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Change the signature of dynahash's alloc function

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Instead of passing the current memory context to the alloc function
via a shared variable, pass it directly as an argument.

Reviewed-by: Tomas Vondra <tomas@vondra.me>
Discussion: https://www.postgresql.org/message-id/01ab1d41-3eda-4705-8bbd-af898f5007f1@iki.fi
This commit is contained in:
Heikki Linnakangas 2026-03-31 16:55:03 +03:00
parent dde69621c3
commit 7b424e3108
3 changed files with 45 additions and 31 deletions
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16
src/backend/storage/ipc/shmem.c
View file

@ -100,6 +100,7 @@ typedef struct ShmemAllocatorData
#define ShmemIndexLock (&ShmemAllocator->index_lock)
static void *ShmemHashAlloc(Size size, void *alloc_arg);
static void *ShmemAllocRaw(Size size, Size *allocated_size);
/* shared memory global variables */
@ -184,7 +185,8 @@ InitShmemAllocator(PGShmemHeader *seghdr)
info.keysize = SHMEM_INDEX_KEYSIZE;
info.entrysize = sizeof(ShmemIndexEnt);
info.dsize = info.max_dsize = hash_select_dirsize(SHMEM_INDEX_SIZE);
info.alloc = ShmemAllocNoError;
info.alloc = ShmemHashAlloc;
info.alloc_arg = NULL;
hash_flags = HASH_ELEM | HASH_STRINGS | HASH_SHARED_MEM | HASH_ALLOC | HASH_DIRSIZE;
if (!IsUnderPostmaster)
{
@ -233,6 +235,15 @@ ShmemAllocNoError(Size size)
return ShmemAllocRaw(size, &allocated_size);
}
/* Alloc callback for shared memory hash tables */
static void *
ShmemHashAlloc(Size size, void *alloc_arg)
{
Size allocated_size;
return ShmemAllocRaw(size, &allocated_size);
}
/*
* ShmemAllocRaw -- allocate align chunk and return allocated size
*
@ -339,7 +350,8 @@ ShmemInitHash(const char *name, /* table string name for shmem index */
* The shared memory allocator must be specified too.
*/
infoP->dsize = infoP->max_dsize = hash_select_dirsize(max_size);
infoP->alloc = ShmemAllocNoError;
infoP->alloc = ShmemHashAlloc;
infoP->alloc_arg = NULL;
hash_flags |= HASH_SHARED_MEM | HASH_ALLOC | HASH_DIRSIZE;
/* look it up in the shmem index */

52
src/backend/utils/hash/dynahash.c
View file

@ -224,6 +224,7 @@ struct HTAB
HashCompareFunc match; /* key comparison function */
HashCopyFunc keycopy; /* key copying function */
HashAllocFunc alloc; /* memory allocator */
void *alloc_arg; /* opaque argument passed to allocator */
MemoryContext hcxt; /* memory context if default allocator used */
char *tabname; /* table name (for error messages) */
bool isshared; /* true if table is in shared memory */
@ -264,7 +265,7 @@ struct HTAB
/*
* Private function prototypes
*/
static void *DynaHashAlloc(Size size);
static void *DynaHashAlloc(Size size, void *alloc_arg);
static HASHSEGMENT seg_alloc(HTAB *hashp);
static bool element_alloc(HTAB *hashp, int nelem, int freelist_idx);
static bool dir_realloc(HTAB *hashp);
@ -287,14 +288,13 @@ static bool has_seq_scans(HTAB *hashp);
/*
* memory allocation support
*/
static MemoryContext CurrentDynaHashCxt = NULL;
static void *
DynaHashAlloc(Size size)
DynaHashAlloc(Size size, void *alloc_arg)
{
Assert(MemoryContextIsValid(CurrentDynaHashCxt));
return MemoryContextAllocExtended(CurrentDynaHashCxt, size,
MCXT_ALLOC_NO_OOM);
MemoryContext hcxt = (MemoryContext) alloc_arg;
Assert(MemoryContextIsValid(hcxt));
return MemoryContextAllocExtended(hcxt, size, MCXT_ALLOC_NO_OOM);
}
@ -355,6 +355,7 @@ hash_create(const char *tabname, int64 nelem, const HASHCTL *info, int flags)
{
HTAB *hashp;
HASHHDR *hctl;
MemoryContext hcxt;
/*
* Hash tables now allocate space for key and data, but you have to say
@ -377,22 +378,21 @@ hash_create(const char *tabname, int64 nelem, const HASHCTL *info, int flags)
if (flags & HASH_SHARED_MEM)
{
/* Set up to allocate the hash header */
CurrentDynaHashCxt = TopMemoryContext;
hcxt = TopMemoryContext;
}
else
{
/* Create the hash table's private memory context */
if (flags & HASH_CONTEXT)
CurrentDynaHashCxt = info->hcxt;
hcxt = info->hcxt;
else
CurrentDynaHashCxt = TopMemoryContext;
CurrentDynaHashCxt = AllocSetContextCreate(CurrentDynaHashCxt,
"dynahash",
ALLOCSET_DEFAULT_SIZES);
hcxt = TopMemoryContext;
hcxt = AllocSetContextCreate(hcxt, "dynahash",
ALLOCSET_DEFAULT_SIZES);
}
/* Initialize the hash header, plus a copy of the table name */
hashp = (HTAB *) MemoryContextAlloc(CurrentDynaHashCxt,
hashp = (HTAB *) MemoryContextAlloc(hcxt,
sizeof(HTAB) + strlen(tabname) + 1);
MemSet(hashp, 0, sizeof(HTAB));
@ -401,7 +401,7 @@ hash_create(const char *tabname, int64 nelem, const HASHCTL *info, int flags)
/* If we have a private context, label it with hashtable's name */
if (!(flags & HASH_SHARED_MEM))
MemoryContextSetIdentifier(CurrentDynaHashCxt, hashp->tabname);
MemoryContextSetIdentifier(hcxt, hashp->tabname);
/*
* Select the appropriate hash function (see comments at head of file).
@ -473,9 +473,15 @@ hash_create(const char *tabname, int64 nelem, const HASHCTL *info, int flags)
/* And select the entry allocation function, too. */
if (flags & HASH_ALLOC)
{
hashp->alloc = info->alloc;
hashp->alloc_arg = info->alloc_arg;
}
else
{
hashp->alloc = DynaHashAlloc;
hashp->alloc_arg = hcxt;
}
if (flags & HASH_SHARED_MEM)
{
@ -504,13 +510,13 @@ hash_create(const char *tabname, int64 nelem, const HASHCTL *info, int flags)
/* setup hash table defaults */
hashp->hctl = NULL;
hashp->dir = NULL;
hashp->hcxt = CurrentDynaHashCxt;
hashp->hcxt = hcxt;
hashp->isshared = false;
}
if (!hashp->hctl)
{
hashp->hctl = (HASHHDR *) hashp->alloc(sizeof(HASHHDR));
hashp->hctl = (HASHHDR *) hashp->alloc(sizeof(HASHHDR), hashp->alloc_arg);
if (!hashp->hctl)
ereport(ERROR,
(errcode(ERRCODE_OUT_OF_MEMORY),
@ -732,9 +738,8 @@ init_htab(HTAB *hashp, int64 nelem)
/* Allocate a directory */
if (!(hashp->dir))
{
CurrentDynaHashCxt = hashp->hcxt;
hashp->dir = (HASHSEGMENT *)
hashp->alloc(hctl->dsize * sizeof(HASHSEGMENT));
hashp->alloc(hctl->dsize * sizeof(HASHSEGMENT), hashp->alloc_arg);
if (!hashp->dir)
return false;
}
@ -1636,8 +1641,7 @@ dir_realloc(HTAB *hashp)
new_dirsize = new_dsize * sizeof(HASHSEGMENT);
old_p = hashp->dir;
CurrentDynaHashCxt = hashp->hcxt;
p = (HASHSEGMENT *) hashp->alloc((Size) new_dirsize);
p = (HASHSEGMENT *) hashp->alloc((Size) new_dirsize, hashp->alloc_arg);
if (p != NULL)
{
@ -1662,8 +1666,7 @@ seg_alloc(HTAB *hashp)
{
HASHSEGMENT segp;
CurrentDynaHashCxt = hashp->hcxt;
segp = (HASHSEGMENT) hashp->alloc(sizeof(HASHBUCKET) * HASH_SEGSIZE);
segp = (HASHSEGMENT) hashp->alloc(sizeof(HASHBUCKET) * HASH_SEGSIZE, hashp->alloc_arg);
if (!segp)
return NULL;
@ -1703,8 +1706,7 @@ element_alloc(HTAB *hashp, int nelem, int freelist_idx)
#endif
/* Allocate the memory. */
CurrentDynaHashCxt = hashp->hcxt;
allocedBlock = hashp->alloc(requestSize);
allocedBlock = hashp->alloc(requestSize, hashp->alloc_arg);
if (!allocedBlock)
return false;

8
src/include/utils/hsearch.h
View file

@ -37,11 +37,10 @@ typedef int (*HashCompareFunc) (const void *key1, const void *key2,
typedef void *(*HashCopyFunc) (void *dest, const void *src, Size keysize);
/*
* Space allocation function for a hashtable --- designed to match malloc().
* Note: there is no free function API; can't destroy a hashtable unless you
* use the default allocator.
* Space allocation function for a hashtable. Note: there is no free function
* API; can't destroy a hashtable unless you use the default allocator.
*/
typedef void *(*HashAllocFunc) (Size request);
typedef void *(*HashAllocFunc) (Size request, void *alloc_arg);
/*
* HASHELEMENT is the private part of a hashtable entry. The caller's data
@ -80,6 +79,7 @@ typedef struct HASHCTL
HashCopyFunc keycopy; /* key copying function */
/* Used if HASH_ALLOC flag is set: */
HashAllocFunc alloc; /* memory allocator */
void *alloc_arg; /* opaque argument passed to allocator */
/* Used if HASH_CONTEXT flag is set: */
MemoryContext hcxt; /* memory context to use for allocations */
/* Used if HASH_SHARED_MEM flag is set: */