From ce0972dca3982538fd123b61fbae3928fad6d1e7 Mon Sep 17 00:00:00 2001
From: Martin Sustrik <sustrik@250bpm.com>
Date: Wed, 1 Sep 2010 07:57:38 +0200
Subject: context creates an inproc endpoint ('inproc://log') to distribute
 0MQ's log messages

---
 src/ctx.cpp    | 25 +++++++++++++++++++++++--
 src/ctx.hpp    | 10 ++++++++++
 src/object.cpp |  5 +++++
 src/object.hpp |  5 +++++
 4 files changed, 43 insertions(+), 2 deletions(-)

diff --git a/src/ctx.cpp b/src/ctx.cpp
index 79145eb..f66e1fe 100644
--- a/src/ctx.cpp
+++ b/src/ctx.cpp
@@ -20,8 +20,6 @@
 #include <new>
 #include <string.h>
 
-#include "../include/zmq.h"
-
 #include "ctx.hpp"
 #include "socket_base.hpp"
 #include "io_thread.hpp"
@@ -68,6 +66,12 @@ zmq::ctx_t::ctx_t (uint32_t io_threads_) :
         empty_slots.push_back (i);
         slots [i] = NULL;
     }
+
+    //  Create the logging infrastructure.
+    log_socket = create_socket (ZMQ_PUB);
+    zmq_assert (log_socket);
+    int rc = log_socket->bind ("inproc://log");
+    zmq_assert (rc == 0);
 }
 
 zmq::ctx_t::~ctx_t ()
@@ -104,6 +108,13 @@ int zmq::ctx_t::terminate ()
     for (sockets_t::size_type i = 0; i != sockets.size (); i++)
         sockets [i]->stop ();
 
+    //  Close the logging infrastructure.
+    log_sync.lock ();
+    int rc = log_socket->close ();
+    zmq_assert (rc == 0);
+    log_socket = NULL;
+    log_sync.unlock ();
+
     //  Find out whether there are any open sockets to care about.
     //  If so, sleep till they are closed. Note that we can use
     //  no_sockets_notify safely out of the critical section as once set
@@ -287,6 +298,16 @@ zmq::socket_base_t *zmq::ctx_t::find_endpoint (const char *addr_)
      return endpoint;
 }
 
+void zmq::ctx_t::log (zmq_msg_t *msg_)
+{
+    //  At this  point we migrate the log socket to the current thread.
+    //  We rely on mutex for executing the memory barrier.
+    log_sync.lock ();
+    if (log_socket)
+        log_socket->send (msg_, 0);
+    log_sync.unlock ();
+}
+
 void zmq::ctx_t::dezombify ()
 {
     //  Try to dezombify each zombie in the list. Note that caller is
diff --git a/src/ctx.hpp b/src/ctx.hpp
index a31e1d8..5f6cc83 100644
--- a/src/ctx.hpp
+++ b/src/ctx.hpp
@@ -24,6 +24,8 @@
 #include <vector>
 #include <string>
 
+#include "../include/zmq.h"
+
 #include "signaler.hpp"
 #include "semaphore.hpp"
 #include "ypipe.hpp"
@@ -74,6 +76,9 @@ namespace zmq
         void unregister_endpoints (class socket_base_t *socket_);
         class socket_base_t *find_endpoint (const char *addr_);
 
+        //  Logging.
+        void log (zmq_msg_t *msg_);
+
     private:
 
         ~ctx_t ();
@@ -125,6 +130,11 @@ namespace zmq
         //  Synchronisation of access to the list of inproc endpoints.
         mutex_t endpoints_sync;
 
+        //  PUB socket for logging. The socket is shared among all the threads,
+        //  thus it is synchronised by a mutex.
+        class socket_base_t *log_socket;
+        mutex_t log_sync;
+
         ctx_t (const ctx_t&);
         void operator = (const ctx_t&);
     };
diff --git a/src/object.cpp b/src/object.cpp
index 5f4a94e..7b5532b 100644
--- a/src/object.cpp
+++ b/src/object.cpp
@@ -137,6 +137,11 @@ zmq::socket_base_t *zmq::object_t::find_endpoint (const char *addr_)
     return ctx->find_endpoint (addr_);
 }
 
+void zmq::object_t::log (zmq_msg_t *msg_)
+{
+    ctx->log (msg_);
+}
+
 zmq::io_thread_t *zmq::object_t::choose_io_thread (uint64_t taskset_)
 {
     return ctx->choose_io_thread (taskset_);
diff --git a/src/object.hpp b/src/object.hpp
index 8652a86..6b52f4b 100644
--- a/src/object.hpp
+++ b/src/object.hpp
@@ -20,6 +20,8 @@
 #ifndef __ZMQ_OBJECT_HPP_INCLUDED__
 #define __ZMQ_OBJECT_HPP_INCLUDED__
 
+#include "../include/zmq.h"
+
 #include "stdint.hpp"
 #include "blob.hpp"
 
@@ -48,6 +50,9 @@ namespace zmq
         void unregister_endpoints (class socket_base_t *socket_);
         class socket_base_t *find_endpoint (const char *addr_);
 
+        //  Logs an message.
+        void log (zmq_msg_t *msg_);
+
         //  Chooses least loaded I/O thread.
         class io_thread_t *choose_io_thread (uint64_t taskset_);
 
-- 
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