com.github.robozonky.app.runtime.LivenessCheck.java Source code

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Here is the source code for com.github.robozonky.app.runtime.LivenessCheck.java

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/*
 * Copyright 2019 The RoboZonky Project
 *
 * 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.github.robozonky.app.runtime;

import java.io.IOException;
import java.net.URL;
import java.time.Duration;
import java.util.Optional;
import java.util.stream.Collectors;

import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.github.robozonky.common.async.Refreshable;
import com.github.robozonky.common.async.Tasks;
import com.github.robozonky.common.remote.ApiProvider;
import com.github.robozonky.internal.api.Defaults;
import com.github.robozonky.internal.util.UrlUtil;
import io.vavr.Lazy;
import io.vavr.control.Try;
import org.apache.commons.io.IOUtils;

/**
 * Periodically queries remote Zonky API, checking whether it's accessible.
 */
class LivenessCheck extends Refreshable<String> {

    private static final String ZONKY_VERSION_URL = ApiProvider.ZONKY_URL + "/version";
    private static final Lazy<ObjectMapper> MAPPER = Lazy.of(ObjectMapper::new); // stored for performance reasons

    private final String url;

    private LivenessCheck(final RefreshListener<String> listener) {
        this(ZONKY_VERSION_URL, listener);
    }

    LivenessCheck(final String url, final RefreshListener<String> listener) {
        super(listener);
        this.url = url;
    }

    LivenessCheck(final String url) {
        this.url = url;
    }

    public static void setup(final MainControl mainThreadControl) {
        final Refreshable<String> liveness = new LivenessCheck(mainThreadControl);
        Tasks.SUPPORTING.scheduler().submit(liveness, Duration.ofSeconds(5));
        liveness.run(); // for testing purposes, making sure the refresh was started
    }

    static String read(final String json) throws IOException {
        final JsonNode actualObj = MAPPER.get().readTree(json);
        return actualObj.get("buildVersion").asText();
    }

    @Override
    protected String getLatestSource() {
        logger.trace("Running.");
        // need to send parsed version, since the object itself changes every time due to currentApiTime field
        return Try.withResources(() -> UrlUtil.open(new URL(url))).of(s -> {
            final String source = IOUtils.readLines(s, Defaults.CHARSET).stream()
                    .collect(Collectors.joining(System.lineSeparator()));
            logger.trace("API info coming from Zonky: {}.", source);
            return read(source);
        }).getOrElseGet(ex -> {
            // don't propagate this exception as it is likely to happen and the calling code would WARN about it
            logger.debug("Zonky servers are likely unavailable.", ex);
            return null; // will fail during transform()
        });
    }

    @Override
    protected Optional<String> transform(final String source) {
        return Optional.ofNullable(source);
    }
}