1 /* mallocator - recycle objects to avoid malloc() / free() */
3 /* Copyright (c) 2006-2012. The SimGrid Team.
4 * All rights reserved. */
6 /* This program is free software; you can redistribute it and/or modify it
7 * under the terms of the license (GNU LGPL) which comes with this package. */
9 #include "xbt/mallocator.h"
10 #include "xbt/asserts.h"
11 #include "xbt/sysdep.h"
12 #include "mc/mc.h" /* kill mallocators when model-checking is enabled */
13 #include "mallocator_private.h"
15 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(xbt_mallocator, xbt, "Mallocators");
17 /** Implementation note on the mallocators:
19 * Mallocators and memory mess introduced by model-checking do not mix well
20 * together: the mallocator will give standard memory when we are using raw
21 * memory (so these blocks are killed on restore) and the contrary (so these
22 * blocks will leak across restores).
24 * In addition, model-checking is activated when the command-line arguments
25 * are parsed, at the beginning of main, while most of the mallocators are
26 * created during the constructor functions launched from xbt_preinit, before
27 * the beginning of the main function.
29 * We want the code as fast as possible when they are active while we can deal
30 * with a little slow-down when they are inactive. So we start the mallocators
31 * as inactive. When they are so, they check at each use whether they should
32 * switch to the fast active mode or should stay in inactive mode.
33 * Finally, we give external elements a way to switch them
34 * all to the active mode (through xbt_mallocator_initialization_is_done).
36 * This design avoids to store all mallocators somewhere for later conversion,
37 * which would be hard to achieve provided that all our data structures use
38 * some mallocators internally...
41 /* Value != 0 when the framework configuration is done. Value > 1 if the
42 * mallocators should be protected from concurrent accesses. */
43 static int initialization_done = 0;
45 static XBT_INLINE void lock_reset(xbt_mallocator_t m)
50 static XBT_INLINE void lock_acquire(xbt_mallocator_t m)
52 if (initialization_done > 1) {
54 while (__sync_lock_test_and_set(lock, 1))
59 static XBT_INLINE void lock_release(xbt_mallocator_t m)
61 if (initialization_done > 1)
62 __sync_lock_release(&m->lock);
66 * This function must be called once the framework configuration is done. If not,
67 * mallocators will never get used. Check the implementation notes in
68 * src/xbt/mallocator.c for the justification of this.
70 * For example, surf_config uses this function to tell to the mallocators that
72 * configuration is now finished and that it can create them if not done yet */
73 void xbt_mallocator_initialization_is_done(int protect)
75 initialization_done = protect ? 2 : 1;
78 /** used by the module to know if it's time to activate the mallocators yet */
79 static XBT_INLINE int xbt_mallocator_is_active(void) {
80 #if MALLOCATOR_COMPILED_IN
81 return initialization_done && !MC_is_active();
89 * \param size size of the internal stack: number of objects the mallocator
90 * will be able to store
91 * \param new_f function to allocate a new object of your datatype, called
92 * in \a xbt_mallocator_get() when the mallocator is empty
93 * \param free_f function to free an object of your datatype, called
94 * in \a xbt_mallocator_release() when the stack is full, and when
95 * the mallocator is freed.
96 * \param reset_f function to reinitialise an object of your datatype, called
97 * when you extract an object from the mallocator (can be NULL)
99 * Create and initialize a new mallocator for a given datatype.
101 * \return pointer to the created mallocator
102 * \see xbt_mallocator_free()
104 xbt_mallocator_t xbt_mallocator_new(int size,
105 pvoid_f_void_t new_f,
106 void_f_pvoid_t free_f,
107 void_f_pvoid_t reset_f)
111 xbt_assert(size > 0, "size must be positive");
112 xbt_assert(new_f != NULL && free_f != NULL, "invalid parameter");
114 m = xbt_new0(s_xbt_mallocator_t, 1);
115 XBT_VERB("Create mallocator %p (%s)",
116 m, xbt_mallocator_is_active() ? "enabled" : "disabled");
120 m->reset_f = reset_f;
126 /** \brief Destructor
127 * \param m the mallocator you want to destroy
129 * Destroy the mallocator and all its data. The function
130 * free_f is called on each object in the mallocator.
132 * \see xbt_mallocator_new()
134 void xbt_mallocator_free(xbt_mallocator_t m)
138 xbt_assert(m != NULL, "Invalid parameter");
140 XBT_VERB("Frees mallocator %p (size:%d/%d)", m, m->current_size,
142 for (i = 0; i < m->current_size; i++) {
143 m->free_f(m->objects[i]);
145 xbt_free(m->objects);
150 * \brief Extract an object from a mallocator
151 * \param m a mallocator
153 * Remove an object from the mallocator and return it.
154 * This function is designed to be used instead of malloc().
155 * If the mallocator is not empty, an object is
156 * extracted from the mallocator and no malloc is done.
158 * If the mallocator is empty, a new object is created,
159 * by calling the function new_f().
161 * In both cases, the function reset_f() (if defined) is called on the object.
163 * \see xbt_mallocator_release()
165 void *xbt_mallocator_get(xbt_mallocator_t m)
169 if (m->objects != NULL) { // this mallocator is active, stop thinking and go for it!
171 if (m->current_size <= 0) {
172 /* No object is ready yet. Create a bunch of them to try to group the
173 * mallocs on the same memory pages (to help the cache lines) */
175 /* XBT_DEBUG("Create a new object for mallocator %p (size:%d/%d)", */
176 /* m, m->current_size, m->max_size); */
178 int amount = MIN(m->max_size / 2, 1000);
179 for (i = 0; i < amount; i++)
180 m->objects[i] = m->new_f();
181 m->current_size = amount;
184 /* there is at least an available object, now */
185 /* XBT_DEBUG("Reuse an old object for mallocator %p (size:%d/%d)", */
186 /* m, m->current_size, m->max_size); */
187 object = m->objects[--m->current_size];
190 if (xbt_mallocator_is_active()) {
191 // We have to switch this mallocator from inactive to active (and then get an object)
192 m->objects = xbt_new0(void *, m->max_size);
194 return xbt_mallocator_get(m);
205 /** \brief Push an object into a mallocator
206 * \param m a mallocator
207 * \param object an object you don't need anymore
209 * Push into the mallocator an object you don't need anymore.
210 * This function is designed to be used instead of free().
211 * If the mallocator is not full, your object if stored into
212 * the mallocator and no free is done.
213 * If the mallocator is full, the object is freed by calling
214 * the function free_f().
216 * \see xbt_mallocator_get()
218 void xbt_mallocator_release(xbt_mallocator_t m, void *object)
220 if (m->objects != NULL) { // Go for it
222 if (m->current_size < m->max_size) {
223 /* there is enough place to push the object */
225 ("Store deleted object in mallocator %p for further use (size:%d/%d)",
226 m, m->current_size, m->max_size); */
227 m->objects[m->current_size++] = object;
231 /* otherwise we don't have a choice, we must free the object */
232 /* XBT_DEBUG("Free deleted object: mallocator %p is full (size:%d/%d)", m,
233 m->current_size, m->max_size); */
237 if (xbt_mallocator_is_active()) {
238 // We have to switch this mallocator from inactive to active (and then store that object)
239 m->objects = xbt_new0(void *, m->max_size);
241 xbt_mallocator_release(m,object);