From 4ed70a930202b103e7e80b8dc925e0aaa4622595 Mon Sep 17 00:00:00 2001
From: Martin Sustrik <sustrik@fastmq.commkdir>
Date: Wed, 29 Jul 2009 12:07:54 +0200
Subject: initial commit

---
 src/fair_aggregator.cpp | 143 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 143 insertions(+)
 create mode 100644 src/fair_aggregator.cpp

(limited to 'src/fair_aggregator.cpp')

diff --git a/src/fair_aggregator.cpp b/src/fair_aggregator.cpp
new file mode 100644
index 0000000..65bfac0
--- /dev/null
+++ b/src/fair_aggregator.cpp
@@ -0,0 +1,143 @@
+/*
+    Copyright (c) 2007-2009 FastMQ Inc.
+
+    This file is part of 0MQ.
+
+    0MQ is free software; you can redistribute it and/or modify it under
+    the terms of the Lesser GNU General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    0MQ is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    Lesser GNU General Public License for more details.
+
+    You should have received a copy of the Lesser GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "../include/zs.h"
+
+#include "fair_aggregator.hpp"
+#include "err.hpp"
+#include "pipe_reader.hpp"
+#include "session.hpp"
+
+//  Swaps pipes at specified indices. 
+#define swap_pipes(i1_, i2_) \
+    std::swap (pipes [i1_], pipes [i2_]);\
+    pipes [i1_]->set_index (i1_);\
+    pipes [i2_]->set_index (i2_);
+
+zs::fair_aggregator_t::fair_aggregator_t () :
+    session (NULL),
+    active (0),
+    current (0)
+{
+}
+
+void zs::fair_aggregator_t::set_session (session_t *session_)
+{
+    zs_assert (!session);
+    session = session_;
+}
+
+void zs::fair_aggregator_t::shutdown ()
+{
+    //  No need to deallocate pipes here. They'll be deallocated during the
+    //  shutdown of the dispatcher.
+    delete this;
+}
+
+void zs::fair_aggregator_t::terminate ()
+{
+    //  Pipe unregisters itself during the call to terminate, so the pipes
+    //  list shinks by one in each iteration.
+    while (!pipes.empty ())
+        pipes [0]->terminate ();
+
+   delete this;
+}
+
+zs::fair_aggregator_t::~fair_aggregator_t ()
+{
+}
+
+void zs::fair_aggregator_t::attach_pipe (pipe_reader_t *pipe_)
+{
+    //  Associate new pipe with the mux object.
+    pipe_->set_mux (this);
+    pipes.push_back (pipe_);
+    active++;
+    if (pipes.size () > active)
+        swap_pipes (pipes.size () - 1, active - 1);
+    if (active == 1)
+        session->revive ();
+}
+
+void zs::fair_aggregator_t::detach_pipe (pipe_reader_t *pipe_)
+{
+    //  Move the pipe from the list of active pipes to the list of idle pipes.
+    deactivate (pipe_);
+            
+    //  Move the pipe to the end of the idle list and remove it.
+    swap_pipes (pipe_->get_index (), pipes.size () - 1);
+    pipes.pop_back ();
+}
+
+bool zs::fair_aggregator_t::empty ()
+{
+    return pipes.empty ();
+}
+
+bool zs::fair_aggregator_t::recv (zs_msg *msg_)
+{
+    //  Deallocate old content of the message.
+    zs_msg_close (msg_);
+
+    //  O(1) fair queueing. Round-robin over the active pipes to get
+    //  next message.
+    for (pipes_t::size_type i = active; i != 0; i--) {
+
+        //  Update current.
+        current = (current + 1) % active;
+        
+        //  Try to read from current.
+        if (pipes [current]->read (msg_))
+            return true;
+    }
+
+    //  No message is available. Initialise the output parameter
+    //  to be a 0-byte message.
+    zs_msg_init (msg_);
+    return false;
+}
+
+void zs::fair_aggregator_t::deactivate (pipe_reader_t *pipe_)
+{
+    int index = pipe_->get_index ();
+
+    //  Suspend an active pipe.
+    swap_pipes (index, active - 1);
+    active--;
+
+    //  If the deactiveted pipe is the current one, shift the current one pipe
+    //  backwards so that the pipe that replaced the deactiveted one will be
+    //  processed immediately rather than skipped.
+    if (index == (int) current) {
+        index--;
+        if (index == -1)
+            index = active - 1;
+        current = index;
+    }
+}
+
+void zs::fair_aggregator_t::reactivate (pipe_reader_t *pipe_)
+{
+    //  Revive an idle pipe.
+    swap_pipes (pipe_->get_index (), active);
+    active++;
+    if (active == 1)
+        session->revive ();
+}
-- 
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