/*****************************************************************************\
* Copyright (c) Athena Dev Teams - Licensed under GNU GPL *
* For more information, see LICENCE in the main folder *
* *
* <H1>Entry Reusage System</H1> *
* *
* There are several root entry managers, each with a different entry size. *
* Each manager will keep track of how many instances have been 'created'. *
* They will only automatically destroy themselves after the last instance *
* is destroyed. *
* *
* Entries can be allocated from the managers. *
* If it has reusable entries (freed entry), it uses one. *
* So no assumption should be made about the data of the entry. *
* Entries should be freed in the manager they where allocated from. *
* Failure to do so can lead to unexpected behaviors. *
* *
* <H2>Advantages:</H2> *
* - The same manager is used for entries of the same size. *
* So entries freed in one instance of the manager can be used by other *
* instances of the manager. *
* - Much less memory allocation/deallocation - program will be faster. *
* - Avoids memory fragmentation - program will run better for longer. *
* *
* <H2>Disadvantages:</H2> *
* - Unused entries are almost inevitable - memory being wasted. *
* - A manager will only auto-destroy when all of its instances are *
* destroyed so memory will usually only be recovered near the end. *
* - Always wastes space for entries smaller than a pointer. *
* *
* WARNING: The system is not thread-safe at the moment. *
* *
* HISTORY: *
* 0.1 - Initial version *
* *
* @version 0.1 - Initial version *
* @author Flavio @ Amazon Project *
* @encoding US-ASCII *
\*****************************************************************************/
#ifndef COMMON_ERS_H
#define COMMON_ERS_H
#include "../common/cbasetypes.h"
/*****************************************************************************\
* (1) All public parts of the Entry Reusage System. *
* DISABLE_ERS - Define to disable this system. *
* ERS_ALIGNED - Alignment of the entries in the blocks. *
* ERS - Entry manager. *
* ers_new - Allocate an instance of an entry manager. *
* ers_report - Print a report about the current state. *
* ers_final - Clears the remainder of the managers. *
\*****************************************************************************/
/**
* Define this to disable the Entry Reusage System.
* All code except the typedef of ERInterface will be disabled.
* To allow a smooth transition,
*/
//#define DISABLE_ERS
/**
* Entries are aligned to ERS_ALIGNED bytes in the blocks of entries.
* By default it aligns to one byte, using the "natural order" of the entries.
* This should NEVER be set to zero or less.
* If greater than one, some memory can be wasted. This should never be needed
* but is here just in case some alignment issues arise.
*/
#ifndef ERS_ALIGNED
# define ERS_ALIGNED 1
#endif /* not ERS_ALIGN_ENTRY */
enum ERSOptions {
ERS_OPT_NONE = 0x0,
ERS_OPT_CLEAR = 0x1,/* silently clears any entries left in the manager upon destruction */
ERS_OPT_WAIT = 0x2,/* wait for entries to come in order to list! */
ERS_OPT_FREE_NAME = 0x4,/* name is dynamic memory, and should be freed */
ERS_OPT_CLEAN = 0x8,/* clears used memory upon ers_free so that its all new to be reused on the next alloc */
ERS_OPT_FLEX_CHUNK = 0x10,/* signs that it should look for its own cache given it'll have a dynamic chunk size, so that it doesn't affect the other ERS it'd otherwise be sharing */
/* Compound, is used to determine whether it should be looking for a cache of matching options */
ERS_CACHE_OPTIONS = ERS_OPT_CLEAN|ERS_OPT_FLEX_CHUNK,
};
/**
* Public interface of the entry manager.
* @param alloc Allocate an entry from this manager
* @param free Free an entry allocated from this manager
* @param entry_size Return the size of the entries of this manager
* @param destroy Destroy this instance of the manager
*/
typedef struct eri {
/**
* Allocate an entry from this entry manager.
* If there are reusable entries available, it reuses one instead.
* @param self Interface of the entry manager
* @return An entry
*/
void *(*alloc)(struct eri *self);
/**
* Free an entry allocated from this manager.
* WARNING: Does not check if the entry was allocated by this manager.
* Freeing such an entry can lead to unexpected behavior.
* @param self Interface of the entry manager
* @param entry Entry to be freed
*/
void (*free)(struct eri *self, void *entry);
/**
* Return the size of the entries allocated from this manager.
* @param self Interface of the entry manager
* @return Size of the entries of this manager in bytes
*/
size_t (*entry_size)(struct eri *self);
/**
* Destroy this instance of the manager.
* The manager is actually only destroyed when all the instances are destroyed.
* When destroying the manager a warning is shown if the manager has
* missing/extra entries.
* @param self Interface of the entry manager
*/
void (*destroy)(struct eri *self);
/* */
void (*chunk_size) (struct eri *self, unsigned int new_size);
} ERS;
#ifdef DISABLE_ERS
// Use memory manager to allocate/free and disable other interface functions
# define ers_alloc(obj,type) (type *)aMalloc(sizeof(type))
# define ers_free(obj,entry) aFree(entry)
# define ers_entry_size(obj) (size_t)0
# define ers_destroy(obj)
# define ers_chunk_size(obj,size)
// Disable the public functions
# define ers_new(size,name,options) NULL
# define ers_report()
# define ers_final()
#else /* not DISABLE_ERS */
// These defines should be used to allow the code to keep working whenever
// the system is disabled
# define ers_alloc(obj,type) ((type *)(obj)->alloc(obj))
# define ers_free(obj,entry) ((obj)->free((obj),(entry)))
# define ers_entry_size(obj) ((obj)->entry_size(obj))
# define ers_destroy(obj) ((obj)->destroy(obj))
# define ers_chunk_size(obj,size) ((obj)->chunk_size((obj),(size)))
/**
* Get a new instance of the manager that handles the specified entry size.
* Size has to greater than 0.
* If the specified size is smaller than a pointer, the size of a pointer is
* used instead.
* It's also aligned to ERS_ALIGNED bytes, so the smallest multiple of
* ERS_ALIGNED that is greater or equal to size is what's actually used.
* @param The requested size of the entry in bytes
* @return Interface of the object
*/
ERS *ers_new(uint32 size, char *name, enum ERSOptions options);
/**
* Print a report about the current state of the Entry Reusage System.
* Shows information about the global system and each entry manager.
* The number of entries are checked and a warning is shown if extra reusable
* entries are found.
* The extra entries are included in the count of reusable entries.
*/
void ers_report(void);
/**
* Clears the remainder of the managers
**/
void ers_final(void);
#endif /* DISABLE_ERS / not DISABLE_ERS */
#endif /* COMMON_ERS_H */
