1 #ifndef BABELTRACE_OBJECT_POOL_INTERNAL_H
2 #define BABELTRACE_OBJECT_POOL_INTERNAL_H
5 * Copyright (c) 2018 Philippe Proulx <pproulx@efficios.com>
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
20 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
27 * This is a generic object pool to avoid memory allocation/deallocation
28 * for objects of which the lifespan is typically short, but which are
31 * The object pool, thanks to two user functions, knows how to allocate
32 * a brand new object in memory when the pool is empty and how to
33 * destroy an object when we destroy the pool.
35 * The object pool's user is responsible for:
37 * * Setting whatever references the object needs to keep and reset some
38 * properties _after_ calling bt_object_pool_create_object(). This is
39 * typically done in the bt_*_create() function which calls
40 * bt_object_pool_create_object() (which could call the user-provided
41 * allocation function if the pool is empty) and then sets the
42 * appropriate properties on the possibly recycled object.
44 * * Releasing whatever references the object keeps _before_ calling
45 * bt_object_pool_recycle_object(). This is typically done in a custom
46 * bt_*_recycle() function which does the necessary before calling
47 * bt_object_pool_recycle_object() with an object ready to be reused
52 #include "lib/object.h"
54 /* Protection: this file uses BT_LIB_LOG*() macros directly */
55 #ifndef BT_LIB_LOG_SUPPORTED
56 # error Please include "lib/logging.h" before including this file.
59 typedef void *(*bt_object_pool_new_object_func
)(void *data
);
60 typedef void (*bt_object_pool_destroy_object_func
)(void *obj
, void *data
);
62 struct bt_object_pool
{
64 * Container of recycled objects, owned by this. The array's size
65 * is the pool's capacity.
70 * Pool's size, that is, number of elements in the array above,
71 * starting at index 0, which exist as recycled objects.
77 /* Allocate a new object in memory */
78 bt_object_pool_new_object_func new_object
;
80 /* Free direct and indirect memory occupied by object */
81 bt_object_pool_destroy_object_func destroy_object
;
84 /* User data passed to user functions */
89 * Initializes an object pool which is already allocated.
92 int bt_object_pool_initialize(struct bt_object_pool
*pool
,
93 bt_object_pool_new_object_func new_object_func
,
94 bt_object_pool_destroy_object_func destroy_object_func
,
98 * Finalizes an object pool without deallocating it.
101 void bt_object_pool_finalize(struct bt_object_pool
*pool
);
104 * Creates an object from an object pool. If the pool is empty, this
105 * function calls the "new" user function to allocate a new object
106 * before returning it. Otherwise this function returns a recycled
107 * object, removing it from the pool.
109 * The returned object is owned by the caller.
112 void *bt_object_pool_create_object(struct bt_object_pool
*pool
)
114 struct bt_object
*obj
;
117 BT_LOGT("Creating object from pool: pool-addr=%p, pool-size=%zu, pool-cap=%u",
118 pool
, pool
->size
, pool
->objects
->len
);
120 if (pool
->size
> 0) {
121 /* Pick one from the pool */
123 obj
= pool
->objects
->pdata
[pool
->size
];
124 pool
->objects
->pdata
[pool
->size
] = NULL
;
128 /* Pool is empty: create a brand new object */
129 BT_LOGD("Pool is empty: allocating new object: pool-addr=%p",
131 obj
= pool
->funcs
.new_object(pool
->data
);
134 BT_LOGT("Created one object from pool: pool-addr=%p, obj-addr=%p",
140 * Recycles an object, that is, puts it back into the pool.
142 * The pool becomes the sole owner of the object to recycle.
145 void bt_object_pool_recycle_object(struct bt_object_pool
*pool
, void *obj
)
147 struct bt_object
*bt_obj
= obj
;
151 BT_LOGT("Recycling object: pool-addr=%p, pool-size=%zu, pool-cap=%u, obj-addr=%p",
152 pool
, pool
->size
, pool
->objects
->len
, obj
);
154 if (pool
->size
== pool
->objects
->len
) {
155 /* Backing array is full: make place for recycled object */
156 BT_LOGD("Object pool is full: increasing object pool capacity: "
157 "pool-addr=%p, old-pool-cap=%u, new-pool-cap=%u",
158 pool
, pool
->objects
->len
, pool
->objects
->len
+ 1);
159 g_ptr_array_set_size(pool
->objects
, pool
->size
+ 1);
162 /* Reset reference count to 1 since it could be 0 now */
163 bt_obj
->ref_count
= 1;
165 /* Back to the pool */
166 pool
->objects
->pdata
[pool
->size
] = obj
;
168 BT_LOGT("Recycled object: pool-addr=%p, pool-size=%zu, pool-cap=%u, obj-addr=%p",
169 pool
, pool
->size
, pool
->objects
->len
, obj
);
172 #endif /* BABELTRACE_OBJECT_POOL_INTERNAL_H */