From cfaf71bdfb6cf3cb4d0908080b7fb67fa4d5051c Mon Sep 17 00:00:00 2001
From: Frederic Suter <frederic.suter@cc.in2p3.fr>
Date: Mon, 30 Mar 2020 15:18:32 +0200
Subject: [PATCH] add Mailox_listen_from

---
 include/simgrid/s4u/Mailbox.hpp | 3 +++
 src/msg/msg_task.cpp            | 8 +-------
 src/s4u/s4u_Mailbox.cpp         | 9 +++++++++
 3 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/include/simgrid/s4u/Mailbox.hpp b/include/simgrid/s4u/Mailbox.hpp
index 5c02b70061..f60c07019a 100644
--- a/include/simgrid/s4u/Mailbox.hpp
+++ b/include/simgrid/s4u/Mailbox.hpp
@@ -45,6 +45,9 @@ public:
   /** Check if there is a communication going on in a mailbox. */
   bool listen();
 
+  /** Look if there is a communication going on in a mailbox and return the PID of the sender actor */
+  aid_t listen_from();
+
   /** Check if there is a communication ready to be consumed from a mailbox. */
   bool ready();
 
diff --git a/src/msg/msg_task.cpp b/src/msg/msg_task.cpp
index 139ebc8f47..032624f3cf 100644
--- a/src/msg/msg_task.cpp
+++ b/src/msg/msg_task.cpp
@@ -637,13 +637,7 @@ msg_comm_t MSG_task_irecv_bounded(msg_task_t* task, const char* name, double rat
  */
 int MSG_task_listen_from(const char* alias)
 {
-  /* looks inside the rdv directly. Not clean. */
-  simgrid::kernel::activity::CommImplPtr comm = simgrid::s4u::Mailbox::by_name(alias)->front();
-
-  if (comm && comm->src_actor_)
-    return comm->src_actor_->get_pid();
-  else
-    return -1;
+  return simgrid::s4u::Mailbox::by_name(alias)->listen_from();
 }
 
 /** @brief Destroys the given task.
diff --git a/src/s4u/s4u_Mailbox.cpp b/src/s4u/s4u_Mailbox.cpp
index 190dd9d747..abbf92e21a 100644
--- a/src/s4u/s4u_Mailbox.cpp
+++ b/src/s4u/s4u_Mailbox.cpp
@@ -44,6 +44,15 @@ bool Mailbox::listen()
   return not this->empty() || (pimpl_->permanent_receiver_ && not pimpl_->done_comm_queue_.empty());
 }
 
+aid_t Mailbox::listen_from()
+{
+  kernel::activity::CommImplPtr comm = front();
+  if (comm && comm->src_actor_)
+    return comm->src_actor_->get_pid();
+  else
+    return -1;
+}
+
 bool Mailbox::ready()
 {
   bool comm_ready = false;
-- 
2.20.1