"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, 135 insertions, 0 deletions

diff --git a/src/surveyor.cpp b/src/surveyor.cpp
new file mode 100644
index 0000000..c5216bd
--- /dev/null
+++ b/src/surveyor.cpp
@@ -0,0 +1,135 @@
+/*
+    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 "surveyor.hpp"
+#include "err.hpp"
+#include "msg.hpp"
+#include "wire.hpp"
+#include "likely.hpp"
+#include "random.hpp"
+
+xs::surveyor_t::surveyor_t (class ctx_t *parent_, uint32_t tid_, int sid_) :
+    xsurveyor_t (parent_, tid_, sid_),
+    receiving_responses (false),
+    survey_id (generate_random ())
+{
+    options.type = XS_SURVEYOR;
+}
+
+xs::surveyor_t::~surveyor_t ()
+{
+}
+
+int xs::surveyor_t::xsend (msg_t *msg_, int flags_)
+{
+    int rc;
+
+    //  Survey pattern works only with sigle-part messages.
+    if (flags_ & XS_SNDMORE || msg_->flags () & msg_t::more) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    //  Start the new survey. First, generate new survey ID.
+    ++survey_id;
+    msg_t id;
+    rc = id.init_size (4);
+    errno_assert (rc == 0);
+    put_uint32 ((unsigned char*) id.data (), survey_id);
+    id.set_flags (msg_t::more);
+    rc = xsurveyor_t::xsend (&id, 0);
+    if (rc != 0) {
+        id.close ();
+        return -1;
+    }
+    id.close ();
+
+    //  Now send the body of the survey.
+    rc = xsurveyor_t::xsend (msg_, flags_);
+    errno_assert (rc == 0);
+
+    //  Start waiting for responses from the peers.
+    receiving_responses = true;
+
+    return 0;
+}
+
+int xs::surveyor_t::xrecv (msg_t *msg_, int flags_)
+{
+    int rc;
+
+    //  If there's no survey underway, it's an error.
+    if (!receiving_responses) {
+        errno = EFSM;
+        return -1;
+    }
+
+    //  Get the first part of the response -- the survey ID.
+    rc = xsurveyor_t::xrecv (msg_, flags_);
+    if (rc != 0)
+        return rc;
+
+    //  Check whether this is response for the onging survey. If not, we can
+    //  drop the response.
+    if (unlikely (!(msg_->flags () & msg_t::more) || msg_->size () != 4 ||
+          get_uint32 ((unsigned char*) msg_->data ()) != survey_id)) {
+        while (true) {
+            rc = xsurveyor_t::xrecv (msg_, flags_);
+            errno_assert (rc == 0);
+            if (!(msg_->flags () & msg_t::more))
+                break;
+        }
+        msg_->close ();
+        msg_->init ();
+        errno = EAGAIN;
+        return -1;
+    }
+
+    //  Get the body of the response.
+    rc = xsurveyor_t::xrecv (msg_, flags_);
+    errno_assert (rc == 0);
+
+    return 0;
+}
+
+bool xs::surveyor_t::xhas_in ()
+{
+    //  TODO: We need a prefetched_message here...
+    xs_assert (false);
+    return false;
+}
+
+bool xs::surveyor_t::xhas_out ()
+{
+    return xsurveyor_t::xhas_out ();
+}
+
+xs::surveyor_session_t::surveyor_session_t (io_thread_t *io_thread_,
+      bool connect_, socket_base_t *socket_, const options_t &options_,
+      const char *protocol_, const char *address_) :
+    xsurveyor_session_t (io_thread_, connect_, socket_, options_, protocol_,
+        address_)
+{
+}
+
+xs::surveyor_session_t::~surveyor_session_t ()
+{
+}
+