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Diffstat (limited to 'sca-cpp/trunk/components/cache/memocache.cpp')
-rw-r--r-- | sca-cpp/trunk/components/cache/memocache.cpp | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/sca-cpp/trunk/components/cache/memocache.cpp b/sca-cpp/trunk/components/cache/memocache.cpp new file mode 100644 index 0000000000..2482c2202b --- /dev/null +++ b/sca-cpp/trunk/components/cache/memocache.cpp @@ -0,0 +1,77 @@ +/* + * 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. + */ + +/* $Rev$ $Date$ */ + +/** + * A cache component implementation which memoizes the value of function + * applications, keyed by the function arguments, in a key/value cache passed + * as a reference. + * + * This is useful if your functions are idempotent and applied many times to + * the same arguments. The results can then be retrieved quickly from the + * cache without actually applying the function. + */ + +#include "string.hpp" +#include "function.hpp" +#include "list.hpp" +#include "value.hpp" +#include "monad.hpp" + +namespace tuscany { +namespace memocache { + +/** + * Memoize the value of a function application in a cache. + */ +const failable<value> memoize(const list<value>& params, const lambda<value(const list<value>&)> relay, const lambda<value(const list<value>&)> cache) { + debug(params, "memocache::memoize::params"); + + // Lookup memoized value from cache + const value val = cache(mklist<value>("get", params)); + if (!isNil(val)) { + debug(val, "memocache::memoize::cached"); + return val; + } + + // Apply the given function + const value res = relay(params); + debug(res, "memocache::memoize::res"); + + // Store the result value in the cache + cache(mklist<value>("put", params, res)); + + return res; +} + +} +} + +extern "C" { + +const tuscany::value apply(const tuscany::list<tuscany::value>& params) { + const tuscany::value func(car(params)); + if (func == "start" || func == "stop") + return tuscany::mkfailure<tuscany::value>(); + const tuscany::list<tuscany::value> rev = tuscany::reverse(params); + return tuscany::memocache::memoize(tuscany::reverse(tuscany::cddr(rev)), tuscany::cadr(rev), tuscany::car(rev)); +} + +} |