Don't rely on random to generate temporary file names.

[simgrid.git] / src / smpi / internals / smpi_memory.cpp

diff --git a/src/smpi/internals/smpi_memory.cpp b/src/smpi/internals/smpi_memory.cpp
index 1b41547..49e4ab1 100644 (file)
--- a/src/smpi/internals/smpi_memory.cpp
+++ b/src/smpi/internals/smpi_memory.cpp
@@ -1,4 +1,4 @@
-/* Copyright (c) 2015-2018. The SimGrid Team. All rights reserved.          */
+/* Copyright (c) 2015-2019. 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. */
@@ -184,10 +184,16 @@ smpi_privatization_region_t smpi_init_global_memory_segment_process()
   char path[24];
   int status;
 
-  do {
-    snprintf(path, sizeof(path), "/smpi-buffer-%06x", rand() % 0xffffffU);
+  constexpr unsigned VAL_MASK = 0xffffffU;
+  static unsigned prev_val    = VAL_MASK;
+  for (unsigned i = (prev_val + 1) & VAL_MASK; i != prev_val; i = (i + 1) & VAL_MASK) {
+    snprintf(path, sizeof(path), "/smpi-buffer-%06x", i);
     file_descriptor = shm_open(path, O_RDWR | O_CREAT | O_EXCL, S_IRUSR | S_IWUSR);
-  } while (file_descriptor == -1 && errno == EEXIST);
+    if (file_descriptor != -1 || errno != EEXIST) {
+      prev_val = i;
+      break;
+    }
+  }
   if (file_descriptor < 0) {
     if (errno == EMFILE) {
       xbt_die("Impossible to create temporary file for memory mapping: %s\n\
@@ -243,43 +249,32 @@ void smpi_destroy_global_memory_segments(){
 #endif
 }
 
+static int sendbuffer_size = 0;
+static char* sendbuffer    = nullptr;
+static int recvbuffer_size = 0;
+static char* recvbuffer    = nullptr;
 
-//allocate a single buffer for all sends, and an other of all reads, for each actor.
-//buffer size is growing if needed
-
-typedef std::tuple</*buffer adress*/ char*, /*buffer size*/ int> buffer_tuple;
-static std::map<aid_t, buffer_tuple> sendbuffer_map;
-static std::map<aid_t, buffer_tuple> recvbuffer_map;
-static void* smpi_get_tmp_buffer(int size, std::map<aid_t, buffer_tuple> buffer_map)
+//allocate a single buffer for all sends, growing it if needed
+void* smpi_get_tmp_sendbuffer(int size)
 {
-  // Because this kind of process maintain is own list of buffers and call
-  // `smpi_free_tmp_buffer(void* buf)` to free them
   if (not smpi_process()->replaying())
     return xbt_malloc(size);
-
-  // check if the process is registered
-  aid_t id = simgrid::s4u::this_actor::get_pid();
-  if (not (buffer_map.find(id) == buffer_map.end()))
-  {
-    // This tuple represents a buffer and his size
-    buffer_tuple buffer_tuple(nullptr, 0);
-    buffer_map[id] = buffer_tuple;
-  }
-  if (std::get<1>(buffer_map[id]) < size){
-      std::get<0>(buffer_map[id]) = static_cast<char*>(xbt_realloc(std::get<0>(buffer_map[id]), size));
-      std::get<1>(buffer_map[id]) = size;
+  if (sendbuffer_size<size){
+    sendbuffer=static_cast<char*>(xbt_realloc(sendbuffer,size));
+    sendbuffer_size=size;
   }
-  return std::get<0>(buffer_map[id]);
-}
-
-void* smpi_get_tmp_sendbuffer(int size)
-{
-    return smpi_get_tmp_buffer(size, sendbuffer_map);
+  return sendbuffer;
 }
 
-void* smpi_get_tmp_recvbuffer(int size)
-{
-    return smpi_get_tmp_buffer(size, recvbuffer_map);
+//allocate a single buffer for all recv
+void* smpi_get_tmp_recvbuffer(int size){
+  if (not smpi_process()->replaying())
+    return xbt_malloc(size);
+  if (recvbuffer_size<size){
+    recvbuffer=static_cast<char*>(xbt_realloc(recvbuffer,size));
+    recvbuffer_size=size;
+  }
+  return recvbuffer;
 }
 
 void smpi_free_tmp_buffer(void* buf){
@@ -288,7 +283,6 @@ void smpi_free_tmp_buffer(void* buf){
 }
 
 void smpi_free_replay_tmp_buffers(){
-  aid_t id = simgrid::s4u::this_actor::get_pid();
-  xbt_free(std::get<0>(recvbuffer_map[id]));
-  xbt_free(std::get<0>(sendbuffer_map[id]));
+  xbt_free(sendbuffer);
+  xbt_free(recvbuffer);
 }