X-Git-Url: http://info.iut-bm.univ-fcomte.fr/pub/gitweb/simgrid.git/blobdiff_plain/e0a285adff7bc710c372ad0b74445be3100515c9..4bd1f48f0bf1ad1703be680ec2a38d626c6a2668:/src/xbt/mallocator.c

diff --git a/src/xbt/mallocator.c b/src/xbt/mallocator.c
index c2b1d3c003..fa9f5828e8 100644
--- a/src/xbt/mallocator.c
+++ b/src/xbt/mallocator.c
@@ -1,32 +1,129 @@
+/* mallocator - recycle objects to avoid malloc() / free()                  */
+
+/* Copyright (c) 2006-2014. The SimGrid Team.
+ * All rights reserved.                                                     */
+
+/* This program is free software; you can redistribute it and/or modify it
+ * under the terms of the license (GNU LGPL) which comes with this package. */
+
 #include "xbt/mallocator.h"
+#include "mallocator_private.h"
+#include "simgrid/modelchecker.h" /* kill mallocators when model-checking is enabled */
+#include "src/internal_config.h"
 #include "xbt/asserts.h"
 #include "xbt/sysdep.h"
-#include "mallocator_private.h"
 
-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) {
-  xbt_assert0(size > 0, "size must be positive");
-  xbt_assert0(new_f != NULL && free_f != NULL && reset_f != NULL,
-	      "invalid parameter");
-  xbt_mallocator_t m = xbt_new0(s_xbt_mallocator_t, 1);
+XBT_LOG_NEW_DEFAULT_SUBCATEGORY(xbt_mallocator, xbt, "Mallocators");
 
-  m->objects = xbt_new0(void*, size);
-  m->max_size = size;
+/** 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 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...
+ */
+
+/* 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 inline void lock_reset(xbt_mallocator_t m)
+{
+  m->lock = 0;
+}
+
+static 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 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 inline int xbt_mallocator_is_active(void) {
+#if SIMGRID_HAVE_MALLOCATOR
+  return initialization_done && !MC_is_active();
+#else
+  return 0;
+#endif
+}
+
+/**
+ * \brief Constructor
+ * \param size size of the internal stack: number of objects the mallocator will be able to store
+ * \param new_f function to allocate a new object of your datatype, called in \a xbt_mallocator_get() when the
+ *              mallocator is empty
+ * \param free_f function to free an object of your datatype, called in \a xbt_mallocator_release() when the stack is
+ *                full, and when the mallocator is freed.
+ * \param reset_f function to reinitialise an object of your datatype, called when you extract an object from the
+ *                mallocator (can be NULL)
+ *
+ * Create and initialize a new mallocator for a given datatype.
+ *
+ * \return pointer to the created mallocator
+ * \see xbt_mallocator_free()
+ */
+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)
+{
+  xbt_mallocator_t m;
+
+  xbt_assert(size > 0, "size must be positive");
+  xbt_assert(new_f != NULL && free_f != NULL, "invalid parameter");
+
+  m = xbt_new0(s_xbt_mallocator_t, 1);
+  XBT_VERB("Create mallocator %p (%s)", 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;
 
   return m;
 }
 
-/* Destroy the mallocator and all its data */
-void xbt_mallocator_free(xbt_mallocator_t m) {
-  xbt_assert0(m != NULL, "Invalid parameter");
-
+/** \brief Destructor
+ * \param m the mallocator you want to destroy
+ *
+ * Destroy the mallocator and all its data. The function free_f is called on each object in the mallocator.
+ *
+ * \see xbt_mallocator_new()
+ */
+void xbt_mallocator_free(xbt_mallocator_t m)
+{
   int i;
+  xbt_assert(m != NULL, "Invalid parameter");
+
+  XBT_VERB("Frees mallocator %p (size:%d/%d)", m, m->current_size, m->max_size);
   for (i = 0; i < m->current_size; i++) {
     m->free_f(m->objects[i]);
   }
@@ -34,33 +131,95 @@ void xbt_mallocator_free(xbt_mallocator_t m) {
   xbt_free(m);
 }
 
-/* Return an object (use this function instead of malloc) */
-void *xbt_mallocator_get(xbt_mallocator_t m) {
-  xbt_assert0(m != NULL, "Invalid parameter");
-
+/**
+ * \brief Extract an object from a mallocator
+ * \param m a mallocator
+ *
+ * Remove an object from the mallocator and return it.
+ * This function is designed to be used instead of malloc().
+ * If the mallocator is not empty, an object is extracted from the mallocator and no malloc is done.
+ *
+ * If the mallocator is empty, a new object is created, by calling the function new_f().
+ *
+ * In both cases, the function reset_f() (if defined) is called on the object.
+ *
+ * \see xbt_mallocator_release()
+ */
+void *xbt_mallocator_get(xbt_mallocator_t m)
+{
   void *object;
-  if (m->current_size > 0) {
-    /* there is at least an available object */
+
+  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("Create a new object for mallocator %p (size:%d/%d)", m, m->current_size, m->max_size); */
+      int i;
+      int amount = MIN(m->max_size / 2, 1000);
+      for (i = 0; i < amount; i++)
+        m->objects[i] = m->new_f();
+      m->current_size = amount;
+    }
+
+    /* there is at least an available object, now */
+    /* 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];
+    lock_release(m);
+  } else {
+    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_reset(m);
+      return xbt_mallocator_get(m);
+    } else {
+      object = m->new_f();
+    }
   }
-  else {
-    /* otherwise we must allocate a new object */
-    object = m->new_f();
-  }
-  m->reset_f(object);
+
+  if (m->reset_f)
+    m->reset_f(object);
   return object;
 }
 
-/* Release an object (use this function instead of free) */
-void xbt_mallocator_release(xbt_mallocator_t m, void *object) {
-  xbt_assert0(m != NULL && object != NULL, "Invalid parameter");
-
-  if (m->current_size < m->max_size) {
-    /* there is enough place to push the object */
-    m->objects[m->current_size++] = object;
-  }
-  else {
-    /* otherwise we don't have a choice, we must free the object */
-    m->free_f(object);
+/** \brief Push an object into a mallocator
+ * \param m a mallocator
+ * \param object an object you don't need anymore
+ *
+ * Push into the mallocator an object you don't need anymore.
+ * This function is designed to be used instead of free().
+ * If the mallocator is not full, your object if stored into the mallocator and no free is done.
+ * If the mallocator is full, the object is freed by calling the function free_f().
+ *
+ * \see xbt_mallocator_get()
+ */
+void xbt_mallocator_release(xbt_mallocator_t m, void *object)
+{
+  if (m == NULL) // The mallocators are already destroyed. Bail out ASAP.
+     return;
+  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;
+      lock_release(m);
+    } else {
+      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 {
+    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_reset(m);
+      xbt_mallocator_release(m,object);
+    } else {
+      m->free_f(object);
+    }
   }
 }