/* * This file is part of FFmpeg. * * FFmpeg 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. * * FFmpeg 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 FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #ifndef AVUTIL_REFSTRUCT_H#define AVUTIL_REFSTRUCT_H #include <stddef.h> /** * RefStruct is an API for creating reference-counted objects * with minimal overhead. The API is designed for objects, * not buffers like the AVBuffer API. The main differences * to the AVBuffer API are as follows: * * - It uses void* instead of uint8_t* as its base type due to * its focus on objects. * - There are no equivalents of AVBuffer and AVBufferRef. * E.g. there is no way to get the usable size of the object: * The user is supposed to know what is at the other end of * the pointer. It also avoids one level of indirection. * - Custom allocators are not supported. This allows to simplify * the implementation and reduce the amount of allocations. * - It also has the advantage that the user's free callback need * only free the resources owned by the object, but not the * object itself. * - Because referencing (and replacing) an object managed by the * RefStruct API does not involve allocations, they can not fail * and therefore need not be checked. * * @note Referencing and unreferencing the buffers is thread-safe and thus * may be done from multiple threads simultaneously without any need for * additional locking. */ /** * This union is used for all opaque parameters in this API to spare the user * to cast const away in case the opaque to use is const-qualified. * * The functions provided by this API with an AVRefStructOpaque come in pairs * named foo_c and foo. The foo function accepts void* as opaque and is just * a wrapper around the foo_c function; "_c" means "(potentially) const". */typedef union { void *nc; const void *c;} AVRefStructOpaque; /** * If this flag is set in av_refstruct_alloc_ext_c(), the object will not * be initially zeroed. */#define AV_REFSTRUCT_FLAG_NO_ZEROING (1 << 0) /** * Allocate a refcounted object of usable size `size` managed via * the RefStruct API. * * By default (in the absence of flags to the contrary), * the returned object is initially zeroed. * * @param size Desired usable size of the returned object. * @param flags A bitwise combination of av_refstruct_FLAG_* flags. * @param opaque A pointer that will be passed to the free_cb callback. * @param free_cb A callback for freeing this object's content * when its reference count reaches zero; * it must not free the object itself. * @return A pointer to an object of the desired size or NULL on failure. */void *av_refstruct_alloc_ext_c(size_t size, unsigned flags, AVRefStructOpaque opaque, void (*free_cb)(AVRefStructOpaque opaque, void *obj)); /** * A wrapper around av_refstruct_alloc_ext_c() for the common case * of a non-const qualified opaque. * * @see av_refstruct_alloc_ext_c() */static inlinevoid *av_refstruct_alloc_ext(size_t size, unsigned flags, void *opaque, void (*free_cb)(AVRefStructOpaque opaque, void *obj)){ return av_refstruct_alloc_ext_c(size, flags, (AVRefStructOpaque){.nc = opaque}, free_cb);} /** * Equivalent to av_refstruct_alloc_ext(size, 0, NULL, NULL) */static inlinevoid *av_refstruct_allocz(size_t size){ return av_refstruct_alloc_ext(size, 0, NULL, NULL);} /** * Decrement the reference count of the underlying object and automatically * free the object if there are no more references to it. * * `*objp == NULL` is legal and a no-op. * * @param objp Pointer to a pointer that is either NULL or points to an object * managed via this API. `*objp` is set to NULL on return. */void av_refstruct_unref(void *objp); /** * Create a new reference to an object managed via this API, * i.e. increment the reference count of the underlying object * and return obj. * @return a pointer equal to obj. */void *av_refstruct_ref(void *obj); /** * Analog of av_refstruct_ref(), but for constant objects. * @see av_refstruct_ref() */const void *av_refstruct_ref_c(const void *obj); /** * Ensure `*dstp` refers to the same object as src. * * If `*dstp` is already equal to src, do nothing. Otherwise unreference `*dstp` * and replace it with a new reference to src in case `src != NULL` (this * involves incrementing the reference count of src's underlying object) or * with NULL otherwise. * * @param dstp Pointer to a pointer that is either NULL or points to an object * managed via this API. * @param src A pointer to an object managed via this API or NULL. */void av_refstruct_replace(void *dstp, const void *src); /** * Check whether the reference count of an object managed * via this API is 1. * * @param obj A pointer to an object managed via this API. * @return 1 if the reference count of obj is 1; 0 otherwise. */int av_refstruct_exclusive(const void *obj); /** * AVRefStructPool is an API for a thread-safe pool of objects managed * via the RefStruct API. * * Frequently allocating and freeing large or complicated objects may be slow * and wasteful. This API is meant to solve this in cases when the caller * needs a set of interchangable objects. * * At the beginning, the user must call allocate the pool via * av_refstruct_pool_alloc() or its analogue av_refstruct_pool_alloc_ext(). * Then whenever an object is needed, call av_refstruct_pool_get() to * get a new or reused object from the pool. This new object works in all * aspects the same way as the ones created by av_refstruct_alloc_ext(). * However, when the last reference to this object is unreferenced, it is * (optionally) reset and returned to the pool instead of being freed and * will be reused for subsequent av_refstruct_pool_get() calls. * * When the caller is done with the pool and no longer needs to create any new * objects, av_refstruct_pool_uninit() must be called to mark the pool as * freeable. Then entries returned to the pool will then be freed. * Once all the entries are freed, the pool will automatically be freed. * * Allocating and releasing objects with this API is thread-safe as long as * the user-supplied callbacks (if provided) are thread-safe. */ /** * The buffer pool. This structure is opaque and not meant to be accessed * directly. It is allocated with the allocators below and freed with * av_refstruct_pool_uninit(). */typedef struct AVRefStructPool AVRefStructPool; /** * If this flag is not set, every object in the pool will be zeroed before * the init callback is called or before it is turned over to the user * for the first time if no init callback has been provided. */#define AV_REFSTRUCT_POOL_FLAG_NO_ZEROING AV_REFSTRUCT_FLAG_NO_ZEROING/** * If this flag is set and both init_cb and reset_cb callbacks are provided, * then reset_cb will be called if init_cb fails. * The object passed to reset_cb will be in the state left by init_cb. */#define AV_REFSTRUCT_POOL_FLAG_RESET_ON_INIT_ERROR (1 << 16)/** * If this flag is set and both init_cb and free_entry_cb callbacks are * provided, then free_cb will be called if init_cb fails. * * It will be called after reset_cb in case reset_cb and the * av_refstruct_POOL_FLAG_RESET_ON_INIT_ERROR flag are also set. * * The object passed to free_cb will be in the state left by * the callbacks applied earlier (init_cb potentially followed by reset_cb). */#define AV_REFSTRUCT_POOL_FLAG_FREE_ON_INIT_ERROR (1 << 17)/** * If this flag is set, the entries will be zeroed before * being returned to the user (after the init or reset callbacks * have been called (if provided)). Furthermore, to avoid zeroing twice * it also makes the pool behave as if the av_refstruct_POOL_FLAG_NO_ZEROING * flag had been provided. */#define AV_REFSTRUCT_POOL_FLAG_ZERO_EVERY_TIME (1 << 18) /** * Equivalent to av_refstruct_pool_alloc(size, flags, NULL, NULL, NULL, NULL, NULL) */AVRefStructPool *av_refstruct_pool_alloc(size_t size, unsigned flags); /** * Allocate an AVRefStructPool, potentially using complex callbacks. * * @param size size of the entries of the pool * @param flags a bitwise combination of av_refstruct_POOL_FLAG_* flags * @param opaque A pointer that will be passed to the callbacks below. * @param init A callback that will be called directly after a new entry * has been allocated. obj has already been zeroed unless * the av_refstruct_POOL_FLAG_NO_ZEROING flag is in use. * @param reset A callback that will be called after an entry has been * returned to the pool and before it is reused. * @param free_entry A callback that will be called when an entry is freed * after the pool has been marked as to be uninitialized. * @param free A callback that will be called when the pool itself is * freed (after the last entry has been returned and freed). */AVRefStructPool *av_refstruct_pool_alloc_ext_c(size_t size, unsigned flags, AVRefStructOpaque opaque, int (*init_cb)(AVRefStructOpaque opaque, void *obj), void (*reset_cb)(AVRefStructOpaque opaque, void *obj), void (*free_entry_cb)(AVRefStructOpaque opaque, void *obj), void (*free_cb)(AVRefStructOpaque opaque)); /** * A wrapper around av_refstruct_pool_alloc_ext_c() for the common case * of a non-const qualified opaque. * * @see av_refstruct_pool_alloc_ext_c() */static inlineAVRefStructPool *av_refstruct_pool_alloc_ext(size_t size, unsigned flags, void *opaque, int (*init_cb)(AVRefStructOpaque opaque, void *obj), void (*reset_cb)(AVRefStructOpaque opaque, void *obj), void (*free_entry_cb)(AVRefStructOpaque opaque, void *obj), void (*free_cb)(AVRefStructOpaque opaque)){ return av_refstruct_pool_alloc_ext_c(size, flags, (AVRefStructOpaque){.nc = opaque}, init_cb, reset_cb, free_entry_cb, free_cb);} /** * Get an object from the pool, reusing an old one from the pool when * available. * * Every call to this function must happen before av_refstruct_pool_uninit(). * Otherwise undefined behaviour may occur. * * @param pool the pool from which to get the object * @return a reference to the object on success, NULL on error. */void *av_refstruct_pool_get(AVRefStructPool *pool); /** * Mark the pool as being available for freeing. It will actually be freed * only once all the allocated buffers associated with the pool are released. * Thus it is safe to call this function while some of the allocated buffers * are still in use. * * It is illegal to try to get a new entry after this function has been called. * * @param poolp pointer to a pointer to either NULL or a pool to be freed. * `*poolp` will be set to NULL. */static inline void av_refstruct_pool_uninit(AVRefStructPool **poolp){ av_refstruct_unref(poolp);} #endif /* AVUTIL_REFSTRUCT_H */
/*
* This file is part of FFmpeg.
*
* FFmpeg 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.
*
* FFmpeg 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 FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef AVUTIL_REFSTRUCT_H
#define AVUTIL_REFSTRUCT_H
#include <stddef.h>
/**
* RefStruct is an API for creating reference-counted objects
* with minimal overhead. The API is designed for objects,
* not buffers like the AVBuffer API. The main differences
* to the AVBuffer API are as follows:
*
* - It uses void* instead of uint8_t* as its base type due to
* its focus on objects.
* - There are no equivalents of AVBuffer and AVBufferRef.
* E.g. there is no way to get the usable size of the object:
* The user is supposed to know what is at the other end of
* the pointer. It also avoids one level of indirection.
* - Custom allocators are not supported. This allows to simplify
* the implementation and reduce the amount of allocations.
* - It also has the advantage that the user's free callback need
* only free the resources owned by the object, but not the
* object itself.
* - Because referencing (and replacing) an object managed by the
* RefStruct API does not involve allocations, they can not fail
* and therefore need not be checked.
*
* @note Referencing and unreferencing the buffers is thread-safe and thus
* may be done from multiple threads simultaneously without any need for
* additional locking.
*/
/**
* This union is used for all opaque parameters in this API to spare the user
* to cast const away in case the opaque to use is const-qualified.
*
* The functions provided by this API with an AVRefStructOpaque come in pairs
* named foo_c and foo. The foo function accepts void* as opaque and is just
* a wrapper around the foo_c function; "_c" means "(potentially) const".
*/
typedef union {
void *nc;
const void *c;
} AVRefStructOpaque;
/**
* If this flag is set in av_refstruct_alloc_ext_c(), the object will not
* be initially zeroed.
*/
#define AV_REFSTRUCT_FLAG_NO_ZEROING (1 << 0)
/**
* Allocate a refcounted object of usable size `size` managed via
* the RefStruct API.
*
* By default (in the absence of flags to the contrary),
* the returned object is initially zeroed.
*
* @param size Desired usable size of the returned object.
* @param flags A bitwise combination of av_refstruct_FLAG_* flags.
* @param opaque A pointer that will be passed to the free_cb callback.
* @param free_cb A callback for freeing this object's content
* when its reference count reaches zero;
* it must not free the object itself.
* @return A pointer to an object of the desired size or NULL on failure.
*/
void *av_refstruct_alloc_ext_c(size_t size, unsigned flags, AVRefStructOpaque opaque,
void (*free_cb)(AVRefStructOpaque opaque, void *obj));
/**
* A wrapper around av_refstruct_alloc_ext_c() for the common case
* of a non-const qualified opaque.
*
* @see av_refstruct_alloc_ext_c()
*/
static inline
void *av_refstruct_alloc_ext(size_t size, unsigned flags, void *opaque,
void (*free_cb)(AVRefStructOpaque opaque, void *obj))
{
return av_refstruct_alloc_ext_c(size, flags, (AVRefStructOpaque){.nc = opaque},
free_cb);
}
/**
* Equivalent to av_refstruct_alloc_ext(size, 0, NULL, NULL)
*/
static inline
void *av_refstruct_allocz(size_t size)
{
return av_refstruct_alloc_ext(size, 0, NULL, NULL);
}
/**
* Decrement the reference count of the underlying object and automatically
* free the object if there are no more references to it.
*
* `*objp == NULL` is legal and a no-op.
*
* @param objp Pointer to a pointer that is either NULL or points to an object
* managed via this API. `*objp` is set to NULL on return.
*/
void av_refstruct_unref(void *objp);
/**
* Create a new reference to an object managed via this API,
* i.e. increment the reference count of the underlying object
* and return obj.
* @return a pointer equal to obj.
*/
void *av_refstruct_ref(void *obj);
/**
* Analog of av_refstruct_ref(), but for constant objects.
* @see av_refstruct_ref()
*/
const void *av_refstruct_ref_c(const void *obj);
/**
* Ensure `*dstp` refers to the same object as src.
*
* If `*dstp` is already equal to src, do nothing. Otherwise unreference `*dstp`
* and replace it with a new reference to src in case `src != NULL` (this
* involves incrementing the reference count of src's underlying object) or
* with NULL otherwise.
*
* @param dstp Pointer to a pointer that is either NULL or points to an object
* managed via this API.
* @param src A pointer to an object managed via this API or NULL.
*/
void av_refstruct_replace(void *dstp, const void *src);
/**
* Check whether the reference count of an object managed
* via this API is 1.
*
* @param obj A pointer to an object managed via this API.
* @return 1 if the reference count of obj is 1; 0 otherwise.
*/
int av_refstruct_exclusive(const void *obj);
/**
* AVRefStructPool is an API for a thread-safe pool of objects managed
* via the RefStruct API.
*
* Frequently allocating and freeing large or complicated objects may be slow
* and wasteful. This API is meant to solve this in cases when the caller
* needs a set of interchangable objects.
*
* At the beginning, the user must call allocate the pool via
* av_refstruct_pool_alloc() or its analogue av_refstruct_pool_alloc_ext().
* Then whenever an object is needed, call av_refstruct_pool_get() to
* get a new or reused object from the pool. This new object works in all
* aspects the same way as the ones created by av_refstruct_alloc_ext().
* However, when the last reference to this object is unreferenced, it is
* (optionally) reset and returned to the pool instead of being freed and
* will be reused for subsequent av_refstruct_pool_get() calls.
*
* When the caller is done with the pool and no longer needs to create any new
* objects, av_refstruct_pool_uninit() must be called to mark the pool as
* freeable. Then entries returned to the pool will then be freed.
* Once all the entries are freed, the pool will automatically be freed.
*
* Allocating and releasing objects with this API is thread-safe as long as
* the user-supplied callbacks (if provided) are thread-safe.
*/
/**
* The buffer pool. This structure is opaque and not meant to be accessed
* directly. It is allocated with the allocators below and freed with
* av_refstruct_pool_uninit().
*/
typedef struct AVRefStructPool AVRefStructPool;
/**
* If this flag is not set, every object in the pool will be zeroed before
* the init callback is called or before it is turned over to the user
* for the first time if no init callback has been provided.
*/
#define AV_REFSTRUCT_POOL_FLAG_NO_ZEROING AV_REFSTRUCT_FLAG_NO_ZEROING
/**
* If this flag is set and both init_cb and reset_cb callbacks are provided,
* then reset_cb will be called if init_cb fails.
* The object passed to reset_cb will be in the state left by init_cb.
*/
#define AV_REFSTRUCT_POOL_FLAG_RESET_ON_INIT_ERROR (1 << 16)
/**
* If this flag is set and both init_cb and free_entry_cb callbacks are
* provided, then free_cb will be called if init_cb fails.
*
* It will be called after reset_cb in case reset_cb and the
* av_refstruct_POOL_FLAG_RESET_ON_INIT_ERROR flag are also set.
*
* The object passed to free_cb will be in the state left by
* the callbacks applied earlier (init_cb potentially followed by reset_cb).
*/
#define AV_REFSTRUCT_POOL_FLAG_FREE_ON_INIT_ERROR (1 << 17)
/**
* If this flag is set, the entries will be zeroed before
* being returned to the user (after the init or reset callbacks
* have been called (if provided)). Furthermore, to avoid zeroing twice
* it also makes the pool behave as if the av_refstruct_POOL_FLAG_NO_ZEROING
* flag had been provided.
*/
#define AV_REFSTRUCT_POOL_FLAG_ZERO_EVERY_TIME (1 << 18)
/**
* Equivalent to av_refstruct_pool_alloc(size, flags, NULL, NULL, NULL, NULL, NULL)
*/
AVRefStructPool *av_refstruct_pool_alloc(size_t size, unsigned flags);
/**
* Allocate an AVRefStructPool, potentially using complex callbacks.
*
* @param size size of the entries of the pool
* @param flags a bitwise combination of av_refstruct_POOL_FLAG_* flags
* @param opaque A pointer that will be passed to the callbacks below.
* @param init A callback that will be called directly after a new entry
* has been allocated. obj has already been zeroed unless
* the av_refstruct_POOL_FLAG_NO_ZEROING flag is in use.
* @param reset A callback that will be called after an entry has been
* returned to the pool and before it is reused.
* @param free_entry A callback that will be called when an entry is freed
* after the pool has been marked as to be uninitialized.
* @param free A callback that will be called when the pool itself is
* freed (after the last entry has been returned and freed).
*/
AVRefStructPool *av_refstruct_pool_alloc_ext_c(size_t size, unsigned flags,
AVRefStructOpaque opaque,
int (*init_cb)(AVRefStructOpaque opaque, void *obj),
void (*reset_cb)(AVRefStructOpaque opaque, void *obj),
void (*free_entry_cb)(AVRefStructOpaque opaque, void *obj),
void (*free_cb)(AVRefStructOpaque opaque));
/**
* A wrapper around av_refstruct_pool_alloc_ext_c() for the common case
* of a non-const qualified opaque.
*
* @see av_refstruct_pool_alloc_ext_c()
*/
static inline
AVRefStructPool *av_refstruct_pool_alloc_ext(size_t size, unsigned flags,
void *opaque,
int (*init_cb)(AVRefStructOpaque opaque, void *obj),
void (*reset_cb)(AVRefStructOpaque opaque, void *obj),
void (*free_entry_cb)(AVRefStructOpaque opaque, void *obj),
void (*free_cb)(AVRefStructOpaque opaque))
{
return av_refstruct_pool_alloc_ext_c(size, flags, (AVRefStructOpaque){.nc = opaque},
init_cb, reset_cb, free_entry_cb, free_cb);
}
/**
* Get an object from the pool, reusing an old one from the pool when
* available.
*
* Every call to this function must happen before av_refstruct_pool_uninit().
* Otherwise undefined behaviour may occur.
*
* @param pool the pool from which to get the object
* @return a reference to the object on success, NULL on error.
*/
void *av_refstruct_pool_get(AVRefStructPool *pool);
/**
* Mark the pool as being available for freeing. It will actually be freed
* only once all the allocated buffers associated with the pool are released.
* Thus it is safe to call this function while some of the allocated buffers
* are still in use.
*
* It is illegal to try to get a new entry after this function has been called.
*
* @param poolp pointer to a pointer to either NULL or a pool to be freed.
* `*poolp` will be set to NULL.
*/
static inline void av_refstruct_pool_uninit(AVRefStructPool **poolp)
{
av_refstruct_unref(poolp);
}
#endif /* AVUTIL_REFSTRUCT_H */