shm_toc.h File Reference

#include "storage/shmem.h"

Include dependency graph for shm_toc.h:

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Go to the source code of this file.

Data Structures
struct	shm_toc_estimator

Macros
#define	shm_toc_initialize_estimator(e)    ((e)->space_for_chunks = 0, (e)->number_of_keys = 0)
#define	shm_toc_estimate_chunk(e, sz)    ((e)->space_for_chunks = add_size((e)->space_for_chunks, BUFFERALIGN(sz)))
#define	shm_toc_estimate_keys(e, cnt)    ((e)->number_of_keys = add_size((e)->number_of_keys, cnt))

Typedefs
typedef struct shm_toc	shm_toc

Functions
shm_toc *	shm_toc_create (uint64 magic, void *address, Size nbytes)
shm_toc *	shm_toc_attach (uint64 magic, void *address)
void *	shm_toc_allocate (shm_toc *toc, Size nbytes)
Size	shm_toc_freespace (shm_toc *toc)
void	shm_toc_insert (shm_toc *toc, uint64 key, void *address)
void *	shm_toc_lookup (shm_toc *toc, uint64 key, bool noError)
Size	shm_toc_estimate (shm_toc_estimator *e)

Macro Definition Documentation

shm_toc_estimate_chunk

#define shm_toc_estimate_chunk	(		e,
			sz
	)		((e)->space_for_chunks = add_size((e)->space_for_chunks, BUFFERALIGN(sz)))

Definition at line 51 of file shm_toc.h.

shm_toc_estimate_keys

#define shm_toc_estimate_keys	(		e,
			cnt
	)		((e)->number_of_keys = add_size((e)->number_of_keys, cnt))

Definition at line 53 of file shm_toc.h.

shm_toc_initialize_estimator

#define shm_toc_initialize_estimator

(

e

)

((e)->space_for_chunks = 0, (e)->number_of_keys = 0)

Definition at line 49 of file shm_toc.h.

Typedef Documentation

shm_toc

typedef struct shm_toc shm_toc

Definition at line 1 of file shm_toc.h.

Function Documentation

shm_toc_allocate()

void* shm_toc_allocate	(	shm_toc *	toc,
		Size	nbytes
	)

Definition at line 88 of file shm_toc.c.

{
    volatile shm_toc *vtoc = toc;
    Size        total_bytes;
    Size        allocated_bytes;
    Size        nentry;
    Size        toc_bytes;
 
    /*
     * Make sure request is well-aligned.  XXX: MAXALIGN is not enough,
     * because atomic ops might need a wider alignment.  We don't have a
     * proper definition for the minimum to make atomic ops safe, but
     * BUFFERALIGN ought to be enough.
     */
    nbytes = BUFFERALIGN(nbytes);
 
    SpinLockAcquire(&toc->toc_mutex);
 
    total_bytes = vtoc->toc_total_bytes;
    allocated_bytes = vtoc->toc_allocated_bytes;
    nentry = vtoc->toc_nentry;
    toc_bytes = offsetof(shm_toc, toc_entry) + nentry * sizeof(shm_toc_entry)
        + allocated_bytes;
 
    /* Check for memory exhaustion and overflow. */
    if (toc_bytes + nbytes > total_bytes || toc_bytes + nbytes < toc_bytes)
    {
        SpinLockRelease(&toc->toc_mutex);
        ereport(ERROR,
                (errcode(ERRCODE_OUT_OF_MEMORY),
                 errmsg("out of shared memory")));
    }
    vtoc->toc_allocated_bytes += nbytes;
 
    SpinLockRelease(&toc->toc_mutex);
 
    return ((char *) toc) + (total_bytes - allocated_bytes - nbytes);
}

References BUFFERALIGN, ereport, errcode(), errmsg(), ERROR, SpinLockAcquire, SpinLockRelease, shm_toc::toc_allocated_bytes, shm_toc::toc_mutex, shm_toc::toc_nentry, and shm_toc::toc_total_bytes.

Referenced by _brin_begin_parallel(), _bt_begin_parallel(), ExecAggInitializeDSM(), ExecAppendInitializeDSM(), ExecBitmapHeapInitializeDSM(), ExecCustomScanInitializeDSM(), ExecForeignScanInitializeDSM(), ExecHashInitializeDSM(), ExecHashJoinInitializeDSM(), ExecIncrementalSortInitializeDSM(), ExecIndexOnlyScanInitializeDSM(), ExecIndexScanInitializeDSM(), ExecInitParallelPlan(), ExecMemoizeInitializeDSM(), ExecParallelSetupTupleQueues(), ExecSeqScanInitializeDSM(), ExecSortInitializeDSM(), GetSessionDsmHandle(), InitializeParallelDSM(), pa_setup_dsm(), parallel_vacuum_init(), and setup_dynamic_shared_memory().

shm_toc_attach()

shm_toc* shm_toc_attach	(	uint64	magic,
		void *	address
	)

Definition at line 64 of file shm_toc.c.

{
    shm_toc    *toc = (shm_toc *) address;
 
    if (toc->toc_magic != magic)
        return NULL;
 
    Assert(toc->toc_total_bytes >= toc->toc_allocated_bytes);
    Assert(toc->toc_total_bytes > offsetof(shm_toc, toc_entry));
 
    return toc;
}

References Assert, shm_toc::toc_allocated_bytes, shm_toc::toc_magic, and shm_toc::toc_total_bytes.

Referenced by AttachSession(), ParallelApplyWorkerMain(), ParallelWorkerMain(), and test_shm_mq_main().

shm_toc_create()

shm_toc* shm_toc_create	(	uint64	magic,
		void *	address,
		Size	nbytes
	)

Definition at line 40 of file shm_toc.c.

{
    shm_toc    *toc = (shm_toc *) address;
 
    Assert(nbytes > offsetof(shm_toc, toc_entry));
    toc->toc_magic = magic;
    SpinLockInit(&toc->toc_mutex);
 
    /*
     * The alignment code in shm_toc_allocate() assumes that the starting
     * value is buffer-aligned.
     */
    toc->toc_total_bytes = BUFFERALIGN_DOWN(nbytes);
    toc->toc_allocated_bytes = 0;
    toc->toc_nentry = 0;
 
    return toc;
}

References Assert, BUFFERALIGN_DOWN, SpinLockInit, shm_toc::toc_allocated_bytes, shm_toc::toc_magic, shm_toc::toc_mutex, shm_toc::toc_nentry, and shm_toc::toc_total_bytes.

Referenced by GetSessionDsmHandle(), InitializeParallelDSM(), pa_setup_dsm(), and setup_dynamic_shared_memory().

shm_toc_estimate()

Size shm_toc_estimate

(

shm_toc_estimator *

e

)

Definition at line 263 of file shm_toc.c.

{
    Size        sz;
 
    sz = offsetof(shm_toc, toc_entry);
    sz = add_size(sz, mul_size(e->number_of_keys, sizeof(shm_toc_entry)));
    sz = add_size(sz, e->space_for_chunks);
 
    return BUFFERALIGN(sz);
}

References add_size(), BUFFERALIGN, and mul_size().

Referenced by GetSessionDsmHandle(), InitializeParallelDSM(), pa_setup_dsm(), and setup_dynamic_shared_memory().

shm_toc_freespace()

Size shm_toc_freespace

(

shm_toc *

toc

)

Definition at line 131 of file shm_toc.c.

{
    volatile shm_toc *vtoc = toc;
    Size        total_bytes;
    Size        allocated_bytes;
    Size        nentry;
    Size        toc_bytes;
 
    SpinLockAcquire(&toc->toc_mutex);
    total_bytes = vtoc->toc_total_bytes;
    allocated_bytes = vtoc->toc_allocated_bytes;
    nentry = vtoc->toc_nentry;
    SpinLockRelease(&toc->toc_mutex);
 
    toc_bytes = offsetof(shm_toc, toc_entry) + nentry * sizeof(shm_toc_entry);
    Assert(allocated_bytes + BUFFERALIGN(toc_bytes) <= total_bytes);
    return total_bytes - (allocated_bytes + BUFFERALIGN(toc_bytes));
}

References Assert, BUFFERALIGN, SpinLockAcquire, SpinLockRelease, shm_toc::toc_allocated_bytes, shm_toc::toc_mutex, shm_toc::toc_nentry, and shm_toc::toc_total_bytes.

shm_toc_insert()

void shm_toc_insert	(	shm_toc *	toc,
		uint64	key,
		void *	address
	)

Definition at line 171 of file shm_toc.c.

{
    volatile shm_toc *vtoc = toc;
    Size        total_bytes;
    Size        allocated_bytes;
    Size        nentry;
    Size        toc_bytes;
    Size        offset;
 
    /* Relativize pointer. */
    Assert(address > (void *) toc);
    offset = ((char *) address) - (char *) toc;
 
    SpinLockAcquire(&toc->toc_mutex);
 
    total_bytes = vtoc->toc_total_bytes;
    allocated_bytes = vtoc->toc_allocated_bytes;
    nentry = vtoc->toc_nentry;
    toc_bytes = offsetof(shm_toc, toc_entry) + nentry * sizeof(shm_toc_entry)
        + allocated_bytes;
 
    /* Check for memory exhaustion and overflow. */
    if (toc_bytes + sizeof(shm_toc_entry) > total_bytes ||
        toc_bytes + sizeof(shm_toc_entry) < toc_bytes ||
        nentry >= PG_UINT32_MAX)
    {
        SpinLockRelease(&toc->toc_mutex);
        ereport(ERROR,
                (errcode(ERRCODE_OUT_OF_MEMORY),
                 errmsg("out of shared memory")));
    }
 
    Assert(offset < total_bytes);
    vtoc->toc_entry[nentry].key = key;
    vtoc->toc_entry[nentry].offset = offset;
 
    /*
     * By placing a write barrier after filling in the entry and before
     * updating the number of entries, we make it safe to read the TOC
     * unlocked.
     */
    pg_write_barrier();
 
    vtoc->toc_nentry++;
 
    SpinLockRelease(&toc->toc_mutex);
}

References Assert, ereport, errcode(), errmsg(), ERROR, shm_toc_entry::key, sort-test::key, shm_toc_entry::offset, PG_UINT32_MAX, pg_write_barrier, SpinLockAcquire, SpinLockRelease, shm_toc::toc_allocated_bytes, shm_toc::toc_entry, shm_toc::toc_mutex, shm_toc::toc_nentry, and shm_toc::toc_total_bytes.

Referenced by _brin_begin_parallel(), _bt_begin_parallel(), ExecAggInitializeDSM(), ExecAppendInitializeDSM(), ExecBitmapHeapInitializeDSM(), ExecCustomScanInitializeDSM(), ExecForeignScanInitializeDSM(), ExecHashInitializeDSM(), ExecHashJoinInitializeDSM(), ExecIncrementalSortInitializeDSM(), ExecIndexOnlyScanInitializeDSM(), ExecIndexScanInitializeDSM(), ExecInitParallelPlan(), ExecMemoizeInitializeDSM(), ExecParallelSetupTupleQueues(), ExecSeqScanInitializeDSM(), ExecSortInitializeDSM(), GetSessionDsmHandle(), InitializeParallelDSM(), pa_setup_dsm(), parallel_vacuum_init(), and setup_dynamic_shared_memory().

shm_toc_lookup()

void* shm_toc_lookup	(	shm_toc *	toc,
		uint64	key,
		bool	noError
	)

Definition at line 232 of file shm_toc.c.

{
    uint32      nentry;
    uint32      i;
 
    /*
     * Read the number of entries before we examine any entry.  We assume that
     * reading a uint32 is atomic.
     */
    nentry = toc->toc_nentry;
    pg_read_barrier();
 
    /* Now search for a matching entry. */
    for (i = 0; i < nentry; ++i)
    {
        if (toc->toc_entry[i].key == key)
            return ((char *) toc) + toc->toc_entry[i].offset;
    }
 
    /* No matching entry was found. */
    if (!noError)
        elog(ERROR, "could not find key " UINT64_FORMAT " in shm TOC at %p",
             key, toc);
    return NULL;
}

References elog, ERROR, i, shm_toc_entry::key, sort-test::key, pg_read_barrier, shm_toc::toc_entry, shm_toc::toc_nentry, and UINT64_FORMAT.

Referenced by _brin_parallel_build_main(), _bt_parallel_build_main(), attach_to_queues(), AttachSession(), ExecAggInitializeWorker(), ExecAppendInitializeWorker(), ExecBitmapHeapInitializeWorker(), ExecCustomScanInitializeWorker(), ExecCustomScanReInitializeDSM(), ExecForeignScanInitializeWorker(), ExecForeignScanReInitializeDSM(), ExecHashInitializeWorker(), ExecHashJoinInitializeWorker(), ExecHashJoinReInitializeDSM(), ExecIncrementalSortInitializeWorker(), ExecIndexOnlyScanInitializeWorker(), ExecIndexScanInitializeWorker(), ExecMemoizeInitializeWorker(), ExecParallelGetQueryDesc(), ExecParallelGetReceiver(), ExecParallelReinitialize(), ExecParallelSetupTupleQueues(), ExecSeqScanInitializeWorker(), ExecSortInitializeWorker(), parallel_vacuum_main(), ParallelApplyWorkerMain(), ParallelQueryMain(), ParallelWorkerMain(), ReinitializeParallelDSM(), test_shm_mq_main(), and WaitForParallelWorkersToFinish().