block: document job API

I am not sure that these are really proper GtkDoc, but they follow
the existing documentation in block_int.h.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
This commit is contained in:
Paolo Bonzini 2012-03-30 13:17:13 +02:00 committed by Kevin Wolf
parent 9f25eccc1c
commit dc534f8fc0

View File

@ -63,8 +63,13 @@ typedef struct BlockIOBaseValue {
uint64_t ios[2];
} BlockIOBaseValue;
typedef void BlockJobCancelFunc(void *opaque);
typedef struct BlockJob BlockJob;
/**
* BlockJobType:
*
* A class type for block job objects.
*/
typedef struct BlockJobType {
/** Derived BlockJob struct size */
size_t instance_size;
@ -77,20 +82,48 @@ typedef struct BlockJobType {
} BlockJobType;
/**
* Long-running operation on a BlockDriverState
* BlockJob:
*
* Long-running operation on a BlockDriverState.
*/
struct BlockJob {
/** The job type, including the job vtable. */
const BlockJobType *job_type;
/** The block device on which the job is operating. */
BlockDriverState *bs;
/**
* 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 detected that the cancelled flag is
* true, it should not anymore issue any I/O operation to the
* block device.
*/
bool cancelled;
/**
* Set to false by the job while it is in a quiescent state, where
* no I/O is pending and cancellation can be processed without
* issuing new I/O. The busy flag must be set to false when the
* job goes to sleep on any condition that is not detected by
* #qemu_aio_wait, such as a timer.
*/
bool busy;
/* These fields are published by the query-block-jobs QMP API */
/** Offset that is published by the query-block-jobs QMP API */
int64_t offset;
/** Length that is published by the query-block-jobs QMP API */
int64_t len;
/** Speed that was set with @block_job_set_speed. */
int64_t speed;
/** The completion function that will be called when the job completes. */
BlockDriverCompletionFunc *cb;
/** The opaque value that is passed to the completion function. */
void *opaque;
};
@ -306,14 +339,90 @@ void bdrv_set_io_limits(BlockDriverState *bs,
int is_windows_drive(const char *filename);
#endif
/**
* block_job_create:
* @job_type: The class object for the newly-created job.
* @bs: The block
* @cb: Completion function for the job.
* @opaque: Opaque pointer value passed to @cb.
*
* Create a new long-running block device job and return it. The job
* will call @cb asynchronously when the job completes. Note that
* @bs may have been closed at the time the @cb it is called. If
* this is the case, the job may be reported as either cancelled or
* completed.
*
* This function is not part of the public job interface; it should be
* called from a wrapper that is specific to the job type.
*/
void *block_job_create(const BlockJobType *job_type, BlockDriverState *bs,
BlockDriverCompletionFunc *cb, void *opaque);
/**
* block_job_complete:
* @job: The job being completed.
* @ret: The status code.
*
* Call the completion function that was registered at creation time, and
* free @job.
*/
void block_job_complete(BlockJob *job, int ret);
/**
* block_job_set_speed:
* @job: The job to set the speed for.
* @speed: The new value
*
* Set a rate-limiting parameter for the job; the actual meaning may
* vary depending on the job type.
*/
int block_job_set_speed(BlockJob *job, int64_t value);
/**
* block_job_cancel:
* @job: The job to be canceled.
*
* Asynchronously cancel the specified job.
*/
void block_job_cancel(BlockJob *job);
/**
* block_job_is_cancelled:
* @job: The job being queried.
*
* Returns whether the job is scheduled for cancellation.
*/
bool block_job_is_cancelled(BlockJob *job);
/**
* block_job_cancel:
* @job: The job to be canceled.
*
* Asynchronously cancel the job and wait for it to reach a quiescent
* state. Note that the completion callback will still be called
* asynchronously, hence it is *not* valid to call #bdrv_delete
* immediately after #block_job_cancel_sync. Users of block jobs
* will usually protect the BlockDriverState objects with a reference
* count, should this be a concern.
*/
void block_job_cancel_sync(BlockJob *job);
/**
* stream_start:
* @bs: Block device to operate on.
* @base: Block device that will become the new base, or %NULL to
* flatten the whole backing file chain onto @bs.
* @base_id: The file name that will be written to @bs as the new
* backing file if the job completes. Ignored if @base is %NULL.
* @cb: Completion function for the job.
* @opaque: Opaque pointer value passed to @cb.
*
* Start a streaming operation on @bs. Clusters that are unallocated
* in @bs, but allocated in any image between @base and @bs (both
* exclusive) will be written to @bs. At the end of a successful
* streaming job, the backing file of @bs will be changed to
* @base_id in the written image and to @base in the live BlockDriverState.
*/
int stream_start(BlockDriverState *bs, BlockDriverState *base,
const char *base_id, BlockDriverCompletionFunc *cb,
void *opaque);