Re: [Qemu-devel] [PATCH v5 09/14] block: Add block job transactions

[Max Reitz]

On 07.09.2015 09:34, Fam Zheng wrote:
> Sometimes block jobs must execute as a transaction group.  Finishing
> jobs wait until all other jobs are ready to complete successfully.
> Failure or cancellation of one job cancels the other jobs in the group.
> 
> Signed-off-by: Stefan Hajnoczi <address@hidden>
> [Rewrite the implementation which is now contained in block_job_completed.
> --Fam]
> Signed-off-by: Fam Zheng <address@hidden>
> ---
>  blockjob.c               | 134 
> ++++++++++++++++++++++++++++++++++++++++++++++-
>  include/block/block.h    |   1 +
>  include/block/blockjob.h |  38 ++++++++++++++
>  3 files changed, 171 insertions(+), 2 deletions(-)
> 

[snip]

> diff --git a/include/block/block.h b/include/block/block.h
> index e619b99..f80d984 100644
> --- a/include/block/block.h
> +++ b/include/block/block.h

[snip]

> @@ -395,4 +398,39 @@ void block_job_defer_to_main_loop(BlockJob *job,
>                                    BlockJobDeferToMainLoopFn *fn,
>                                    void *opaque);
>  
> +/**
> + * block_job_txn_new:
> + *
> + * Allocate and return a new block job transaction.  Jobs can be added to the
> + * transaction using block_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.
> + */
> +BlockJobTxn *block_job_txn_new(void);
> +
> +/**
> + * block_job_txn_unref:
> + *
> + * Release a reference that was previously acquired with 
> block_job_txn_add_job
> + * or block_job_txn_new. If it's the last reference to the object, it will be
> + * freed.
> + */
> +void block_job_txn_unref(BlockJobTxn *txn);
> +
> +/**
> + * block_job_txn_add_job:
> + * @txn: The transaction (may be NULL)
> + * @job: Job to add to the transaction
> + *
> + * Add @job to the transaction.  The @job must not already be in a 
> transaction.
> + * The block job driver must call block_job_txn_prepare_to_complete() before
> + * final cleanup and completion.

This comment still needs a fixup (block_job_txn_prepare_to_complete()
does not exist).

Looks good other than that.

Max

> + */
> +void block_job_txn_add_job(BlockJobTxn *txn, BlockJob *job);
> +
>  #endif
>

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