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23 * @file svn_object_pool.h
24 * @brief multithreaded object pool API
26 * This is the core data structure behind various object pools. It
27 * provides a thread-safe associative container for object instances of
30 * Memory and lifetime management for the objects are handled by the pool.
31 * Reference counting takes care that neither objects nor the object pool
32 * get actually destroyed while other parts depend on them. All objects
33 * are thought to be recycle-able and live in their own root memory pools
34 * making them (potentially) safe to be used from different threads.
35 * Currently unused objects may be kept around for a while and returned
38 * Two modes are supported: shared use and exclusive use. In shared mode,
39 * any object can be handed out to multiple users and in potentially
40 * different threads at the same time. In exclusive mode, the same object
41 * will only be referenced at most once.
43 * Object creation and access must be provided outside this structure.
44 * In particular, the using container will usually wrap the actual object
45 * in a meta-data struct containing key information etc and must provide
46 * getters and setters for those wrapper structs.
51 #ifndef SVN_OBJECT_POOL_H
52 #define SVN_OBJECT_POOL_H
54 #include <apr.h> /* for apr_int64_t */
55 #include <apr_pools.h> /* for apr_pool_t */
56 #include <apr_hash.h> /* for apr_hash_t */
58 #include "svn_types.h"
60 #include "private/svn_mutex.h"
61 #include "private/svn_string_private.h"
65 /* The opaque object container type. */
66 typedef struct svn_object_pool__t svn_object_pool__t;
68 /* Extract the actual object from the WRAPPER using optional information
69 * from BATON (provided through #svn_object_pool__lookup) and return it.
70 * The result will be used with POOL and must remain valid throughout
73 * It is legal to return a copy, allocated in POOL, of the wrapped object.
75 typedef void * (* svn_object_pool__getter_t)(void *wrapper,
79 /* Copy the information from the SOURCE object wrapper into the already
80 * existing *TARGET object wrapper using POOL for allocations and BATON
81 * for optional context (provided through #svn_object_pool__insert).
83 typedef svn_error_t * (* svn_object_pool__setter_t)(void **target,
88 /* Create a new object pool in POOL and return it in *OBJECT_POOL.
89 * Objects will be extracted using GETTER and updated using SETTER. Either
90 * one (or both) may be NULL and the default implementation assumes that
91 * wrapper == object and updating is a no-op.
93 * If THREAD_SAFE is not set, neither the object pool nor the object
94 * references returned from it may be accessed from multiple threads.
96 * It is not legal to call any API on the object pool after POOL got
97 * cleared or destroyed. However, existing object references handed out
98 * from the object pool remain valid and will keep the internal pool data
99 * structures alive for as long as such object references exist.
102 svn_object_pool__create(svn_object_pool__t **object_pool,
103 svn_object_pool__getter_t getter,
104 svn_object_pool__setter_t setter,
105 svn_boolean_t thread_safe,
108 /* Return the root pool containing the OBJECT_POOL and all sub-structures.
111 svn_object_pool__new_wrapper_pool(svn_object_pool__t *object_pool);
113 /* Return the mutex used to serialize all OBJECT_POOL access.
116 svn_object_pool__mutex(svn_object_pool__t *object_pool);
118 /* Return the number of object instances (used or unused) in OBJECT_POOL.
121 svn_object_pool__count(svn_object_pool__t *object_pool);
123 /* In OBJECT_POOL, look for an available object by KEY and return a
124 * reference to it in *OBJECT. If none can be found, *OBJECT will be NULL.
125 * BATON will be passed to OBJECT_POOL's getter function. The reference
126 * will be returned when *RESULT_POOL gets cleaned up or destroyed.
129 svn_object_pool__lookup(void **object,
130 svn_object_pool__t *object_pool,
133 apr_pool_t *result_pool);
135 /* Store the wrapped object WRAPPER under KEY in OBJECT_POOL and return
136 * a reference to the object in *OBJECT (just like lookup).
138 * The object must have been created in WRAPPER_POOL and the latter must
139 * be a sub-pool of OBJECT_POOL's root POOL (see #svn_object_pool__pool).
141 * BATON will be passed to OBJECT_POOL's setter and getter functions.
142 * The reference will be returned when *RESULT_POOL gets cleaned up or
146 svn_object_pool__insert(void **object,
147 svn_object_pool__t *object_pool,
148 const svn_membuf_t *key,
151 apr_pool_t *wrapper_pool,
152 apr_pool_t *result_pool);
154 #endif /* SVN_OBJECT_POOL_H */