diff options
Diffstat (limited to 'src/include/utils/memutils.h')
| -rw-r--r-- | src/include/utils/memutils.h | 224 |
1 files changed, 224 insertions, 0 deletions
diff --git a/src/include/utils/memutils.h b/src/include/utils/memutils.h new file mode 100644 index 0000000..909bc2e --- /dev/null +++ b/src/include/utils/memutils.h @@ -0,0 +1,224 @@ +/*------------------------------------------------------------------------- + * + * memutils.h + * This file contains declarations for memory allocation utility + * functions. These are functions that are not quite widely used + * enough to justify going in utils/palloc.h, but are still part + * of the API of the memory management subsystem. + * + * + * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * src/include/utils/memutils.h + * + *------------------------------------------------------------------------- + */ +#ifndef MEMUTILS_H +#define MEMUTILS_H + +#include "nodes/memnodes.h" + + +/* + * MaxAllocSize, MaxAllocHugeSize + * Quasi-arbitrary limits on size of allocations. + * + * Note: + * There is no guarantee that smaller allocations will succeed, but + * larger requests will be summarily denied. + * + * palloc() enforces MaxAllocSize, chosen to correspond to the limiting size + * of varlena objects under TOAST. See VARSIZE_4B() and related macros in + * postgres.h. Many datatypes assume that any allocatable size can be + * represented in a varlena header. This limit also permits a caller to use + * an "int" variable for an index into or length of an allocation. Callers + * careful to avoid these hazards can access the higher limit with + * MemoryContextAllocHuge(). Both limits permit code to assume that it may + * compute twice an allocation's size without overflow. + */ +#define MaxAllocSize ((Size) 0x3fffffff) /* 1 gigabyte - 1 */ + +#define AllocSizeIsValid(size) ((Size) (size) <= MaxAllocSize) + +#define MaxAllocHugeSize (SIZE_MAX / 2) + +#define AllocHugeSizeIsValid(size) ((Size) (size) <= MaxAllocHugeSize) + + +/* + * Standard top-level memory contexts. + * + * Only TopMemoryContext and ErrorContext are initialized by + * MemoryContextInit() itself. + */ +extern PGDLLIMPORT MemoryContext TopMemoryContext; +extern PGDLLIMPORT MemoryContext ErrorContext; +extern PGDLLIMPORT MemoryContext PostmasterContext; +extern PGDLLIMPORT MemoryContext CacheMemoryContext; +extern PGDLLIMPORT MemoryContext MessageContext; +extern PGDLLIMPORT MemoryContext TopTransactionContext; +extern PGDLLIMPORT MemoryContext CurTransactionContext; + +/* This is a transient link to the active portal's memory context: */ +extern PGDLLIMPORT MemoryContext PortalContext; + +/* Backwards compatibility macro */ +#define MemoryContextResetAndDeleteChildren(ctx) MemoryContextReset(ctx) + + +/* + * Memory-context-type-independent functions in mcxt.c + */ +extern void MemoryContextInit(void); +extern void MemoryContextReset(MemoryContext context); +extern void MemoryContextDelete(MemoryContext context); +extern void MemoryContextResetOnly(MemoryContext context); +extern void MemoryContextResetChildren(MemoryContext context); +extern void MemoryContextDeleteChildren(MemoryContext context); +extern void MemoryContextSetIdentifier(MemoryContext context, const char *id); +extern void MemoryContextSetParent(MemoryContext context, + MemoryContext new_parent); +extern Size GetMemoryChunkSpace(void *pointer); +extern MemoryContext MemoryContextGetParent(MemoryContext context); +extern bool MemoryContextIsEmpty(MemoryContext context); +extern Size MemoryContextMemAllocated(MemoryContext context, bool recurse); +extern void MemoryContextStats(MemoryContext context); +extern void MemoryContextStatsDetail(MemoryContext context, int max_children); +extern void MemoryContextAllowInCriticalSection(MemoryContext context, + bool allow); + +#ifdef MEMORY_CONTEXT_CHECKING +extern void MemoryContextCheck(MemoryContext context); +#endif +extern bool MemoryContextContains(MemoryContext context, void *pointer); + +/* Handy macro for copying and assigning context ID ... but note double eval */ +#define MemoryContextCopyAndSetIdentifier(cxt, id) \ + MemoryContextSetIdentifier(cxt, MemoryContextStrdup(cxt, id)) + +/* + * GetMemoryChunkContext + * Given a currently-allocated chunk, determine the context + * it belongs to. + * + * All chunks allocated by any memory context manager are required to be + * preceded by the corresponding MemoryContext stored, without padding, in the + * preceding sizeof(void*) bytes. A currently-allocated chunk must contain a + * backpointer to its owning context. The backpointer is used by pfree() and + * repalloc() to find the context to call. + */ +#ifndef FRONTEND +static inline MemoryContext +GetMemoryChunkContext(void *pointer) +{ + MemoryContext context; + + /* + * Try to detect bogus pointers handed to us, poorly though we can. + * Presumably, a pointer that isn't MAXALIGNED isn't pointing at an + * allocated chunk. + */ + Assert(pointer != NULL); + Assert(pointer == (void *) MAXALIGN(pointer)); + + /* + * OK, it's probably safe to look at the context. + */ + context = *(MemoryContext *) (((char *) pointer) - sizeof(void *)); + + AssertArg(MemoryContextIsValid(context)); + + return context; +} +#endif + +/* + * 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, + const MemoryContextMethods *methods, + MemoryContext parent, + const char *name); + + +/* + * Memory-context-type-specific functions + */ + +/* aset.c */ +extern MemoryContext AllocSetContextCreateInternal(MemoryContext parent, + const char *name, + Size minContextSize, + Size initBlockSize, + Size maxBlockSize); + +/* + * This wrapper macro exists to check for non-constant strings used as context + * names; that's no longer supported. (Use MemoryContextSetIdentifier if you + * want to provide a variable identifier.) + */ +#ifdef HAVE__BUILTIN_CONSTANT_P +#define AllocSetContextCreate(parent, name, ...) \ + (StaticAssertExpr(__builtin_constant_p(name), \ + "memory context names must be constant strings"), \ + AllocSetContextCreateInternal(parent, name, __VA_ARGS__)) +#else +#define AllocSetContextCreate \ + AllocSetContextCreateInternal +#endif + +/* slab.c */ +extern MemoryContext SlabContextCreate(MemoryContext parent, + const char *name, + Size blockSize, + Size chunkSize); + +/* generation.c */ +extern MemoryContext GenerationContextCreate(MemoryContext parent, + const char *name, + Size blockSize); + +/* + * Recommended default alloc parameters, suitable for "ordinary" contexts + * that might hold quite a lot of data. + */ +#define ALLOCSET_DEFAULT_MINSIZE 0 +#define ALLOCSET_DEFAULT_INITSIZE (8 * 1024) +#define ALLOCSET_DEFAULT_MAXSIZE (8 * 1024 * 1024) +#define ALLOCSET_DEFAULT_SIZES \ + ALLOCSET_DEFAULT_MINSIZE, ALLOCSET_DEFAULT_INITSIZE, ALLOCSET_DEFAULT_MAXSIZE + +/* + * Recommended alloc parameters for "small" contexts that are never expected + * to contain much data (for example, a context to contain a query plan). + */ +#define ALLOCSET_SMALL_MINSIZE 0 +#define ALLOCSET_SMALL_INITSIZE (1 * 1024) +#define ALLOCSET_SMALL_MAXSIZE (8 * 1024) +#define ALLOCSET_SMALL_SIZES \ + ALLOCSET_SMALL_MINSIZE, ALLOCSET_SMALL_INITSIZE, ALLOCSET_SMALL_MAXSIZE + +/* + * Recommended alloc parameters for contexts that should start out small, + * but might sometimes grow big. + */ +#define ALLOCSET_START_SMALL_SIZES \ + ALLOCSET_SMALL_MINSIZE, ALLOCSET_SMALL_INITSIZE, ALLOCSET_DEFAULT_MAXSIZE + + +/* + * Threshold above which a request in an AllocSet context is certain to be + * allocated separately (and thereby have constant allocation overhead). + * Few callers should be interested in this, but tuplesort/tuplestore need + * to know it. + */ +#define ALLOCSET_SEPARATE_THRESHOLD 8192 + +#define SLAB_DEFAULT_BLOCK_SIZE (8 * 1024) +#define SLAB_LARGE_BLOCK_SIZE (8 * 1024 * 1024) + +#endif /* MEMUTILS_H */ |