1/* -*- C++ -*-
2 This file declares the QueuePolicy class.
3
4 SPDX-FileCopyrightText: 2004, 2005, 2006 Mirko Boehm <mirko@kde.org>
5
6 SPDX-License-Identifier: LGPL-2.0-or-later
7
8 $Id: DebuggingAids.h 30 2005-08-16 16:16:04Z mirko $
9*/
10
11#ifndef QUEUEPOLICY_H
12#define QUEUEPOLICY_H
13
14#include "jobpointer.h"
15#include "threadweaver_export.h"
16
17namespace ThreadWeaver
18{
19class JobInterface;
20
21/*!
22 * \class ThreadWeaver::QueuePolicy
23 * \inheaderfile ThreadWeaver/QueuePolicy
24 * \inmodule ThreadWeaver
25 *
26 * \brief QueuePolicy is an interface for customizations of the queueing behaviour of jobs.
27 *
28 * A job can have a number of queue policies assigned. In that case, the job is only
29 * executed when the method canRun() of all assigned policies return true. For every call to
30 * canRun() that returns true, it is guaranteed that the method free() or the method release()
31 * is called. Calling free() means the job has been executed, while calling release() means
32 * the job was not executed for external reasons, and will be tried later on.
33 *
34 * As an example, dependencies can be implemented using a QueuePolicy: canRun() returns true
35 * when the job has no unresolved dependencies. free() and release() are empty.
36 *
37 * A job can have multiple queue policies assigned, and will only be executed if all of them
38 * return true from canRun() within the same execution attempt. Jobs only keep a reference to the
39 * QueuePolicy. Therefore, the same policy object can be assigned to multiple jobs and this way
40 * control the way all those jobs are executed. Jobs never assume ownership of their assigned queue
41 * policies.
42 */
43class THREADWEAVER_EXPORT QueuePolicy
44{
45public:
46 /*!
47 */
48 virtual ~QueuePolicy()
49 {
50 }
51
52 /*! \brief canRun() is called before the job is executed.
53 * The job will only be executed if canRun() returns true.
54 */
55 virtual bool canRun(JobPointer) = 0;
56
57 /*! \brief free() is called after the job has been executed.
58 * It is guaranteed that free is called only after canRun()
59 * returned true at an earlier time.
60 */
61 virtual void free(JobPointer) = 0;
62
63 /*! \brief release() is called if canRun() returned true, but the job has not been executed for external reasons.
64 *
65 * For example, a second QueuePolicy could have returned false from canRun() for the same job.
66 */
67 virtual void release(JobPointer) = 0;
68
69 /*! \brief destructing() is called when a Job that has this queue policy assigned gets destructed.
70 */
71 virtual void destructed(JobInterface *job) = 0;
72};
73
74}
75
76#endif
77

source code of threadweaver/src/queuepolicy.h