/*
* Declarations for background jobs
*
* Copyright (c) 2011 IBM Corp.
* Copyright (c) 2012, 2018 Red Hat, Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#ifndef JOB_H
#define JOB_H
#include "qapi/qapi-types-job.h"
#include "qemu/queue.h"
#include "qemu/progress_meter.h"
#include "qemu/coroutine.h"
#include "block/aio.h"
typedef struct JobDriver JobDriver;
typedef struct JobTxn JobTxn;
/**
* Long-running operation.
*/
typedef struct Job {
/* Fields set at initialization (job_create), and never modified */
/** The ID of the job. May be NULL for internal jobs. */
char *id;
/**
* The type of this job.
* All callbacks are called with job_mutex *not* held.
*/
const JobDriver *driver;
/**
* The coroutine that executes the job. If not NULL, it is reentered when
* busy is false and the job is cancelled.
* Initialized in job_start()
*/
Coroutine *co;
/** True if this job should automatically finalize itself */
bool auto_finalize;
/** True if this job should automatically dismiss itself */
bool auto_dismiss;
/**
* The completion function that will be called when the job completes.
* Called with AioContext lock held, since many callback implementations
* use bdrv_* functions that require to hold the lock.
*/
BlockCompletionFunc *cb;
/** The opaque value that is passed to the completion function. */
void *opaque;
/* ProgressMeter API is thread-safe */
ProgressMeter progress;
/**
* AioContext to run the job coroutine in.
* The job Aiocontext can be read when holding *either*
* the BQL (so we are in the main loop) or the job_mutex.
* It can only be written when we hold *both* BQL
* and the job_mutex.
*/
AioContext *aio_context;
/** Protected by job_mutex */
/** Reference count of the block job */
int refcnt;
/** Current state; See @JobStatus for details. */
JobStatus status;
/**
* Timer that is used by @job_sleep_ns. Accessed under job_mutex (in
* job.c).
*/
QEMUTimer sleep_timer;
/**
* Counter for pause request. If non-zero, the block job is either paused,
* or if busy == true will pause itself as soon as possible.
*/
int pause_count;
/**
* Set to false by the job while the coroutine has yielded and may be
* re-entered by job_enter(). There may still be I/O or event loop activity
* pending. Accessed under job_mutex.
*
* When the job is deferred to the main loop, busy is true as long as the
* bottom half is still pending.
*/
bool busy;
/**
* Set to true by the job while it is in a quiescent state, where
* no I/O or event loop activity is pending.
*/
bool paused;
/**
* Set to true if the job is paused by user. Can be unpaused with the
* block-job-resume QMP command.
*/
bool user_paused;
/**
* Set to true if the job should cancel itself. The flag must
* always be tested just before toggling the busy flag from false
* to true. After a job has been cancelled, it should only yield
* if #aio_poll will ("sooner or later") reenter the coroutine.
*/
bool cancelled;
/**
* Set to true if the job should abort immediately without waiting
* for data to be in sync.
*/
bool force_cancel;
/** Set to true when the job has deferred work to the main loop. */
bool deferred_to_main_loop;
/**
* Return code from @run and/or @prepare callback(s).
* Not final until the job has reached the CONCLUDED status.
* 0 on success, -errno on failure.
*/
int ret;
/**
* Error object for a failed job.
* If job->ret is nonzero and an error object was not set, it will be set
* to strerror(-job->ret) during job_completed.
*/
Error *err;
/** Notifiers called when a cancelled job is finalised */
NotifierList on_finalize_cancelled;
/** Notifiers called when a successfully completed job is finalised */
NotifierList on_finalize_completed;
/** Notifiers called when the job transitions to PENDING */
NotifierList on_pending;
/** Notifiers called when the job transitions to READY */
NotifierList on_ready;
/** Notifiers called when the job coroutine yields or terminates */
NotifierList on_idle;
/** Element of the list of jobs */
QLIST_ENTRY(Job) job_list;
/** Transaction this job is part of */
JobTxn *txn;
/** Element of the list of jobs in a job transaction */
QLIST_ENTRY(Job) txn_list;
} Job;
/**
* Callbacks and other information about a Job driver.
* All callbacks are invoked with job_mutex *not* held.
*/
struct JobDriver {
/*
* These fields are initialized when this object is created,
* and are never changed afterwards
*/
/** Derived Job struct size */
size_t instance_size;
/** Enum describing the operation */
JobType job_type;
/**
* Mandatory: Entrypoint for the Coroutine.
*
* This callback will be invoked when moving from CREATED to RUNNING.
*
* If this callback returns nonzero, the job transaction it is part of is
* aborted. If it returns zero, the job moves into the WAITING state. If it
* is the last job to complete in its transaction, all jobs in the
* transaction move from WAITING to PENDING.
*
* This callback must be run in the job's context.
*/
int coroutine_fn (*run)(Job *job, Error **errp);
/*
* Functions run without regard to the BQL that may run in any
* arbitrary thread. These functions do not need to be thread-safe
* because the caller ensures that they are invoked from one
* thread at time.
*/
/**
* If the callback is not NULL, it will be invoked when the job transitions
* into the paused state. Paused jobs must not perform any asynchronous
* I/O or event loop activity. This callback is used to quiesce jobs.
*/
void coroutine_fn (*pause)(Job *job);
/**
* If the callback is not NULL, it will be invoked when the job transitions
* out of the paused state. Any asynchronous I/O or event loop activity
* should be restarted from this callback.
*/
void coroutine_fn (*resume)(Job *job);
/*
* Global state (GS) API. These functions run under the BQL.
*
* See include/block/block-global-state.h for more information about
* the GS API.
*/
/**
* Called when the job is resumed by the user (i.e. user_paused becomes
* false). .user_resume is called before .resume.
*/
void (*user_resume)(Job *job);
/**
* Optional callback for job types whose completion must be triggered
* manually.
*/
void (*complete)(Job *job, Error **errp);
/**
* If the callback is not NULL, prepare will be invoked when all the jobs
* belonging to the same transaction complete; or upon this job's completion
* if it is not in a transaction.
*
* This callback will not be invoked if the job has already failed.
* If it fails, abort and then clean will be called.
*
* Called with AioContext lock held, since many callbacs implementations
* use bdrv_* functions that require to hold the lock.
*/
int (*prepare)(Job *job);
/**
* If the callback is not NULL, it will be invoked when all the jobs
* belonging to the same transaction complete; or upon this job's
* completion if it is not in a transaction. Skipped if NULL.
*
* All jobs will complete with a call to either .commit() or .abort() but
* never both.
*
* Called with AioContext lock held, since many callback implementations
* use bdrv_* functions that require to hold the lock.
*/
void (*commit)(Job *job);
/**
* If the callback is not NULL, it will be invoked when any job in the
* same transaction fails; or upon this job's failure (due to error or
* cancellation) if it is not in a transaction. Skipped if NULL.
*
* All jobs will complete with a call to either .commit() or .abort() but
* never both.
*
* Called with AioContext lock held, since many callback implementations
* use bdrv_* functions that require to hold the lock.
*/
void (*abort)(Job *job);
/**
* If the callback is not NULL, it will be invoked after a call to either
* .commit() or .abort(). Regardless of which callback is invoked after
* completion, .clean() will always be called, even if the job does not
* belong to a transaction group.
*
* Called with AioContext lock held, since many callbacs implementations
* use bdrv_* functions that require to hold the lock.
*/
void (*clean)(Job *job);
/**
* If the callback is not NULL, it will be invoked in job_cancel_async
*
* This function must return true if the job will be cancelled
* immediately without any further I/O (mandatory if @force is
* true), and false otherwise. This lets the generic job layer
* know whether a job has been truly (force-)cancelled, or whether
* it is just in a special completion mode (like mirror after
* READY).
* (If the callback is NULL, the job is assumed to terminate
* without I/O.)
*
* Called with AioContext lock held, since many callback implementations
* use bdrv_* functions that require to hold the lock.
*/
bool (*cancel)(Job *job, bool force);
/**
* Called when the job is freed.
* Called with AioContext lock held, since many callback implementations
* use bdrv_* functions that require to hold the lock.
*/
void (*free)(Job *job);
};
typedef enum JobCreateFlags {
/* Default behavior */
JOB_DEFAULT = 0x00,
/* Job is not QMP-created and should not send QMP events */
JOB_INTERNAL = 0x01,
/* Job requires manual finalize step */
JOB_MANUAL_FINALIZE = 0x02,
/* Job requires manual dismiss step */
JOB_MANUAL_DISMISS = 0x04,
} JobCreateFlags;
extern QemuMutex job_mutex;
#define JOB_LOCK_GUARD() QEMU_LOCK_GUARD(&job_mutex)
#define WITH_JOB_LOCK_GUARD() WITH_QEMU_LOCK_GUARD(&job_mutex)
/**
* job_lock:
*
* Take the mutex protecting the list of jobs and their status.
* Most functions called by the monitor need to call job_lock
* and job_unlock manually. On the other hand, function called
* by the block jobs themselves and by the block layer will take the
* lock for you.
*/
void job_lock(void);
/**
* job_unlock:
*
* Release the mutex protecting the list of jobs and their status.
*/
void job_unlock(void);
/**
* Allocate and return a new job transaction. Jobs can be added to the
* transaction using job_txn_add_job().
*
* The transaction is automatically freed when the last job completes or is
* cancelled.
*
* All jobs in the transaction either complete successfully or fail/cancel as a
* group. Jobs wait for each other before completing. Cancelling one job
* cancels all jobs in the transaction.
*/
JobTxn *job_txn_new(void);
/**
* Release a reference that was previously acquired with job_txn_add_job or
* job_txn_new. If it's the last reference to the object, it will be freed.
*
* Called with job lock *not* held.
*/
void job_txn_unref(JobTxn *txn);
/*
* Same as job_txn_unref(), but called with job lock held.
* Might release the lock temporarily.
*/
void job_txn_unref_locked(JobTxn *txn);
/**
* Create a new long-running job and return it.
* Called with job_mutex *not* held.
*
* @job_id: The id of the newly-created job, or %NULL for internal jobs
* @driver: The class object for the newly-created job.
* @txn: The transaction this job belongs to, if any. %NULL otherwise.
* @ctx: The AioContext to run the job coroutine in.
* @flags: Creation flags for the job. See @JobCreateFlags.
* @cb: Completion function for the job.
* @opaque: Opaque pointer value passed to @cb.
* @errp: Error object.
*/
void *job_create(const char *job_id, const JobDriver *driver, JobTxn *txn,
AioContext *ctx, int flags, BlockCompletionFunc *cb,
void *opaque, Error **errp);
/**
* Add a reference to Job refcnt, it will be decreased with job_unref, and then
* be freed if it comes to be the last reference.
*
* Called with job lock held.
*/
void job_ref_locked(Job *job);
/**
* Release a reference that was previously acquired with job_ref_locked() or
* job_create(). If it's the last reference to the object, it will be freed.
*
* Takes AioContext lock internally to invoke a job->driver callback.
* Called with job lock held.
*/
void job_unref_locked(Job *job);
/**
* @job: The job that has made progress
* @done: How much progress the job made since the last call
*
* Updates the progress counter of the job.
*
* May be called with mutex held or not held.
*/
void job_progress_update(Job *job, uint64_t done);
/**
* @job: The job whose expected progress end value is set
* @remaining: Missing progress (on top of the current progress counter value)
* until the new expected end value is reached
*
* Sets the expected end value of the progress counter of a job so that a
* completion percentage can be calculated when the progress is updated.
*
* May be called with mutex held or not held.
*/
void job_progress_set_remaining(Job *job, uint64_t remaining);
/**
* @job: The job whose expected progress end value is updated
* @delta: Value which is to be added to the current expected end
* value
*
* Increases the expected end value of the progress counter of a job.
* This is useful for parenthesis operations: If a job has to
* conditionally perform a high-priority operation as part of its
* progress, it calls this function with the expected operation's
* length before, and job_progress_update() afterwards.
* (So the operation acts as a parenthesis in regards to the main job
* operation running in background.)
*
* May be called with mutex held or not held.
*/
void job_progress_increase_remaining(Job *job, uint64_t delta);
/**
* Conditionally enter the job coroutine if the job is ready to run, not
* already busy and fn() returns true. fn() is called while under the job_lock
* critical section.
*
* Called with job lock held, but might release it temporarily.
*/
void job_enter_cond_locked(Job *job, bool(*fn)(Job *job));
/**
* @job: A job that has not yet been started.
*
* Begins execution of a job.
* Takes ownership of one reference to the job object.
*
* Called with job_mutex *not* held.
*/
void job_start(Job *job);
/**
* @job: The job to enter.
*
* Continue the specified job by entering the coroutine.
* Called with job_mutex *not* held.
*/
void job_enter(Job *job);
/**
* @job: The job that is ready to pause.
*
* Pause now if job_pause() has been called. Jobs that perform lots of I/O
* must call this between requests so that the job can be paused.
*
* Called with job_mutex *not* held.
*/
void coroutine_fn job_pause_point(Job *job);
/**
* @job: The job that calls the function.
*
* Yield the job coroutine.
* Called with job_mutex *not* held.
*/
void coroutine_fn job_yield(Job *job);
/**
* @job: The job that calls the function.
* @ns: How many nanoseconds to stop for.
*
* Put the job to sleep (assuming that it wasn't canceled) for @ns
* %QEMU_CLOCK_REALTIME nanoseconds. Canceling the job will immediately
* interrupt the wait.
*
* Called with job_mutex *not* held.
*/
void coroutine_fn job_sleep_ns(Job *job, int64_t ns);
/** Returns the JobType of a given Job. */
JobType job_type(const Job *job);
/** Returns the enum string for the JobType of a given Job. */
const char *job_type_str(const Job *job);
/** Returns true if the job should not be visible to the management layer. */
bool job_is_internal(Job *job);
/**
* Returns whether the job is being cancelled.
* Called with job_mutex *not* held.
*/
bool job_is_cancelled(Job *job);
/* Same as job_is_cancelled(), but called with job lock held. */
bool job_is_cancelled_locked(Job *job);
/**
* Returns whether the job is scheduled for cancellation (at an
* indefinite point).
* Called with job_mutex *not* held.
*/
bool job_cancel_requested(Job *job);
/**
* Returns whether the job is in a completed state.
* Called with job lock held.
*/
bool job_is_completed_locked(Job *job);
/**
* Returns whether the job is ready to be completed.
* Called with job_mutex *not* held.
*/
bool job_is_ready(Job *job);
/* Same as job_is_ready(), but called with job lock held. */
bool job_is_ready_locked(Job *job);
/**
* Request @job to pause at the next pause point. Must be paired with
* job_resume(). If the job is supposed to be resumed by user action, call
* job_user_pause_locked() instead.
*
* Called with job lock *not* held.
*/
void job_pause(Job *job);
/* Same as job_pause(), but called with job lock held. */
void job_pause_locked(Job *job);
/** Resumes a @job paused with job_pause. Called with job lock *not* held. */
void job_resume(Job *job);
/*
* Same as job_resume(), but called with job lock held.
* Might release the lock temporarily.
*/
void job_resume_locked(Job *job);
/**
* Asynchronously pause the specified @job.
* Do not allow a resume until a matching call to job_user_resume.
* Called with job lock held.
*/
void job_user_pause_locked(Job *job, Error **errp);
/**
* Returns true if the job is user-paused.
* Called with job lock held.
*/
bool job_user_paused_locked(Job *job);
/**
* Resume the specified @job.
* Must be paired with a preceding job_user_pause_locked.
* Called with job lock held, but might release it temporarily.
*/
void job_user_resume_locked(Job *job, Error **errp);
/**
* Get the next element from the list of block jobs after @job, or the
* first one if @job is %NULL.
*
* Returns the requested job, or %NULL if there are no more jobs left.
* Called with job lock *not* held.
*/
Job *job_next(Job *job);
/* Same as job_next(), but called with job lock held. */
Job *job_next_locked(Job *job);
/**
* Get the job identified by @id (which must not be %NULL).
*
* Returns the requested job, or %NULL if it doesn't exist.
* Called with job lock held.
*/
Job *job_get_locked(const char *id);
/**
* Check whether the verb @verb can be applied to @job in its current state.
* Returns 0 if the verb can be applied; otherwise errp is set and -EPERM
* returned.
*
* Called with job lock held.
*/
int job_apply_verb_locked(Job *job, JobVerb verb, Error **errp);
/**
* The @job could not be started, free it.
* Called with job_mutex *not* held.
*/
void job_early_fail(Job *job);
/**
* Moves the @job from RUNNING to READY.
* Called with job_mutex *not* held.
*/
void job_transition_to_ready(Job *job);
/**
* Asynchronously complete the specified @job.
* Called with job lock held, but might release it temporarily.
*/
void job_complete_locked(Job *job, Error **errp);
/**
* Asynchronously cancel the specified @job. If @force is true, the job should
* be cancelled immediately without waiting for a consistent state.
* Called with job lock held.
*/
void job_cancel_locked(Job *job, bool force);
/**
* Cancels the specified job like job_cancel_locked(), but may refuse
* to do so if the operation isn't meaningful in the current state of the job.
* Called with job lock held.
*/
void job_user_cancel_locked(Job *job, bool force, Error **errp);
/**
* Synchronously cancel the @job. The completion callback is called
* before the function returns. If @force is false, the job may
* actually complete instead of canceling itself; the circumstances
* under which this happens depend on the kind of job that is active.
*
* Returns the return value from the job if the job actually completed
* during the call, or -ECANCELED if it was canceled.
*
* Called with job_lock *not* held.
*/
int job_cancel_sync(Job *job, bool force);
/* Same as job_cancel_sync, but called with job lock held. */
int job_cancel_sync_locked(Job *job, bool force);
/**
* Synchronously force-cancels all jobs using job_cancel_sync_locked().
*
* Called with job_lock *not* held.
*/
void job_cancel_sync_all(void);
/**
* @job: The job to be completed.
* @errp: Error object which may be set by job_complete_locked(); this is not
* necessarily set on every error, the job return value has to be
* checked as well.
*
* Synchronously complete the job. The completion callback is called before the
* function returns, unless it is NULL (which is permissible when using this
* function).
*
* Returns the return value from the job.
* Called with job_lock held.
*/
int job_complete_sync_locked(Job *job, Error **errp);
/**
* For a @job that has finished its work and is pending awaiting explicit
* acknowledgement to commit its work, this will commit that work.
*
* FIXME: Make the below statement universally true:
* For jobs that support the manual workflow mode, all graph changes that occur
* as a result will occur after this command and before a successful reply.
*
* Called with job lock held.
*/
void job_finalize_locked(Job *job, Error **errp);
/**
* Remove the concluded @job from the query list and resets the passed pointer
* to %NULL. Returns an error if the job is not actually concluded.
*
* Called with job lock held.
*/
void job_dismiss_locked(Job **job, Error **errp);
/**
* Synchronously finishes the given @job. If @finish is given, it is called to
* trigger completion or cancellation of the job.
*
* Returns 0 if the job is successfully completed, -ECANCELED if the job was
* cancelled before completing, and -errno in other error cases.
*
* Called with job_lock held, but might release it temporarily.
*/
int job_finish_sync_locked(Job *job, void (*finish)(Job *, Error **errp),
Error **errp);
/**
* Sets the @job->aio_context.
* Called with job_mutex *not* held.
*
* This function must run in the main thread to protect against
* concurrent read in job_finish_sync_locked(), takes the job_mutex
* lock to protect against the read in job_do_yield_locked(), and must
* be called when the job is quiescent.
*/
void job_set_aio_context(Job *job, AioContext *ctx);
#endif
