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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 partitioner component implementation which forwards data access requests to a
* dynamically selected data store component. The selection is externalized, performed
* by a selector component, responsible for selecting the target data stores given the
* data access request key and a list of references to available data store components.
* This pattern can be used for sharding or load balancing for example.
*/
#define WANT_HTTPD_LOG 1
#include "string.hpp"
#include "function.hpp"
#include "list.hpp"
#include "tree.hpp"
#include "value.hpp"
#include "monad.hpp"
namespace tuscany {
namespace partitioner {
/**
* Return a list of target partitions for a key.
*/
const failable<list<value> > partition(const value& key, const lvvlambda& selector, const list<value>& partitions) {
// Call the selector component to convert the given key to a list of partitions
const value p = selector(mklist<value>("get", key, partitions));
if (isNull(p)) {
ostringstream os;
os << "Couldn't get partition: " << key;
return mkfailure<list<value> >(str(os), -1, false);
}
return (list<value>)p;
}
/**
* Get lists of items from a list of partitions.
*/
const failable<list<value> > getlist(const value& key, const list<value>& partitions) {
if (isNull(partitions))
return nilListValue;
const lvvlambda l = car(partitions);
const value val = l(mklist<value>("get", key));
if (isNull(val))
return getlist(key, cdr(partitions));
if (!isList(val)) {
ostringstream os;
os << "Couldn't get list of entries from partition: " << key;
return mkfailure<list<value> >(str(os), 500, false);
}
const failable<list<value> > cdrval = getlist(key, cdr(partitions));
if (!hasContent(cdrval))
return cdrval;
return append<value>((list<value>)val, content(cdrval));
}
/**
* Return the rank of a result item if available.
*/
const value itemrank(const value& val) {
if (isList(val) && !isNull(val)) {
const value e = car<value>(val);
if (isList(e) && !isNull(e)) {
if (car<value>(e) == "entry") {
const list<value> ae = cdr<value>(e);
const list<value> li = assoc<value>("id", ae);
const list<value> lr = assoc<value>("rank", ae);
if (!isNull(li) && !isNull(lr))
return mklist<value>(lr, li);
}
}
}
return val;
}
/**
* Compare the ranks of two result items.
*/
const int rankitems(const value& a, const value& b) {
const value ra = itemrank(a);
const value rb = itemrank(b);
if (ra == rb)
return 0;
if (ra < rb)
return -1;
return 1;
}
/**
* Convert a key to a (param name, value) assoc.
*/
const list<value> keyparams(const list<value>& key) {
if (isNull(key))
return nilListValue;
if (!isList(car(key)))
return keyparams(cdr(key));
return cons<value>(car(key), keyparams(cdr(key)));
}
/**
* Get an item from a partition.
*/
const failable<value> get(const value& key, const lvvlambda& selector, const list<value>& partitions) {
debug(key, "partitioner::get::key");
// Select partition
const failable<list<value> > fp = partition(key, selector, partitions);
if (!hasContent(fp))
return mkfailure<value>(fp);
const list<value> p = content(fp);
// Get a single item from the selected partition
if (length(p) == 1) {
const lvvlambda l = car(p);
const value val = l(mklist<value>("get", key));
if (isNull(val)) {
ostringstream os;
os << "Couldn't get entry from partition: " << key;
return mkfailure<value>(str(os), 404, false);
}
debug(val, "partitioner::get::val");
return val;
}
// Get list of items from the list of selected partitions
const failable<list<value> > val = getlist(key, p);
if (!hasContent(val))
return mkfailure<value>(val);
const list<value> cval = content(val);
debug(cval, "partitioner::get::cval");
// Apply any ranking sort and result limit
const list<value> kparams = isList(key)? keyparams(key) : nilListValue;
const list<value> sval = (!isNull(assoc<value>("textsearch", kparams)) || !isNull(assoc<value>("rank", kparams)))? reverse<value>(sort<value>(cval, rankitems)) : cval;
const list<value> limit = assoc<value>("limit", kparams);
const list<value> lval = !isNull(limit)? listHead(sval, (int)cadr(limit)) : sval;
debug(lval, "partitioner::get::lval");
return (value)lval;
}
/**
* Post an item to a partition.
*/
const failable<value> post(const value& key, const value& val, const lvvlambda& selector, const list<value>& partitions) {
const value id = append<value>(key, mklist(mkuuid()));
// Select partition
const failable<list<value> > p = partition(id, selector, partitions);
if (!hasContent(p))
return mkfailure<value>(p);
// Put into select partition
const lvvlambda l = car(content(p));
l(mklist<value>("post", id, val));
return id;
}
/**
* Put an item into a partition.
*/
const failable<value> put(const value& key, const value& val, const lvvlambda& selector, const list<value>& partitions) {
// Select partition
const failable<list<value> > p = partition(key, selector, partitions);
if (!hasContent(p))
return mkfailure<value>(p);
// Put into selected partition
const lvvlambda l = car(content(p));
l(mklist<value>("put", key, val));
return trueValue;
}
/**
* Patch an item in a partition.
*/
const failable<value> patch(const value& key, const value& val, const lvvlambda& selector, const list<value>& partitions) {
// Select partition
const failable<list<value> > p = partition(key, selector, partitions);
if (!hasContent(p))
return mkfailure<value>(p);
// Path item in selected partition
const lvvlambda l = car(content(p));
l(mklist<value>("patch", key, val));
return trueValue;
}
/**
* Delete an item from a partition.
*/
const failable<value> del(const value& key, const lvvlambda& selector, const list<value>& partitions) {
// Select partition
const failable<list<value> > p = partition(key, selector, partitions);
if (!hasContent(p))
return mkfailure<value>(p);
// Delete from selected partition
const lvvlambda l = car(content(p));
l(mklist<value>("delete", key));
return trueValue;
}
}
}
extern "C" {
const tuscany::value apply(const tuscany::list<tuscany::value>& params) {
const tuscany::value func(car(params));
if (func == "get")
return tuscany::partitioner::get(cadr(params), caddr(params), cdddr(params));
if (func == "post")
return tuscany::partitioner::post(cadr(params), caddr(params), cadddr(params), cddddr(params));
if (func == "put")
return tuscany::partitioner::put(cadr(params), caddr(params), cadddr(params), cddddr(params));
if (func == "patch")
return tuscany::partitioner::patch(cadr(params), caddr(params), cadddr(params), cddddr(params));
if (func == "delete")
return tuscany::partitioner::del(cadr(params), caddr(params), cdddr(params));
return tuscany::mkfailure<tuscany::value>();
}
}
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