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Add pairingheap_initialize() for shared memory usage

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The existing pairingheap_allocate() uses palloc(), which allocates
from process-local memory. For shared memory use cases, the pairingheap
structure must be allocated via ShmemAlloc() or embedded in a shared
memory struct. Add pairingheap_initialize() to initialize an already-
allocated pairingheap structure in-place, enabling shared memory usage.

Discussion: https://www.postgresql.org/message-id/flat/CAPpHfdsjtZLVzxjGT8rJHCYbM0D5dwkO+BBjcirozJ6nYbOW8Q@mail.gmail.com
Discussion: https://www.postgresql.org/message-id/flat/CABPTF7UNft368x-RgOXkfj475OwEbp%2BVVO-wEXz7StgjD_%3D6sw%40mail.gmail.com
Author: Kartyshov Ivan <i.kartyshov@postgrespro.ru>
Author: Alexander Korotkov <aekorotkov@gmail.com>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Reviewed-by: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Reviewed-by: Dilip Kumar <dilipbalaut@gmail.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Reviewed-by: Alexander Lakhin <exclusion@gmail.com>
Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>
Reviewed-by: Euler Taveira <euler@eulerto.com>
Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi>
Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Reviewed-by: Xuneng Zhou <xunengzhou@gmail.com>
This commit is contained in:
Alexander Korotkov
2025-11-05 11:40:27 +02:00
parent 0ea5eee376
commit 8af3ae0d4b
2 changed files with 19 additions and 2 deletions
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18
src/backend/lib/pairingheap.c
View File

@@ -44,12 +44,26 @@ pairingheap_allocate(pairingheap_comparator compare, void *arg)
pairingheap *heap;
heap = (pairingheap *) palloc(sizeof(pairingheap));
pairingheap_initialize(heap, compare, arg);
return heap;
}
/*
* pairingheap_initialize
*
* Same as pairingheap_allocate(), but initializes the pairing heap in-place
* rather than allocating a new chunk of memory. Useful to store the pairing
* heap in a shared memory.
*/
void
pairingheap_initialize(pairingheap *heap, pairingheap_comparator compare,
void *arg)
{
heap->ph_compare = compare;
heap->ph_arg = arg;
heap->ph_root = NULL;
return heap;
}
/*

3
src/include/lib/pairingheap.h
View File

@@ -77,6 +77,9 @@ typedef struct pairingheap
extern pairingheap *pairingheap_allocate(pairingheap_comparator compare,
void *arg);
extern void pairingheap_initialize(pairingheap *heap,
pairingheap_comparator compare,
void *arg);
extern void pairingheap_free(pairingheap *heap);
extern void pairingheap_add(pairingheap *heap, pairingheap_node *node);
extern pairingheap_node *pairingheap_first(pairingheap *heap);