com.hotels.styx.server.netty.connectors.ExceptionStatusMapper Maven / Gradle / Ivy

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/**
 * Copyright (C) 2013-2017 Expedia Inc.
 *
 * Licensed 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.
 */
package com.hotels.styx.server.netty.connectors;

import com.google.common.collect.HashMultimap;
import com.google.common.collect.ImmutableMultimap;
import com.google.common.collect.Multimap;
import io.netty.handler.codec.http.HttpResponseStatus;
import org.slf4j.Logger;

import java.util.List;
import java.util.Map;
import java.util.Optional;

import static java.util.Arrays.asList;
import static java.util.stream.Collectors.toList;
import static org.slf4j.LoggerFactory.getLogger;

/**
 * Default list of exception mappers.
 */
final class ExceptionStatusMapper {
    private static final Logger LOG = getLogger(ExceptionStatusMapper.class);

    private final Multimap> multimap;

    private ExceptionStatusMapper(Builder builder) {
        this.multimap = ImmutableMultimap.copyOf(builder.multimap);
    }

    Optional statusFor(Throwable throwable) {
        List matchingStatuses = this.multimap.entries().stream()
                .filter(entry -> entry.getValue().isInstance(throwable))
                .map(Map.Entry::getKey)
                .collect(toList());



        if (matchingStatuses.size() > 1) {
            LOG.error("Multiple matching statuses for throwable={} statuses={}", throwable, matchingStatuses);
            return Optional.empty();
        }

        return matchingStatuses.stream().findFirst();
    }

    static final class Builder {
        private final Multimap> multimap;

        public Builder() {
            this.multimap = HashMultimap.create();
        }

        @SafeVarargs
        public final Builder add(HttpResponseStatus status, Class... classes) {
            multimap.putAll(status, asList(classes));
            return this;
        }

        public ExceptionStatusMapper build() {
            return new ExceptionStatusMapper(this);
        }
    }
}