generation.c File Reference

#include "postgres.h"
#include "lib/ilist.h"
#include "port/pg_bitutils.h"
#include "utils/memdebug.h"
#include "utils/memutils.h"
#include "utils/memutils_internal.h"
#include "utils/memutils_memorychunk.h"

Include dependency graph for generation.c:

Go to the source code of this file.

Data Structures
struct	GenerationContext
struct	GenerationBlock

Macros
#define	Generation_BLOCKHDRSZ   MAXALIGN(sizeof(GenerationBlock))
#define	Generation_CHUNKHDRSZ   sizeof(MemoryChunk)
#define	Generation_CHUNK_FRACTION   8
#define	GenerationIsValid(set)    (PointerIsValid(set) && IsA(set, GenerationContext))
#define	GenerationBlockIsValid(block)    (PointerIsValid(block) && GenerationIsValid((block)->context))
#define	GenerationBlockIsEmpty(b)   ((b)->nchunks == 0)
#define	ExternalChunkGetBlock(chunk)    (GenerationBlock *) ((char *) chunk - Generation_BLOCKHDRSZ)
#define	KeeperBlock(set)
#define	IsKeeperBlock(set, block)   ((block) == (KeeperBlock(set)))

Typedefs
typedef struct GenerationBlock	GenerationBlock
typedef void *	GenerationPointer
typedef struct GenerationContext	GenerationContext

Functions
static void	GenerationBlockInit (GenerationContext *context, GenerationBlock *block, Size blksize)
static void	GenerationBlockMarkEmpty (GenerationBlock *block)
static Size	GenerationBlockFreeBytes (GenerationBlock *block)
static void	GenerationBlockFree (GenerationContext *set, GenerationBlock *block)
MemoryContext	GenerationContextCreate (MemoryContext parent, const char *name, Size minContextSize, Size initBlockSize, Size maxBlockSize)
void	GenerationReset (MemoryContext context)
void	GenerationDelete (MemoryContext context)
static pg_noinline void *	GenerationAllocLarge (MemoryContext context, Size size, int flags)
static void *	GenerationAllocChunkFromBlock (MemoryContext context, GenerationBlock *block, Size size, Size chunk_size)
static pg_noinline void *	GenerationAllocFromNewBlock (MemoryContext context, Size size, int flags, Size chunk_size)
void *	GenerationAlloc (MemoryContext context, Size size, int flags)
void	GenerationFree (void *pointer)
void *	GenerationRealloc (void *pointer, Size size, int flags)
MemoryContext	GenerationGetChunkContext (void *pointer)
Size	GenerationGetChunkSpace (void *pointer)
bool	GenerationIsEmpty (MemoryContext context)
void	GenerationStats (MemoryContext context, MemoryStatsPrintFunc printfunc, void *passthru, MemoryContextCounters *totals, bool print_to_stderr)

Macro Definition Documentation

ExternalChunkGetBlock

#define ExternalChunkGetBlock

(

chunk

)

(GenerationBlock *) ((char *) chunk - Generation_BLOCKHDRSZ)

Definition at line 123 of file generation.c.

Generation_BLOCKHDRSZ

#define Generation_BLOCKHDRSZ   MAXALIGN(sizeof(GenerationBlock))

Definition at line 46 of file generation.c.

Generation_CHUNK_FRACTION

#define Generation_CHUNK_FRACTION   8

Definition at line 49 of file generation.c.

Generation_CHUNKHDRSZ

#define Generation_CHUNKHDRSZ   sizeof(MemoryChunk)

Definition at line 47 of file generation.c.

GenerationBlockIsEmpty

#define GenerationBlockIsEmpty

(

b

)

((b)->nchunks == 0)

Definition at line 116 of file generation.c.

GenerationBlockIsValid

#define GenerationBlockIsValid

(

block

)

(PointerIsValid(block) && GenerationIsValid((block)->context))

Definition at line 109 of file generation.c.

GenerationIsValid

#define GenerationIsValid

(

set

)

(PointerIsValid(set) && IsA(set, GenerationContext))

Definition at line 102 of file generation.c.

IsKeeperBlock

#define IsKeeperBlock	(		set,
			block
	)		((block) == (KeeperBlock(set)))

Definition at line 132 of file generation.c.

KeeperBlock

#define KeeperBlock

(

set

)

Value:

    ((GenerationBlock *) (((char *) set) + \
    MAXALIGN(sizeof(GenerationContext))))

Definition at line 127 of file generation.c.

Typedef Documentation

GenerationBlock

typedef struct GenerationBlock GenerationBlock

Definition at line 51 of file generation.c.

GenerationContext

typedef struct GenerationContext GenerationContext

GenerationPointer

typedef void* GenerationPointer

Definition at line 53 of file generation.c.

Function Documentation

GenerationAlloc()

void * GenerationAlloc	(	MemoryContext	context,
		Size	size,
		int	flags
	)

Definition at line 527 of file generation.c.

{
    GenerationContext *set = (GenerationContext *) context;
    GenerationBlock *block;
    Size        chunk_size;
    Size        required_size;
 
    Assert(GenerationIsValid(set));
 
#ifdef MEMORY_CONTEXT_CHECKING
    /* ensure there's always space for the sentinel byte */
    chunk_size = MAXALIGN(size + 1);
#else
    chunk_size = MAXALIGN(size);
#endif
 
    /*
     * If requested size exceeds maximum for chunks we hand the request off to
     * GenerationAllocLarge().
     */
    if (chunk_size > set->allocChunkLimit)
        return GenerationAllocLarge(context, size, flags);
 
    required_size = chunk_size + Generation_CHUNKHDRSZ;
 
    /*
     * Not an oversized chunk.  We try to first make use of the current block,
     * but if there's not enough space in it, instead of allocating a new
     * block, we look to see if the empty freeblock has enough space.  We
     * don't try reusing the keeper block.  If it's become empty we'll reuse
     * that again only if the context is reset.
     *
     * We only try reusing the freeblock if we've no space for this allocation
     * on the current block.  When a freeblock exists, we'll switch to it once
     * the first time we can't fit an allocation in the current block.  We
     * avoid ping-ponging between the two as we need to be careful not to
     * fragment differently sized consecutive allocations between several
     * blocks.  Going between the two could cause fragmentation for FIFO
     * workloads, which generation is meant to be good at.
     */
    block = set->block;
 
    if (unlikely(GenerationBlockFreeBytes(block) < required_size))
    {
        GenerationBlock *freeblock = set->freeblock;
 
        /* freeblock, if set, must be empty */
        Assert(freeblock == NULL || GenerationBlockIsEmpty(freeblock));
 
        /* check if we have a freeblock and if it's big enough */
        if (freeblock != NULL &&
            GenerationBlockFreeBytes(freeblock) >= required_size)
        {
            /* make the freeblock the current block */
            set->freeblock = NULL;
            set->block = freeblock;
 
            return GenerationAllocChunkFromBlock(context,
                                                 freeblock,
                                                 size,
                                                 chunk_size);
        }
        else
        {
            /*
             * No freeblock, or it's not big enough for this allocation.  Make
             * a new block.
             */
            return GenerationAllocFromNewBlock(context, size, flags, chunk_size);
        }
    }
 
    /* The current block has space, so just allocate chunk there. */
    return GenerationAllocChunkFromBlock(context, block, size, chunk_size);
}

References GenerationContext::allocChunkLimit, Assert(), GenerationContext::block, GenerationContext::freeblock, Generation_CHUNKHDRSZ, GenerationAllocChunkFromBlock(), GenerationAllocFromNewBlock(), GenerationAllocLarge(), GenerationBlockFreeBytes(), GenerationBlockIsEmpty, GenerationIsValid, MAXALIGN, and unlikely.

Referenced by GenerationRealloc().

GenerationAllocChunkFromBlock()

static void * GenerationAllocChunkFromBlock ( MemoryContext  context, GenerationBlock *  block, Size  size, Size  chunk_size  )

inlinestatic

Definition at line 413 of file generation.c.

{
    MemoryChunk *chunk = (MemoryChunk *) (block->freeptr);
 
    /* validate we've been given a block with enough free space */
    Assert(block != NULL);
    Assert((block->endptr - block->freeptr) >=
           Generation_CHUNKHDRSZ + chunk_size);
 
    /* Prepare to initialize the chunk header. */
    VALGRIND_MAKE_MEM_UNDEFINED(chunk, Generation_CHUNKHDRSZ);
 
    block->nchunks += 1;
    block->freeptr += (Generation_CHUNKHDRSZ + chunk_size);
 
    Assert(block->freeptr <= block->endptr);
 
    MemoryChunkSetHdrMask(chunk, block, chunk_size, MCTX_GENERATION_ID);
#ifdef MEMORY_CONTEXT_CHECKING
    chunk->requested_size = size;
    /* set mark to catch clobber of "unused" space */
    Assert(size < chunk_size);
    set_sentinel(MemoryChunkGetPointer(chunk), size);
#endif
#ifdef RANDOMIZE_ALLOCATED_MEMORY
    /* fill the allocated space with junk */
    randomize_mem((char *) MemoryChunkGetPointer(chunk), size);
#endif
 
    /* Ensure any padding bytes are marked NOACCESS. */
    VALGRIND_MAKE_MEM_NOACCESS((char *) MemoryChunkGetPointer(chunk) + size,
                               chunk_size - size);
 
    /* Disallow access to the chunk header. */
    VALGRIND_MAKE_MEM_NOACCESS(chunk, Generation_CHUNKHDRSZ);
 
    return MemoryChunkGetPointer(chunk);
}

References Assert(), GenerationBlock::endptr, GenerationBlock::freeptr, Generation_CHUNKHDRSZ, MCTX_GENERATION_ID, MemoryChunkGetPointer, MemoryChunkSetHdrMask(), GenerationBlock::nchunks, VALGRIND_MAKE_MEM_NOACCESS, and VALGRIND_MAKE_MEM_UNDEFINED.

Referenced by GenerationAlloc(), and GenerationAllocFromNewBlock().

GenerationAllocFromNewBlock()

static pg_noinline void * GenerationAllocFromNewBlock ( MemoryContext  context, Size  size, int  flags, Size  chunk_size  )

static

Definition at line 461 of file generation.c.

{
    GenerationContext *set = (GenerationContext *) context;
    GenerationBlock *block;
    Size        blksize;
    Size        required_size;
 
    /*
     * The first such block has size initBlockSize, and we double the space in
     * each succeeding block, but not more than maxBlockSize.
     */
    blksize = set->nextBlockSize;
    set->nextBlockSize <<= 1;
    if (set->nextBlockSize > set->maxBlockSize)
        set->nextBlockSize = set->maxBlockSize;
 
    /* we'll need space for the chunk, chunk hdr and block hdr */
    required_size = chunk_size + Generation_CHUNKHDRSZ + Generation_BLOCKHDRSZ;
 
    /* round the size up to the next power of 2 */
    if (blksize < required_size)
        blksize = pg_nextpower2_size_t(required_size);
 
    block = (GenerationBlock *) malloc(blksize);
 
    if (block == NULL)
        return MemoryContextAllocationFailure(context, size, flags);
 
    context->mem_allocated += blksize;
 
    /* initialize the new block */
    GenerationBlockInit(set, block, blksize);
 
    /* add it to the doubly-linked list of blocks */
    dlist_push_head(&set->blocks, &block->node);
 
    /* make this the current block */
    set->block = block;
 
    return GenerationAllocChunkFromBlock(context, block, size, chunk_size);
}

References GenerationContext::block, GenerationContext::blocks, dlist_push_head(), Generation_BLOCKHDRSZ, Generation_CHUNKHDRSZ, GenerationAllocChunkFromBlock(), GenerationBlockInit(), malloc, GenerationContext::maxBlockSize, MemoryContextData::mem_allocated, MemoryContextAllocationFailure(), GenerationContext::nextBlockSize, GenerationBlock::node, and pg_nextpower2_size_t.

Referenced by GenerationAlloc().

GenerationAllocLarge()

static pg_noinline void * GenerationAllocLarge ( MemoryContext  context, Size  size, int  flags  )

static

Definition at line 343 of file generation.c.

{
    GenerationContext *set = (GenerationContext *) context;
    GenerationBlock *block;
    MemoryChunk *chunk;
    Size        chunk_size;
    Size        required_size;
    Size        blksize;
 
    /* validate 'size' is within the limits for the given 'flags' */
    MemoryContextCheckSize(context, size, flags);
 
#ifdef MEMORY_CONTEXT_CHECKING
    /* ensure there's always space for the sentinel byte */
    chunk_size = MAXALIGN(size + 1);
#else
    chunk_size = MAXALIGN(size);
#endif
    required_size = chunk_size + Generation_CHUNKHDRSZ;
    blksize = required_size + Generation_BLOCKHDRSZ;
 
    block = (GenerationBlock *) malloc(blksize);
    if (block == NULL)
        return MemoryContextAllocationFailure(context, size, flags);
 
    context->mem_allocated += blksize;
 
    /* block with a single (used) chunk */
    block->context = set;
    block->blksize = blksize;
    block->nchunks = 1;
    block->nfree = 0;
 
    /* the block is completely full */
    block->freeptr = block->endptr = ((char *) block) + blksize;
 
    chunk = (MemoryChunk *) (((char *) block) + Generation_BLOCKHDRSZ);
 
    /* mark the MemoryChunk as externally managed */
    MemoryChunkSetHdrMaskExternal(chunk, MCTX_GENERATION_ID);
 
#ifdef MEMORY_CONTEXT_CHECKING
    chunk->requested_size = size;
    /* set mark to catch clobber of "unused" space */
    Assert(size < chunk_size);
    set_sentinel(MemoryChunkGetPointer(chunk), size);
#endif
#ifdef RANDOMIZE_ALLOCATED_MEMORY
    /* fill the allocated space with junk */
    randomize_mem((char *) MemoryChunkGetPointer(chunk), size);
#endif
 
    /* add the block to the list of allocated blocks */
    dlist_push_head(&set->blocks, &block->node);
 
    /* Ensure any padding bytes are marked NOACCESS. */
    VALGRIND_MAKE_MEM_NOACCESS((char *) MemoryChunkGetPointer(chunk) + size,
                               chunk_size - size);
 
    /* Disallow access to the chunk header. */
    VALGRIND_MAKE_MEM_NOACCESS(chunk, Generation_CHUNKHDRSZ);
 
    return MemoryChunkGetPointer(chunk);
}

References Assert(), GenerationBlock::blksize, GenerationContext::blocks, GenerationBlock::context, dlist_push_head(), GenerationBlock::endptr, GenerationBlock::freeptr, Generation_BLOCKHDRSZ, Generation_CHUNKHDRSZ, malloc, MAXALIGN, MCTX_GENERATION_ID, MemoryContextData::mem_allocated, MemoryChunkGetPointer, MemoryChunkSetHdrMaskExternal(), MemoryContextAllocationFailure(), MemoryContextCheckSize(), GenerationBlock::nchunks, GenerationBlock::nfree, GenerationBlock::node, and VALGRIND_MAKE_MEM_NOACCESS.

Referenced by GenerationAlloc().

GenerationBlockFree()

static void GenerationBlockFree ( GenerationContext *  set, GenerationBlock *  block  )

inlinestatic

Definition at line 664 of file generation.c.

{
    /* Make sure nobody tries to free the keeper block */
    Assert(!IsKeeperBlock(set, block));
    /* We shouldn't be freeing the freeblock either */
    Assert(block != set->freeblock);
 
    /* release the block from the list of blocks */
    dlist_delete(&block->node);
 
    ((MemoryContext) set)->mem_allocated -= block->blksize;
 
#ifdef CLOBBER_FREED_MEMORY
    wipe_mem(block, block->blksize);
#endif
 
    free(block);
}

References Assert(), GenerationBlock::blksize, dlist_delete(), free, GenerationContext::freeblock, IsKeeperBlock, and GenerationBlock::node.

Referenced by GenerationFree(), and GenerationReset().

GenerationBlockFreeBytes()

static Size GenerationBlockFreeBytes ( GenerationBlock *  block )

inlinestatic

Definition at line 654 of file generation.c.

{
    return (block->endptr - block->freeptr);
}

References GenerationBlock::endptr, and GenerationBlock::freeptr.

Referenced by GenerationAlloc().

GenerationBlockInit()

static void GenerationBlockInit ( GenerationContext *  context, GenerationBlock *  block, Size  blksize  )

inlinestatic

Definition at line 609 of file generation.c.

{
    block->context = context;
    block->blksize = blksize;
    block->nchunks = 0;
    block->nfree = 0;
 
    block->freeptr = ((char *) block) + Generation_BLOCKHDRSZ;
    block->endptr = ((char *) block) + blksize;
 
    /* Mark unallocated space NOACCESS. */
    VALGRIND_MAKE_MEM_NOACCESS(block->freeptr,
                               blksize - Generation_BLOCKHDRSZ);
}

References GenerationBlock::blksize, GenerationBlock::context, GenerationBlock::endptr, GenerationBlock::freeptr, Generation_BLOCKHDRSZ, GenerationBlock::nchunks, GenerationBlock::nfree, and VALGRIND_MAKE_MEM_NOACCESS.

Referenced by GenerationAllocFromNewBlock(), and GenerationContextCreate().

GenerationBlockMarkEmpty()

static void GenerationBlockMarkEmpty ( GenerationBlock *  block )

inlinestatic

Definition at line 630 of file generation.c.

{
#if defined(USE_VALGRIND) || defined(CLOBBER_FREED_MEMORY)
    char       *datastart = ((char *) block) + Generation_BLOCKHDRSZ;
#endif
 
#ifdef CLOBBER_FREED_MEMORY
    wipe_mem(datastart, block->freeptr - datastart);
#else
    /* wipe_mem() would have done this */
    VALGRIND_MAKE_MEM_NOACCESS(datastart, block->freeptr - datastart);
#endif
 
    /* Reset the block, but don't return it to malloc */
    block->nchunks = 0;
    block->nfree = 0;
    block->freeptr = ((char *) block) + Generation_BLOCKHDRSZ;
}

References GenerationBlock::freeptr, Generation_BLOCKHDRSZ, GenerationBlock::nchunks, GenerationBlock::nfree, and VALGRIND_MAKE_MEM_NOACCESS.

Referenced by GenerationFree(), and GenerationReset().

GenerationContextCreate()

MemoryContext GenerationContextCreate	(	MemoryContext	parent,
		const char *	name,
		Size	minContextSize,
		Size	initBlockSize,
		Size	maxBlockSize
	)

Definition at line 160 of file generation.c.

{
    Size        firstBlockSize;
    Size        allocSize;
    GenerationContext *set;
    GenerationBlock *block;
 
    /* ensure MemoryChunk's size is properly maxaligned */
    StaticAssertDecl(Generation_CHUNKHDRSZ == MAXALIGN(Generation_CHUNKHDRSZ),
                     "sizeof(MemoryChunk) is not maxaligned");
 
    /*
     * First, validate allocation parameters.  Asserts seem sufficient because
     * nobody varies their parameters at runtime.  We somewhat arbitrarily
     * enforce a minimum 1K block size.  We restrict the maximum block size to
     * MEMORYCHUNK_MAX_BLOCKOFFSET as MemoryChunks are limited to this in
     * regards to addressing the offset between the chunk and the block that
     * the chunk is stored on.  We would be unable to store the offset between
     * the chunk and block for any chunks that were beyond
     * MEMORYCHUNK_MAX_BLOCKOFFSET bytes into the block if the block was to be
     * larger than this.
     */
    Assert(initBlockSize == MAXALIGN(initBlockSize) &&
           initBlockSize >= 1024);
    Assert(maxBlockSize == MAXALIGN(maxBlockSize) &&
           maxBlockSize >= initBlockSize &&
           AllocHugeSizeIsValid(maxBlockSize)); /* must be safe to double */
    Assert(minContextSize == 0 ||
           (minContextSize == MAXALIGN(minContextSize) &&
            minContextSize >= 1024 &&
            minContextSize <= maxBlockSize));
    Assert(maxBlockSize <= MEMORYCHUNK_MAX_BLOCKOFFSET);
 
    /* Determine size of initial block */
    allocSize = MAXALIGN(sizeof(GenerationContext)) +
        Generation_BLOCKHDRSZ + Generation_CHUNKHDRSZ;
    if (minContextSize != 0)
        allocSize = Max(allocSize, minContextSize);
    else
        allocSize = Max(allocSize, initBlockSize);
 
    /*
     * Allocate the initial block.  Unlike other generation.c blocks, it
     * starts with the context header and its block header follows that.
     */
    set = (GenerationContext *) malloc(allocSize);
    if (set == NULL)
    {
        MemoryContextStats(TopMemoryContext);
        ereport(ERROR,
                (errcode(ERRCODE_OUT_OF_MEMORY),
                 errmsg("out of memory"),
                 errdetail("Failed while creating memory context \"%s\".",
                           name)));
    }
 
    /*
     * Avoid writing code that can fail between here and MemoryContextCreate;
     * we'd leak the header if we ereport in this stretch.
     */
    dlist_init(&set->blocks);
 
    /* Fill in the initial block's block header */
    block = KeeperBlock(set);
    /* determine the block size and initialize it */
    firstBlockSize = allocSize - MAXALIGN(sizeof(GenerationContext));
    GenerationBlockInit(set, block, firstBlockSize);
 
    /* add it to the doubly-linked list of blocks */
    dlist_push_head(&set->blocks, &block->node);
 
    /* use it as the current allocation block */
    set->block = block;
 
    /* No free block, yet */
    set->freeblock = NULL;
 
    /* Fill in GenerationContext-specific header fields */
    set->initBlockSize = (uint32) initBlockSize;
    set->maxBlockSize = (uint32) maxBlockSize;
    set->nextBlockSize = (uint32) initBlockSize;
 
    /*
     * Compute the allocation chunk size limit for this context.
     *
     * Limit the maximum size a non-dedicated chunk can be so that we can fit
     * at least Generation_CHUNK_FRACTION of chunks this big onto the maximum
     * sized block.  We must further limit this value so that it's no more
     * than MEMORYCHUNK_MAX_VALUE.  We're unable to have non-external chunks
     * larger than that value as we store the chunk size in the MemoryChunk
     * 'value' field in the call to MemoryChunkSetHdrMask().
     */
    set->allocChunkLimit = Min(maxBlockSize, MEMORYCHUNK_MAX_VALUE);
    while ((Size) (set->allocChunkLimit + Generation_CHUNKHDRSZ) >
           (Size) ((Size) (maxBlockSize - Generation_BLOCKHDRSZ) / Generation_CHUNK_FRACTION))
        set->allocChunkLimit >>= 1;
 
    /* Finally, do the type-independent part of context creation */
    MemoryContextCreate((MemoryContext) set,
                        T_GenerationContext,
                        MCTX_GENERATION_ID,
                        parent,
                        name);
 
    ((MemoryContext) set)->mem_allocated = firstBlockSize;
 
    return (MemoryContext) set;
}

References GenerationContext::allocChunkLimit, AllocHugeSizeIsValid, Assert(), GenerationContext::block, GenerationContext::blocks, dlist_init(), dlist_push_head(), ereport, errcode(), errdetail(), errmsg(), ERROR, GenerationContext::freeblock, Generation_BLOCKHDRSZ, Generation_CHUNK_FRACTION, Generation_CHUNKHDRSZ, GenerationBlockInit(), GenerationContext::initBlockSize, KeeperBlock, malloc, Max, MAXALIGN, GenerationContext::maxBlockSize, MCTX_GENERATION_ID, MEMORYCHUNK_MAX_BLOCKOFFSET, MEMORYCHUNK_MAX_VALUE, MemoryContextCreate(), MemoryContextStats(), Min, name, GenerationContext::nextBlockSize, GenerationBlock::node, StaticAssertDecl, and TopMemoryContext.

Referenced by gistvacuumscan(), ReorderBufferAllocate(), and tuplestore_begin_common().

GenerationDelete()

void GenerationDelete

(

MemoryContext

context

)

Definition at line 328 of file generation.c.

{
    /* Reset to release all releasable GenerationBlocks */
    GenerationReset(context);
    /* And free the context header and keeper block */
    free(context);
}

References free, and GenerationReset().

GenerationFree()

void GenerationFree

(

void *

pointer

)

Definition at line 689 of file generation.c.

{
    MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
    GenerationBlock *block;
    GenerationContext *set;
#if (defined(MEMORY_CONTEXT_CHECKING) && defined(USE_ASSERT_CHECKING)) \
    || defined(CLOBBER_FREED_MEMORY)
    Size        chunksize;
#endif
 
    /* Allow access to the chunk header. */
    VALGRIND_MAKE_MEM_DEFINED(chunk, Generation_CHUNKHDRSZ);
 
    if (MemoryChunkIsExternal(chunk))
    {
        block = ExternalChunkGetBlock(chunk);
 
        /*
         * Try to verify that we have a sane block pointer: the block header
         * should reference a generation context.
         */
        if (!GenerationBlockIsValid(block))
            elog(ERROR, "could not find block containing chunk %p", chunk);
 
#if (defined(MEMORY_CONTEXT_CHECKING) && defined(USE_ASSERT_CHECKING)) \
    || defined(CLOBBER_FREED_MEMORY)
        chunksize = block->endptr - (char *) pointer;
#endif
    }
    else
    {
        block = MemoryChunkGetBlock(chunk);
 
        /*
         * In this path, for speed reasons we just Assert that the referenced
         * block is good.  Future field experience may show that this Assert
         * had better become a regular runtime test-and-elog check.
         */
        Assert(GenerationBlockIsValid(block));
 
#if (defined(MEMORY_CONTEXT_CHECKING) && defined(USE_ASSERT_CHECKING)) \
    || defined(CLOBBER_FREED_MEMORY)
        chunksize = MemoryChunkGetValue(chunk);
#endif
    }
 
#ifdef MEMORY_CONTEXT_CHECKING
    /* Test for someone scribbling on unused space in chunk */
    Assert(chunk->requested_size < chunksize);
    if (!sentinel_ok(pointer, chunk->requested_size))
        elog(WARNING, "detected write past chunk end in %s %p",
             ((MemoryContext) block->context)->name, chunk);
#endif
 
#ifdef CLOBBER_FREED_MEMORY
    wipe_mem(pointer, chunksize);
#endif
 
#ifdef MEMORY_CONTEXT_CHECKING
    /* Reset requested_size to InvalidAllocSize in freed chunks */
    chunk->requested_size = InvalidAllocSize;
#endif
 
    block->nfree += 1;
 
    Assert(block->nchunks > 0);
    Assert(block->nfree <= block->nchunks);
    Assert(block != block->context->freeblock);
 
    /* If there are still allocated chunks in the block, we're done. */
    if (likely(block->nfree < block->nchunks))
        return;
 
    set = block->context;
 
    /*-----------------------
     * The block this allocation was on has now become completely empty of
     * chunks.  In the general case, we can now return the memory for this
     * block back to malloc.  However, there are cases where we don't want to
     * do that:
     *
     * 1)   If it's the keeper block.  This block was malloc'd in the same
     *      allocation as the context itself and can't be free'd without
     *      freeing the context.
     * 2)   If it's the current block.  We could free this, but doing so would
     *      leave us nothing to set the current block to, so we just mark the
     *      block as empty so new allocations can reuse it again.
     * 3)   If we have no "freeblock" set, then we save a single block for
     *      future allocations to avoid having to malloc a new block again.
     *      This is useful for FIFO workloads as it avoids continual
     *      free/malloc cycles.
     */
    if (IsKeeperBlock(set, block) || set->block == block)
        GenerationBlockMarkEmpty(block);    /* case 1 and 2 */
    else if (set->freeblock == NULL)
    {
        /* case 3 */
        GenerationBlockMarkEmpty(block);
        set->freeblock = block;
    }
    else
        GenerationBlockFree(set, block);    /* Otherwise, free it */
}

References Assert(), GenerationContext::block, GenerationBlock::context, elog, GenerationBlock::endptr, ERROR, ExternalChunkGetBlock, GenerationContext::freeblock, Generation_CHUNKHDRSZ, GenerationBlockFree(), GenerationBlockIsValid, GenerationBlockMarkEmpty(), InvalidAllocSize, IsKeeperBlock, likely, MemoryChunkGetBlock(), MemoryChunkGetValue(), MemoryChunkIsExternal(), GenerationBlock::nchunks, GenerationBlock::nfree, PointerGetMemoryChunk, VALGRIND_MAKE_MEM_DEFINED, and WARNING.

Referenced by GenerationRealloc().

GenerationGetChunkContext()

MemoryContext GenerationGetChunkContext

(

void *

pointer

)

Definition at line 947 of file generation.c.

{
    MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
    GenerationBlock *block;
 
    /* Allow access to the chunk header. */
    VALGRIND_MAKE_MEM_DEFINED(chunk, Generation_CHUNKHDRSZ);
 
    if (MemoryChunkIsExternal(chunk))
        block = ExternalChunkGetBlock(chunk);
    else
        block = (GenerationBlock *) MemoryChunkGetBlock(chunk);
 
    /* Disallow access to the chunk header. */
    VALGRIND_MAKE_MEM_NOACCESS(chunk, Generation_CHUNKHDRSZ);
 
    Assert(GenerationBlockIsValid(block));
    return &block->context->header;
}

References Assert(), GenerationBlock::context, ExternalChunkGetBlock, Generation_CHUNKHDRSZ, GenerationBlockIsValid, GenerationContext::header, MemoryChunkGetBlock(), MemoryChunkIsExternal(), PointerGetMemoryChunk, VALGRIND_MAKE_MEM_DEFINED, and VALGRIND_MAKE_MEM_NOACCESS.

GenerationGetChunkSpace()

Size GenerationGetChunkSpace

(

void *

pointer

)

Definition at line 973 of file generation.c.

{
    MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
    Size        chunksize;
 
    /* Allow access to the chunk header. */
    VALGRIND_MAKE_MEM_DEFINED(chunk, Generation_CHUNKHDRSZ);
 
    if (MemoryChunkIsExternal(chunk))
    {
        GenerationBlock *block = ExternalChunkGetBlock(chunk);
 
        Assert(GenerationBlockIsValid(block));
        chunksize = block->endptr - (char *) pointer;
    }
    else
        chunksize = MemoryChunkGetValue(chunk);
 
    /* Disallow access to the chunk header. */
    VALGRIND_MAKE_MEM_NOACCESS(chunk, Generation_CHUNKHDRSZ);
 
    return Generation_CHUNKHDRSZ + chunksize;
}

References Assert(), GenerationBlock::endptr, ExternalChunkGetBlock, Generation_CHUNKHDRSZ, GenerationBlockIsValid, MemoryChunkGetValue(), MemoryChunkIsExternal(), PointerGetMemoryChunk, VALGRIND_MAKE_MEM_DEFINED, and VALGRIND_MAKE_MEM_NOACCESS.

GenerationIsEmpty()

bool GenerationIsEmpty

(

MemoryContext

context

)

Definition at line 1002 of file generation.c.

{
    GenerationContext *set = (GenerationContext *) context;
    dlist_iter  iter;
 
    Assert(GenerationIsValid(set));
 
    dlist_foreach(iter, &set->blocks)
    {
        GenerationBlock *block = dlist_container(GenerationBlock, node, iter.cur);
 
        if (block->nchunks > 0)
            return false;
    }
 
    return true;
}

References Assert(), GenerationContext::blocks, dlist_iter::cur, dlist_container, dlist_foreach, GenerationIsValid, and GenerationBlock::nchunks.

GenerationRealloc()

void * GenerationRealloc	(	void *	pointer,
		Size	size,
		int	flags
	)

Definition at line 800 of file generation.c.

{
    MemoryChunk *chunk = PointerGetMemoryChunk(pointer);
    GenerationContext *set;
    GenerationBlock *block;
    GenerationPointer newPointer;
    Size        oldsize;
 
    /* Allow access to the chunk header. */
    VALGRIND_MAKE_MEM_DEFINED(chunk, Generation_CHUNKHDRSZ);
 
    if (MemoryChunkIsExternal(chunk))
    {
        block = ExternalChunkGetBlock(chunk);
 
        /*
         * Try to verify that we have a sane block pointer: the block header
         * should reference a generation context.
         */
        if (!GenerationBlockIsValid(block))
            elog(ERROR, "could not find block containing chunk %p", chunk);
 
        oldsize = block->endptr - (char *) pointer;
    }
    else
    {
        block = MemoryChunkGetBlock(chunk);
 
        /*
         * In this path, for speed reasons we just Assert that the referenced
         * block is good.  Future field experience may show that this Assert
         * had better become a regular runtime test-and-elog check.
         */
        Assert(GenerationBlockIsValid(block));
 
        oldsize = MemoryChunkGetValue(chunk);
    }
 
    set = block->context;
 
#ifdef MEMORY_CONTEXT_CHECKING
    /* Test for someone scribbling on unused space in chunk */
    Assert(chunk->requested_size < oldsize);
    if (!sentinel_ok(pointer, chunk->requested_size))
        elog(WARNING, "detected write past chunk end in %s %p",
             ((MemoryContext) set)->name, chunk);
#endif
 
    /*
     * Maybe the allocated area already big enough.  (In particular, we always
     * fall out here if the requested size is a decrease.)
     *
     * This memory context does not use power-of-2 chunk sizing and instead
     * carves the chunks to be as small as possible, so most repalloc() calls
     * will end up in the palloc/memcpy/pfree branch.
     *
     * XXX Perhaps we should annotate this condition with unlikely()?
     */
#ifdef MEMORY_CONTEXT_CHECKING
    /* With MEMORY_CONTEXT_CHECKING, we need an extra byte for the sentinel */
    if (oldsize > size)
#else
    if (oldsize >= size)
#endif
    {
#ifdef MEMORY_CONTEXT_CHECKING
        Size        oldrequest = chunk->requested_size;
 
#ifdef RANDOMIZE_ALLOCATED_MEMORY
        /* We can only fill the extra space if we know the prior request */
        if (size > oldrequest)
            randomize_mem((char *) pointer + oldrequest,
                          size - oldrequest);
#endif
 
        chunk->requested_size = size;
 
        /*
         * If this is an increase, mark any newly-available part UNDEFINED.
         * Otherwise, mark the obsolete part NOACCESS.
         */
        if (size > oldrequest)
            VALGRIND_MAKE_MEM_UNDEFINED((char *) pointer + oldrequest,
                                        size - oldrequest);
        else
            VALGRIND_MAKE_MEM_NOACCESS((char *) pointer + size,
                                       oldsize - size);
 
        /* set mark to catch clobber of "unused" space */
        set_sentinel(pointer, size);
#else                           /* !MEMORY_CONTEXT_CHECKING */
 
        /*
         * We don't have the information to determine whether we're growing
         * the old request or shrinking it, so we conservatively mark the
         * entire new allocation DEFINED.
         */
        VALGRIND_MAKE_MEM_NOACCESS(pointer, oldsize);
        VALGRIND_MAKE_MEM_DEFINED(pointer, size);
#endif
 
        /* Disallow access to the chunk header. */
        VALGRIND_MAKE_MEM_NOACCESS(chunk, Generation_CHUNKHDRSZ);
 
        return pointer;
    }
 
    /* allocate new chunk (this also checks size is valid) */
    newPointer = GenerationAlloc((MemoryContext) set, size, flags);
 
    /* leave immediately if request was not completed */
    if (newPointer == NULL)
    {
        /* Disallow access to the chunk header. */
        VALGRIND_MAKE_MEM_NOACCESS(chunk, Generation_CHUNKHDRSZ);
        return MemoryContextAllocationFailure((MemoryContext) set, size, flags);
    }
 
    /*
     * GenerationAlloc() may have returned a region that is still NOACCESS.
     * Change it to UNDEFINED for the moment; memcpy() will then transfer
     * definedness from the old allocation to the new.  If we know the old
     * allocation, copy just that much.  Otherwise, make the entire old chunk
     * defined to avoid errors as we copy the currently-NOACCESS trailing
     * bytes.
     */
    VALGRIND_MAKE_MEM_UNDEFINED(newPointer, size);
#ifdef MEMORY_CONTEXT_CHECKING
    oldsize = chunk->requested_size;
#else
    VALGRIND_MAKE_MEM_DEFINED(pointer, oldsize);
#endif
 
    /* transfer existing data (certain to fit) */
    memcpy(newPointer, pointer, oldsize);
 
    /* free old chunk */
    GenerationFree(pointer);
 
    return newPointer;
}

References Assert(), GenerationBlock::context, elog, GenerationBlock::endptr, ERROR, ExternalChunkGetBlock, Generation_CHUNKHDRSZ, GenerationAlloc(), GenerationBlockIsValid, GenerationFree(), MemoryChunkGetBlock(), MemoryChunkGetValue(), MemoryChunkIsExternal(), MemoryContextAllocationFailure(), name, PointerGetMemoryChunk, VALGRIND_MAKE_MEM_DEFINED, VALGRIND_MAKE_MEM_NOACCESS, VALGRIND_MAKE_MEM_UNDEFINED, and WARNING.

GenerationReset()

void GenerationReset

(

MemoryContext

context

)

Definition at line 283 of file generation.c.

{
    GenerationContext *set = (GenerationContext *) context;
    dlist_mutable_iter miter;
 
    Assert(GenerationIsValid(set));
 
#ifdef MEMORY_CONTEXT_CHECKING
    /* Check for corruption and leaks before freeing */
    GenerationCheck(context);
#endif
 
    /*
     * NULLify the free block pointer.  We must do this before calling
     * GenerationBlockFree as that function never expects to free the
     * freeblock.
     */
    set->freeblock = NULL;
 
    dlist_foreach_modify(miter, &set->blocks)
    {
        GenerationBlock *block = dlist_container(GenerationBlock, node, miter.cur);
 
        if (IsKeeperBlock(set, block))
            GenerationBlockMarkEmpty(block);
        else
            GenerationBlockFree(set, block);
    }
 
    /* set it so new allocations to make use of the keeper block */
    set->block = KeeperBlock(set);
 
    /* Reset block size allocation sequence, too */
    set->nextBlockSize = set->initBlockSize;
 
    /* Ensure there is only 1 item in the dlist */
    Assert(!dlist_is_empty(&set->blocks));
    Assert(!dlist_has_next(&set->blocks, dlist_head_node(&set->blocks)));
}

References Assert(), GenerationContext::block, GenerationContext::blocks, dlist_mutable_iter::cur, dlist_container, dlist_foreach_modify, dlist_has_next(), dlist_head_node(), dlist_is_empty(), GenerationContext::freeblock, GenerationBlockFree(), GenerationBlockMarkEmpty(), GenerationIsValid, GenerationContext::initBlockSize, IsKeeperBlock, KeeperBlock, and GenerationContext::nextBlockSize.

Referenced by GenerationDelete().

GenerationStats()

void GenerationStats	(	MemoryContext	context,
		MemoryStatsPrintFunc	printfunc,
		void *	passthru,
		MemoryContextCounters *	totals,
		bool	print_to_stderr
	)

Definition at line 1033 of file generation.c.

{
    GenerationContext *set = (GenerationContext *) context;
    Size        nblocks = 0;
    Size        nchunks = 0;
    Size        nfreechunks = 0;
    Size        totalspace;
    Size        freespace = 0;
    dlist_iter  iter;
 
    Assert(GenerationIsValid(set));
 
    /* Include context header in totalspace */
    totalspace = MAXALIGN(sizeof(GenerationContext));
 
    dlist_foreach(iter, &set->blocks)
    {
        GenerationBlock *block = dlist_container(GenerationBlock, node, iter.cur);
 
        nblocks++;
        nchunks += block->nchunks;
        nfreechunks += block->nfree;
        totalspace += block->blksize;
        freespace += (block->endptr - block->freeptr);
    }
 
    if (printfunc)
    {
        char        stats_string[200];
 
        snprintf(stats_string, sizeof(stats_string),
                 "%zu total in %zu blocks (%zu chunks); %zu free (%zu chunks); %zu used",
                 totalspace, nblocks, nchunks, freespace,
                 nfreechunks, totalspace - freespace);
        printfunc(context, passthru, stats_string, print_to_stderr);
    }
 
    if (totals)
    {
        totals->nblocks += nblocks;
        totals->freechunks += nfreechunks;
        totals->totalspace += totalspace;
        totals->freespace += freespace;
    }
}

References Assert(), GenerationBlock::blksize, GenerationContext::blocks, dlist_iter::cur, dlist_container, dlist_foreach, GenerationBlock::endptr, MemoryContextCounters::freechunks, GenerationBlock::freeptr, MemoryContextCounters::freespace, GenerationIsValid, MAXALIGN, MemoryContextCounters::nblocks, GenerationBlock::nchunks, GenerationBlock::nfree, snprintf, and MemoryContextCounters::totalspace.