diff options
Diffstat (limited to 'src/include')
| -rw-r--r-- | src/include/storage/aio.h | 2 | ||||
| -rw-r--r-- | src/include/storage/aio_internal.h | 22 |
2 files changed, 22 insertions, 2 deletions
diff --git a/src/include/storage/aio.h b/src/include/storage/aio.h index 6b083040943..c6bf7c4ccf5 100644 --- a/src/include/storage/aio.h +++ b/src/include/storage/aio.h @@ -80,7 +80,7 @@ typedef enum PgAioHandleFlags /* * The IO operations supported by the AIO subsystem. * - * This could be in aio_internal.h, as it is not pubicly referenced, but + * This could be in aio_internal.h, as it is not publicly referenced, but * PgAioOpData currently *does* need to be public, therefore keeping this * public seems to make sense. */ diff --git a/src/include/storage/aio_internal.h b/src/include/storage/aio_internal.h index fb0425ccbfc..7f18da2c856 100644 --- a/src/include/storage/aio_internal.h +++ b/src/include/storage/aio_internal.h @@ -34,6 +34,11 @@ * linearly through all states. * * State changes should all go through pgaio_io_update_state(). + * + * Note that the externally visible functions to start IO + * (e.g. FileStartReadV(), via pgaio_io_start_readv()) move an IO from + * PGAIO_HS_HANDED_OUT to at least PGAIO_HS_STAGED and at most + * PGAIO_HS_COMPLETED_LOCAL (at which point the handle will be reused). */ typedef enum PgAioHandleState { @@ -285,6 +290,9 @@ typedef struct IoMethodOps /* * Start executing passed in IOs. * + * Shall advance state to at least PGAIO_HS_SUBMITTED. (By the time this + * returns, other backends might have advanced the state further.) + * * Will not be called if ->needs_synchronous_execution() returned true. * * num_staged_ios is <= PGAIO_SUBMIT_BATCH_SIZE. @@ -293,12 +301,24 @@ typedef struct IoMethodOps */ int (*submit) (uint16 num_staged_ios, PgAioHandle **staged_ios); - /* + /* --- * Wait for the IO to complete. Optional. * + * On return, state shall be on of + * - PGAIO_HS_COMPLETED_IO + * - PGAIO_HS_COMPLETED_SHARED + * - PGAIO_HS_COMPLETED_LOCAL + * + * The callback must not block if the handle is already in one of those + * states, or has been reused (see pgaio_io_was_recycled()). If, on + * return, the state is PGAIO_HS_COMPLETED_IO, state will reach + * PGAIO_HS_COMPLETED_SHARED without further intervention by the IO + * method. + * * If not provided, it needs to be guaranteed that the IO method calls * pgaio_io_process_completion() without further interaction by the * issuing backend. + * --- */ void (*wait_one) (PgAioHandle *ioh, uint64 ref_generation); |