[v5,03/15] block: add BlockJob interface for long-running operations

Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
---
 block.c     |   48 ++++++++++++++++++++++++++++++++++++++++++++++++
 block_int.h |   40 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 88 insertions(+), 0 deletions(-)

Am 13.01.2012 14:14, schrieb Stefan Hajnoczi:
> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
> ---
>  block.c     |   48 ++++++++++++++++++++++++++++++++++++++++++++++++
>  block_int.h |   40 ++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 88 insertions(+), 0 deletions(-)
> 
> diff --git a/block.c b/block.c
> index daf92c2..d588ee8 100644
> --- a/block.c
> +++ b/block.c
> @@ -3877,3 +3877,51 @@ out:
>  
>      return ret;
>  }
> +
> +void *block_job_create(const BlockJobType *job_type, BlockDriverState *bs,
> +                       BlockDriverCompletionFunc *cb, void *opaque)
> +{
> +    BlockJob *job;
> +
> +    if (bs->job || bdrv_in_use(bs)) {
> +        return NULL;
> +    }
> +    bdrv_set_in_use(bs, 1);
> +
> +    job = g_malloc0(job_type->instance_size);
> +    job->job_type      = job_type;
> +    job->bs            = bs;
> +    job->cb            = cb;
> +    job->opaque        = opaque;
> +    bs->job = job;
> +    return job;
> +}
> +
> +void block_job_complete(BlockJob *job, int ret)
> +{
> +    BlockDriverState *bs = job->bs;
> +
> +    assert(bs->job == job);
> +    job->cb(job->opaque, ret);
> +    bs->job = NULL;
> +    g_free(job);
> +    bdrv_set_in_use(bs, 0);
> +}
> +
> +int block_job_set_speed(BlockJob *job, int64_t value)
> +{
> +    if (!job->job_type->set_speed) {
> +        return -ENOTSUP;
> +    }
> +    return job->job_type->set_speed(job, value);
> +}
> +
> +void block_job_cancel(BlockJob *job)
> +{
> +    job->cancelled = true;
> +}
> +
> +bool block_job_is_cancelled(BlockJob *job)
> +{
> +    return job->cancelled;
> +}
> diff --git a/block_int.h b/block_int.h
> index 5362180..316443e 100644
> --- a/block_int.h
> +++ b/block_int.h
> @@ -69,6 +69,36 @@ typedef struct BlockIOBaseValue {
>      uint64_t ios[2];
>  } BlockIOBaseValue;
>  
> +typedef void BlockJobCancelFunc(void *opaque);
> +typedef struct BlockJob BlockJob;
> +typedef struct BlockJobType {
> +    /** Derived BlockJob struct size */
> +    size_t instance_size;
> +
> +    /** String describing the operation, part of query-block-jobs QMP API */
> +    const char *job_type;
> +
> +    /** Optional callback for job types that support setting a speed limit */
> +    int (*set_speed)(BlockJob *job, int64_t value);

Would be worth mentioning what the unit of value is.

Kevin

On Tue, Jan 17, 2012 at 1:00 PM, Kevin Wolf <kwolf@redhat.com> wrote:
> Am 13.01.2012 14:14, schrieb Stefan Hajnoczi:
>> +typedef struct BlockJobType {
>> +    /** Derived BlockJob struct size */
>> +    size_t instance_size;
>> +
>> +    /** String describing the operation, part of query-block-jobs QMP API */
>> +    const char *job_type;
>> +
>> +    /** Optional callback for job types that support setting a speed limit */
>> +    int (*set_speed)(BlockJob *job, int64_t value);
>
> Would be worth mentioning what the unit of value is.

I left this open on purpose so future block jobs could support
block_job_set_speed with whatever unit makes sense for them.  At the
interface level it's an arbitrary int64_t.  Each block job type can
decide how to interpret the values.

I could add "The meaning of value and its units depend on the block
job type".  Or do you think it's problematic to allow different
meanings?

Stefan

Am 17.01.2012 14:33, schrieb Stefan Hajnoczi:
> On Tue, Jan 17, 2012 at 1:00 PM, Kevin Wolf <kwolf@redhat.com> wrote:
>> Am 13.01.2012 14:14, schrieb Stefan Hajnoczi:
>>> +typedef struct BlockJobType {
>>> +    /** Derived BlockJob struct size */
>>> +    size_t instance_size;
>>> +
>>> +    /** String describing the operation, part of query-block-jobs QMP API */
>>> +    const char *job_type;
>>> +
>>> +    /** Optional callback for job types that support setting a speed limit */
>>> +    int (*set_speed)(BlockJob *job, int64_t value);
>>
>> Would be worth mentioning what the unit of value is.
> 
> I left this open on purpose so future block jobs could support
> block_job_set_speed with whatever unit makes sense for them.  At the
> interface level it's an arbitrary int64_t.  Each block job type can
> decide how to interpret the values.

I see.

> I could add "The meaning of value and its units depend on the block
> job type".  Or do you think it's problematic to allow different
> meanings?

Might be confusing to have different meanings. But we can leave it open
for now and commit the comment as it is.

Kevin