include/qemu/job.h

   1 /*
   2  * Declarations for background jobs
   3  *
   4  * Copyright (c) 2011 IBM Corp.
   5  * Copyright (c) 2012, 2018 Red Hat, Inc.
   6  *
   7  * Permission is hereby granted, free of charge, to any person obtaining a copy
   8  * of this software and associated documentation files (the "Software"), to deal
   9  * in the Software without restriction, including without limitation the rights
  10  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  11  * copies of the Software, and to permit persons to whom the Software is
  12  * furnished to do so, subject to the following conditions:
  13  *
  14  * The above copyright notice and this permission notice shall be included in
  15  * all copies or substantial portions of the Software.
  16  *
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
  20  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  21  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  22  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  23  * THE SOFTWARE.
  24  */
  25
  26 #ifndef JOB_H
  27 #define JOB_H
  28
  29 #include "qapi/qapi-types-block-core.h"
  30 #include "qemu/queue.h"
  31
  32 typedef struct JobDriver JobDriver;
  33
  34 /**
  35  * Long-running operation.
  36  */
  37 typedef struct Job {
  38     /** The ID of the job. May be NULL for internal jobs. */
  39     char *id;
  40
  41     /** The type of this job. */
  42     const JobDriver *driver;
  43
  44     /** Reference count of the block job */
  45     int refcnt;
  46
  47     /** Current state; See @JobStatus for details. */
  48     JobStatus status;
  49
  50     /** AioContext to run the job coroutine in */
  51     AioContext *aio_context;
  52
  53     /**
  54      * Set to true if the job should cancel itself.  The flag must
  55      * always be tested just before toggling the busy flag from false
  56      * to true.  After a job has been cancelled, it should only yield
  57      * if #aio_poll will ("sooner or later") reenter the coroutine.
  58      */
  59     bool cancelled;
  60
  61     /** Element of the list of jobs */
  62     QLIST_ENTRY(Job) job_list;
  63 } Job;
  64
  65 /**
  66  * Callbacks and other information about a Job driver.
  67  */
  68 struct JobDriver {
  69     /** Derived Job struct size */
  70     size_t instance_size;
  71
  72     /** Enum describing the operation */
  73     JobType job_type;
  74
  75     /** Called when the job is freed */
  76     void (*free)(Job *job);
  77 };
  78
  79
  80 /**
  81  * Create a new long-running job and return it.
  82  *
  83  * @job_id: The id of the newly-created job, or %NULL for internal jobs
  84  * @driver: The class object for the newly-created job.
  85  * @ctx: The AioContext to run the job coroutine in.
  86  * @errp: Error object.
  87  */
  88 void *job_create(const char *job_id, const JobDriver *driver, AioContext *ctx,
  89                  Error **errp);
  90
  91 /**
  92  * Add a reference to Job refcnt, it will be decreased with job_unref, and then
  93  * be freed if it comes to be the last reference.
  94  */
  95 void job_ref(Job *job);
  96
  97 /**
  98  * Release a reference that was previously acquired with job_ref() or
  99  * job_create(). If it's the last reference to the object, it will be freed.
 100  */
 101 void job_unref(Job *job);
 102
 103 /** Returns the JobType of a given Job. */
 104 JobType job_type(const Job *job);
 105
 106 /** Returns the enum string for the JobType of a given Job. */
 107 const char *job_type_str(const Job *job);
 108
 109 /** Returns whether the job is scheduled for cancellation. */
 110 bool job_is_cancelled(Job *job);
 111
 112 /**
 113  * Get the next element from the list of block jobs after @job, or the
 114  * first one if @job is %NULL.
 115  *
 116  * Returns the requested job, or %NULL if there are no more jobs left.
 117  */
 118 Job *job_next(Job *job);
 119
 120 /**
 121  * Get the job identified by @id (which must not be %NULL).
 122  *
 123  * Returns the requested job, or %NULL if it doesn't exist.
 124  */
 125 Job *job_get(const char *id);
 126
 127 /**
 128  * Check whether the verb @verb can be applied to @job in its current state.
 129  * Returns 0 if the verb can be applied; otherwise errp is set and -EPERM
 130  * returned.
 131  */
 132 int job_apply_verb(Job *job, JobVerb verb, Error **errp);
 133
 134 /* TODO To be removed from the public interface */
 135 void job_state_transition(Job *job, JobStatus s1);
 136
 137 #endif