workaround a possible race condition

[simgrid.git] / src / s4u / s4u_mailbox.cpp

diff --git a/src/s4u/s4u_mailbox.cpp b/src/s4u/s4u_mailbox.cpp
index 781284f..d18150d 100644 (file)
--- a/src/s4u/s4u_mailbox.cpp
+++ b/src/s4u/s4u_mailbox.cpp
@@ -10,24 +10,34 @@
 
 #include "simgrid/s4u/mailbox.hpp"
 
-XBT_LOG_NEW_DEFAULT_CATEGORY(s4u_channel,"S4U Communication Mailboxes");
+XBT_LOG_EXTERNAL_CATEGORY(s4u);
+XBT_LOG_NEW_DEFAULT_SUBCATEGORY(s4u_channel,s4u,"S4U Communication Mailboxes");
 
 
 using namespace simgrid;
 
-boost::unordered_map <std::string, s4u::Mailbox *> *s4u::Mailbox::channels = new boost::unordered_map<std::string, s4u::Mailbox*> ();
+boost::unordered_map <std::string, s4u::Mailbox *> *s4u::Mailbox::mailboxes = new boost::unordered_map<std::string, s4u::Mailbox*> ();
 
 
 s4u::Mailbox::Mailbox(const char*name, smx_rdv_t inferior) {
        p_inferior = inferior;
-       channels->insert({name, this});
+       p_name = name;
+       mailboxes->insert({name, this});
+}
+const char *s4u::Mailbox::getName() {
+       return p_name.c_str();
 }
 s4u::Mailbox *s4u::Mailbox::byName(const char*name) {
-       s4u::Mailbox * res;
+       s4u::Mailbox *res;
        try {
-               res = channels->at(name);
+               res = mailboxes->at(name);
        } catch (std::out_of_range& e) {
-               res = new Mailbox(name,simcall_rdv_create(name));
+               // FIXME: there is a potential race condition here where two actors run Mailbox::byName on a non-existent mailbox
+               // during the same scheduling round. Both will be interrupted in the simcall creating the underlying simix rdv.
+               // Only one simix object will be created, but two S4U objects will be created.
+               // Only one S4U object will be stored in the hashmap and used, and the other one will be leaked.
+               new Mailbox(name,simcall_rdv_create(name));
+               res = mailboxes->at(name); // Use the stored one, even if it's not the one I created myself.
        }
        return res;
 }