/*

    File:       WorkerThread.c

    Description: Sample code showing how to send messages between the main thread and a worker pthread.

                 You could have an instance of this worker pthread interface for each window, for example.

    Author:     QuickTime Engineering

    Copyright:  © Copyright 2003-2004 Apple Computer, Inc. All rights reserved.

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    Change History (most recent first):  <1> dts 04/05/04 minor fixes for initial release

*/

#ifndef WORKER_THREAD_H

#define WORKER_THREAD_H

#include <CoreServices/CoreServices.h>

// This is the interface to a worker thread.

struct WorkerThread;

typedef struct WorkerThread *WorkerThreadRef;

// This encapsulates individual work requests that will be performed by a worker thread.

struct WorkerRequest;

typedef struct WorkerRequest *WorkerRequestRef;

// This is the routine called on the worker thread

typedef void (*WorkerActionRoutine)( void *refcon, WorkerRequestRef request );

// This is a routine that can be called to cancel the current action

// while WorkerActionRoutine is running.  (It's not called for requests that are 

// cancelled before the action starts.)  

/// If there's no way to do that, pass NULL to createWorkerThread instead.

typedef void (*WorkerCancelRoutine)( void *refcon, WorkerRequestRef request );

// This is called on the main thread after a request is completed or cancelled

typedef void (*WorkerResponseMainThreadCallback)( void *refcon, WorkerRequestRef request );

// Call this on the main thread to create a worker thread to run your requests.

OSErr createWorkerThread(

    WorkerActionRoutine actionRoutine,

    WorkerCancelRoutine cancelRoutine,

    WorkerResponseMainThreadCallback responseCallback,

    void *refcon,

    WorkerThreadRef *outWorker );

// In case you need it.

void retainWorkerThread(

    WorkerThreadRef worker );

// Call this on the main thread to release the worker thread.  

// This does not block; when when the reference count drops to zero and the worker thread 

// has finished all work, it will clean up by itself.

void releaseWorkerThread(

    WorkerThreadRef worker );

// Call this from the main thread to create a request object; then set attributes 

// of the request object and send it.  When the request is done, your responseCallback 

// will be called on the main thread.  If you want to cancel the request early,

// call cancelWorkerRequest from the main thread.  If not cancelled before it finishes,

// the request will be handled by a call to your actionRoutine on the worker thread.

OSErr createWorkerRequest( 

    WorkerThreadRef worker, 

    WorkerRequestRef *outRequest );

// These are setters and getters for objects or values that are passed between the 

// main thread and worker thread.  The messaging code doesn't care about these, and you

// can add whatever extra fields and accessors you want.

// These accessors are not protected; you must prevent your code from manipulating 

// a request's objects from the main thread between sending the request and receiving 

// the response.

OSErr setWorkerRequestFile( 

    WorkerRequestRef request, 

    FSRef fileRef );

OSErr getWorkerRequestFile( 

    WorkerRequestRef request, 

    FSRef *fileRef );

OSErr setWorkerRequestDoc( 

    WorkerRequestRef request, 

    UInt32 doc );

OSErr getWorkerRequestDoc ( 

        WorkerRequestRef request, 

        UInt32 *doc );

OSErr setWorkerRequestThreadData ( 

    WorkerRequestRef request, 

    void * threadData );

OSErr getWorkerRequestThreadData ( 

        WorkerRequestRef request, 

        void **threadDataPtr );

// ++ add more accessors as you like ++

// Call this to schedule the request to be sent to the worker thread.

// The worker thread will process them in first-in, first-out order.

// If you don't want to send the request after all, just release it 

// before sending.

OSErr sendWorkerRequest( 

    WorkerRequestRef request );

// Call this from the main thread to cancel an already-scheduled request.

// If the request has not yet started, the action routine will not be called;

// if the action routine has started running, the cancel routine (if provided) 

// will be called.  If the action routine has completed, this will have no effect.

void cancelWorkerRequest( 

    WorkerRequestRef request );

// Call this from your response callback to find out whether the request was cancelled.

Boolean wasWorkerRequestCancelled( 

    WorkerRequestRef request );

// I'm not sure if clients will ever need to call this, but here it is.

void retainWorkerRequest( 

    WorkerRequestRef request );

// Call this from your response callback to release the worker request.

// If you don't release requests, you will leak not only the request entries but the worker thread too.

void releaseWorkerRequest( 

    WorkerRequestRef request );

#endif // WORKER_THREAD_H