| 1 | /* |
| 2 | * SPDX-License-Identifier: MIT |
| 3 | * |
| 4 | * Copyright (c) 2018 EfficiOS Inc. and Linux Foundation |
| 5 | * Copyright (c) 2018 Philippe Proulx <pproulx@efficios.com> |
| 6 | */ |
| 7 | |
| 8 | #ifndef BABELTRACE_CTF_WRITER_OBJECT_POOL_H |
| 9 | #define BABELTRACE_CTF_WRITER_OBJECT_POOL_H |
| 10 | |
| 11 | /* |
| 12 | * This is a generic object pool to avoid memory allocation/deallocation |
| 13 | * for objects of which the lifespan is typically short, but which are |
| 14 | * created a lot. |
| 15 | * |
| 16 | * The object pool, thanks to two user functions, knows how to allocate |
| 17 | * a brand new object in memory when the pool is empty and how to |
| 18 | * destroy an object when we destroy the pool. |
| 19 | * |
| 20 | * The object pool's user is responsible for: |
| 21 | * |
| 22 | * * Setting whatever references the object needs to keep and reset some |
| 23 | * properties _after_ calling bt_ctf_object_pool_create_object(). This is |
| 24 | * typically done in the bt_*_create() function which calls |
| 25 | * bt_ctf_object_pool_create_object() (which could call the user-provided |
| 26 | * allocation function if the pool is empty) and then sets the |
| 27 | * appropriate properties on the possibly recycled object. |
| 28 | * |
| 29 | * * Releasing whatever references the object keeps _before_ calling |
| 30 | * bt_ctf_object_pool_recycle_object(). This is typically done in a custom |
| 31 | * bt_*_recycle() function which does the necessary before calling |
| 32 | * bt_ctf_object_pool_recycle_object() with an object ready to be reused |
| 33 | * at any time. |
| 34 | */ |
| 35 | |
| 36 | #include <glib.h> |
| 37 | |
| 38 | #include "object.h" |
| 39 | |
| 40 | typedef void *(*bt_ctf_object_pool_new_object_func)(void *data); |
| 41 | typedef void *(*bt_ctf_object_pool_destroy_object_func)(void *obj, void *data); |
| 42 | |
| 43 | struct bt_ctf_object_pool { |
| 44 | /* |
| 45 | * Container of recycled objects, owned by this. The array's size |
| 46 | * is the pool's capacity. |
| 47 | */ |
| 48 | GPtrArray *objects; |
| 49 | |
| 50 | /* |
| 51 | * Pool's size, that is, number of elements in the array above, |
| 52 | * starting at index 0, which exist as recycled objects. |
| 53 | */ |
| 54 | size_t size; |
| 55 | |
| 56 | /* User functions */ |
| 57 | struct { |
| 58 | /* Allocate a new object in memory */ |
| 59 | bt_ctf_object_pool_new_object_func new_object; |
| 60 | |
| 61 | /* Free direct and indirect memory occupied by object */ |
| 62 | bt_ctf_object_pool_destroy_object_func destroy_object; |
| 63 | } funcs; |
| 64 | |
| 65 | /* User data passed to user functions */ |
| 66 | void *data; |
| 67 | }; |
| 68 | |
| 69 | /* |
| 70 | * Initializes an object pool which is already allocated. |
| 71 | */ |
| 72 | int bt_ctf_object_pool_initialize(struct bt_ctf_object_pool *pool, |
| 73 | bt_ctf_object_pool_new_object_func new_object_func, |
| 74 | bt_ctf_object_pool_destroy_object_func destroy_object_func, |
| 75 | void *data); |
| 76 | |
| 77 | /* |
| 78 | * Finalizes an object pool without deallocating it. |
| 79 | */ |
| 80 | void bt_ctf_object_pool_finalize(struct bt_ctf_object_pool *pool); |
| 81 | |
| 82 | /* |
| 83 | * Creates an object from an object pool. If the pool is empty, this |
| 84 | * function calls the "new" user function to allocate a new object |
| 85 | * before returning it. Otherwise this function returns a recycled |
| 86 | * object, removing it from the pool. |
| 87 | * |
| 88 | * The returned object is owned by the caller. |
| 89 | */ |
| 90 | static inline |
| 91 | void *bt_ctf_object_pool_create_object(struct bt_ctf_object_pool *pool) |
| 92 | { |
| 93 | struct bt_ctf_object *obj; |
| 94 | |
| 95 | BT_ASSERT_DBG(pool); |
| 96 | |
| 97 | #ifdef BT_LOGT |
| 98 | BT_LOGT("Creating object from pool: pool-addr=%p, pool-size=%zu, pool-cap=%u", |
| 99 | pool, pool->size, pool->objects->len); |
| 100 | #endif |
| 101 | |
| 102 | if (pool->size > 0) { |
| 103 | /* Pick one from the pool */ |
| 104 | pool->size--; |
| 105 | obj = pool->objects->pdata[pool->size]; |
| 106 | pool->objects->pdata[pool->size] = NULL; |
| 107 | goto end; |
| 108 | } |
| 109 | |
| 110 | /* Pool is empty: create a brand new object */ |
| 111 | #ifdef BT_LOGT |
| 112 | BT_LOGT("Pool is empty: allocating new object: pool-addr=%p", |
| 113 | pool); |
| 114 | #endif |
| 115 | |
| 116 | obj = pool->funcs.new_object(pool->data); |
| 117 | |
| 118 | end: |
| 119 | #ifdef BT_LOGT |
| 120 | BT_LOGT("Created one object from pool: pool-addr=%p, obj-addr=%p", |
| 121 | pool, obj); |
| 122 | #endif |
| 123 | |
| 124 | return obj; |
| 125 | } |
| 126 | |
| 127 | /* |
| 128 | * Recycles an object, that is, puts it back into the pool. |
| 129 | * |
| 130 | * The pool becomes the sole owner of the object to recycle. |
| 131 | */ |
| 132 | static inline |
| 133 | void bt_ctf_object_pool_recycle_object(struct bt_ctf_object_pool *pool, void *obj) |
| 134 | { |
| 135 | struct bt_ctf_object *bt_obj = obj; |
| 136 | |
| 137 | BT_ASSERT_DBG(pool); |
| 138 | BT_ASSERT_DBG(obj); |
| 139 | |
| 140 | #ifdef BT_LOGT |
| 141 | BT_LOGT("Recycling object: pool-addr=%p, pool-size=%zu, pool-cap=%u, obj-addr=%p", |
| 142 | pool, pool->size, pool->objects->len, obj); |
| 143 | #endif |
| 144 | |
| 145 | if (pool->size == pool->objects->len) { |
| 146 | /* Backing array is full: make place for recycled object */ |
| 147 | #ifdef BT_LOGT |
| 148 | BT_LOGT("Object pool is full: increasing object pool capacity: " |
| 149 | "pool-addr=%p, old-pool-cap=%u, new-pool-cap=%u", |
| 150 | pool, pool->objects->len, pool->objects->len + 1); |
| 151 | #endif |
| 152 | g_ptr_array_set_size(pool->objects, pool->size + 1); |
| 153 | } |
| 154 | |
| 155 | /* Reset reference count to 1 since it could be 0 now */ |
| 156 | bt_obj->ref_count = 1; |
| 157 | |
| 158 | /* Back to the pool */ |
| 159 | pool->objects->pdata[pool->size] = obj; |
| 160 | pool->size++; |
| 161 | |
| 162 | #ifdef BT_LOGT |
| 163 | BT_LOGT("Recycled object: pool-addr=%p, pool-size=%zu, pool-cap=%u, obj-addr=%p", |
| 164 | pool, pool->size, pool->objects->len, obj); |
| 165 | #endif |
| 166 | } |
| 167 | |
| 168 | #endif /* BABELTRACE_CTF_WRITER_OBJECT_POOL_H */ |