From 793184f903550583a9d23a67374df45e9b67612d Mon Sep 17 00:00:00 2001
From: Fred Suter <suterf@ornl.gov>
Date: Thu, 5 Oct 2023 08:30:25 -0400
Subject: [PATCH] Reducing the number of refcount changes for ActivityImpl

---
 src/kernel/activity/MailboxImpl.cpp | 15 +++++++--------
 src/kernel/activity/MailboxImpl.hpp | 16 ++++++----------
 2 files changed, 13 insertions(+), 18 deletions(-)

diff --git a/src/kernel/activity/MailboxImpl.cpp b/src/kernel/activity/MailboxImpl.cpp
index cb49f3b2b8..aaeeb83dc4 100644
--- a/src/kernel/activity/MailboxImpl.cpp
+++ b/src/kernel/activity/MailboxImpl.cpp
@@ -46,7 +46,7 @@ void MailboxImpl::set_receiver(s4u::ActorPtr actor)
 /** @brief Pushes a communication activity into a mailbox
  *  @param comm What to add
  */
-void MailboxImpl::push(CommImplPtr comm)
+void MailboxImpl::push(const CommImplPtr& comm)
 {
   comm->set_mailbox(this);
   this->comm_queue_.push_back(std::move(comm));
@@ -61,12 +61,11 @@ void MailboxImpl::remove(const CommImplPtr& comm)
              (comm->get_mailbox() ? comm->get_mailbox()->get_cname() : "(null)"), this->get_cname());
 
   comm->set_mailbox(nullptr);
-  for (auto it = this->comm_queue_.begin(); it != this->comm_queue_.end(); it++)
-    if (*it == comm) {
-      this->comm_queue_.erase(it);
-      return;
-    }
-  xbt_die("Comm %p not found in mailbox %s", comm.get(), this->get_cname());
+  auto it = std::find(this->comm_queue_.begin(), this->comm_queue_.end(), comm);
+  if (it != this->comm_queue_.end())
+    this->comm_queue_.erase(it);
+  else
+    xbt_die("Comm %p not found in mailbox %s", comm.get(), this->get_cname());
 }
 
 /** @brief Removes all communication activities from a mailbox
@@ -74,7 +73,7 @@ void MailboxImpl::remove(const CommImplPtr& comm)
 void MailboxImpl::clear(bool do_finish)
 {
   // CommImpl::cancel() will remove the comm from the mailbox..
-  for (auto comm : done_comm_queue_) {
+  for (const auto& comm : done_comm_queue_) {
     comm->cancel();
     comm->set_state(State::FAILED);
     if (do_finish)
diff --git a/src/kernel/activity/MailboxImpl.hpp b/src/kernel/activity/MailboxImpl.hpp
index 199fcd12cc..715e7626b4 100644
--- a/src/kernel/activity/MailboxImpl.hpp
+++ b/src/kernel/activity/MailboxImpl.hpp
@@ -11,21 +11,17 @@
 #include "src/kernel/activity/CommImpl.hpp"
 #include "src/kernel/actor/ActorImpl.hpp"
 
-#include <boost/circular_buffer.hpp>
-
 namespace simgrid::kernel::activity {
 
 /** @brief Implementation of the s4u::Mailbox */
 
 class MailboxImpl {
-  static constexpr size_t MAX_MAILBOX_SIZE = 10000000;
-
   s4u::Mailbox piface_;
   std::string name_;
   actor::ActorImplPtr permanent_receiver_; // actor to which the mailbox is attached
-  boost::circular_buffer_space_optimized<CommImplPtr> comm_queue_{MAX_MAILBOX_SIZE};
+  std::list<CommImplPtr> comm_queue_;
   // messages already received in the permanent receive mode
-  boost::circular_buffer_space_optimized<CommImplPtr> done_comm_queue_{MAX_MAILBOX_SIZE};
+  std::list<CommImplPtr> done_comm_queue_;
 
   friend s4u::Engine;
   friend s4u::Mailbox;
@@ -50,8 +46,8 @@ public:
   const std::string& get_name() const { return name_; }
   const char* get_cname() const { return name_.c_str(); }
   void set_receiver(s4u::ActorPtr actor);
-  void push(CommImplPtr comm);
-  void push_done(CommImplPtr done_comm) { done_comm_queue_.push_back(done_comm); }
+  void push(const CommImplPtr& comm);
+  void push_done(const CommImplPtr& done_comm) { done_comm_queue_.push_back(done_comm); }
   void remove(const CommImplPtr& comm);
   void clear(bool do_finish);
   CommImplPtr iprobe(int type, const std::function<bool(void*, void*, CommImpl*)>& match_fun, void* data);
@@ -61,9 +57,9 @@ public:
   actor::ActorImplPtr get_permanent_receiver() const { return permanent_receiver_; }
   bool empty() const { return comm_queue_.empty(); }
   size_t size() const { return comm_queue_.size(); }
-  CommImplPtr front() const { return comm_queue_.front(); }
+  const CommImplPtr& front() const { return comm_queue_.front(); }
   bool has_some_done_comm() const { return not done_comm_queue_.empty(); }
-  CommImplPtr done_front() const { return done_comm_queue_.front(); }
+  const CommImplPtr& done_front() const { return done_comm_queue_.front(); }
 };
 } // namespace simgrid::kernel::activity
 
-- 
2.20.1