| /* $Id$ |
| * |
| */ |
| |
| #ifndef __PJ_POOL_H__ |
| #define __PJ_POOL_H__ |
| |
| /** |
| * @file pool.h |
| * @brief Memory Pool. |
| */ |
| |
| #include <pj/list.h> |
| |
| PJ_BEGIN_DECL |
| |
| /** |
| * @defgroup PJ_POOL_GROUP Memory Pool Management |
| * @ingroup PJ |
| * @brief |
| * Memory pool management provides API to allocate and deallocate memory from |
| * memory pool and to manage and establish policy for pool creation and |
| * destruction in pool factory. |
| * |
| * \section PJ_POOL_FACTORY_SEC Pool Factory |
| * See: \ref PJ_POOL_FACTORY "Pool Factory" |
| * |
| * A memory pool 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_POLICY_SEC Pool Factory Policy |
| * See: \ref PJ_POOL_FACTORY "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. |
| * |
| * |
| * \section PJ_POOL_POOL_SEC The Pool |
| * See: \ref PJ_POOL "Pool" |
| * |
| * 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 or #pj_pool_calloc. 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. |
| * |
| * \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 |
| */ |
| |
| /** |
| * @defgroup PJ_POOL Memory Pool. |
| * @ingroup PJ_POOL_GROUP |
| * @brief |
| * 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. Subsequent memory allocations by user |
| * will use up portions of these block. |
| * 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. |
| * @{ |
| */ |
| |
| /** |
| * 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) |
| |
| /** Pool name */ |
| char obj_name[PJ_MAX_OBJ_NAME]; |
| |
| /** Pool factory. */ |
| pj_pool_factory *factory; |
| |
| /** Current capacity allocated by the pool. */ |
| pj_size_t capacity; |
| |
| /** Number of memory used/allocated. */ |
| pj_size_t used_size; |
| |
| /** 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 ); |
| |
| /** |
| * 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. |
| */ |
| 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); |
| |
| |
| /** |
| * @def pj_pool_zalloc(pj_pool_t *pool, pj_size_t size) |
| * 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. |
| */ |
| #define pj_pool_zalloc(pool, size) pj_pool_calloc(pool, 1, size) |
| |
| |
| /** |
| * @} // PJ_POOL |
| */ |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| /** |
| * @defgroup PJ_POOL_FACTORY Pool Factory and Policy. |
| * @ingroup PJ_POOL_GROUP |
| * @brief |
| * Pool factory declares an interface to create and destroy pool. There may |
| * be several strategies for pool creation, and these strategies should |
| * implement the interface defined by pool factory. |
| * |
| * \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. |
| * 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; |
| |
| /** |
| * This constant denotes the exception number that will be thrown by default |
| * memory factory policy when memory allocation fails. |
| */ |
| extern int PJ_NO_MEMORY_EXCEPTION; |
| |
| /** |
| * 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). |
| */ |
| extern pj_pool_factory_policy pj_pool_factory_default_policy; |
| |
| /** |
| * 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 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 ); |
| |
| |
| /** |
| * @} // 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; |
| |
| /** |
| * 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; |
| }; |
| |
| |
| |
| /** |
| * 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__ */ |
| |