Jerry/D-Modem
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity
D-Modem/pjproject-2.11.1/pjlib/include/pj/pool.h
Dan Bastone 636959b37b initial commit
2021-10-29 14:41:03 -04:00

918 lines
30 KiB
C
Raw Blame History

/* $Id$ */
/*
* Copyright (C) 2008-2011 Teluu Inc. (http://www.teluu.com)
* Copyright (C) 2003-2008 Benny Prijono <benny@prijono.org>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <pj/list.h>
/* See if we use pool's alternate API.
* The alternate API is used e.g. to implement pool debugging.
*/
#if PJ_HAS_POOL_ALT_API
# include <pj/pool_alt.h>
#endif
#ifndef __PJ_POOL_H__
#define __PJ_POOL_H__
/**
* @file pool.h
* @brief Memory Pool.
*/
PJ_BEGIN_DECL
/**
* @defgroup PJ_POOL_GROUP Fast Memory Pool
* @brief
* Memory pools allow dynamic memory allocation comparable to malloc or the
* new in operator C++. Those implementations are not desirable for very
* high performance applications or real-time systems, because of the
* performance bottlenecks and it suffers from fragmentation issue.
*
* \section PJ_POOL_INTRO_SEC PJLIB's Memory Pool
* \subsection PJ_POOL_ADVANTAGE_SUBSEC Advantages
*
* PJLIB's pool has many advantages over traditional malloc/new operator and
* over other memory pool implementations, because:
* - unlike other memory pool implementation, it allows allocation of
* memory chunks of different sizes,
* - it's very very fast.
* \n
* Memory chunk allocation is not only an O(1)
* operation, but it's also very simple (just
* few pointer arithmetic operations) and it doesn't require locking
* any mutex,
* - it's memory efficient.
* \n
* Pool doesn't keep track individual memory chunks allocated by
* applications, so there is no additional overhead needed for each
* memory allocation (other than possible additional of few bytes, up to
* PJ_POOL_ALIGNMENT-1, for aligning the memory).
* But see the @ref PJ_POOL_CAVEATS_SUBSEC below.
* - it prevents memory leaks.
* \n
* Memory pool inherently has garbage collection functionality. In fact,
* there is no need to free the chunks allocated from the memory pool.
* All chunks previously allocated from the pool will be freed once the
* pool itself is destroyed. This would prevent memory leaks that haunt
* programmers for decades, and it provides additional performance
* advantage over traditional malloc/new operator.
*
* Even more, PJLIB's memory pool provides some additional usability and
* flexibility for applications:
* - memory leaks are easily traceable, since memory pool is assigned name,
* and application can inspect what pools currently active in the system.
* - by design, memory allocation from a pool is not thread safe. We assumed
* that a pool will be owned by a higher level object, and thread safety
* should be handled by that object. This enables very fast pool operations
* and prevents unnecessary locking operations,
* - by default, the memory pool API behaves more like C++ new operator,
* in that it will throw PJ_NO_MEMORY_EXCEPTION exception (see
* @ref PJ_EXCEPT) when memory chunk allocation fails. This enables failure
* handling to be done on more high level function (instead of checking
* the result of pj_pool_alloc() everytime). If application doesn't like
* this, the default behavior can be changed on global basis by supplying
* different policy to the pool factory.
* - any memory allocation backend allocator/deallocator may be used. By
* default, the policy uses malloc() and free() to manage the pool's block,
* but application may use different strategy, for example to allocate
* memory blocks from a globally static memory location.
*
*
* \subsection PJ_POOL_PERFORMANCE_SUBSEC Performance
*
* The result of PJLIB's memory design and careful implementation is a
* memory allocation strategy that can speed-up the memory allocations
* and deallocations by up to <b>30 times</b> compared to standard
* malloc()/free() (more than 150 million allocations per second on a
* P4/3.0GHz Linux machine).
*
* (Note: your mileage may vary, of course. You can see how much PJLIB's
* pool improves the performance over malloc()/free() in your target
* system by running pjlib-test application).
*
*
* \subsection PJ_POOL_CAVEATS_SUBSEC Caveats
*
* There are some caveats though!
*
* When creating pool, PJLIB requires applications to specify the initial
* pool size, and as soon as the pool is created, PJLIB allocates memory
* from the system by that size. Application designers MUST choose the
* initial pool size carefully, since choosing too big value will result in
* wasting system's memory.
*
* But the pool can grow. Application designer can specify how the
* pool will grow in size, by specifying the size increment when creating
* the pool.
*
* The pool, however, <b>cannot</b> shrink! Since there is <b>no</b>
* function to deallocate memory chunks, there is no way for the pool to
* release back unused memory to the system.
* Application designers must be aware that constant memory allocations
* from pool that has infinite life-time may cause the memory usage of
* the application to grow over time.
*
*
* \section PJ_POOL_USING_SEC Using Memory Pool
*
* This section describes how to use PJLIB's memory pool framework.
* As we hope the readers will witness, PJLIB's memory pool API is quite
* straightforward.
*
* \subsection PJ_POOL_USING_F Create Pool Factory
* First, application needs to initialize a pool factory (this normally
* only needs to be done once in one application). PJLIB provides
* a pool factory implementation called caching pool (see @ref
* PJ_CACHING_POOL), and it is initialized by calling #pj_caching_pool_init().
*
* \subsection PJ_POOL_USING_P Create The Pool
* Then application creates the pool object itself with #pj_pool_create(),
* specifying among other thing the pool factory where the pool should
* be created from, the pool name, initial size, and increment/expansion
* size.
*
* \subsection PJ_POOL_USING_M Allocate Memory as Required
* Then whenever application needs to allocate dynamic memory, it would
* call #pj_pool_alloc(), #pj_pool_calloc(), or #pj_pool_zalloc() to
* allocate memory chunks from the pool.
*
* \subsection PJ_POOL_USING_DP Destroy the Pool
* When application has finished with the pool, it should call
* #pj_pool_release() to release the pool object back to the factory.
* Depending on the types of the factory, this may release the memory back
* to the operating system.
*
* \subsection PJ_POOL_USING_Dc Destroy the Pool Factory
* And finally, before application quites, it should deinitialize the
* pool factory, to make sure that all memory blocks allocated by the
* factory are released back to the operating system. After this, of
* course no more memory pool allocation can be requested.
*
* \subsection PJ_POOL_USING_EX Example
* Below is a sample complete program that utilizes PJLIB's memory pool.
*
* \code
#include <pjlib.h>
#define THIS_FILE "pool_sample.c"
static void my_perror(const char *title, pj_status_t status)
{
PJ_PERROR(1,(THIS_FILE, status, title));
}
static void pool_demo_1(pj_pool_factory *pfactory)
{
unsigned i;
pj_pool_t *pool;
// Must create pool before we can allocate anything
pool = pj_pool_create(pfactory, // the factory
"pool1", // pool's name
4000, // initial size
4000, // increment size
NULL); // use default callback.
if (pool == NULL) {
my_perror("Error creating pool", PJ_ENOMEM);
return;
}
// Demo: allocate some memory chunks
for (i=0; i<1000; ++i) {
void *p;
p = pj_pool_alloc(pool, (pj_rand()+1) % 512);
// Do something with p
...
// Look! No need to free p!!
}
// Done with silly demo, must free pool to release all memory.
pj_pool_release(pool);
}
int main()
{
pj_caching_pool cp;
pj_status_t status;
// Must init PJLIB before anything else
status = pj_init();
if (status != PJ_SUCCESS) {
my_perror("Error initializing PJLIB", status);
return 1;
}
// Create the pool factory, in this case, a caching pool,
// using default pool policy.
pj_caching_pool_init(&cp, NULL, 1024*1024 );
// Do a demo
pool_demo_1(&cp.factory);
// Done with demos, destroy caching pool before exiting app.
pj_caching_pool_destroy(&cp);
return 0;
}
\endcode
*
* More information about pool factory, the pool object, and caching pool
* can be found on the Module Links below.
*/
/**
* @defgroup PJ_POOL Memory Pool Object
* @ingroup PJ_POOL_GROUP
* @brief
* The memory pool is an opaque object created by pool factory.
* Application uses this object to request a memory chunk, by calling
* #pj_pool_alloc(), #pj_pool_calloc(), or #pj_pool_zalloc().
* When the application has finished using
* the pool, it must call #pj_pool_release() to free all the chunks previously
* allocated and release the pool back to the factory.
*
* A memory pool is initialized with an initial amount of memory, which is
* called a block. Pool can be configured to dynamically allocate more memory
* blocks when it runs out of memory.
*
* The pool doesn't keep track of individual memory allocations
* by user, and the user doesn't have to free these indidual allocations. This
* makes memory allocation simple and very fast. All the memory allocated from
* the pool will be destroyed when the pool itself is destroyed.
*
* \section PJ_POOL_THREADING_SEC More on Threading Policies
* - By design, memory allocation from a pool is not thread safe. We assumed
* that a pool will be owned by an object, and thread safety should be
* handled by that object. Thus these functions are not thread safe:
* - #pj_pool_alloc,
* - #pj_pool_calloc,
* - and other pool statistic functions.
* - Threading in the pool factory is decided by the policy set for the
* factory when it was created.
*
* \section PJ_POOL_EXAMPLES_SEC Examples
*
* For some sample codes on how to use the pool, please see:
* - @ref page_pjlib_pool_test
*
* @{
*/
/**
* The type for function to receive callback from the pool when it is unable
* to allocate memory. The elegant way to handle this condition is to throw
* exception, and this is what is expected by most of this library
* components.
*/
typedef void pj_pool_callback(pj_pool_t *pool, pj_size_t size);
/**
* This class, which is used internally by the pool, describes a single
* block of memory from which user memory allocations will be allocated from.
*/
typedef struct pj_pool_block
{
PJ_DECL_LIST_MEMBER(struct pj_pool_block); /**< List's prev and next. */
unsigned char *buf; /**< Start of buffer. */
unsigned char *cur; /**< Current alloc ptr. */
unsigned char *end; /**< End of buffer. */
} pj_pool_block;
/**
* This structure describes the memory pool. Only implementors of pool factory
* need to care about the contents of this structure.
*/
struct pj_pool_t
{
PJ_DECL_LIST_MEMBER(struct pj_pool_t); /**< Standard list elements. */
/** Pool name */
char obj_name[PJ_MAX_OBJ_NAME];
/** Pool factory. */
pj_pool_factory *factory;
/** Data put by factory */
void *factory_data;
/** Current capacity allocated by the pool. */
pj_size_t capacity;
/** Size of memory block to be allocated when the pool runs out of memory */
pj_size_t increment_size;
/** List of memory blocks allcoated by the pool. */
pj_pool_block block_list;
/** The callback to be called when the pool is unable to allocate memory. */
pj_pool_callback *callback;
};
/**
* Guidance on how much memory required for initial pool administrative data.
*/
#define PJ_POOL_SIZE (sizeof(struct pj_pool_t))
/**
* Pool memory alignment (must be power of 2).
*/
#ifndef PJ_POOL_ALIGNMENT
# define PJ_POOL_ALIGNMENT 4
#endif
/**
* Create a new pool from the pool factory. This wrapper will call create_pool
* member of the pool factory.
*
* @param factory The pool factory.
* @param name The name to be assigned to the pool. The name should
* not be longer than PJ_MAX_OBJ_NAME (32 chars), or
* otherwise it will be truncated.
* @param initial_size The size of initial memory blocks taken by the pool.
* Note that the pool will take 68+20 bytes for
* administrative area from this block.
* @param increment_size the size of each additional blocks to be allocated
* when the pool is running out of memory. If user
* requests memory which is larger than this size, then
* an error occurs.
* Note that each time a pool allocates additional block,
* it needs PJ_POOL_SIZE more to store some
* administrative info.
* @param callback Callback to be called when error occurs in the pool.
* If this value is NULL, then the callback from pool
* factory policy will be used.
* Note that when an error occurs during pool creation,
* the callback itself is not called. Instead, NULL
* will be returned.
*
* @return The memory pool, or NULL.
*/
PJ_IDECL(pj_pool_t*) pj_pool_create(pj_pool_factory *factory,
const char *name,
pj_size_t initial_size,
pj_size_t increment_size,
pj_pool_callback *callback);
/**
* Release the pool back to pool factory.
*
* @param pool Memory pool.
*/
PJ_IDECL(void) pj_pool_release( pj_pool_t *pool );
/**
* Release the pool back to pool factory and set the pool pointer to zero.
*
* @param ppool Pointer to memory pool.
*/
PJ_IDECL(void) pj_pool_safe_release( pj_pool_t **ppool );
/**
* Release the pool back to pool factory and set the pool pointer to zero.
* The memory pool content will be wiped out first before released.
*
* @param ppool Pointer to memory pool.
*/
PJ_IDECL(void) pj_pool_secure_release( pj_pool_t **ppool );
/**
* Get pool object name.
*
* @param pool the pool.
*
* @return pool name as NULL terminated string.
*/
PJ_IDECL(const char *) pj_pool_getobjname( const pj_pool_t *pool );
/**
* Reset the pool to its state when it was initialized.
* This means that if additional blocks have been allocated during runtime,
* then they will be freed. Only the original block allocated during
* initialization is retained. This function will also reset the internal
* counters, such as pool capacity and used size.
*
* @param pool the pool.
*/
PJ_DECL(void) pj_pool_reset( pj_pool_t *pool );
/**
* Get the pool capacity, that is, the system storage that have been allocated
* by the pool, and have been used/will be used to allocate user requests.
* There's no guarantee that the returned value represent a single
* contiguous block, because the capacity may be spread in several blocks.
*
* @param pool the pool.
*
* @return the capacity.
*/
PJ_IDECL(pj_size_t) pj_pool_get_capacity( pj_pool_t *pool );
/**
* Get the total size of user allocation request.
*
* @param pool the pool.
*
* @return the total size.
*/
PJ_IDECL(pj_size_t) pj_pool_get_used_size( pj_pool_t *pool );
/**
* Allocate storage with the specified size from the pool.
* If there's no storage available in the pool, then the pool can allocate more
* blocks if the increment size is larger than the requested size.
*
* @param pool the pool.
* @param size the requested size.
*
* @return pointer to the allocated memory.
*
* @see PJ_POOL_ALLOC_T
*/
PJ_IDECL(void*) pj_pool_alloc( pj_pool_t *pool, pj_size_t size);
/**
* Allocate storage from the pool, and initialize it to zero.
* This function behaves like pj_pool_alloc(), except that the storage will
* be initialized to zero.
*
* @param pool the pool.
* @param count the number of elements in the array.
* @param elem the size of individual element.
*
* @return pointer to the allocated memory.
*/
PJ_IDECL(void*) pj_pool_calloc( pj_pool_t *pool, pj_size_t count,
pj_size_t elem);
/**
* Allocate storage from the pool and initialize it to zero.
*
* @param pool The pool.
* @param size The size to be allocated.
*
* @return Pointer to the allocated memory.
*
* @see PJ_POOL_ZALLOC_T
*/
PJ_INLINE(void*) pj_pool_zalloc(pj_pool_t *pool, pj_size_t size)
{
return pj_pool_calloc(pool, 1, size);
}
/**
* This macro allocates memory from the pool and returns the instance of
* the specified type. It provides a stricker type safety than pj_pool_alloc()
* since the return value of this macro will be type-casted to the specified
* type.
*
* @param pool The pool
* @param type The type of object to be allocated
*
* @return Memory buffer of the specified type.
*/
#define PJ_POOL_ALLOC_T(pool,type) \
((type*)pj_pool_alloc(pool, sizeof(type)))
/**
* This macro allocates memory from the pool, zeroes the buffer, and
* returns the instance of the specified type. It provides a stricker type
* safety than pj_pool_zalloc() since the return value of this macro will be
* type-casted to the specified type.
*
* @param pool The pool
* @param type The type of object to be allocated
*
* @return Memory buffer of the specified type.
*/
#define PJ_POOL_ZALLOC_T(pool,type) \
((type*)pj_pool_zalloc(pool, sizeof(type)))
/*
* Internal functions
*/
PJ_IDECL(void*) pj_pool_alloc_from_block(pj_pool_block *block, pj_size_t size);
PJ_DECL(void*) pj_pool_allocate_find(pj_pool_t *pool, pj_size_t size);
/**
* @} // PJ_POOL
*/
/* **************************************************************************/
/**
* @defgroup PJ_POOL_FACTORY Pool Factory and Policy
* @ingroup PJ_POOL_GROUP
* @brief
* A pool object must be created through a factory. A factory not only provides
* generic interface functions to create and release pool, but also provides
* strategy to manage the life time of pools. One sample implementation,
* \a pj_caching_pool, can be set to keep the pools released by application for
* future use as long as the total memory is below the limit.
*
* The pool factory interface declared in PJLIB is designed to be extensible.
* Application can define its own strategy by creating it's own pool factory
* implementation, and this strategy can be used even by existing library
* without recompilation.
*
* \section PJ_POOL_FACTORY_ITF Pool Factory Interface
* The pool factory defines the following interface:
* - \a policy: the memory pool factory policy.
* - \a create_pool(): create a new memory pool.
* - \a release_pool(): release memory pool back to factory.
*
* \section PJ_POOL_FACTORY_POL Pool Factory Policy.
*
* A pool factory only defines functions to create and release pool and how
* to manage pools, but the rest of the functionalities are controlled by
* policy. A pool policy defines:
* - how memory block is allocated and deallocated (the default implementation
* allocates and deallocate memory by calling malloc() and free()).
* - callback to be called when memory allocation inside a pool fails (the
* default implementation will throw PJ_NO_MEMORY_EXCEPTION exception).
* - concurrency when creating and releasing pool from/to the factory.
*
* A pool factory can be given different policy during creation to make
* it behave differently. For example, caching pool factory can be configured
* to allocate and deallocate from a static/contiguous/preallocated memory
* instead of using malloc()/free().
*
* What strategy/factory and what policy to use is not defined by PJLIB, but
* instead is left to application to make use whichever is most efficient for
* itself.
*
* The pool factory policy controls the behaviour of memory factories, and
* defines the following interface:
* - \a block_alloc(): allocate memory block from backend memory mgmt/system.
* - \a block_free(): free memory block back to backend memory mgmt/system.
* @{
*/
/* We unfortunately don't have support for factory policy options as now,
so we keep this commented at the moment.
enum PJ_POOL_FACTORY_OPTION
{
PJ_POOL_FACTORY_SERIALIZE = 1
};
*/
/**
* This structure declares pool factory interface.
*/
typedef struct pj_pool_factory_policy
{
/**
* Allocate memory block (for use by pool). This function is called
* by memory pool to allocate memory block.
*
* @param factory Pool factory.
* @param size The size of memory block to allocate.
*
* @return Memory block.
*/
void* (*block_alloc)(pj_pool_factory *factory, pj_size_t size);
/**
* Free memory block.
*
* @param factory Pool factory.
* @param mem Memory block previously allocated by block_alloc().
* @param size The size of memory block.
*/
void (*block_free)(pj_pool_factory *factory, void *mem, pj_size_t size);
/**
* Default callback to be called when memory allocation fails.
*/
pj_pool_callback *callback;
/**
* Option flags.
*/
unsigned flags;
} pj_pool_factory_policy;
/**
* \def PJ_NO_MEMORY_EXCEPTION
* This constant denotes the exception number that will be thrown by default
* memory factory policy when memory allocation fails.
*
* @see pj_NO_MEMORY_EXCEPTION()
*/
PJ_DECL_DATA(int) PJ_NO_MEMORY_EXCEPTION;
/**
* Get #PJ_NO_MEMORY_EXCEPTION constant.
*/
PJ_DECL(int) pj_NO_MEMORY_EXCEPTION(void);
/**
* This global variable points to default memory pool factory policy.
* The behaviour of the default policy is:
* - block allocation and deallocation use malloc() and free().
* - callback will raise PJ_NO_MEMORY_EXCEPTION exception.
* - access to pool factory is not serialized (i.e. not thread safe).
*
* @see pj_pool_factory_get_default_policy
*/
PJ_DECL_DATA(pj_pool_factory_policy) pj_pool_factory_default_policy;
/**
* Get the default pool factory policy.
*
* @return the pool policy.
*/
PJ_DECL(const pj_pool_factory_policy*) pj_pool_factory_get_default_policy(void);
/**
* This structure contains the declaration for pool factory interface.
*/
struct pj_pool_factory
{
/**
* Memory pool policy.
*/
pj_pool_factory_policy policy;
/**
* Create a new pool from the pool factory.
*
* @param factory The pool factory.
* @param name the name to be assigned to the pool. The name should
* not be longer than PJ_MAX_OBJ_NAME (32 chars), or
* otherwise it will be truncated.
* @param initial_size the size of initial memory blocks taken by the pool.
* Note that the pool will take 68+20 bytes for
* administrative area from this block.
* @param increment_size the size of each additional blocks to be allocated
* when the pool is running out of memory. If user
* requests memory which is larger than this size, then
* an error occurs.
* Note that each time a pool allocates additional block,
* it needs 20 bytes (equal to sizeof(pj_pool_block)) to
* store some administrative info.
* @param callback Cllback to be called when error occurs in the pool.
* Note that when an error occurs during pool creation,
* the callback itself is not called. Instead, NULL
* will be returned.
*
* @return the memory pool, or NULL.
*/
pj_pool_t* (*create_pool)( pj_pool_factory *factory,
const char *name,
pj_size_t initial_size,
pj_size_t increment_size,
pj_pool_callback *callback);
/**
* Release the pool to the pool factory.
*
* @param factory The pool factory.
* @param pool The pool to be released.
*/
void (*release_pool)( pj_pool_factory *factory, pj_pool_t *pool );
/**
* Dump pool status to log.
*
* @param factory The pool factory.
*/
void (*dump_status)( pj_pool_factory *factory, pj_bool_t detail );
/**
* This is optional callback to be called by allocation policy when
* it allocates a new memory block. The factory may use this callback
* for example to keep track of the total number of memory blocks
* currently allocated by applications.
*
* @param factory The pool factory.
* @param size Size requested by application.
*
* @return MUST return PJ_TRUE, otherwise the block
* allocation is cancelled.
*/
pj_bool_t (*on_block_alloc)(pj_pool_factory *factory, pj_size_t size);
/**
* This is optional callback to be called by allocation policy when
* it frees memory block. The factory may use this callback
* for example to keep track of the total number of memory blocks
* currently allocated by applications.
*
* @param factory The pool factory.
* @param size Size freed.
*/
void (*on_block_free)(pj_pool_factory *factory, pj_size_t size);
};
/**
* This function is intended to be used by pool factory implementors.
* @param factory Pool factory.
* @param name Pool name.
* @param initial_size Initial size.
* @param increment_size Increment size.
* @param callback Callback.
* @return The pool object, or NULL.
*/
PJ_DECL(pj_pool_t*) pj_pool_create_int( pj_pool_factory *factory,
const char *name,
pj_size_t initial_size,
pj_size_t increment_size,
pj_pool_callback *callback);
/**
* This function is intended to be used by pool factory implementors.
* @param pool The pool.
* @param name Pool name.
* @param increment_size Increment size.
* @param callback Callback function.
*/
PJ_DECL(void) pj_pool_init_int( pj_pool_t *pool,
const char *name,
pj_size_t increment_size,
pj_pool_callback *callback);
/**
* This function is intended to be used by pool factory implementors.
* @param pool The memory pool.
*/
PJ_DECL(void) pj_pool_destroy_int( pj_pool_t *pool );
/**
* Dump pool factory state.
* @param pf The pool factory.
* @param detail Detail state required.
*/
PJ_INLINE(void) pj_pool_factory_dump( pj_pool_factory *pf,
pj_bool_t detail )
{
(*pf->dump_status)(pf, detail);
}
/**
* @} // PJ_POOL_FACTORY
*/
/* **************************************************************************/
/**
* @defgroup PJ_CACHING_POOL Caching Pool Factory
* @ingroup PJ_POOL_GROUP
* @brief
* Caching pool is one sample implementation of pool factory where the
* factory can reuse memory to create a pool. Application defines what the
* maximum memory the factory can hold, and when a pool is released the
* factory decides whether to destroy the pool or to keep it for future use.
* If the total amount of memory in the internal cache is still within the
* limit, the factory will keep the pool in the internal cache, otherwise the
* pool will be destroyed, thus releasing the memory back to the system.
*
* @{
*/
/**
* Number of unique sizes, to be used as index to the free list.
* Each pool in the free list is organized by it's size.
*/
#define PJ_CACHING_POOL_ARRAY_SIZE 16
/**
* Declaration for caching pool. Application doesn't normally need to
* care about the contents of this struct, it is only provided here because
* application need to define an instance of this struct (we can not allocate
* the struct from a pool since there is no pool factory yet!).
*/
struct pj_caching_pool
{
/** Pool factory interface, must be declared first. */
pj_pool_factory factory;
/** Current factory's capacity, i.e. number of bytes that are allocated
* and available for application in this factory. The factory's
* capacity represents the size of all pools kept by this factory
* in it's free list, which will be returned to application when it
* requests to create a new pool.
*/
pj_size_t capacity;
/** Maximum size that can be held by this factory. Once the capacity
* has exceeded @a max_capacity, further #pj_pool_release() will
* flush the pool. If the capacity is still below the @a max_capacity,
* #pj_pool_release() will save the pool to the factory's free list.
*/
pj_size_t max_capacity;
/**
* Number of pools currently held by applications. This number gets
* incremented everytime #pj_pool_create() is called, and gets
* decremented when #pj_pool_release() is called.
*/
pj_size_t used_count;
/**
* Total size of memory currently used by application.
*/
pj_size_t used_size;
/**
* The maximum size of memory used by application throughout the life
* of the caching pool.
*/
pj_size_t peak_used_size;
/**
* Lists of pools in the cache, indexed by pool size.
*/
pj_list free_list[PJ_CACHING_POOL_ARRAY_SIZE];
/**
* List of pools currently allocated by applications.
*/
pj_list used_list;
/**
* Internal pool.
*/
char pool_buf[256 * (sizeof(size_t) / 4)];
/**
* Mutex.
*/
pj_lock_t *lock;
};
/**
* Initialize caching pool.
*
* @param ch_pool The caching pool factory to be initialized.
* @param policy Pool factory policy.
* @param max_capacity The total capacity to be retained in the cache. When
* the pool is returned to the cache, it will be kept in
* recycling list if the total capacity of pools in this
* list plus the capacity of the pool is still below this
* value.
*/
PJ_DECL(void) pj_caching_pool_init( pj_caching_pool *ch_pool,
const pj_pool_factory_policy *policy,
pj_size_t max_capacity);
/**
* Destroy caching pool, and release all the pools in the recycling list.
*
* @param ch_pool The caching pool.
*/
PJ_DECL(void) pj_caching_pool_destroy( pj_caching_pool *ch_pool );
/**
* @} // PJ_CACHING_POOL
*/
# if PJ_FUNCTIONS_ARE_INLINED
# include "pool_i.h"
# endif
PJ_END_DECL
#endif /* __PJ_POOL_H__ */
Reference in a new issue View git blame Copy permalink