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Annotation of XNU/iokit/IOKit/network/IOOQLockFIFOQueue.h, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1998-2000 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * The contents of this file constitute Original Code as defined in and
        !             7:  * are subject to the Apple Public Source License Version 1.1 (the
        !             8:  * "License").  You may not use this file except in compliance with the
        !             9:  * License.  Please obtain a copy of the License at
        !            10:  * http://www.apple.com/publicsource and read it before using this file.
        !            11:  * 
        !            12:  * This Original Code and all software distributed under the License are
        !            13:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            14:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            15:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            16:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            17:  * License for the specific language governing rights and limitations
        !            18:  * under the License.
        !            19:  * 
        !            20:  * @APPLE_LICENSE_HEADER_END@
        !            21:  */
        !            22: /*
        !            23:  * Copyright (c) 1999 Apple Computer, Inc.  All rights reserved. 
        !            24:  *
        !            25:  * IOOQLockFIFOQueue.h
        !            26:  * 
        !            27:  * HISTORY
        !            28:  *
        !            29:  */
        !            30: 
        !            31: #ifndef _IOOQLOCKFIFOQUEUE_H
        !            32: #define _IOOQLOCKFIFOQUEUE_H
        !            33: 
        !            34: /*
        !            35:  * Aliases.
        !            36:  */
        !            37: #define IOLockedFIFOQueue IOOQLockFIFOQueue
        !            38: 
        !            39: #include <IOKit/IOLocks.h>
        !            40: #include <IOKit/network/IOOutputQueue.h>
        !            41: 
        !            42: /*! @class IOOQLockFIFOQueue
        !            43:     @abstract A concrete implementation of an IOOutputQueue. This object
        !            44:     provides a FIFO packet queue to hold the incoming packets provided
        !            45:     by the client transmit threads. A mutex lock is used to serialize
        !            46:     access to the target's output handler. The mutex lock is local to the
        !            47:     queue and there is no serialization performed between calls to the
        !            48:     target's output handler, and any other threads that may be running on
        !            49:     the target. See IOOutputQueue for additional information. */
        !            50: 
        !            51: class IOOQLockFIFOQueue : public IOOutputQueue
        !            52: {
        !            53:     OSDeclareDefaultStructors(IOOQLockFIFOQueue)
        !            54: 
        !            55: protected:
        !            56:     IOLock *                _mutex;
        !            57:     volatile bool           _serviceActive;
        !            58:     volatile UInt32         _enqueueCount;
        !            59: 
        !            60: /*! @function serviceThread
        !            61:     @discussion Provide an implementation for the interface defined in
        !            62:     IOOutputQueue. This method is called by a callout thread when
        !            63:     service() is performed asynchronously. */
        !            64: 
        !            65:     virtual void serviceThread();
        !            66: 
        !            67: /*! @function dequeue
        !            68:     @discussion Responsible for removing all packets from the queue and calling
        !            69:     the target's output handler. This method returns when the queue becomes
        !            70:     empty or if the queue's state is no longer kIOOQStateRunning. The target's
        !            71:     output handler is called for every packet removed from the queue. Only a
        !            72:     single packet is sent to the target for every call, the packets are never
        !            73:     chained. A mutex lock enforces single threaded access to the target's
        !            74:     output handler. */
        !            75: 
        !            76:     virtual void dequeue();
        !            77: 
        !            78: /*! @function free
        !            79:     @discussion Frees the IOOQLockFIFOQueue instance. */
        !            80: 
        !            81:     virtual void free();
        !            82: 
        !            83: public:
        !            84: 
        !            85: /*! @function init
        !            86:     @discussion Initialize an IOOQLockFIFOQueue instance.
        !            87:     @param target The object that shall receive packets from the queue,
        !            88:     and is usually a subclass of IONetworkController. If the target is
        !            89:     not an IONetworkController instance, then the target must immediately
        !            90:     call registerOutputHandler() after initializing the queue.
        !            91:     @param capacity The initial capacity of the output queue, defined as
        !            92:     the number of packets that the queue can hold without dropping.
        !            93:     @result true if initialized successfully, false otherwise. */
        !            94: 
        !            95:     virtual bool init(OSObject * target, UInt32 capacity = 0);
        !            96: 
        !            97: /*! @function withTarget
        !            98:     @discussion Factory method that will construct and initialize an
        !            99:     IOOQLockFIFOQueue instance.
        !           100:     @param target Same as init().
        !           101:     @param capacity Same as init().
        !           102:     @result An IOOQLockFIFOQueue instance upon success, or 0 otherwise. */
        !           103: 
        !           104:     static IOOQLockFIFOQueue * withTarget(OSObject * target,
        !           105:                                           UInt32     capacity = 0);
        !           106: 
        !           107: /*! @function enqueue
        !           108:     @discussion Handles packet (or a packet chain) sent to the queue.
        !           109:     This method can handle calls from multiple simultaneous client threads.
        !           110:     A client thread that calls enqueue() will acquire a mutex lock and
        !           111:     call dequeue() if it detects that no other thread is actively
        !           112:     dequeueing packets from the queue. The dequeue() method will return
        !           113:     when the queue becomes empty, or if the target stalls the queue.
        !           114:     This method may block its caller.
        !           115:     @param m The packet (or a packet chain) to be queued for transmission.
        !           116:     @result The number of dropped packets. */
        !           117: 
        !           118:     virtual UInt32 enqueue(struct mbuf * m);
        !           119: 
        !           120: /*! @function start
        !           121:     @discussion This method is called by the target to start the queue.
        !           122:     Once started, the queue will be allowed to call the target's
        !           123:     output handler. Before that, with the queue stopped, the queue will
        !           124:     absorb incoming packets sent to the enqueue() method, but no packets
        !           125:     will be dequeued, and the target's output handler will not be called.
        !           126:     @result true if the queue was successfully started, false otherwise. */
        !           127: 
        !           128:     virtual bool start();
        !           129: 
        !           130: /*! @function stop
        !           131:     @discussion Stops the queue to prevent it from calling the target's
        !           132:     output handler. This call is synchronous the caller may block.
        !           133:     The target's output handler must never call this method, or any other
        !           134:     queue methods. */
        !           135: 
        !           136:     virtual void stop();
        !           137: 
        !           138: /*! @function service
        !           139:     @discussion If the queue becomes stalled, then service() must be called
        !           140:     to restart the queue when the target is ready to accept more packets.
        !           141:     If the queue is not empty, this method will also call dequeue().
        !           142:     Note that if the target never sends a kIOOQReturnActionStall action 
        !           143:     code to the queue, then the queue will never stall on its own accord.
        !           144:     Calling this method on a running queue that is not stalled is harmless.
        !           145:     @param sync True if the service action should be performed synchronously,
        !           146:     false to perform the action asynchronously without blocking the caller,
        !           147:     but with a much higher latency cost.
        !           148:     @result true if the queue needed servicing, false otherwise. */
        !           149: 
        !           150:     virtual bool service(bool sync = true);
        !           151: };
        !           152: 
        !           153: #endif /* !_IOOQLOCKFIFOQUEUE_H */

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