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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-04 12:19:15 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-04 12:19:15 +0000 |
commit | 6eb9c5a5657d1fe77b55cc261450f3538d35a94d (patch) | |
tree | 657d8194422a5daccecfd42d654b8a245ef7b4c8 /src/include/storage/shm_mq.h | |
parent | Initial commit. (diff) | |
download | postgresql-13-upstream.tar.xz postgresql-13-upstream.zip |
Adding upstream version 13.4.upstream/13.4upstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'src/include/storage/shm_mq.h')
-rw-r--r-- | src/include/storage/shm_mq.h | 85 |
1 files changed, 85 insertions, 0 deletions
diff --git a/src/include/storage/shm_mq.h b/src/include/storage/shm_mq.h new file mode 100644 index 0000000..5005f2c --- /dev/null +++ b/src/include/storage/shm_mq.h @@ -0,0 +1,85 @@ +/*------------------------------------------------------------------------- + * + * shm_mq.h + * single-reader, single-writer shared memory message queue + * + * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * src/include/storage/shm_mq.h + * + *------------------------------------------------------------------------- + */ +#ifndef SHM_MQ_H +#define SHM_MQ_H + +#include "postmaster/bgworker.h" +#include "storage/dsm.h" +#include "storage/proc.h" + +/* The queue itself, in shared memory. */ +struct shm_mq; +typedef struct shm_mq shm_mq; + +/* Backend-private state. */ +struct shm_mq_handle; +typedef struct shm_mq_handle shm_mq_handle; + +/* Descriptors for a single write spanning multiple locations. */ +typedef struct +{ + const char *data; + Size len; +} shm_mq_iovec; + +/* Possible results of a send or receive operation. */ +typedef enum +{ + SHM_MQ_SUCCESS, /* Sent or received a message. */ + SHM_MQ_WOULD_BLOCK, /* Not completed; retry later. */ + SHM_MQ_DETACHED /* Other process has detached queue. */ +} shm_mq_result; + +/* + * Primitives to create a queue and set the sender and receiver. + * + * Both the sender and the receiver must be set before any messages are read + * or written, but they need not be set by the same process. Each must be + * set exactly once. + */ +extern shm_mq *shm_mq_create(void *address, Size size); +extern void shm_mq_set_receiver(shm_mq *mq, PGPROC *); +extern void shm_mq_set_sender(shm_mq *mq, PGPROC *); + +/* Accessor methods for sender and receiver. */ +extern PGPROC *shm_mq_get_receiver(shm_mq *); +extern PGPROC *shm_mq_get_sender(shm_mq *); + +/* Set up backend-local queue state. */ +extern shm_mq_handle *shm_mq_attach(shm_mq *mq, dsm_segment *seg, + BackgroundWorkerHandle *handle); + +/* Associate worker handle with shm_mq. */ +extern void shm_mq_set_handle(shm_mq_handle *, BackgroundWorkerHandle *); + +/* Break connection, release handle resources. */ +extern void shm_mq_detach(shm_mq_handle *mqh); + +/* Get the shm_mq from handle. */ +extern shm_mq *shm_mq_get_queue(shm_mq_handle *mqh); + +/* Send or receive messages. */ +extern shm_mq_result shm_mq_send(shm_mq_handle *mqh, + Size nbytes, const void *data, bool nowait); +extern shm_mq_result shm_mq_sendv(shm_mq_handle *mqh, + shm_mq_iovec *iov, int iovcnt, bool nowait); +extern shm_mq_result shm_mq_receive(shm_mq_handle *mqh, + Size *nbytesp, void **datap, bool nowait); + +/* Wait for our counterparty to attach to the queue. */ +extern shm_mq_result shm_mq_wait_for_attach(shm_mq_handle *mqh); + +/* Smallest possible queue. */ +extern PGDLLIMPORT const Size shm_mq_minimum_size; + +#endif /* SHM_MQ_H */ |