1 /* mallocator - recycle objects to avoid malloc() / free() */
3 /* Copyright (c) 2006-2011. 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;
46 * This function must be called once the framework configuration is done. If not,
47 * mallocators will never get used. Check the implementation notes in
48 * src/xbt/mallocator.c for the justification of this.
50 * For example, surf_config uses this function to tell to the mallocators that
52 * configuration is now finished and that it can create them if not done yet */
53 void xbt_mallocator_initialization_is_done(int protect)
55 initialization_done = protect ? 2 : 1;
58 /** used by the module to know if it's time to activate the mallocators yet */
59 static XBT_INLINE int xbt_mallocator_is_active(void) {
60 #if MALLOCATOR_COMPILED_IN
61 return initialization_done && !MC_is_active();
69 * \param size size of the internal stack: number of objects the mallocator
70 * will be able to store
71 * \param new_f function to allocate a new object of your datatype, called
72 * in \a xbt_mallocator_get() when the mallocator is empty
73 * \param free_f function to free an object of your datatype, called
74 * in \a xbt_mallocator_release() when the stack is full, and when
75 * the mallocator is freed.
76 * \param reset_f function to reinitialise an object of your datatype, called
77 * when you extract an object from the mallocator (can be NULL)
79 * Create and initialize a new mallocator for a given datatype.
81 * \return pointer to the created mallocator
82 * \see xbt_mallocator_free()
84 xbt_mallocator_t xbt_mallocator_new(int size,
86 void_f_pvoid_t free_f,
87 void_f_pvoid_t reset_f)
91 xbt_assert(size > 0, "size must be positive");
92 xbt_assert(new_f != NULL && free_f != NULL, "invalid parameter");
94 m = xbt_new0(s_xbt_mallocator_t, 1);
95 XBT_VERB("Create mallocator %p (%s)",
96 m, xbt_mallocator_is_active() ? "enabled" : "disabled");
100 m->reset_f = reset_f;
106 /** \brief Destructor
107 * \param m the mallocator you want to destroy
109 * Destroy the mallocator and all its data. The function
110 * free_f is called on each object in the mallocator.
112 * \see xbt_mallocator_new()
114 void xbt_mallocator_free(xbt_mallocator_t m)
118 xbt_assert(m != NULL, "Invalid parameter");
120 XBT_VERB("Frees mallocator %p (size:%d/%d)", m, m->current_size,
122 for (i = 0; i < m->current_size; i++) {
123 m->free_f(m->objects[i]);
125 xbt_free(m->objects);
127 xbt_os_mutex_destroy(m->mutex);
132 * \brief Extract an object from a mallocator
133 * \param m a mallocator
135 * Remove an object from the mallocator and return it.
136 * This function is designed to be used instead of malloc().
137 * If the mallocator is not empty, an object is
138 * extracted from the mallocator and no malloc is done.
140 * If the mallocator is empty, a new object is created,
141 * by calling the function new_f().
143 * In both cases, the function reset_f() (if defined) is called on the object.
145 * \see xbt_mallocator_release()
147 void *xbt_mallocator_get(xbt_mallocator_t m)
151 if (m->objects != NULL) { // this mallocator is active, stop thinking and go for it!
153 xbt_os_mutex_acquire(m->mutex);
154 if (m->current_size <= 0) {
155 /* No object is ready yet. Create a bunch of them to try to group the
156 * mallocs on the same memory pages (to help the cache lines) */
158 /* XBT_DEBUG("Create a new object for mallocator %p (size:%d/%d)", */
159 /* m, m->current_size, m->max_size); */
161 int amount = MIN(m->max_size / 2, 1000);
162 for (i = 0; i < amount; i++)
163 m->objects[i] = m->new_f();
164 m->current_size = amount;
167 /* there is at least an available object, now */
168 /* XBT_DEBUG("Reuse an old object for mallocator %p (size:%d/%d)", */
169 /* m, m->current_size, m->max_size); */
170 object = m->objects[--m->current_size];
172 xbt_os_mutex_release(m->mutex);
174 if (xbt_mallocator_is_active()) {
175 // We have to switch this mallocator from inactive to active (and then get an object)
176 m->objects = xbt_new0(void *, m->max_size);
177 m->mutex = initialization_done > 1 ? xbt_os_mutex_init() : NULL;
178 return xbt_mallocator_get(m);
189 /** \brief Push an object into a mallocator
190 * \param m a mallocator
191 * \param object an object you don't need anymore
193 * Push into the mallocator an object you don't need anymore.
194 * This function is designed to be used instead of free().
195 * If the mallocator is not full, your object if stored into
196 * the mallocator and no free is done.
197 * If the mallocator is full, the object is freed by calling
198 * the function free_f().
200 * \see xbt_mallocator_get()
202 void xbt_mallocator_release(xbt_mallocator_t m, void *object)
204 if (m->objects != NULL) { // Go for it
206 xbt_os_mutex_acquire(m->mutex);
207 if (m->current_size < m->max_size) {
208 /* there is enough place to push the object */
210 ("Store deleted object in mallocator %p for further use (size:%d/%d)",
211 m, m->current_size, m->max_size); */
212 m->objects[m->current_size++] = object;
214 xbt_os_mutex_release(m->mutex);
217 xbt_os_mutex_release(m->mutex);
218 /* otherwise we don't have a choice, we must free the object */
219 /* XBT_DEBUG("Free deleted object: mallocator %p is full (size:%d/%d)", m,
220 m->current_size, m->max_size); */
224 if (xbt_mallocator_is_active()) {
225 // We have to switch this mallocator from inactive to active (and then store that object)
226 m->objects = xbt_new0(void *, m->max_size);
227 m->mutex = initialization_done > 1 ? xbt_os_mutex_init() : NULL;
228 xbt_mallocator_release(m,object);