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/*
* 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 data cache component implementation which coordinates access to two
* levels of backend read/write caches or stores. Each cache or store is
* accessed through two references: a writer reference and a reader reference.
*
* This is useful if your level2 store is made of a master and slave
* replicated databases, you can then wire the writer reference to the master
* database and the reader reference to one your slave databases (assuming
* that the updates eventually get replicated to the slave database, in the
* meantime the updates will be retrieved from the level1 cache).
*/
#define WANT_HTTPD_LOG 1
#include "string.hpp"
#include "function.hpp"
#include "list.hpp"
#include "value.hpp"
#include "monad.hpp"
namespace tuscany {
namespace datacache {
/**
* Get an item from the cache.
*/
const failable<value> get(const value& key, const lambda<value(const list<value>&)> rcache1, const lambda<value(const list<value>&)> wcache1, const lambda<value(const list<value>&)> rcache2, unused const lambda<value(const list<value>&)> wcache2) {
// Lookup level1 cache
const value val1 = rcache1(mklist<value>("get", key));
if (!isNil(val1))
return val1;
// Lookup level2 cache
const value val2 = rcache2(mklist<value>("get", key));
if (isNil(val2)) {
ostringstream os;
os << "Couldn't get cache entry: " << key;
return mkfailure<value>(str(os), false);
}
// Update level1 cache
wcache1(mklist<value>("put", key, val2));
return val2;
}
/**
* Post an item to the cache.
*/
const failable<value> post(const value& key, const value& val, unused const lambda<value(const list<value>&)> rcache1, const lambda<value(const list<value>&)> wcache1, unused const lambda<value(const list<value>&)> rcache2, const lambda<value(const list<value>&)> wcache2) {
const value id = append<value>(key, mklist(mkuuid()));
// Update level1 cache
wcache1(mklist<value>("put", id, val));
// Update level2 cache
wcache2(mklist<value>("put", id, val));
return id;
}
/**
* Put an item into the cache.
*/
const failable<value> put(const value& key, const value& val, unused const lambda<value(const list<value>&)> rcache1, const lambda<value(const list<value>&)> wcache1, unused const lambda<value(const list<value>&)> rcache2, const lambda<value(const list<value>&)> wcache2) {
// Update level1 cache
wcache1(mklist<value>("put", key, val));
// Update level2 cache
wcache2(mklist<value>("put", key, val));
return value(true);
}
/**
* Delete an item from the cache.
*/
const failable<value> del(const value& key, unused const lambda<value(const list<value>&)> rcache1, const lambda<value(const list<value>&)> wcache1, unused const lambda<value(const list<value>&)> rcache2, const lambda<value(const list<value>&)> wcache2) {
// Delete from level1 cache
wcache1(mklist<value>("delete", key));
// Delete from level2 cache
wcache2(mklist<value>("delete", key));
return value(true);
}
}
}
extern "C" {
const tuscany::value apply(const tuscany::list<tuscany::value>& params) {
const tuscany::value func(car(params));
if (func == "get")
return tuscany::datacache::get(cadr(params), caddr(params), cadddr(params), caddddr(params), cadddddr(params));
if (func == "post")
return tuscany::datacache::post(cadr(params), caddr(params), cadddr(params), caddddr(params), cadddddr(params), caddddddr(params));
if (func == "put")
return tuscany::datacache::put(cadr(params), caddr(params), cadddr(params), caddddr(params), cadddddr(params), caddddddr(params));
if (func == "delete")
return tuscany::datacache::del(cadr(params), caddr(params), cadddr(params), caddddr(params), cadddddr(params));
return tuscany::mkfailure<tuscany::value>();
}
}
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