| 1 | #ifndef BABELTRACE_OBJECT_POOL_INTERNAL_H |
| 2 | #define BABELTRACE_OBJECT_POOL_INTERNAL_H |
| 3 | |
| 4 | /* |
| 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> |
| 52 | #include "lib/object.h" |
| 53 | |
| 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. |
| 57 | #endif |
| 58 | |
| 59 | typedef void *(*bt_object_pool_new_object_func)(void *data); |
| 60 | typedef void *(*bt_object_pool_destroy_object_func)(void *obj, void *data); |
| 61 | |
| 62 | struct bt_object_pool { |
| 63 | /* |
| 64 | * Container of recycled objects, owned by this. The array's size |
| 65 | * is the pool's capacity. |
| 66 | */ |
| 67 | GPtrArray *objects; |
| 68 | |
| 69 | /* |
| 70 | * Pool's size, that is, number of elements in the array above, |
| 71 | * starting at index 0, which exist as recycled objects. |
| 72 | */ |
| 73 | size_t size; |
| 74 | |
| 75 | /* User functions */ |
| 76 | struct { |
| 77 | /* Allocate a new object in memory */ |
| 78 | bt_object_pool_new_object_func new_object; |
| 79 | |
| 80 | /* Free direct and indirect memory occupied by object */ |
| 81 | bt_object_pool_destroy_object_func destroy_object; |
| 82 | } funcs; |
| 83 | |
| 84 | /* User data passed to user functions */ |
| 85 | void *data; |
| 86 | }; |
| 87 | |
| 88 | /* |
| 89 | * Initializes an object pool which is already allocated. |
| 90 | */ |
| 91 | int bt_object_pool_initialize(struct bt_object_pool *pool, |
| 92 | bt_object_pool_new_object_func new_object_func, |
| 93 | bt_object_pool_destroy_object_func destroy_object_func, |
| 94 | void *data); |
| 95 | |
| 96 | /* |
| 97 | * Finalizes an object pool without deallocating it. |
| 98 | */ |
| 99 | void bt_object_pool_finalize(struct bt_object_pool *pool); |
| 100 | |
| 101 | /* |
| 102 | * Creates an object from an object pool. If the pool is empty, this |
| 103 | * function calls the "new" user function to allocate a new object |
| 104 | * before returning it. Otherwise this function returns a recycled |
| 105 | * object, removing it from the pool. |
| 106 | * |
| 107 | * The returned object is owned by the caller. |
| 108 | */ |
| 109 | static inline |
| 110 | void *bt_object_pool_create_object(struct bt_object_pool *pool) |
| 111 | { |
| 112 | struct bt_object *obj; |
| 113 | |
| 114 | BT_ASSERT(pool); |
| 115 | BT_LOGT("Creating object from pool: pool-addr=%p, pool-size=%zu, pool-cap=%u", |
| 116 | pool, pool->size, pool->objects->len); |
| 117 | |
| 118 | if (pool->size > 0) { |
| 119 | /* Pick one from the pool */ |
| 120 | pool->size--; |
| 121 | obj = pool->objects->pdata[pool->size]; |
| 122 | pool->objects->pdata[pool->size] = NULL; |
| 123 | goto end; |
| 124 | } |
| 125 | |
| 126 | /* Pool is empty: create a brand new object */ |
| 127 | BT_LOGD("Pool is empty: allocating new object: pool-addr=%p", |
| 128 | pool); |
| 129 | obj = pool->funcs.new_object(pool->data); |
| 130 | |
| 131 | end: |
| 132 | BT_LOGT("Created one object from pool: pool-addr=%p, obj-addr=%p", |
| 133 | pool, obj); |
| 134 | return obj; |
| 135 | } |
| 136 | |
| 137 | /* |
| 138 | * Recycles an object, that is, puts it back into the pool. |
| 139 | * |
| 140 | * The pool becomes the sole owner of the object to recycle. |
| 141 | */ |
| 142 | static inline |
| 143 | void bt_object_pool_recycle_object(struct bt_object_pool *pool, void *obj) |
| 144 | { |
| 145 | struct bt_object *bt_obj = obj; |
| 146 | |
| 147 | BT_ASSERT(pool); |
| 148 | BT_ASSERT(obj); |
| 149 | BT_LOGT("Recycling object: pool-addr=%p, pool-size=%zu, pool-cap=%u, obj-addr=%p", |
| 150 | pool, pool->size, pool->objects->len, obj); |
| 151 | |
| 152 | if (pool->size == pool->objects->len) { |
| 153 | /* Backing array is full: make place for recycled object */ |
| 154 | BT_LOGD("Object pool is full: increasing object pool capacity: " |
| 155 | "pool-addr=%p, old-pool-cap=%u, new-pool-cap=%u", |
| 156 | pool, pool->objects->len, pool->objects->len + 1); |
| 157 | g_ptr_array_set_size(pool->objects, pool->size + 1); |
| 158 | } |
| 159 | |
| 160 | /* Reset reference count to 1 since it could be 0 now */ |
| 161 | bt_obj->ref_count = 1; |
| 162 | |
| 163 | /* Back to the pool */ |
| 164 | pool->objects->pdata[pool->size] = obj; |
| 165 | pool->size++; |
| 166 | BT_LOGT("Recycled object: pool-addr=%p, pool-size=%zu, pool-cap=%u, obj-addr=%p", |
| 167 | pool, pool->size, pool->objects->len, obj); |
| 168 | } |
| 169 | |
| 170 | #endif /* BABELTRACE_OBJECT_POOL_INTERNAL_H */ |