102 lines
3.0 KiB
Java
102 lines
3.0 KiB
Java
package org.gcube.resources.discovery.client.impl;
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import static org.gcube.data.streams.dsl.Streams.*;
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import java.util.ArrayList;
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import java.util.List;
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import org.gcube.data.streams.Stream;
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import org.gcube.data.streams.exceptions.StreamSkipSignal;
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import org.gcube.data.streams.exceptions.StreamStopSignal;
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import org.gcube.data.streams.generators.Generator;
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import org.gcube.resources.discovery.client.api.DiscoveryClient;
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import org.gcube.resources.discovery.client.api.DiscoveryException;
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import org.gcube.resources.discovery.client.api.InvalidResultException;
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import org.gcube.resources.discovery.client.api.ResultParser;
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import org.gcube.resources.discovery.client.queries.api.Query;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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/**
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* A {@link DiscoveryClient} that delegates the execution of queries to another {@link DiscoveryClient} that
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* does not perform result parsing and the parsing itself to a dedicated {@link ResultParser}.
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*
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*
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* @author Fabio Simeoni
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*
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* @param <R> the type of query results
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*/
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public class DelegateClient<R> implements DiscoveryClient<R> {
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private static Logger log = LoggerFactory.getLogger(DelegateClient.class);
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private final ResultParser<R> parser;
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private final DiscoveryClient<String> inner;
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/**
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* Creates an instance with a given {@link ResultParser} and a {@link DiscoveryClient} that produces untyped results
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* @param parser the parser
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* @param inner the client
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*/
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public DelegateClient(ResultParser<R> parser,DiscoveryClient<String> inner) {
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this.parser=parser;
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this.inner=inner;
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}
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/**
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* {@inheritDoc}
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* <p>
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* Result parsing errors are only logged as long as some results are successfully parsed. Otherwise, the
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* client flags the parsing errors as likely due to the parser itself.
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*/
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public List<R> submit(Query query) throws DiscoveryException, InvalidResultException {
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List<R> parsed = new ArrayList<R>();
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List<String> unparsed = inner.submit(query);
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int errors = 0;
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for (String result : unparsed)
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try {
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parsed.add(parser.parse(result));
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}
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catch(Exception e) {
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log.warn("discarded invalid result "+result,e);
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errors++;
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}
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if (errors>0 && parsed.size()==0)
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throw new InvalidResultException("no success but "+errors+" errors parsing results");
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return parsed;
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}
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/**
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* {@inheritDoc}
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* <p>
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* Result parsing errors are only logged as long as they do results are successfully parsed. Otherwise, the
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* client flags the parsing errors as likely due to the parser itself.
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*/
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public Stream<R> submitForStream(Query query) throws DiscoveryException {
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Stream<String> unparsed = inner.submitForStream(query);
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return pipe(unparsed).through(new ParsingGenerator());
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}
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//helper
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private class ParsingGenerator implements Generator<String,R> {
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public R yield(String result) throws StreamSkipSignal, StreamStopSignal {
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try {
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return parser.parse(result);
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}
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catch(Exception e) {
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throw new InvalidResultException(e);
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}
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}
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}
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}
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