Topic filter implemented

The filter is build into libxs rather than being a plug-in.
It's ID is XS_FILTER_TOPIC.

The filter assumed that the messages are text-based and consider
binary 0 to be a delimiter separating message topic from the message
body. Use of the delimiter is not mandatory though. If binary zero
is not present, whole message is used for matching.

The topic is separated into elements using dots, e.g.
"animals.dogs.fluffy".

Subscriptions match individual elements. Each element can be matched
by either literal string or a wildcard (*), for example:
"animals.*.fluffy" matches all animals called Fluffy irrsepctive
of whether they are dogs, cats or whatever.

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

5 files changed, 259 insertions, 2 deletions

diff --git a/src/Makefile.am b/src/Makefile.am
index 8c3de7c..1daee23 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -77,6 +77,7 @@ libxs_la_SOURCES = \
     tcp_connecter.hpp \
     tcp_listener.hpp \
     thread.hpp \
+    topic_filter.hpp \
     upoll.hpp \
     windows.hpp \
     wire.hpp \
@@ -136,6 +137,7 @@ libxs_la_SOURCES = \
     tcp_connecter.cpp \
     tcp_listener.cpp \
     thread.cpp \
+    topic_filter.cpp \
     upoll.cpp \
     xpub.cpp \
     xrep.cpp \
diff --git a/src/ctx.cpp b/src/ctx.cpp
index 7f4c88a..6460dd2 100644
--- a/src/ctx.cpp
+++ b/src/ctx.cpp
@@ -56,6 +56,7 @@
 #include "err.hpp"
 #include "msg.hpp"
 #include "prefix_filter.hpp"
+#include "topic_filter.hpp"
 
 xs::ctx_t::ctx_t () :
     tag (0xbadcafe0),
@@ -73,7 +74,8 @@ xs::ctx_t::ctx_t () :
     //  Plug in the standard plugins.
     rc = plug (prefix_filter);
     errno_assert (rc == 0);
-
+    rc = plug (topic_filter);
+    errno_assert (rc == 0);
 
     //  Now plug in all the extensions found in plugin directory.
 
diff --git a/src/prefix_filter.cpp b/src/prefix_filter.cpp
index 06a77f5..abf68d0 100644
--- a/src/prefix_filter.cpp
+++ b/src/prefix_filter.cpp
@@ -594,7 +594,7 @@ static xs_filter_t pfx_filter = {
     sf_destroy,
     sf_subscribe,
     sf_unsubscribe,
-    sf_match,
+    sf_match
 };
 
 void *xs::prefix_filter = (void*) &pfx_filter;
diff --git a/src/topic_filter.cpp b/src/topic_filter.cpp
new file mode 100644
index 0000000..8fda252
--- /dev/null
+++ b/src/topic_filter.cpp
@@ -0,0 +1,221 @@
+/*
+    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 <vector>
+#include <string>
+#include <map>
+
+#include "../include/xs/xs.h"
+
+#include "topic_filter.hpp"
+#include "err.hpp"
+
+typedef std::vector <void*> subscribers_t;
+typedef std::map <std::string, subscribers_t> topic_t;
+
+static bool topic_match (const char *topic_,
+    const unsigned char *data_, size_t size_)
+{
+    while (true) {
+
+        //  Check whether matching is done.
+        if (*topic_ == 0)
+            return true;
+
+        // Match one element.
+        if (topic_ [0] == '*') {
+
+            //  March wildcard element.
+            ++topic_;
+            while (size_ && *data_ != 0 && *data_ != '.')
+                ++data_, --size_;
+        }
+        else {
+
+            //  Match literal element.
+            while (true) {
+                if (topic_ [0] == '.' || topic_ [0] == 0)
+                    break;
+                if (!size_)
+                    return false;
+                if (topic_ [0] != *data_)
+                    return false; 
+                ++data_;
+                --size_;
+                ++topic_;
+            }
+        }
+
+        //  Check whether matching is done.
+        if (topic_ [0] == 0)
+            return true;
+
+        //  Match dot.
+        if (topic_ [0] != '.')
+            return false;  //  Malformed subscription, e.g. "*abc"
+        if (!size_)
+            return false;
+        if (*data_ != '.')
+            return false;
+        ++data_;
+        --size_;
+        ++topic_;
+    }
+}
+
+static int id (void *core_)
+{
+    return XS_FILTER_TOPIC;
+}
+
+static void *pf_create (void *core_)
+{
+    topic_t *pf = new (std::nothrow) topic_t;
+    alloc_assert (pf);
+    return (void*) pf;
+}
+
+static void pf_destroy (void *core_, void *pf_)
+{
+    xs_assert (pf_);
+    delete (topic_t*) pf_;
+}
+
+static int pf_subscribe (void *core_, void *pf_, void *subscriber_,
+    const unsigned char *data_, size_t size_)
+{
+    topic_t *self = (topic_t*) pf_;
+    (*self) [std::string ((char*) data_, size_)].push_back (subscriber_);
+    return xs_filter_subscribed (core_, data_, size_);
+}
+
+static int pf_unsubscribe (void *core_, void *pf_, void *subscriber_,
+    const unsigned char *data_, size_t size_)
+{
+    topic_t *self = (topic_t*) pf_;
+
+    topic_t::iterator it = self->find (std::string ((char*) data_, size_));
+    if (it == self->end ()) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    bool found = false;
+    for (subscribers_t::iterator its = it->second.begin ();
+          its != it->second.end (); ++its) {
+        if (*its == subscriber_) {
+            it->second.erase (its);
+            found = true;
+            break;
+        }
+    }
+    if (!found) {
+        errno = EINVAL;
+        return -1;
+    }
+
+    if (it->second.empty ())
+        self->erase (it);
+
+    return 0;
+}
+
+static void pf_unsubscribe_all (void *core_, void *pf_, void *subscriber_)
+{
+    topic_t *self = (topic_t*) pf_;
+
+    for (topic_t::iterator it = self->begin (); it != self->end ();) {
+        for (subscribers_t::size_type i = 0; i < it->second.size (); ++i) {
+            if (it->second [i] == subscriber_)
+                it->second.erase (it->second.begin () + i--);
+        }
+        if (it->second.empty ())
+            self->erase (it++);
+        else
+            ++it;
+    }
+}
+
+static void pf_match (void *core_, void *pf_,
+    const unsigned char *data_, size_t size_)
+{
+    topic_t *self = (topic_t*) pf_;
+    for (topic_t::iterator it = self->begin (); it != self->end (); ++it) {
+        if (topic_match (it->first.c_str (), data_, size_)) {
+            for (subscribers_t::iterator its = it->second.begin ();
+                  its != it->second.end (); ++its) {
+                int rc = xs_filter_matching (core_, *its);
+                errno_assert (rc == 0);
+            }
+        }
+    }
+}
+
+static void *sf_create (void *core_)
+{
+    return pf_create (core_);
+}
+
+static void sf_destroy (void *core_, void *sf_)
+{
+    pf_destroy (core_, sf_);
+}
+
+static int sf_subscribe (void *core_, void *sf_,
+    const unsigned char *data_, size_t size_)
+{
+    return pf_subscribe (core_, sf_, NULL, data_, size_);
+}
+
+static int sf_unsubscribe (void *core_, void *sf_,
+    const unsigned char *data_, size_t size_)
+{
+    return pf_unsubscribe (core_, sf_, NULL, data_, size_);
+}
+
+static int sf_match (void *core_, void *sf_,
+    const unsigned char *data_, size_t size_)
+{
+    topic_t *self = (topic_t*) sf_;
+    for (topic_t::iterator it = self->begin (); it != self->end (); ++it)
+       if (topic_match (it->first.c_str (), data_, size_))
+           return 1;
+    return 0;
+}
+
+static xs_filter_t rgxp_filter = {
+    XS_PLUGIN_FILTER,
+    1,
+    id,
+    pf_create,
+    pf_destroy,
+    pf_subscribe,
+    pf_unsubscribe,
+    pf_unsubscribe_all,
+    pf_match,
+    sf_create,
+    sf_destroy,
+    sf_subscribe,
+    sf_unsubscribe,
+    sf_match
+};
+
+void *xs::topic_filter = (void*) &rgxp_filter;
+
diff --git a/src/topic_filter.hpp b/src/topic_filter.hpp
new file mode 100644
index 0000000..bc81675
--- /dev/null
+++ b/src/topic_filter.hpp
@@ -0,0 +1,32 @@
+/*
+    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/>.
+*/
+
+#ifndef __XS_TOPIC_FILTER_HPP_INCLUDED__
+#define __XS_TOPIC_FILTER_HPP_INCLUDED__
+
+namespace xs
+{
+
+    //  Canonical extension object.
+    extern void *topic_filter;
+
+}
+
+#endif