memutils_internal.h

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/*-------------------------------------------------------------------------
 *
 * memutils_internal.h
 *    This file contains declarations for memory allocation utility
 *    functions for internal use.
 *
 *
 * Portions Copyright (c) 2022-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/utils/memutils_internal.h
 *
 *-------------------------------------------------------------------------
 */
 
#ifndef MEMUTILS_INTERNAL_H
#define MEMUTILS_INTERNAL_H
 
#include "utils/memutils.h"
 
/* These functions implement the MemoryContext API for AllocSet context. */
extern void *AllocSetAlloc(MemoryContext context, Size size, int flags);
extern void AllocSetFree(void *pointer);
extern void *AllocSetRealloc(void *pointer, Size size, int flags);
extern void AllocSetReset(MemoryContext context);
extern void AllocSetDelete(MemoryContext context);
extern MemoryContext AllocSetGetChunkContext(void *pointer);
extern Size AllocSetGetChunkSpace(void *pointer);
extern bool AllocSetIsEmpty(MemoryContext context);
extern void AllocSetStats(MemoryContext context,
                          MemoryStatsPrintFunc printfunc, void *passthru,
                          MemoryContextCounters *totals,
                          bool print_to_stderr);
#ifdef MEMORY_CONTEXT_CHECKING
extern void AllocSetCheck(MemoryContext context);
#endif
 
/* These functions implement the MemoryContext API for Generation context. */
extern void *GenerationAlloc(MemoryContext context, Size size, int flags);
extern void GenerationFree(void *pointer);
extern void *GenerationRealloc(void *pointer, Size size, int flags);
extern void GenerationReset(MemoryContext context);
extern void GenerationDelete(MemoryContext context);
extern MemoryContext GenerationGetChunkContext(void *pointer);
extern Size GenerationGetChunkSpace(void *pointer);
extern bool GenerationIsEmpty(MemoryContext context);
extern void GenerationStats(MemoryContext context,
                            MemoryStatsPrintFunc printfunc, void *passthru,
                            MemoryContextCounters *totals,
                            bool print_to_stderr);
#ifdef MEMORY_CONTEXT_CHECKING
extern void GenerationCheck(MemoryContext context);
#endif
 
 
/* These functions implement the MemoryContext API for Slab context. */
extern void *SlabAlloc(MemoryContext context, Size size, int flags);
extern void SlabFree(void *pointer);
extern void *SlabRealloc(void *pointer, Size size, int flags);
extern void SlabReset(MemoryContext context);
extern void SlabDelete(MemoryContext context);
extern MemoryContext SlabGetChunkContext(void *pointer);
extern Size SlabGetChunkSpace(void *pointer);
extern bool SlabIsEmpty(MemoryContext context);
extern void SlabStats(MemoryContext context,
                      MemoryStatsPrintFunc printfunc, void *passthru,
                      MemoryContextCounters *totals,
                      bool print_to_stderr);
#ifdef MEMORY_CONTEXT_CHECKING
extern void SlabCheck(MemoryContext context);
#endif
 
/*
 * These functions support the implementation of palloc_aligned() and are not
 * part of a fully-fledged MemoryContext type.
 */
extern void AlignedAllocFree(void *pointer);
extern void *AlignedAllocRealloc(void *pointer, Size size, int flags);
extern MemoryContext AlignedAllocGetChunkContext(void *pointer);
extern Size AlignedAllocGetChunkSpace(void *pointer);
 
 /* These functions implement the MemoryContext API for the Bump context. */
extern void *BumpAlloc(MemoryContext context, Size size, int flags);
extern void BumpFree(void *pointer);
extern void *BumpRealloc(void *pointer, Size size, int flags);
extern void BumpReset(MemoryContext context);
extern void BumpDelete(MemoryContext context);
extern MemoryContext BumpGetChunkContext(void *pointer);
extern Size BumpGetChunkSpace(void *pointer);
extern bool BumpIsEmpty(MemoryContext context);
extern void BumpStats(MemoryContext context, MemoryStatsPrintFunc printfunc,
                      void *passthru, MemoryContextCounters *totals,
                      bool print_to_stderr);
#ifdef MEMORY_CONTEXT_CHECKING
extern void BumpCheck(MemoryContext context);
#endif
 
/*
 * How many extra bytes do we need to request in order to ensure that we can
 * align a pointer to 'alignto'.  Since palloc'd pointers are already aligned
 * to MAXIMUM_ALIGNOF we can subtract that amount.  We also need to make sure
 * there is enough space for the redirection MemoryChunk.
 */
#define PallocAlignedExtraBytes(alignto) \
    ((alignto) + (sizeof(MemoryChunk) - MAXIMUM_ALIGNOF))
 
/*
 * MemoryContextMethodID
 *      A unique identifier for each MemoryContext implementation which
 *      indicates the index into the mcxt_methods[] array. See mcxt.c.
 *
 * For robust error detection, ensure that MemoryContextMethodID has a value
 * for each possible bit-pattern of MEMORY_CONTEXT_METHODID_MASK, and make
 * dummy entries for unused IDs in the mcxt_methods[] array.  We also try
 * to avoid using bit-patterns as valid IDs if they are likely to occur in
 * garbage data, or if they could falsely match on chunks that are really from
 * malloc not palloc.  (We can't tell that for most malloc implementations,
 * but it happens that glibc stores flag bits in the same place where we put
 * the MemoryContextMethodID, so the possible values are predictable for it.)
 */
typedef enum MemoryContextMethodID
{
    MCTX_0_RESERVED_UNUSEDMEM_ID,   /* 0000 occurs in never-used memory */
    MCTX_1_RESERVED_GLIBC_ID,   /* glibc malloc'd chunks usually match 0001 */
    MCTX_2_RESERVED_GLIBC_ID,   /* glibc malloc'd chunks > 128kB match 0010 */
    MCTX_ASET_ID,
    MCTX_GENERATION_ID,
    MCTX_SLAB_ID,
    MCTX_ALIGNED_REDIRECT_ID,
    MCTX_BUMP_ID,
    MCTX_8_UNUSED_ID,
    MCTX_9_UNUSED_ID,
    MCTX_10_UNUSED_ID,
    MCTX_11_UNUSED_ID,
    MCTX_12_UNUSED_ID,
    MCTX_13_UNUSED_ID,
    MCTX_14_UNUSED_ID,
    MCTX_15_RESERVED_WIPEDMEM_ID    /* 1111 occurs in wipe_mem'd memory */
} MemoryContextMethodID;
 
/*
 * The number of bits that 8-byte memory chunk headers can use to encode the
 * MemoryContextMethodID.
 */
#define MEMORY_CONTEXT_METHODID_BITS 4
#define MEMORY_CONTEXT_METHODID_MASK \
    ((((uint64) 1) << MEMORY_CONTEXT_METHODID_BITS) - 1)
 
/*
 * This routine handles the context-type-independent part of memory
 * context creation.  It's intended to be called from context-type-
 * specific creation routines, and noplace else.
 */
extern void MemoryContextCreate(MemoryContext node,
                                NodeTag tag,
                                MemoryContextMethodID method_id,
                                MemoryContext parent,
                                const char *name);
 
extern void *MemoryContextAllocationFailure(MemoryContext context, Size size,
                                            int flags);
 
extern void MemoryContextSizeFailure(MemoryContext context, Size size,
                                     int flags) pg_attribute_noreturn();
 
static inline void
MemoryContextCheckSize(MemoryContext context, Size size, int flags)
{
    if (unlikely(!AllocSizeIsValid(size)))
    {
        if (!(flags & MCXT_ALLOC_HUGE) || !AllocHugeSizeIsValid(size))
            MemoryContextSizeFailure(context, size, flags);
    }
}
 
#endif                          /* MEMUTILS_INTERNAL_H */