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 #include "qemu/coroutine.h"
  32 #include "block/aio.h"
  33
  34 typedef struct JobDriver JobDriver;
  35 typedef struct JobTxn JobTxn;
  36
  37
  38 /**
  39  * Long-running operation.
  40  */
  41 typedef struct Job {
  42     /** The ID of the job. May be NULL for internal jobs. */
  43     char *id;
  44
  45     /** The type of this job. */
  46     const JobDriver *driver;
  47
  48     /** Reference count of the block job */
  49     int refcnt;
  50
  51     /** Current state; See @JobStatus for details. */
  52     JobStatus status;
  53
  54     /** AioContext to run the job coroutine in */
  55     AioContext *aio_context;
  56
  57     /**
  58      * The coroutine that executes the job.  If not NULL, it is reentered when
  59      * busy is false and the job is cancelled.
  60      */
  61     Coroutine *co;
  62
  63     /**
  64      * Timer that is used by @job_sleep_ns. Accessed under job_mutex (in
  65      * job.c).
  66      */
  67     QEMUTimer sleep_timer;
  68
  69     /**
  70      * Counter for pause request. If non-zero, the block job is either paused,
  71      * or if busy == true will pause itself as soon as possible.
  72      */
  73     int pause_count;
  74
  75     /**
  76      * Set to false by the job while the coroutine has yielded and may be
  77      * re-entered by job_enter(). There may still be I/O or event loop activity
  78      * pending. Accessed under block_job_mutex (in blockjob.c).
  79      */
  80     bool busy;
  81
  82     /**
  83      * Set to true by the job while it is in a quiescent state, where
  84      * no I/O or event loop activity is pending.
  85      */
  86     bool paused;
  87
  88     /**
  89      * Set to true if the job is paused by user.  Can be unpaused with the
  90      * block-job-resume QMP command.
  91      */
  92     bool user_paused;
  93
  94     /**
  95      * Set to true if the job should cancel itself.  The flag must
  96      * always be tested just before toggling the busy flag from false
  97      * to true.  After a job has been cancelled, it should only yield
  98      * if #aio_poll will ("sooner or later") reenter the coroutine.
  99      */
 100     bool cancelled;
 101
 102     /**
 103      * Set to true if the job should abort immediately without waiting
 104      * for data to be in sync.
 105      */
 106     bool force_cancel;
 107
 108     /** Set to true when the job has deferred work to the main loop. */
 109     bool deferred_to_main_loop;
 110
 111     /** True if this job should automatically finalize itself */
 112     bool auto_finalize;
 113
 114     /** True if this job should automatically dismiss itself */
 115     bool auto_dismiss;
 116
 117     /**
 118      * Current progress. The unit is arbitrary as long as the ratio between
 119      * progress_current and progress_total represents the estimated percentage
 120      * of work already done.
 121      */
 122     int64_t progress_current;
 123
 124     /** Estimated progress_current value at the completion of the job */
 125     int64_t progress_total;
 126
 127     /** Error string for a failed job (NULL if, and only if, job->ret == 0) */
 128     char *error;
 129
 130     /** ret code passed to job_completed. */
 131     int ret;
 132
 133     /** The completion function that will be called when the job completes.  */
 134     BlockCompletionFunc *cb;
 135
 136     /** The opaque value that is passed to the completion function.  */
 137     void *opaque;
 138
 139     /** Notifiers called when a cancelled job is finalised */
 140     NotifierList on_finalize_cancelled;
 141
 142     /** Notifiers called when a successfully completed job is finalised */
 143     NotifierList on_finalize_completed;
 144
 145     /** Notifiers called when the job transitions to PENDING */
 146     NotifierList on_pending;
 147
 148     /** Notifiers called when the job transitions to READY */
 149     NotifierList on_ready;
 150
 151     /** Element of the list of jobs */
 152     QLIST_ENTRY(Job) job_list;
 153
 154     /** Transaction this job is part of */
 155     JobTxn *txn;
 156
 157     /** Element of the list of jobs in a job transaction */
 158     QLIST_ENTRY(Job) txn_list;
 159 } Job;
 160
 161 /**
 162  * Callbacks and other information about a Job driver.
 163  */
 164 struct JobDriver {
 165     /** Derived Job struct size */
 166     size_t instance_size;
 167
 168     /** Enum describing the operation */
 169     JobType job_type;
 170
 171     /** Mandatory: Entrypoint for the Coroutine. */
 172     CoroutineEntry *start;
 173
 174     /**
 175      * If the callback is not NULL, it will be invoked when the job transitions
 176      * into the paused state.  Paused jobs must not perform any asynchronous
 177      * I/O or event loop activity.  This callback is used to quiesce jobs.
 178      */
 179     void coroutine_fn (*pause)(Job *job);
 180
 181     /**
 182      * If the callback is not NULL, it will be invoked when the job transitions
 183      * out of the paused state.  Any asynchronous I/O or event loop activity
 184      * should be restarted from this callback.
 185      */
 186     void coroutine_fn (*resume)(Job *job);
 187
 188     /**
 189      * Called when the job is resumed by the user (i.e. user_paused becomes
 190      * false). .user_resume is called before .resume.
 191      */
 192     void (*user_resume)(Job *job);
 193
 194     /**
 195      * Optional callback for job types whose completion must be triggered
 196      * manually.
 197      */
 198     void (*complete)(Job *job, Error **errp);
 199
 200     /*
 201      * If the callback is not NULL, it will be invoked when the job has to be
 202      * synchronously cancelled or completed; it should drain any activities
 203      * as required to ensure progress.
 204      */
 205     void (*drain)(Job *job);
 206
 207     /**
 208      * If the callback is not NULL, prepare will be invoked when all the jobs
 209      * belonging to the same transaction complete; or upon this job's completion
 210      * if it is not in a transaction.
 211      *
 212      * This callback will not be invoked if the job has already failed.
 213      * If it fails, abort and then clean will be called.
 214      */
 215     int (*prepare)(Job *job);
 216
 217     /**
 218      * If the callback is not NULL, it will be invoked when all the jobs
 219      * belonging to the same transaction complete; or upon this job's
 220      * completion if it is not in a transaction. Skipped if NULL.
 221      *
 222      * All jobs will complete with a call to either .commit() or .abort() but
 223      * never both.
 224      */
 225     void (*commit)(Job *job);
 226
 227     /**
 228      * If the callback is not NULL, it will be invoked when any job in the
 229      * same transaction fails; or upon this job's failure (due to error or
 230      * cancellation) if it is not in a transaction. Skipped if NULL.
 231      *
 232      * All jobs will complete with a call to either .commit() or .abort() but
 233      * never both.
 234      */
 235     void (*abort)(Job *job);
 236
 237     /**
 238      * If the callback is not NULL, it will be invoked after a call to either
 239      * .commit() or .abort(). Regardless of which callback is invoked after
 240      * completion, .clean() will always be called, even if the job does not
 241      * belong to a transaction group.
 242      */
 243     void (*clean)(Job *job);
 244
 245
 246     /** Called when the job is freed */
 247     void (*free)(Job *job);
 248 };
 249
 250 typedef enum JobCreateFlags {
 251     /* Default behavior */
 252     JOB_DEFAULT = 0x00,
 253     /* Job is not QMP-created and should not send QMP events */
 254     JOB_INTERNAL = 0x01,
 255     /* Job requires manual finalize step */
 256     JOB_MANUAL_FINALIZE = 0x02,
 257     /* Job requires manual dismiss step */
 258     JOB_MANUAL_DISMISS = 0x04,
 259 } JobCreateFlags;
 260
 261 /**
 262  * Allocate and return a new job transaction. Jobs can be added to the
 263  * transaction using job_txn_add_job().
 264  *
 265  * The transaction is automatically freed when the last job completes or is
 266  * cancelled.
 267  *
 268  * All jobs in the transaction either complete successfully or fail/cancel as a
 269  * group.  Jobs wait for each other before completing.  Cancelling one job
 270  * cancels all jobs in the transaction.
 271  */
 272 JobTxn *job_txn_new(void);
 273
 274 /**
 275  * Release a reference that was previously acquired with job_txn_add_job or
 276  * job_txn_new. If it's the last reference to the object, it will be freed.
 277  */
 278 void job_txn_unref(JobTxn *txn);
 279
 280 /**
 281  * @txn: The transaction (may be NULL)
 282  * @job: Job to add to the transaction
 283  *
 284  * Add @job to the transaction.  The @job must not already be in a transaction.
 285  * The caller must call either job_txn_unref() or job_completed() to release
 286  * the reference that is automatically grabbed here.
 287  *
 288  * If @txn is NULL, the function does nothing.
 289  */
 290 void job_txn_add_job(JobTxn *txn, Job *job);
 291
 292 /**
 293  * Create a new long-running job and return it.
 294  *
 295  * @job_id: The id of the newly-created job, or %NULL for internal jobs
 296  * @driver: The class object for the newly-created job.
 297  * @txn: The transaction this job belongs to, if any. %NULL otherwise.
 298  * @ctx: The AioContext to run the job coroutine in.
 299  * @flags: Creation flags for the job. See @JobCreateFlags.
 300  * @cb: Completion function for the job.
 301  * @opaque: Opaque pointer value passed to @cb.
 302  * @errp: Error object.
 303  */
 304 void *job_create(const char *job_id, const JobDriver *driver, JobTxn *txn,
 305                  AioContext *ctx, int flags, BlockCompletionFunc *cb,
 306                  void *opaque, Error **errp);
 307
 308 /**
 309  * Add a reference to Job refcnt, it will be decreased with job_unref, and then
 310  * be freed if it comes to be the last reference.
 311  */
 312 void job_ref(Job *job);
 313
 314 /**
 315  * Release a reference that was previously acquired with job_ref() or
 316  * job_create(). If it's the last reference to the object, it will be freed.
 317  */
 318 void job_unref(Job *job);
 319
 320 /**
 321  * @job: The job that has made progress
 322  * @done: How much progress the job made since the last call
 323  *
 324  * Updates the progress counter of the job.
 325  */
 326 void job_progress_update(Job *job, uint64_t done);
 327
 328 /**
 329  * @job: The job whose expected progress end value is set
 330  * @remaining: Missing progress (on top of the current progress counter value)
 331  *             until the new expected end value is reached
 332  *
 333  * Sets the expected end value of the progress counter of a job so that a
 334  * completion percentage can be calculated when the progress is updated.
 335  */
 336 void job_progress_set_remaining(Job *job, uint64_t remaining);
 337
 338 /**
 339  * @job: The job whose expected progress end value is updated
 340  * @delta: Value which is to be added to the current expected end
 341  *         value
 342  *
 343  * Increases the expected end value of the progress counter of a job.
 344  * This is useful for parenthesis operations: If a job has to
 345  * conditionally perform a high-priority operation as part of its
 346  * progress, it calls this function with the expected operation's
 347  * length before, and job_progress_update() afterwards.
 348  * (So the operation acts as a parenthesis in regards to the main job
 349  * operation running in background.)
 350  */
 351 void job_progress_increase_remaining(Job *job, uint64_t delta);
 352
 353 /** To be called when a cancelled job is finalised. */
 354 void job_event_cancelled(Job *job);
 355
 356 /** To be called when a successfully completed job is finalised. */
 357 void job_event_completed(Job *job);
 358
 359 /**
 360  * Conditionally enter the job coroutine if the job is ready to run, not
 361  * already busy and fn() returns true. fn() is called while under the job_lock
 362  * critical section.
 363  */
 364 void job_enter_cond(Job *job, bool(*fn)(Job *job));
 365
 366 /**
 367  * @job: A job that has not yet been started.
 368  *
 369  * Begins execution of a job.
 370  * Takes ownership of one reference to the job object.
 371  */
 372 void job_start(Job *job);
 373
 374 /**
 375  * @job: The job to enter.
 376  *
 377  * Continue the specified job by entering the coroutine.
 378  */
 379 void job_enter(Job *job);
 380
 381 /**
 382  * @job: The job that is ready to pause.
 383  *
 384  * Pause now if job_pause() has been called. Jobs that perform lots of I/O
 385  * must call this between requests so that the job can be paused.
 386  */
 387 void coroutine_fn job_pause_point(Job *job);
 388
 389 /**
 390  * @job: The job that calls the function.
 391  *
 392  * Yield the job coroutine.
 393  */
 394 void job_yield(Job *job);
 395
 396 /**
 397  * @job: The job that calls the function.
 398  * @ns: How many nanoseconds to stop for.
 399  *
 400  * Put the job to sleep (assuming that it wasn't canceled) for @ns
 401  * %QEMU_CLOCK_REALTIME nanoseconds.  Canceling the job will immediately
 402  * interrupt the wait.
 403  */
 404 void coroutine_fn job_sleep_ns(Job *job, int64_t ns);
 405
 406
 407 /** Returns the JobType of a given Job. */
 408 JobType job_type(const Job *job);
 409
 410 /** Returns the enum string for the JobType of a given Job. */
 411 const char *job_type_str(const Job *job);
 412
 413 /** Returns true if the job should not be visible to the management layer. */
 414 bool job_is_internal(Job *job);
 415
 416 /** Returns whether the job is scheduled for cancellation. */
 417 bool job_is_cancelled(Job *job);
 418
 419 /** Returns whether the job is in a completed state. */
 420 bool job_is_completed(Job *job);
 421
 422 /** Returns whether the job is ready to be completed. */
 423 bool job_is_ready(Job *job);
 424
 425 /**
 426  * Request @job to pause at the next pause point. Must be paired with
 427  * job_resume(). If the job is supposed to be resumed by user action, call
 428  * job_user_pause() instead.
 429  */
 430 void job_pause(Job *job);
 431
 432 /** Resumes a @job paused with job_pause. */
 433 void job_resume(Job *job);
 434
 435 /**
 436  * Asynchronously pause the specified @job.
 437  * Do not allow a resume until a matching call to job_user_resume.
 438  */
 439 void job_user_pause(Job *job, Error **errp);
 440
 441 /** Returns true if the job is user-paused. */
 442 bool job_user_paused(Job *job);
 443
 444 /**
 445  * Resume the specified @job.
 446  * Must be paired with a preceding job_user_pause.
 447  */
 448 void job_user_resume(Job *job, Error **errp);
 449
 450 /*
 451  * Drain any activities as required to ensure progress. This can be called in a
 452  * loop to synchronously complete a job.
 453  */
 454 void job_drain(Job *job);
 455
 456 /**
 457  * Get the next element from the list of block jobs after @job, or the
 458  * first one if @job is %NULL.
 459  *
 460  * Returns the requested job, or %NULL if there are no more jobs left.
 461  */
 462 Job *job_next(Job *job);
 463
 464 /**
 465  * Get the job identified by @id (which must not be %NULL).
 466  *
 467  * Returns the requested job, or %NULL if it doesn't exist.
 468  */
 469 Job *job_get(const char *id);
 470
 471 /**
 472  * Check whether the verb @verb can be applied to @job in its current state.
 473  * Returns 0 if the verb can be applied; otherwise errp is set and -EPERM
 474  * returned.
 475  */
 476 int job_apply_verb(Job *job, JobVerb verb, Error **errp);
 477
 478 /** The @job could not be started, free it. */
 479 void job_early_fail(Job *job);
 480
 481 /** Moves the @job from RUNNING to READY */
 482 void job_transition_to_ready(Job *job);
 483
 484 /**
 485  * @job: The job being completed.
 486  * @ret: The status code.
 487  * @error: The error message for a failing job (only with @ret < 0). If @ret is
 488  *         negative, but NULL is given for @error, strerror() is used.
 489  *
 490  * Marks @job as completed. If @ret is non-zero, the job transaction it is part
 491  * of is aborted. If @ret is zero, the job moves into the WAITING state. If it
 492  * is the last job to complete in its transaction, all jobs in the transaction
 493  * move from WAITING to PENDING.
 494  */
 495 void job_completed(Job *job, int ret, Error *error);
 496
 497 /** Asynchronously complete the specified @job. */
 498 void job_complete(Job *job, Error **errp);
 499
 500 /**
 501  * Asynchronously cancel the specified @job. If @force is true, the job should
 502  * be cancelled immediately without waiting for a consistent state.
 503  */
 504 void job_cancel(Job *job, bool force);
 505
 506 /**
 507  * Cancels the specified job like job_cancel(), but may refuse to do so if the
 508  * operation isn't meaningful in the current state of the job.
 509  */
 510 void job_user_cancel(Job *job, bool force, Error **errp);
 511
 512 /**
 513  * Synchronously cancel the @job.  The completion callback is called
 514  * before the function returns.  The job may actually complete
 515  * instead of canceling itself; the circumstances under which this
 516  * happens depend on the kind of job that is active.
 517  *
 518  * Returns the return value from the job if the job actually completed
 519  * during the call, or -ECANCELED if it was canceled.
 520  */
 521 int job_cancel_sync(Job *job);
 522
 523 /** Synchronously cancels all jobs using job_cancel_sync(). */
 524 void job_cancel_sync_all(void);
 525
 526 /**
 527  * @job: The job to be completed.
 528  * @errp: Error object which may be set by job_complete(); this is not
 529  *        necessarily set on every error, the job return value has to be
 530  *        checked as well.
 531  *
 532  * Synchronously complete the job.  The completion callback is called before the
 533  * function returns, unless it is NULL (which is permissible when using this
 534  * function).
 535  *
 536  * Returns the return value from the job.
 537  */
 538 int job_complete_sync(Job *job, Error **errp);
 539
 540 /**
 541  * For a @job that has finished its work and is pending awaiting explicit
 542  * acknowledgement to commit its work, this will commit that work.
 543  *
 544  * FIXME: Make the below statement universally true:
 545  * For jobs that support the manual workflow mode, all graph changes that occur
 546  * as a result will occur after this command and before a successful reply.
 547  */
 548 void job_finalize(Job *job, Error **errp);
 549
 550 /**
 551  * Remove the concluded @job from the query list and resets the passed pointer
 552  * to %NULL. Returns an error if the job is not actually concluded.
 553  */
 554 void job_dismiss(Job **job, Error **errp);
 555
 556 typedef void JobDeferToMainLoopFn(Job *job, void *opaque);
 557
 558 /**
 559  * @job: The job
 560  * @fn: The function to run in the main loop
 561  * @opaque: The opaque value that is passed to @fn
 562  *
 563  * This function must be called by the main job coroutine just before it
 564  * returns.  @fn is executed in the main loop with the job AioContext acquired.
 565  *
 566  * Block jobs must call bdrv_unref(), bdrv_close(), and anything that uses
 567  * bdrv_drain_all() in the main loop.
 568  *
 569  * The @job AioContext is held while @fn executes.
 570  */
 571 void job_defer_to_main_loop(Job *job, JobDeferToMainLoopFn *fn, void *opaque);
 572
 573 /**
 574  * Synchronously finishes the given @job. If @finish is given, it is called to
 575  * trigger completion or cancellation of the job.
 576  *
 577  * Returns 0 if the job is successfully completed, -ECANCELED if the job was
 578  * cancelled before completing, and -errno in other error cases.
 579  */
 580 int job_finish_sync(Job *job, void (*finish)(Job *, Error **errp), Error **errp);
 581
 582 #endif