src/pulsecore/memblock.h

#ifndef foopulsememblockhfoo
#define foopulsememblockhfoo

/***
  This file is part of PulseAudio.

  Copyright 2004-2006 Lennart Poettering
  Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB

  PulseAudio is free software; you can redistribute it and/or modify
  it under the terms of the GNU Lesser General Public License as
  published by the Free Software Foundation; either version 2.1 of the
  License, or (at your option) any later version.

  PulseAudio is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
***/

typedef struct pa_memblock pa_memblock;

#include <sys/types.h>
#include <inttypes.h>

#include <pulse/def.h>
#include <pulse/xmalloc.h>
#include <pulsecore/atomic.h>
#include <pulsecore/memchunk.h>
#include <pulsecore/mem.h>

/* A pa_memblock is a reference counted memory block. PulseAudio
 * passes references to pa_memblocks around instead of copying
 * data. See pa_memchunk for a structure that describes parts of
 * memory blocks. */

/* The type of memory this block points to */
typedef enum pa_memblock_type {
    PA_MEMBLOCK_POOL,             /* Memory is part of the memory pool */
    PA_MEMBLOCK_POOL_EXTERNAL,    /* Data memory is part of the memory pool but the pa_memblock structure itself is not */
    PA_MEMBLOCK_APPENDED,         /* The data is appended to the memory block */
    PA_MEMBLOCK_USER,             /* User supplied memory, to be freed with free_cb */
    PA_MEMBLOCK_FIXED,            /* Data is a pointer to fixed memory that needs not to be freed */
    PA_MEMBLOCK_IMPORTED,         /* Memory is imported from another process via shm */
    PA_MEMBLOCK_TYPE_MAX
} pa_memblock_type_t;

typedef struct pa_mempool pa_mempool;
typedef struct pa_mempool_stat pa_mempool_stat;
typedef struct pa_memimport_segment pa_memimport_segment;
typedef struct pa_memimport pa_memimport;
typedef struct pa_memexport pa_memexport;

typedef void (*pa_memimport_release_cb_t)(pa_memimport *i, uint32_t block_id, void *userdata);
typedef void (*pa_memexport_revoke_cb_t)(pa_memexport *e, uint32_t block_id, void *userdata);

/* Please note that updates to this structure are not locked,
 * i.e. n_allocated might be updated at a point in time where
 * n_accumulated is not yet. Take these values with a grain of salt,
 * they are here for purely statistical reasons.*/
struct pa_mempool_stat {
    pa_atomic_t n_allocated;
    pa_atomic_t n_accumulated;
    pa_atomic_t n_imported;
    pa_atomic_t n_exported;
    pa_atomic_t allocated_size;
    pa_atomic_t accumulated_size;
    pa_atomic_t imported_size;
    pa_atomic_t exported_size;

    pa_atomic_t n_too_large_for_pool;
    pa_atomic_t n_pool_full;

    pa_atomic_t n_allocated_by_type[PA_MEMBLOCK_TYPE_MAX];
    pa_atomic_t n_accumulated_by_type[PA_MEMBLOCK_TYPE_MAX];
};

/* Allocate a new memory block of type PA_MEMBLOCK_MEMPOOL or PA_MEMBLOCK_APPENDED, depending on the size */
pa_memblock *pa_memblock_new(pa_mempool *, size_t length);

/* Allocate a new memory block of type PA_MEMBLOCK_MEMPOOL. If the requested size is too large, return NULL */
pa_memblock *pa_memblock_new_pool(pa_mempool *, size_t length);

/* Allocate a new memory block of type PA_MEMBLOCK_USER */
pa_memblock *pa_memblock_new_user(pa_mempool *, void *data, size_t length, pa_free_cb_t free_cb, void *free_cb_data, bool read_only);

/* A special case of pa_memblock_new_user: take a memory buffer previously allocated with pa_xmalloc()  */
static inline pa_memblock *pa_memblock_new_malloced(pa_mempool *p, void *data, size_t length) {
    return pa_memblock_new_user(p, data, length, pa_xfree, data, 0);
}

/* Allocate a new memory block of type PA_MEMBLOCK_FIXED */
pa_memblock *pa_memblock_new_fixed(pa_mempool *, void *data, size_t length, bool read_only);

void pa_memblock_unref(pa_memblock*b);
pa_memblock* pa_memblock_ref(pa_memblock*b);

/* This special unref function has to be called by the owner of the
memory of a static memory block when they want to release all
references to the memory. This causes the memory to be copied and
converted into a pool of malloc'ed memory block. Please note that this
function is not multiple caller safe, i.e. needs to be locked
manually if called from more than one thread at the same time. */
void pa_memblock_unref_fixed(pa_memblock*b);

bool pa_memblock_is_ours(pa_memblock *b);
bool pa_memblock_is_read_only(pa_memblock *b);
bool pa_memblock_is_silence(pa_memblock *b);
bool pa_memblock_ref_is_one(pa_memblock *b);
void pa_memblock_set_is_silence(pa_memblock *b, bool v);

void* pa_memblock_acquire(pa_memblock *b);
void *pa_memblock_acquire_chunk(const pa_memchunk *c);
void pa_memblock_release(pa_memblock *b);

size_t pa_memblock_get_length(pa_memblock *b);

/* Note! Always unref the returned pool after use */
pa_mempool * pa_memblock_get_pool(pa_memblock *b);

pa_memblock *pa_memblock_will_need(pa_memblock *b);

/* The memory block manager */
pa_mempool *pa_mempool_new(pa_mem_type_t type, size_t size, bool per_client);
void pa_mempool_unref(pa_mempool *p);
pa_mempool* pa_mempool_ref(pa_mempool *p);
const pa_mempool_stat* pa_mempool_get_stat(pa_mempool *p);
void pa_mempool_vacuum(pa_mempool *p);
int pa_mempool_get_shm_id(pa_mempool *p, uint32_t *id);
bool pa_mempool_is_shared(pa_mempool *p);
bool pa_mempool_is_memfd_backed(const pa_mempool *p);
bool pa_mempool_is_global(pa_mempool *p);
bool pa_mempool_is_per_client(pa_mempool *p);
bool pa_mempool_is_remote_writable(pa_mempool *p);
void pa_mempool_set_is_remote_writable(pa_mempool *p, bool writable);
size_t pa_mempool_block_size_max(pa_mempool *p);

int pa_mempool_take_memfd_fd(pa_mempool *p);
int pa_mempool_get_memfd_fd(pa_mempool *p);

/* For receiving blocks from other nodes */
pa_memimport* pa_memimport_new(pa_mempool *p, pa_memimport_release_cb_t cb, void *userdata);
void pa_memimport_free(pa_memimport *i);
int pa_memimport_attach_memfd(pa_memimport *i, uint32_t shm_id, int memfd_fd, bool writable);
pa_memblock* pa_memimport_get(pa_memimport *i, pa_mem_type_t type, uint32_t block_id,
                              uint32_t shm_id, size_t offset, size_t size, bool writable);
int pa_memimport_process_revoke(pa_memimport *i, uint32_t block_id);

/* For sending blocks to other nodes */
pa_memexport* pa_memexport_new(pa_mempool *p, pa_memexport_revoke_cb_t cb, void *userdata);
void pa_memexport_free(pa_memexport *e);
int pa_memexport_put(pa_memexport *e, pa_memblock *b, pa_mem_type_t *type, uint32_t *block_id,
                     uint32_t *shm_id, size_t *offset, size_t * size);
int pa_memexport_process_release(pa_memexport *e, uint32_t id);

#endif