234 lines
6.8 KiB
C++
234 lines
6.8 KiB
C++
/*
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File: CAThreadSafeList.h
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Abstract: Part of CoreAudio Utility Classes
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Version: 1.1
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Disclaimer: IMPORTANT: This Apple software is supplied to you by Apple
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Inc. ("Apple") in consideration of your agreement to the following
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terms, and your use, installation, modification or redistribution of
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this Apple software constitutes acceptance of these terms. If you do
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not agree with these terms, please do not use, install, modify or
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redistribute this Apple software.
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In consideration of your agreement to abide by the following terms, and
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subject to these terms, Apple grants you a personal, non-exclusive
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license, under Apple's copyrights in this original Apple software (the
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"Apple Software"), to use, reproduce, modify and redistribute the Apple
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Software, with or without modifications, in source and/or binary forms;
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provided that if you redistribute the Apple Software in its entirety and
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without modifications, you must retain this notice and the following
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text and disclaimers in all such redistributions of the Apple Software.
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Neither the name, trademarks, service marks or logos of Apple Inc. may
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be used to endorse or promote products derived from the Apple Software
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without specific prior written permission from Apple. Except as
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expressly stated in this notice, no other rights or licenses, express or
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implied, are granted by Apple herein, including but not limited to any
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patent rights that may be infringed by your derivative works or by other
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works in which the Apple Software may be incorporated.
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The Apple Software is provided by Apple on an "AS IS" basis. APPLE
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MAKES NO WARRANTIES, EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION
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THE IMPLIED WARRANTIES OF NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS
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FOR A PARTICULAR PURPOSE, REGARDING THE APPLE SOFTWARE OR ITS USE AND
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OPERATION ALONE OR IN COMBINATION WITH YOUR PRODUCTS.
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IN NO EVENT SHALL APPLE BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL
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OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) ARISING IN ANY WAY OUT OF THE USE, REPRODUCTION,
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MODIFICATION AND/OR DISTRIBUTION OF THE APPLE SOFTWARE, HOWEVER CAUSED
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AND WHETHER UNDER THEORY OF CONTRACT, TORT (INCLUDING NEGLIGENCE),
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STRICT LIABILITY OR OTHERWISE, EVEN IF APPLE HAS BEEN ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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Copyright (C) 2014 Apple Inc. All Rights Reserved.
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*/
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#ifndef __CAThreadSafeList_h__
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#define __CAThreadSafeList_h__
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#include "CAAtomicStack.h"
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// linked list of T's
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// T must define operator ==
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template <class T>
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class TThreadSafeList {
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private:
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enum EEventType { kAdd, kRemove, kClear };
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class Node {
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public:
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Node * mNext;
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EEventType mEventType;
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T mObject;
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Node *& next() { return mNext; }
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};
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public:
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class iterator {
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public:
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iterator() { }
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iterator(Node *n) : mNode(n) { }
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bool operator == (const iterator &other) const { return this->mNode == other.mNode; }
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bool operator != (const iterator &other) const { return this->mNode != other.mNode; }
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T & operator * () const { return mNode->mObject; }
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iterator & operator ++ () { mNode = mNode->next(); return *this; } // preincrement
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iterator operator ++ (int) { iterator tmp = *this; mNode = mNode->next(); return tmp; } // postincrement
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private:
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Node * mNode;
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};
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TThreadSafeList() { }
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~TThreadSafeList()
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{
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mActiveList.free_all();
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mPendingList.free_all();
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mFreeList.free_all();
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}
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// These may be called on any thread
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void deferred_add(const T &obj) // can be called on any thread
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{
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Node *node = AllocNode();
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node->mEventType = kAdd;
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node->mObject = obj;
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mPendingList.push_atomic(node);
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//mPendingList.dump("pending after add");
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}
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void deferred_remove(const T &obj) // can be called on any thread
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{
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Node *node = AllocNode();
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node->mEventType = kRemove;
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node->mObject = obj;
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mPendingList.push_atomic(node);
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//mPendingList.dump("pending after remove");
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}
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void deferred_clear() // can be called on any thread
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{
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Node *node = AllocNode();
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node->mEventType = kClear;
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mPendingList.push_atomic(node);
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}
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// These must be called from only one thread
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void update() // must only be called from one thread
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{
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NodeStack reversed;
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Node *event, *node, *next;
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bool workDone = false;
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// reverse the events so they are in order
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event = mPendingList.pop_all();
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while (event != NULL) {
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next = event->mNext;
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reversed.push_NA(event);
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event = next;
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workDone = true;
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}
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if (workDone) {
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//reversed.dump("pending popped");
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//mActiveList.dump("active before update");
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// now process them
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while ((event = reversed.pop_NA()) != NULL) {
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switch (event->mEventType) {
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case kAdd:
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{
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Node **pnode;
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bool needToInsert = true;
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for (pnode = mActiveList.phead(); *pnode != NULL; pnode = &node->mNext) {
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node = *pnode;
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if (node->mObject == event->mObject) {
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//printf("already active!!!\n");
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FreeNode(event);
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needToInsert = false;
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break;
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}
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}
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if (needToInsert) {
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// link the new event in at the end of the active list
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*pnode = event;
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event->mNext = NULL;
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}
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}
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break;
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case kRemove:
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// find matching node in the active list, remove it
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for (Node **pnode = mActiveList.phead(); *pnode != NULL; ) {
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node = *pnode;
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if (node->mObject == event->mObject) {
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*pnode = node->mNext; // remove from linked list
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FreeNode(node);
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break;
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}
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pnode = &node->mNext;
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}
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// dispose the request node
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FreeNode(event);
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break;
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case kClear:
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for (node = mActiveList.head(); node != NULL; ) {
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next = node->mNext;
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FreeNode(node);
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node = next;
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}
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FreeNode(event);
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break;
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default:
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//printf("invalid node type %d!\n", event->mEventType);
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break;
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}
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}
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//mActiveList.dump("active after update");
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}
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}
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iterator begin() const {
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//mActiveList.dump("active at begin");
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return iterator(mActiveList.head());
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}
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iterator end() const { return iterator(NULL); }
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private:
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Node * AllocNode()
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{
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Node *node = mFreeList.pop_atomic();
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if (node == NULL)
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node = (Node *)CA_malloc(sizeof(Node));
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return node;
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}
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void FreeNode(Node *node)
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{
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mFreeList.push_atomic(node);
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}
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private:
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class NodeStack : public TAtomicStack<Node> {
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public:
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void free_all() {
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Node *node;
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while ((node = this->pop_NA()) != NULL)
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free(node);
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}
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Node ** phead() { return &this->mHead; }
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Node * head() const { return this->mHead; }
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};
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NodeStack mActiveList; // what's actually in the container - only accessed on one thread
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NodeStack mPendingList; // add or remove requests - threadsafe
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NodeStack mFreeList; // free nodes for reuse - threadsafe
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};
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#endif // __CAThreadSafeList_h__
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