1 /* mallocator - recycle objects to avoid malloc() / free() */
3 /* Copyright (c) 2006-2022. The SimGrid Team. All rights reserved. */
5 /* This program is free software; you can redistribute it and/or modify it
6 * under the terms of the license (GNU LGPL) which comes with this package. */
8 #include "xbt/mallocator.h"
9 #include "mallocator_private.h"
10 #include "simgrid/modelchecker.h" /* kill mallocators when model-checking is enabled */
11 #include "src/internal_config.h"
12 #include "xbt/asserts.h"
13 #include "xbt/sysdep.h"
16 #define MIN(a, b) ((a) < (b) ? (a) : (b))
19 #define MAX(a, b) ((a) > (b) ? (a) : (b))
22 XBT_LOG_NEW_DEFAULT_SUBCATEGORY(xbt_mallocator, xbt, "Mallocators");
24 /** Implementation note on the mallocators:
26 * Mallocators and memory mess introduced by model-checking do not mix well together: the mallocator will give
27 * standard memory when we are using raw memory (so these blocks are killed on restore) and the contrary (so these
28 * blocks will leak across restores).
30 * In addition, model-checking is activated when the command-line arguments are parsed, at the beginning of main, while
31 * most of the mallocators are created during the constructor functions launched from xbt_preinit, before the beginning
32 * of the main function.
34 * We want the code as fast as possible when they are active while we can deal with a little slow-down when they are
35 * inactive. So we start the mallocators as inactive. When they are so, they check at each use whether they should
36 * switch to the fast active mode or should stay in inactive mode. Finally, we give external elements a way to switch
37 * them all to the active mode (through xbt_mallocator_initialization_is_done).
39 * This design avoids to store all mallocators somewhere for later conversion, which would be hard to achieve provided
40 * that all our data structures use some mallocators internally...
43 /* Value != 0 when the framework configuration is done. Value > 1 if the
44 * mallocators should be protected from concurrent accesses. */
45 static int initialization_done = 0;
47 static inline void lock_reset(xbt_mallocator_t m)
49 atomic_flag_clear(&m->lock);
52 static inline void lock_acquire(xbt_mallocator_t m)
54 if (initialization_done > 1) {
55 while (atomic_flag_test_and_set(&m->lock))
60 static inline void lock_release(xbt_mallocator_t m)
62 if (initialization_done > 1)
63 atomic_flag_clear(&m->lock);
67 * This function must be called once the framework configuration is done. If not, mallocators will never get used.
68 * Check the implementation notes in src/xbt/mallocator.c for the justification of this.
70 * For example, surf_config uses this function to tell to the mallocators that the simgrid configuration is now
71 * finished and that it can create them if not done yet */
72 void xbt_mallocator_initialization_is_done(int protect)
74 initialization_done = protect ? 2 : 1;
77 /** used by the module to know if it's time to activate the mallocators yet */
78 static inline int xbt_mallocator_is_active(void) {
79 #if SIMGRID_HAVE_MALLOCATOR
80 return initialization_done && !MC_is_active();
88 * @param size size of the internal stack: number of objects the mallocator will be able to store
89 * @param new_f function to allocate a new object of your datatype, called in @a xbt_mallocator_get() when the
91 * @param free_f function to free an object of your datatype, called in @a xbt_mallocator_release() when the stack is
92 * full, and when the mallocator is freed.
93 * @param reset_f function to reinitialize an object of your datatype, called when you extract an object from the
94 * mallocator (can be NULL)
96 * Create and initialize a new mallocator for a given datatype.
98 * @return pointer to the created mallocator
99 * @see xbt_mallocator_free()
101 xbt_mallocator_t xbt_mallocator_new(int size, pvoid_f_void_t new_f, void_f_pvoid_t free_f, void_f_pvoid_t reset_f)
105 xbt_assert(size > 0, "size must be positive");
106 xbt_assert(new_f != NULL && free_f != NULL, "invalid parameter");
108 m = xbt_new0(s_xbt_mallocator_t, 1);
109 XBT_VERB("Create mallocator %p (%s)", m, xbt_mallocator_is_active() ? "enabled" : "disabled");
113 m->reset_f = reset_f;
119 /** @brief Destructor
120 * @param m the mallocator you want to destroy
122 * Destroy the mallocator and all its data. The function free_f is called on each object in the mallocator.
124 * @see xbt_mallocator_new()
126 void xbt_mallocator_free(xbt_mallocator_t m)
128 xbt_assert(m != NULL, "Invalid parameter");
130 XBT_VERB("Frees mallocator %p (size:%d/%d)", m, m->current_size, m->max_size);
131 for (int i = 0; i < m->current_size; i++) {
132 m->free_f(m->objects[i]);
134 xbt_free(m->objects);
139 * @brief Extract an object from a mallocator
140 * @param m a mallocator
142 * Remove an object from the mallocator and return it.
143 * This function is designed to be used instead of malloc().
144 * If the mallocator is not empty, an object is extracted from the mallocator and no malloc is done.
146 * If the mallocator is empty, a new object is created, by calling the function new_f().
148 * In both cases, the function reset_f() (if defined) is called on the object.
150 * @see xbt_mallocator_release()
152 void *xbt_mallocator_get(xbt_mallocator_t m)
156 if (m->objects != NULL) { // this mallocator is active, stop thinking and go for it!
158 if (m->current_size <= 0) {
159 /* No object is ready yet. Create a bunch of them to try to group the
160 * mallocs on the same memory pages (to help the cache lines) */
161 int amount = MIN(m->max_size / 2, 1000);
162 for (int 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 object = m->objects[--m->current_size];
171 if (xbt_mallocator_is_active()) {
172 // We have to switch this mallocator from inactive to active (and then get an object)
173 m->objects = xbt_new0(void *, m->max_size);
175 return xbt_mallocator_get(m);
186 /** @brief Push an object into a mallocator
187 * @param m a mallocator
188 * @param object an object you don't need anymore
190 * Push into the mallocator an object you don't need anymore.
191 * This function is designed to be used instead of free().
192 * If the mallocator is not full, your object if stored into the mallocator and no free is done.
193 * If the mallocator is full, the object is freed by calling the function free_f().
195 * @see xbt_mallocator_get()
197 void xbt_mallocator_release(xbt_mallocator_t m, void *object)
199 if (m == NULL) // The mallocators are already destroyed. Bail out ASAP.
201 if (m->objects != NULL) { // Go for it
203 if (m->current_size < m->max_size) {
204 /* there is enough place to push the object */
205 m->objects[m->current_size++] = object;
209 /* otherwise we don't have a choice, we must free the object */
213 if (xbt_mallocator_is_active()) {
214 // We have to switch this mallocator from inactive to active (and then store that object)
215 m->objects = xbt_new0(void *, m->max_size);
217 xbt_mallocator_release(m,object);