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Diffstat (limited to 'sca-cpp/branches/lightweight-sca/components/queue/queue-listener.cpp')
-rw-r--r-- | sca-cpp/branches/lightweight-sca/components/queue/queue-listener.cpp | 159 |
1 files changed, 159 insertions, 0 deletions
diff --git a/sca-cpp/branches/lightweight-sca/components/queue/queue-listener.cpp b/sca-cpp/branches/lightweight-sca/components/queue/queue-listener.cpp new file mode 100644 index 0000000000..483d0de65a --- /dev/null +++ b/sca-cpp/branches/lightweight-sca/components/queue/queue-listener.cpp @@ -0,0 +1,159 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + */ + +/* $Rev$ $Date$ */ + +/** + * AMQP queue listener component implementation. + */ + +#define WANT_HTTPD_LOG 1 +#include "string.hpp" +#include "function.hpp" +#include "list.hpp" +#include "value.hpp" +#include "monad.hpp" +#include "parallel.hpp" +#include "qpid.hpp" + +// Ignore conversion issues and redundant declarations in Qpid headers +#ifdef WANT_MAINTAINER_WARNINGS +#pragma GCC diagnostic ignored "-Wconversion" +#pragma GCC diagnostic ignored "-Wredundant-decls" +#endif + +namespace tuscany { +namespace queue { + +/** + * A relay function that posts the AMQP messages it receives to a relay component reference. + */ +class relay { +public: + relay(const lambda<value(const list<value>&)>& rel) : rel(rel) { + } + + const bool operator()(const value& k, const value& v) const { + debug(k, "queue::relay::key"); + debug(v, "queue::relay::value"); + const value res = rel(mklist<value>("post", isList(k)? (list<value>)k : mklist<value>(k), v)); + return true; + } + +private: + const lambda<value(const list<value>&)> rel; +}; + +/** + * Subscribe and listen to an AMQP queue. + */ +class subscribe { +public: + subscribe(const string& qname, const lambda<bool(const value&, const value&)>& l, const QpidSubscription& qsub) : qname(qname), l(l), qsub(qsub) { + } + + const failable<bool> operator()() const { + gc_pool pool; + debug(qname, "queue::subscribe::listen"); + const failable<bool> r = listen(qname, l, const_cast<QpidSubscription&>(qsub)); + debug(qname, "queue::subscribe::stopped"); + return r; + } + +private: + const string qname; + const lambda<bool(const value&, const value&)> l; + const QpidSubscription qsub; +}; + +/** + * Listener lambda function, responsible for starting an AMQP subscription in a worker thread, and + * apply any function calls to the listener component. The only supported function is stop(), + * called to stop the listener component and shutdown the worker thread. + */ +class listener { +public: + listener(QpidConnection& qc, QpidSession& qs, QpidSubscription& qsub, worker& w) : qc(qc), qs(qs), qsub(qsub), w(w) { + } + + const value operator()(const list<value>& params) const { + const tuscany::value func(car(params)); + + // Stop the component + if (func != "stop") + return mkfailure<value>(); + debug("queue::listener::stop"); + + // TODO check why stop() and close() hang in child processes + stop(const_cast<QpidSubscription&>(qsub)); + close(const_cast<QpidSession&>(qs)); + close(const_cast<QpidConnection&>(qc)); + cancel(const_cast<worker&>(w)); + + debug("queue::listener::stopped"); + return failable<value>(value(lambda<value(const list<value>&)>())); + } + +private: + QpidConnection qc; + QpidSession qs; + QpidSubscription qsub; + worker w; +}; + +/** + * Start the component. + */ +const failable<value> start(const list<value>& params) { + // Extract the relay reference and the AMQP key and queue name + const value rel = car(params); + const value pk = ((lambda<value(const list<value>&)>)cadr(params))(list<value>()); + const value key = isList(pk)? (list<value>)pk : mklist<value>(pk); + const value qname = ((lambda<value(const list<value>&)>)caddr(params))(list<value>()); + + // Create an AMQP session + QpidConnection qc(false); + QpidSession qs(qc, false); + + // Declare the configured AMQP key / queue pair + declareQueue(key, qname, qs); + + // Listen and relay messages in a worker thread + QpidSubscription qsub(qs, false); + worker w(3); + const lambda<bool(const value&, const value&)> rl = relay(rel); + submit<failable<bool> >(w, lambda<failable<bool>()>(subscribe(qname, rl, qsub))); + + // Return the listener component lambda function + return value(lambda<value(const list<value>&)>(listener(qc, qs, qsub, w))); +} + +} +} + +extern "C" { + +const tuscany::value apply(const tuscany::list<tuscany::value>& params) { + const tuscany::value func(car(params)); + if (func == "start") + return tuscany::queue::start(cdr(params)); + return tuscany::mkfailure<tuscany::value>(); +} + +} |