251 lines
7.4 KiB
C
251 lines
7.4 KiB
C
/*
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* Declarations for background jobs
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*
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* Copyright (c) 2011 IBM Corp.
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* Copyright (c) 2012, 2018 Red Hat, Inc.
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#ifndef JOB_H
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#define JOB_H
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#include "qapi/qapi-types-block-core.h"
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#include "qemu/queue.h"
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#include "qemu/coroutine.h"
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typedef struct JobDriver JobDriver;
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/**
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* Long-running operation.
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*/
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typedef struct Job {
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/** The ID of the job. May be NULL for internal jobs. */
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char *id;
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/** The type of this job. */
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const JobDriver *driver;
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/** Reference count of the block job */
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int refcnt;
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/** Current state; See @JobStatus for details. */
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JobStatus status;
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/** AioContext to run the job coroutine in */
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AioContext *aio_context;
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/**
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* The coroutine that executes the job. If not NULL, it is reentered when
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* busy is false and the job is cancelled.
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*/
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Coroutine *co;
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/**
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* Timer that is used by @job_sleep_ns. Accessed under job_mutex (in
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* job.c).
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*/
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QEMUTimer sleep_timer;
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/**
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* Counter for pause request. If non-zero, the block job is either paused,
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* or if busy == true will pause itself as soon as possible.
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*/
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int pause_count;
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/**
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* Set to false by the job while the coroutine has yielded and may be
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* re-entered by block_job_enter(). There may still be I/O or event loop
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* activity pending. Accessed under block_job_mutex (in blockjob.c).
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*/
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bool busy;
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/**
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* Set to true by the job while it is in a quiescent state, where
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* no I/O or event loop activity is pending.
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*/
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bool paused;
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/**
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* Set to true if the job should cancel itself. The flag must
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* always be tested just before toggling the busy flag from false
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* to true. After a job has been cancelled, it should only yield
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* if #aio_poll will ("sooner or later") reenter the coroutine.
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*/
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bool cancelled;
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/** Set to true when the job has deferred work to the main loop. */
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bool deferred_to_main_loop;
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/** Element of the list of jobs */
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QLIST_ENTRY(Job) job_list;
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} Job;
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/**
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* Callbacks and other information about a Job driver.
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*/
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struct JobDriver {
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/** Derived Job struct size */
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size_t instance_size;
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/** Enum describing the operation */
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JobType job_type;
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/** Mandatory: Entrypoint for the Coroutine. */
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CoroutineEntry *start;
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/**
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* If the callback is not NULL, it will be invoked when the job transitions
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* into the paused state. Paused jobs must not perform any asynchronous
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* I/O or event loop activity. This callback is used to quiesce jobs.
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*/
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void coroutine_fn (*pause)(Job *job);
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/**
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* If the callback is not NULL, it will be invoked when the job transitions
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* out of the paused state. Any asynchronous I/O or event loop activity
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* should be restarted from this callback.
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*/
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void coroutine_fn (*resume)(Job *job);
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/** Called when the job is freed */
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void (*free)(Job *job);
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};
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/**
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* Create a new long-running job and return it.
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*
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* @job_id: The id of the newly-created job, or %NULL for internal jobs
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* @driver: The class object for the newly-created job.
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* @ctx: The AioContext to run the job coroutine in.
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* @errp: Error object.
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*/
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void *job_create(const char *job_id, const JobDriver *driver, AioContext *ctx,
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Error **errp);
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/**
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* Add a reference to Job refcnt, it will be decreased with job_unref, and then
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* be freed if it comes to be the last reference.
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*/
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void job_ref(Job *job);
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/**
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* Release a reference that was previously acquired with job_ref() or
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* job_create(). If it's the last reference to the object, it will be freed.
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*/
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void job_unref(Job *job);
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/**
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* Conditionally enter the job coroutine if the job is ready to run, not
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* already busy and fn() returns true. fn() is called while under the job_lock
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* critical section.
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*/
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void job_enter_cond(Job *job, bool(*fn)(Job *job));
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/**
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* @job: A job that has not yet been started.
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*
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* Begins execution of a job.
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* Takes ownership of one reference to the job object.
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*/
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void job_start(Job *job);
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/**
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* @job: The job to enter.
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*
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* Continue the specified job by entering the coroutine.
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*/
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void job_enter(Job *job);
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/**
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* @job: The job that is ready to pause.
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*
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* Pause now if job_pause() has been called. Jobs that perform lots of I/O
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* must call this between requests so that the job can be paused.
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*/
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void coroutine_fn job_pause_point(Job *job);
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/**
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* @job: The job that calls the function.
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* @ns: How many nanoseconds to stop for.
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*
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* Put the job to sleep (assuming that it wasn't canceled) for @ns
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* %QEMU_CLOCK_REALTIME nanoseconds. Canceling the job will immediately
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* interrupt the wait.
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*/
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void coroutine_fn job_sleep_ns(Job *job, int64_t ns);
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/** Returns the JobType of a given Job. */
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JobType job_type(const Job *job);
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/** Returns the enum string for the JobType of a given Job. */
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const char *job_type_str(const Job *job);
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/** Returns whether the job is scheduled for cancellation. */
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bool job_is_cancelled(Job *job);
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/**
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* Get the next element from the list of block jobs after @job, or the
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* first one if @job is %NULL.
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*
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* Returns the requested job, or %NULL if there are no more jobs left.
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*/
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Job *job_next(Job *job);
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/**
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* Get the job identified by @id (which must not be %NULL).
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*
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* Returns the requested job, or %NULL if it doesn't exist.
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*/
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Job *job_get(const char *id);
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/**
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* Check whether the verb @verb can be applied to @job in its current state.
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* Returns 0 if the verb can be applied; otherwise errp is set and -EPERM
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* returned.
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*/
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int job_apply_verb(Job *job, JobVerb verb, Error **errp);
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typedef void JobDeferToMainLoopFn(Job *job, void *opaque);
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/**
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* @job: The job
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* @fn: The function to run in the main loop
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* @opaque: The opaque value that is passed to @fn
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*
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* This function must be called by the main job coroutine just before it
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* returns. @fn is executed in the main loop with the job AioContext acquired.
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*
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* Block jobs must call bdrv_unref(), bdrv_close(), and anything that uses
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* bdrv_drain_all() in the main loop.
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*
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* The @job AioContext is held while @fn executes.
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*/
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void job_defer_to_main_loop(Job *job, JobDeferToMainLoopFn *fn, void *opaque);
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/* TODO To be removed from the public interface */
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void job_state_transition(Job *job, JobStatus s1);
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void coroutine_fn job_do_yield(Job *job, uint64_t ns);
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bool job_should_pause(Job *job);
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bool job_started(Job *job);
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#endif
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