XBT_LOG_NEW_DEFAULT_SUBCATEGORY(xbt_mallocator, xbt, "Mallocators");
-/* Mallocators and memory mess introduced by model-checking do not mix well
+/** Implementation note on the mallocators:
+ *
+ * Mallocators and memory mess introduced by model-checking do not mix well
* together: the mallocator will give standard memory when we are using raw
* memory (so these blocks are killed on restore) and the contrary (so these
- * blocks will leak accross restores).
+ * blocks will leak across restores).
+ *
+ * In addition, model-checking is activated when the command-line arguments
+ * are parsed, at the beginning of main, while most of the mallocators are
+ * created during the constructor functions launched from xbt_preinit, before
+ * the beginning of the main function.
+ *
+ * We want the code as fast as possible when they are active while we can deal
+ * with a little slow-down when they are inactive. So we start the mallocators
+ * as inactive. When they are so, they check at each use whether they should
+ * switch to the fast active mode or should stay in inactive mode.
+ * Finally, we give external elements a way to switch them
+ * all to the active mode (through xbt_mallocator_initialization_is_done).
+ *
+ * This design avoids to store all mallocators somewhere for later conversion,
+ * which would be hard to achieve provided that all our data structures use
+ * some mallocators internally...
*/
-#define MALLOCATOR_IS_ENABLED (MALLOCATOR_IS_WANTED && !MC_is_active())
+
+/* Value != 0 when the framework configuration is done. Value > 1 if the
+ * mallocators should be protected from concurrent accesses. */
+static int initialization_done = 0;
+
+static XBT_INLINE void lock_create(xbt_mallocator_t m)
+{
+ m->lock = 0;
+}
+
+static XBT_INLINE void lock_destroy(xbt_mallocator_t m)
+{
+}
+
+static XBT_INLINE void lock_acquire(xbt_mallocator_t m)
+{
+ if (initialization_done > 1) {
+ int *lock = &m->lock;
+ while (__sync_lock_test_and_set(lock, 1))
+ /* nop */;
+ }
+}
+
+static XBT_INLINE void lock_release(xbt_mallocator_t m)
+{
+ if (initialization_done > 1)
+ __sync_lock_release(&m->lock);
+}
+
+/**
+ * This function must be called once the framework configuration is done. If not,
+ * mallocators will never get used. Check the implementation notes in
+ * src/xbt/mallocator.c for the justification of this.
+ *
+ * For example, surf_config uses this function to tell to the mallocators that
+ * the simgrid
+ * configuration is now finished and that it can create them if not done yet */
+void xbt_mallocator_initialization_is_done(int protect)
+{
+ initialization_done = protect ? 2 : 1;
+}
+
+/** used by the module to know if it's time to activate the mallocators yet */
+static XBT_INLINE int xbt_mallocator_is_active(void) {
+#if MALLOCATOR_COMPILED_IN
+ return initialization_done && !MC_is_active();
+#else
+ return 0;
+#endif
+}
/**
* \brief Constructor
m = xbt_new0(s_xbt_mallocator_t, 1);
XBT_VERB("Create mallocator %p (%s)",
- m, MALLOCATOR_IS_ENABLED ? "enabled" : "disabled");
+ m, xbt_mallocator_is_active() ? "enabled" : "disabled");
m->current_size = 0;
m->new_f = new_f;
m->free_f = free_f;
m->reset_f = reset_f;
+ m->max_size = size;
- if (MALLOCATOR_IS_ENABLED) {
- m->objects = xbt_new0(void *, size);
- m->max_size = size;
- m->mutex = xbt_os_mutex_init();
- } else {
- m->objects = NULL;
- m->max_size = 0;
- m->mutex = NULL;
- }
return m;
}
m->free_f(m->objects[i]);
}
xbt_free(m->objects);
- xbt_os_mutex_destroy(m->mutex);
+ lock_destroy(m);
xbt_free(m);
}
{
void *object;
- if (MALLOCATOR_IS_ENABLED) {
- xbt_os_mutex_acquire(m->mutex);
+ if (m->objects != NULL) { // this mallocator is active, stop thinking and go for it!
+ lock_acquire(m);
if (m->current_size <= 0) {
/* No object is ready yet. Create a bunch of them to try to group the
* mallocs on the same memory pages (to help the cache lines) */
/* XBT_DEBUG("Reuse an old object for mallocator %p (size:%d/%d)", */
/* m, m->current_size, m->max_size); */
object = m->objects[--m->current_size];
- xbt_os_mutex_release(m->mutex);
+ lock_release(m);
} else {
- object = m->new_f();
+ if (xbt_mallocator_is_active()) {
+ // We have to switch this mallocator from inactive to active (and then get an object)
+ m->objects = xbt_new0(void *, m->max_size);
+ lock_create(m);
+ return xbt_mallocator_get(m);
+ } else {
+ object = m->new_f();
+ }
}
if (m->reset_f)
*/
void xbt_mallocator_release(xbt_mallocator_t m, void *object)
{
- if (MALLOCATOR_IS_ENABLED) {
- xbt_os_mutex_acquire(m->mutex);
+ if (m->objects != NULL) { // Go for it
+ lock_acquire(m);
if (m->current_size < m->max_size) {
/* there is enough place to push the object */
/* XBT_DEBUG
("Store deleted object in mallocator %p for further use (size:%d/%d)",
m, m->current_size, m->max_size); */
m->objects[m->current_size++] = object;
- xbt_os_mutex_release(m->mutex);
+ lock_release(m);
} else {
- xbt_os_mutex_release(m->mutex);
+ lock_release(m);
/* otherwise we don't have a choice, we must free the object */
/* XBT_DEBUG("Free deleted object: mallocator %p is full (size:%d/%d)", m,
m->current_size, m->max_size); */
m->free_f(object);
}
} else {
- m->free_f(object);
+ if (xbt_mallocator_is_active()) {
+ // We have to switch this mallocator from inactive to active (and then store that object)
+ m->objects = xbt_new0(void *, m->max_size);
+ lock_create(m);
+ xbt_mallocator_release(m,object);
+ } else {
+ m->free_f(object);
+ }
}
}
