Standardize log levels used by logging statements across the project
[babeltrace.git] / src / lib / object-pool.h
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1#ifndef BABELTRACE_OBJECT_POOL_INTERNAL_H
2#define BABELTRACE_OBJECT_POOL_INTERNAL_H
3
4/*
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5 * Copyright (c) 2018 Philippe Proulx <pproulx@efficios.com>
6 *
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:
13 *
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
16 *
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
23 * SOFTWARE.
24 */
25
26/*
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
29 * created a lot.
30 *
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.
34 *
35 * The object pool's user is responsible for:
36 *
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.
43 *
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
48 * at any time.
49 */
50
51#include <glib.h>
578e048b 52#include "lib/object.h"
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53
54typedef void *(*bt_object_pool_new_object_func)(void *data);
55typedef void *(*bt_object_pool_destroy_object_func)(void *obj, void *data);
56
57struct bt_object_pool {
58 /*
59 * Container of recycled objects, owned by this. The array's size
60 * is the pool's capacity.
61 */
62 GPtrArray *objects;
63
64 /*
65 * Pool's size, that is, number of elements in the array above,
66 * starting at index 0, which exist as recycled objects.
67 */
68 size_t size;
69
70 /* User functions */
71 struct {
72 /* Allocate a new object in memory */
73 bt_object_pool_new_object_func new_object;
74
75 /* Free direct and indirect memory occupied by object */
76 bt_object_pool_destroy_object_func destroy_object;
77 } funcs;
78
79 /* User data passed to user functions */
80 void *data;
81};
82
83/*
84 * Initializes an object pool which is already allocated.
85 */
86int bt_object_pool_initialize(struct bt_object_pool *pool,
87 bt_object_pool_new_object_func new_object_func,
88 bt_object_pool_destroy_object_func destroy_object_func,
89 void *data);
90
91/*
92 * Finalizes an object pool without deallocating it.
93 */
94void bt_object_pool_finalize(struct bt_object_pool *pool);
95
96/*
97 * Creates an object from an object pool. If the pool is empty, this
98 * function calls the "new" user function to allocate a new object
99 * before returning it. Otherwise this function returns a recycled
100 * object, removing it from the pool.
101 *
102 * The returned object is owned by the caller.
103 */
104static inline
105void *bt_object_pool_create_object(struct bt_object_pool *pool)
106{
107 struct bt_object *obj;
108
109 BT_ASSERT(pool);
110
111#ifdef BT_LOGV
112 BT_LOGV("Creating object from pool: pool-addr=%p, pool-size=%zu, pool-cap=%u",
113 pool, pool->size, pool->objects->len);
114#endif
115
116 if (pool->size > 0) {
117 /* Pick one from the pool */
118 pool->size--;
119 obj = pool->objects->pdata[pool->size];
120 pool->objects->pdata[pool->size] = NULL;
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121 goto end;
122 }
123
124 /* Pool is empty: create a brand new object */
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125#ifdef BT_LOGD
126 BT_LOGD("Pool is empty: allocating new object: pool-addr=%p",
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127 pool);
128#endif
129
130 obj = pool->funcs.new_object(pool->data);
131
132end:
133#ifdef BT_LOGV
134 BT_LOGV("Created one object from pool: pool-addr=%p, obj-addr=%p",
135 pool, obj);
136#endif
137
138 return obj;
139}
140
141/*
142 * Recycles an object, that is, puts it back into the pool.
143 *
144 * The pool becomes the sole owner of the object to recycle.
145 */
146static inline
147void bt_object_pool_recycle_object(struct bt_object_pool *pool, void *obj)
148{
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149 struct bt_object *bt_obj = obj;
150
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151 BT_ASSERT(pool);
152 BT_ASSERT(obj);
153
154#ifdef BT_LOGV
155 BT_LOGV("Recycling object: pool-addr=%p, pool-size=%zu, pool-cap=%u, obj-addr=%p",
156 pool, pool->size, pool->objects->len, obj);
157#endif
158
159 if (pool->size == pool->objects->len) {
160 /* Backing array is full: make place for recycled object */
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161#ifdef BT_LOGD
162 BT_LOGD("Object pool is full: increasing object pool capacity: "
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163 "pool-addr=%p, old-pool-cap=%u, new-pool-cap=%u",
164 pool, pool->objects->len, pool->objects->len + 1);
165#endif
166 g_ptr_array_set_size(pool->objects, pool->size + 1);
167 }
168
cdc4693d 169 /* Reset reference count to 1 since it could be 0 now */
3fea54f6 170 bt_obj->ref_count = 1;
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171
172 /* Back to the pool */
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173 pool->objects->pdata[pool->size] = obj;
174 pool->size++;
175
176#ifdef BT_LOGV
177 BT_LOGV("Recycled object: pool-addr=%p, pool-size=%zu, pool-cap=%u, obj-addr=%p",
178 pool, pool->size, pool->objects->len, obj);
179#endif
180}
181
182#endif /* BABELTRACE_OBJECT_POOL_INTERNAL_H */
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