockingPolicy::Lock();
1.189 + }
1.190 +
1.191 + // XXX Do we need this?
1.192 + void Unlock()
1.193 + {
1.194 + LockingPolicy::Unlock();
1.195 + }
1.196 +
1.197 +private:
1.198 + // Queue is not copyable.
1.199 + Queue(const Queue&);
1.200 + Queue & operator=(const Queue&);
1.201 +};
1.202 +
1.203 +END_WORKERS_NAMESPACE
1.204 +
1.205 +#endif /* mozilla_dom_workers_queue_h__ */
