alignedalloc.c File Reference

#include "postgres.h"
#include "utils/memdebug.h"
#include "utils/memutils_memorychunk.h"

Include dependency graph for alignedalloc.c:

Go to the source code of this file.

Functions
void	AlignedAllocFree (void *pointer)
void *	AlignedAllocRealloc (void *pointer, Size size)
MemoryContext	AlignedAllocGetChunkContext (void *pointer)
Size	AlignedAllocGetChunkSpace (void *pointer)

Function Documentation

AlignedAllocFree()

void AlignedAllocFree

(

void *

pointer

)

Definition at line 29 of file alignedalloc.c.

{
    MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
    void       *unaligned;
 
    VALGRIND_MAKE_MEM_DEFINED(chunk, sizeof(MemoryChunk));
 
    Assert(!MemoryChunkIsExternal(chunk));
 
    /* obtain the original (unaligned) allocated pointer */
    unaligned = MemoryChunkGetBlock(chunk);
 
#ifdef MEMORY_CONTEXT_CHECKING
    /* Test for someone scribbling on unused space in chunk */
    if (!sentinel_ok(pointer, chunk->requested_size))
        elog(WARNING, "detected write past chunk end in %s %p",
             GetMemoryChunkContext(unaligned)->name, chunk);
#endif
 
    pfree(unaligned);
}

References Assert(), elog(), GetMemoryChunkContext(), MemoryChunkGetBlock(), MemoryChunkIsExternal(), name, pfree(), PointerGetMemoryChunk, VALGRIND_MAKE_MEM_DEFINED, and WARNING.

AlignedAllocGetChunkContext()

MemoryContext AlignedAllocGetChunkContext

(

void *

pointer

)

Definition at line 118 of file alignedalloc.c.

{
    MemoryChunk *redirchunk = PointerGetMemoryChunk(pointer);
    MemoryContext cxt;
 
    VALGRIND_MAKE_MEM_DEFINED(redirchunk, sizeof(MemoryChunk));
 
    Assert(!MemoryChunkIsExternal(redirchunk));
 
    cxt = GetMemoryChunkContext(MemoryChunkGetBlock(redirchunk));
 
    VALGRIND_MAKE_MEM_NOACCESS(redirchunk, sizeof(MemoryChunk));
 
    return cxt;
}

References Assert(), GetMemoryChunkContext(), MemoryChunkGetBlock(), MemoryChunkIsExternal(), PointerGetMemoryChunk, VALGRIND_MAKE_MEM_DEFINED, and VALGRIND_MAKE_MEM_NOACCESS.

AlignedAllocGetChunkSpace()

Size AlignedAllocGetChunkSpace

(

void *

pointer

)

Definition at line 140 of file alignedalloc.c.

{
    MemoryChunk *redirchunk = PointerGetMemoryChunk(pointer);
    void       *unaligned;
    Size        space;
 
    VALGRIND_MAKE_MEM_DEFINED(redirchunk, sizeof(MemoryChunk));
 
    unaligned = MemoryChunkGetBlock(redirchunk);
    space = GetMemoryChunkSpace(unaligned);
 
    VALGRIND_MAKE_MEM_NOACCESS(redirchunk, sizeof(MemoryChunk));
 
    return space;
}

References GetMemoryChunkSpace(), MemoryChunkGetBlock(), PointerGetMemoryChunk, VALGRIND_MAKE_MEM_DEFINED, and VALGRIND_MAKE_MEM_NOACCESS.

AlignedAllocRealloc()

void* AlignedAllocRealloc	(	void *	pointer,
		Size	size
	)

Definition at line 60 of file alignedalloc.c.

{
    MemoryChunk *redirchunk = PointerGetMemoryChunk(pointer);
    Size        alignto;
    void       *unaligned;
    MemoryContext ctx;
    Size        old_size;
    void       *newptr;
 
    VALGRIND_MAKE_MEM_DEFINED(redirchunk, sizeof(MemoryChunk));
 
    alignto = MemoryChunkGetValue(redirchunk);
    unaligned = MemoryChunkGetBlock(redirchunk);
 
    /* sanity check this is a power of 2 value */
    Assert((alignto & (alignto - 1)) == 0);
 
    /*
     * Determine the size of the original allocation.  We can't determine this
     * exactly as GetMemoryChunkSpace() returns the total space used for the
     * allocation, which for contexts like aset includes rounding up to the
     * next power of 2.  However, this value is just used to memcpy() the old
     * data into the new allocation, so we only need to concern ourselves with
     * not reading beyond the end of the original allocation's memory.  The
     * drawback here is that we may copy more bytes than we need to, which
     * only amounts to wasted effort.  We can safely subtract the extra bytes
     * that we requested to allow us to align the pointer.  We must also
     * subtract the space for the unaligned pointer's MemoryChunk since
     * GetMemoryChunkSpace should have included that.  This does assume that
     * all context types use MemoryChunk as a chunk header.
     */
    old_size = GetMemoryChunkSpace(unaligned) -
        PallocAlignedExtraBytes(alignto) - sizeof(MemoryChunk);
 
#ifdef MEMORY_CONTEXT_CHECKING
    /* check that GetMemoryChunkSpace returned something realistic */
    Assert(old_size >= redirchunk->requested_size);
#endif
 
    ctx = GetMemoryChunkContext(unaligned);
    newptr = MemoryContextAllocAligned(ctx, size, alignto, 0);
 
    /*
     * We may memcpy beyond the end of the original allocation request size,
     * so we must mark the entire allocation as defined.
     */
    VALGRIND_MAKE_MEM_DEFINED(pointer, old_size);
    memcpy(newptr, pointer, Min(size, old_size));
    pfree(unaligned);
 
    return newptr;
}

References Assert(), GetMemoryChunkContext(), GetMemoryChunkSpace(), MemoryChunkGetBlock(), MemoryChunkGetValue(), MemoryContextAllocAligned(), Min, PallocAlignedExtraBytes, pfree(), PointerGetMemoryChunk, and VALGRIND_MAKE_MEM_DEFINED.