chromium/third_party/grpc/src/third_party/upb/upb/arena.h

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 *
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#ifndef UPB_ARENA_H_
#define UPB_ARENA_H_

#include <assert.h>
#include <stdbool.h>
#include <stdint.h>
#include <string.h>

#include "upb/port_def.inc"

#ifdef __cplusplus
extern "C" {
#endif

/** upb_alloc *****************************************************************/

/* A upb_alloc is a possibly-stateful allocator object.
 *
 * It could either be an arena allocator (which doesn't require individual
 * free() calls) or a regular malloc() (which does).  The client must therefore
 * free memory unless it knows that the allocator is an arena allocator. */

struct upb_alloc;
upb_alloc;

/* A malloc()/free() function.
 * If "size" is 0 then the function acts like free(), otherwise it acts like
 * realloc().  Only "oldsize" bytes from a previous allocation are preserved. */
upb_alloc_func;

struct upb_alloc { … };

UPB_INLINE void* upb_malloc(upb_alloc* alloc, size_t size) { … }

UPB_INLINE void* upb_realloc(upb_alloc* alloc, void* ptr, size_t oldsize,
                             size_t size) { … }

UPB_INLINE void upb_free(upb_alloc* alloc, void* ptr) { … }

/* The global allocator used by upb.  Uses the standard malloc()/free(). */

extern upb_alloc upb_alloc_global;

/* Functions that hard-code the global malloc.
 *
 * We still get benefit because we can put custom logic into our global
 * allocator, like injecting out-of-memory faults in debug/testing builds. */

UPB_INLINE void* upb_gmalloc(size_t size) { … }

UPB_INLINE void* upb_grealloc(void* ptr, size_t oldsize, size_t size) { … }

UPB_INLINE void upb_gfree(void* ptr) { … }

/* upb_Arena ******************************************************************/

/* upb_Arena is a specific allocator implementation that uses arena allocation.
 * The user provides an allocator that will be used to allocate the underlying
 * arena blocks.  Arenas by nature do not require the individual allocations
 * to be freed.  However the Arena does allow users to register cleanup
 * functions that will run when the arena is destroyed.
 *
 * A upb_Arena is *not* thread-safe.
 *
 * You could write a thread-safe arena allocator that satisfies the
 * upb_alloc interface, but it would not be as efficient for the
 * single-threaded case. */

upb_CleanupFunc;

struct upb_Arena;
upb_Arena;

_upb_ArenaHead;

/* Creates an arena from the given initial block (if any -- n may be 0).
 * Additional blocks will be allocated from |alloc|.  If |alloc| is NULL, this
 * is a fixed-size arena and cannot grow. */
upb_Arena* upb_Arena_Init(void* mem, size_t n, upb_alloc* alloc);
void upb_Arena_Free(upb_Arena* a);
bool upb_Arena_AddCleanup(upb_Arena* a, void* ud, upb_CleanupFunc* func);
bool upb_Arena_Fuse(upb_Arena* a, upb_Arena* b);
void* _upb_Arena_SlowMalloc(upb_Arena* a, size_t size);

UPB_INLINE upb_alloc* upb_Arena_Alloc(upb_Arena* a) { … }

UPB_INLINE size_t _upb_ArenaHas(upb_Arena* a) { … }

UPB_INLINE void* _upb_Arena_FastMalloc(upb_Arena* a, size_t size) { … }

UPB_INLINE void* upb_Arena_Malloc(upb_Arena* a, size_t size) { … }

// Shrinks the last alloc from arena.
// REQUIRES: (ptr, oldsize) was the last malloc/realloc from this arena.
// We could also add a upb_Arena_TryShrinkLast() which is simply a no-op if
// this was not the last alloc.
UPB_INLINE void upb_Arena_ShrinkLast(upb_Arena* a, void* ptr, size_t oldsize,
                                     size_t size) { … }

UPB_INLINE void* upb_Arena_Realloc(upb_Arena* a, void* ptr, size_t oldsize,
                                   size_t size) { … }

UPB_INLINE upb_Arena* upb_Arena_New(void) { … }

#include "upb/port_undef.inc"

#ifdef __cplusplus
} /* extern "C" */
#endif

#endif /* UPB_ARENA_H_ */