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/*-------------------------------------------------------------------------
*
* aio_types.h
* AIO related types that are useful to include separately, to reduce the
* "include burden".
*
*
* Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/storage/aio_types.h
*
*-------------------------------------------------------------------------
*/
#ifndef AIO_TYPES_H
#define AIO_TYPES_H
#include "storage/block.h"
#include "storage/relfilelocator.h"
typedef struct PgAioHandle PgAioHandle;
typedef struct PgAioHandleCallbacks PgAioHandleCallbacks;
typedef struct PgAioTargetInfo PgAioTargetInfo;
/*
* A reference to an IO that can be used to wait for the IO (using
* pgaio_wref_wait()) to complete.
*
* These can be passed across process boundaries.
*/
typedef struct PgAioWaitRef
{
/* internal ID identifying the specific PgAioHandle */
uint32 aio_index;
/*
* IO handles are reused. To detect if a handle was reused, and thereby
* avoid unnecessarily waiting for a newer IO, each time the handle is
* reused a generation number is increased.
*
* To avoid requiring alignment sufficient for an int64, split the
* generation into two.
*/
uint32 generation_upper;
uint32 generation_lower;
} PgAioWaitRef;
/*
* Information identifying what the IO is being performed on.
*
* This needs sufficient information to
*
* a) Reopen the file for the IO if the IO is executed in a context that
* cannot use the FD provided initially (e.g. because the IO is executed in
* a worker process).
*
* b) Describe the object the IO is performed on in log / error messages.
*/
typedef union PgAioTargetData
{
struct
{
RelFileLocator rlocator; /* physical relation identifier */
BlockNumber blockNum; /* blknum relative to begin of reln */
BlockNumber nblocks;
ForkNumber forkNum:8; /* don't waste 4 byte for four values */
bool is_temp:1; /* proc can be inferred by owning AIO */
bool skip_fsync:1;
} smgr;
} PgAioTargetData;
/*
* The status of an AIO operation.
*/
typedef enum PgAioResultStatus
{
PGAIO_RS_UNKNOWN, /* not yet completed / uninitialized */
PGAIO_RS_OK,
PGAIO_RS_PARTIAL, /* did not fully succeed, no warning/error */
PGAIO_RS_WARNING, /* [partially] succeeded, with a warning */
PGAIO_RS_ERROR, /* failed entirely */
} PgAioResultStatus;
/*
* Result of IO operation, visible only to the initiator of IO.
*
* We need to be careful about the size of PgAioResult, as it is embedded in
* every PgAioHandle, as well as every PgAioReturn. Currently we assume we can
* fit it into one 8 byte value, restricting the space for per-callback error
* data to PGAIO_RESULT_ERROR_BITS.
*/
#define PGAIO_RESULT_ID_BITS 6
#define PGAIO_RESULT_STATUS_BITS 3
#define PGAIO_RESULT_ERROR_BITS 23
typedef struct PgAioResult
{
/*
* This is of type PgAioHandleCallbackID, but can't use a bitfield of an
* enum, because some compilers treat enums as signed.
*/
uint32 id:PGAIO_RESULT_ID_BITS;
/* of type PgAioResultStatus, see above */
uint32 status:PGAIO_RESULT_STATUS_BITS;
/* meaning defined by callback->error */
uint32 error_data:PGAIO_RESULT_ERROR_BITS;
int32 result;
} PgAioResult;
StaticAssertDecl(PGAIO_RESULT_ID_BITS +
PGAIO_RESULT_STATUS_BITS +
PGAIO_RESULT_ERROR_BITS == 32,
"PgAioResult bits divided up incorrectly");
StaticAssertDecl(sizeof(PgAioResult) == 8,
"PgAioResult has unexpected size");
/*
* Combination of PgAioResult with minimal metadata about the IO.
*
* Contains sufficient information to be able, in case the IO [partially]
* fails, to log/raise an error under control of the IO issuing code.
*/
typedef struct PgAioReturn
{
PgAioResult result;
PgAioTargetData target_data;
} PgAioReturn;
#endif /* AIO_TYPES_H */
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