"Survey" pattern implemented

Survey pattern is "multicast with reply". There are two roles:
surveyor and respondent. Surveyor publishes a survey which gets
delivered to all connected respondents. Each repondent can send
a response to the survey. All the responses are delivered to
the original surveyor. Once the surveyor decides that the survey
is over (e.g. deadline was reached) it can send initiate survey.
Late responses from old surveys are automatically discarded by
the surveyor socket.

Socket types: SURVEYOR, XSURVEYOR, RESPONDENT, XRESPONDENT

Patch also includes a test program with surveoyr, two respondents
and an intermediary device.

Signed-off-by: Martin Sustrik <sustrik@250bpm.com>

1 files changed, 278 insertions, 0 deletions

diff --git a/src/xrespondent.cpp b/src/xrespondent.cpp
new file mode 100644
index 0000000..026fe8d
--- /dev/null
+++ b/src/xrespondent.cpp
@@ -0,0 +1,278 @@
+/*
+    Copyright (c) 2012 250bpm s.r.o.
+    Copyright (c) 2012 Other contributors as noted in the AUTHORS file
+
+    This file is part of Crossroads I/O project.
+
+    Crossroads I/O is free software; you can redistribute it and/or modify it
+    under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 3 of the License, or
+    (at your option) any later version.
+
+    Crossroads 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
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "xrespondent.hpp"
+#include "pipe.hpp"
+#include "wire.hpp"
+#include "random.hpp"
+#include "likely.hpp"
+#include "err.hpp"
+
+xs::xrespondent_t::xrespondent_t (class ctx_t *parent_, uint32_t tid_,
+        int sid_) :
+    socket_base_t (parent_, tid_, sid_),
+    prefetched (0),
+    more_in (false),
+    current_out (NULL),
+    more_out (false),
+    next_peer_id (generate_random ())
+{
+    options.type = XS_XRESPONDENT;
+
+    prefetched_msg.init ();
+}
+
+xs::xrespondent_t::~xrespondent_t ()
+{
+    xs_assert (outpipes.empty ());
+    prefetched_msg.close ();
+}
+
+void xs::xrespondent_t::xattach_pipe (pipe_t *pipe_, bool icanhasall_)
+{
+    xs_assert (pipe_);
+
+    //  Add the pipe to the map out outbound pipes.
+    outpipe_t outpipe = {pipe_, true};
+    bool ok = outpipes.insert (outpipes_t::value_type (
+        next_peer_id, outpipe)).second;
+    xs_assert (ok);
+
+    //  Add the pipe to the list of inbound pipes.
+    blob_t identity (4, 0);
+    put_uint32 ((unsigned char*) identity.data (), next_peer_id);
+    pipe_->set_identity (identity);
+    fq.attach (pipe_);
+
+    //  Generate a new unique peer identity.
+    ++next_peer_id;    
+}
+
+void xs::xrespondent_t::xterminated (pipe_t *pipe_)
+{
+    fq.terminated (pipe_);
+
+    for (outpipes_t::iterator it = outpipes.begin ();
+          it != outpipes.end (); ++it) {
+        if (it->second.pipe == pipe_) {
+            outpipes.erase (it);
+            if (pipe_ == current_out)
+                current_out = NULL;
+            return;
+        }
+    }
+    xs_assert (false);
+}
+
+void xs::xrespondent_t::xread_activated (pipe_t *pipe_)
+{
+    fq.activated (pipe_);
+}
+
+void xs::xrespondent_t::xwrite_activated (pipe_t *pipe_)
+{
+    for (outpipes_t::iterator it = outpipes.begin ();
+          it != outpipes.end (); ++it) {
+        if (it->second.pipe == pipe_) {
+            xs_assert (!it->second.active);
+            it->second.active = true;
+            return;
+        }
+    }
+    xs_assert (false);
+}
+
+int xs::xrespondent_t::xsend (msg_t *msg_, int flags_)
+{
+    //  If this is the first part of the message it's the ID of the
+    //  peer to send the message to.
+    if (!more_out) {
+        xs_assert (!current_out);
+
+        //  If we have malformed message (prefix with no subsequent message)
+        //  then just silently ignore it.
+        //  TODO: The connections should be killed instead.
+        if (msg_->flags () & msg_t::more && msg_->size () == 4) {
+
+            more_out = true;
+
+            //  Find the pipe associated with the identity stored in the prefix.
+            //  If there's no such pipe just silently ignore the message.
+            uint32_t identity = get_uint32 ((unsigned char*) msg_->data ());
+            outpipes_t::iterator it = outpipes.find (identity);
+
+            if (it != outpipes.end ()) {
+                current_out = it->second.pipe;
+                msg_t empty;
+                int rc = empty.init ();
+                errno_assert (rc == 0);
+                if (!current_out->check_write (&empty)) {
+                    it->second.active = false;
+                    more_out = false;
+                    current_out = NULL;
+                }
+                rc = empty.close ();
+                errno_assert (rc == 0);
+            }
+
+        }
+
+        int rc = msg_->close ();
+        errno_assert (rc == 0);
+        rc = msg_->init ();
+        errno_assert (rc == 0);
+        return 0;
+    }
+
+    //  Check whether this is the last part of the message.
+    more_out = msg_->flags () & msg_t::more ? true : false;
+
+    //  Push the message into the pipe. If there's no out pipe, just drop it.
+    if (current_out) {
+        bool ok = current_out->write (msg_);
+        if (unlikely (!ok))
+            current_out = NULL;
+        else if (!more_out) {
+            current_out->flush ();
+            current_out = NULL;
+        }
+    }
+    else {
+        int rc = msg_->close ();
+        errno_assert (rc == 0);
+    }
+
+    //  Detach the message from the data buffer.
+    int rc = msg_->init ();
+    errno_assert (rc == 0);
+
+    return 0;
+}
+
+int xs::xrespondent_t::xrecv (msg_t *msg_, int flags_)
+{
+    int rc;
+
+    //  if there is a prefetched identity, return it.
+    if (prefetched == 2)
+    {
+        rc = msg_->init_size (prefetched_id.size ());
+        errno_assert (rc == 0);
+        memcpy (msg_->data (), prefetched_id.data (), prefetched_id.size ());
+        msg_->set_flags (msg_t::more);
+        prefetched = 1;
+        return 0;
+    }
+
+    //  If there is a prefetched message, return it.
+    if (prefetched == 1) {
+        rc = msg_->move (prefetched_msg);
+        errno_assert (rc == 0);
+        more_in = msg_->flags () & msg_t::more ? true : false;
+        prefetched = 0;
+        return 0;
+    }
+
+    //  Get next message part.
+    pipe_t *pipe = NULL;
+    rc = fq.recvpipe (msg_, flags_, &pipe);
+    if (rc != 0)
+        return -1;
+
+    //  If we are in the middle of reading a message, just return the next part.
+    if (more_in) {
+        more_in = msg_->flags () & msg_t::more ? true : false;
+        return 0;
+    }
+ 
+    //  We are at the beginning of a new message. Move the message part we
+    //  have to the prefetched and return the ID of the peer instead.
+    rc = prefetched_msg.move (*msg_);
+    errno_assert (rc == 0);
+    prefetched = 1;
+    rc = msg_->close ();
+    errno_assert (rc == 0);
+
+    blob_t identity = pipe->get_identity ();
+    rc = msg_->init_size (identity.size ());
+    errno_assert (rc == 0);
+    memcpy (msg_->data (), identity.data (), identity.size ());
+    msg_->set_flags (msg_t::more);
+    return 0;
+}
+
+int xs::xrespondent_t::rollback (void)
+{
+    if (current_out) {
+        current_out->rollback ();
+        current_out = NULL;
+        more_out = false;
+    }
+    return 0;
+}
+
+bool xs::xrespondent_t::xhas_in ()
+{
+    //  If we are in  the middle of reading the messages, there are
+    //  definitely more parts available.
+    if (more_in)
+        return true;
+
+    //  We may already have a message pre-fetched.
+    if (prefetched)
+        return true;
+
+    //  Try to read the next message to the pre-fetch buffer. If anything,
+    //  it will be identity of the peer sending the message.
+    msg_t id;
+    id.init ();
+    int rc = xrespondent_t::xrecv (&id, XS_DONTWAIT);
+    if (rc != 0 && errno == EAGAIN) {
+        id.close ();
+        return false;
+    }
+    xs_assert (rc == 0);
+
+    //  We have first part of the message prefetched now. We will store the
+    //  prefetched identity as well.
+    prefetched_id.assign ((unsigned char*) id.data (), id.size ());
+    id.close ();
+    prefetched = 2;
+
+    return true;
+}
+
+bool xs::xrespondent_t::xhas_out ()
+{
+    return true;
+}
+
+xs::xrespondent_session_t::xrespondent_session_t (io_thread_t *io_thread_,
+      bool connect_, socket_base_t *socket_, const options_t &options_,
+      const char *protocol_, const char *address_) :
+    session_base_t (io_thread_, connect_, socket_, options_, protocol_,
+        address_)
+{
+}
+
+xs::xrespondent_session_t::~xrespondent_session_t ()
+{
+}
+