1 /* 2 * Copyright (C) 2005-2018 Team Kodi 3 * This file is part of Kodi - https://kodi.tv 4 * 5 * SPDX-License-Identifier: GPL-2.0-or-later 6 * See LICENSES/README.md for more information. 7 */ 8 9 #pragma once 10 11 class CJob; 12 13 #include <stddef.h> 14 15 #define kJobTypeMediaFlags "mediaflags" 16 #define kJobTypeCacheImage "cacheimage" 17 #define kJobTypeDDSCompress "ddscompress" 18 19 /*! 20 \ingroup jobs 21 \brief Callback interface for asynchronous jobs. 22 23 Used by clients of the CJobManager to receive progress and completion notification of jobs. 24 Clients of small jobs wishing to perform actions on job completion should implement the 25 IJobCallback::OnJobComplete() function. Clients of larger jobs may choose to implement the 26 IJobCallback::OnJobProgress() function in order to be kept informed of progress. 27 28 \sa CJobManager and CJob 29 */ 30 class IJobCallback 31 { 32 public: 33 /*! 34 \brief Destructor for job call back objects. 35 36 \sa CJobManager and CJob 37 */ 38 virtual ~IJobCallback() = default; 39 40 /*! 41 \brief The callback used when a job completes. 42 43 OnJobComplete is called at the completion of the job's DoWork() function, and is used 44 to return information to the caller on the result of the job. On returning form this function 45 the CJobManager will destroy this job. 46 47 \param jobID the unique id of the job (as retrieved from CJobManager::AddJob) 48 \param success the result from the DoWork call 49 \param job the job that has been processed. The job will be destroyed after this function returns 50 \sa CJobManager and CJob 51 */ 52 virtual void OnJobComplete(unsigned int jobID, bool success, CJob *job)=0; 53 54 /*! 55 \brief An optional callback function that a job may call while processing. 56 57 OnJobProgress may be called periodically by a job during it's DoWork() function. It is used 58 by the job to report on progress. 59 60 \param jobID the unique id of the job (as retrieved from CJobManager::AddJob) 61 \param progress the current progress of the job, out of total. 62 \param total the total amount of work to be processed. 63 \param job the job that has been processed. 64 \sa CJobManager and CJob 65 */ OnJobProgress(unsigned int jobID,unsigned int progress,unsigned int total,const CJob * job)66 virtual void OnJobProgress(unsigned int jobID, unsigned int progress, unsigned int total, const CJob *job) {}; 67 }; 68 69 class CJobManager; 70 71 /*! 72 \ingroup jobs 73 \brief Base class for jobs that are executed asynchronously. 74 75 Clients of the CJobManager should subclass CJob and provide the DoWork() function. Data should be 76 passed to the job on creation, and any data sharing between the job and the client should be kept to within 77 the callback functions if possible, and guarded with critical sections as appropriate. 78 79 Jobs typically fall into two groups: small jobs that perform a single function, and larger jobs that perform a 80 sequence of functions. Clients with small jobs should implement the IJobCallback::OnJobComplete() callback to receive results. 81 Clients with larger jobs may wish to implement both the IJobCallback::OnJobComplete() and IJobCallback::OnJobProgress() 82 callbacks to receive updates. Jobs may be cancelled at any point by the client via CJobManager::CancelJob(), however 83 effort should be taken to ensure that any callbacks and cancellation is suitably guarded against simultaneous thread access. 84 85 Handling cancellation of jobs within the OnJobProgress callback is a threadsafe operation, as all execution is 86 then in the Job thread. 87 88 \sa CJobManager and IJobCallback 89 */ 90 class CJob 91 { 92 public: 93 /*! 94 \brief Priority levels for jobs, specified by clients when adding jobs to the CJobManager. 95 \sa CJobManager 96 */ 97 enum PRIORITY { 98 PRIORITY_LOW_PAUSABLE = 0, 99 PRIORITY_LOW, 100 PRIORITY_NORMAL, 101 PRIORITY_HIGH, 102 PRIORITY_DEDICATED, // will create a new worker if no worker is available at queue time 103 }; CJob()104 CJob() { m_callback = NULL; }; 105 106 /*! 107 \brief Destructor for job objects. 108 109 Jobs are destroyed by the CJobManager after the OnJobComplete() callback is complete. 110 CJob subclasses should therefore supply a virtual destructor to cleanup any memory allocated by 111 complete or cancelled jobs. 112 113 \sa CJobManager 114 */ 115 virtual ~CJob() = default; 116 117 /*! 118 \brief Main workhorse function of CJob instances 119 120 All CJob subclasses must implement this function, performing all processing. Once this function 121 is complete, the OnJobComplete() callback is called, and the job is then destroyed. 122 123 \sa CJobManager, IJobCallback::OnJobComplete() 124 */ 125 virtual bool DoWork() = 0; // function to do the work 126 127 /*! 128 \brief Function that returns the type of job. 129 130 CJob subclasses may optionally implement this function to specify the type of job. 131 This is useful for the CJobManager::AddLIFOJob() routine, which preempts similar jobs 132 with the new job. 133 134 \return a unique character string describing the job. 135 \sa CJobManager 136 */ GetType()137 virtual const char *GetType() const { return ""; }; 138 139 virtual bool operator==(const CJob* job) const 140 { 141 return false; 142 } 143 144 /*! 145 \brief Function for longer jobs to report progress and check whether they have been cancelled. 146 147 Jobs that contain loops that may take time should check this routine each iteration of the loop, 148 both to (optionally) report progress, and to check for cancellation. 149 150 \param progress the amount of the job performed, out of total. 151 \param total the total amount of processing to be performed 152 \return if true, the job has been asked to cancel. 153 154 \sa IJobCallback::OnJobProgress() 155 */ 156 virtual bool ShouldCancel(unsigned int progress, unsigned int total) const; 157 private: 158 friend class CJobManager; 159 CJobManager *m_callback; 160 }; 161