net.morimekta.config.source.RefreshingFileConfigSupplier Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of config-util Show documentation

Configuration Utilities. NOTE: This module is deprecated and will be removed at the end of the v2.x versions of the utilities. Preferred config system after that is either to use true type-safe config with `net.morimekta.providence:providence-config` or to use a simple JSON or YAML library or java properties files. The semi-typesafe layered config did not really solve the problems I had hoped it would, and in essence this was just a helper for merging maps and getting pre-cast values out of it.

There is a newer version: 2.7.1

Show newest version

/*
 * Copyright (c) 2016, Stein Eldar Johnsen
 *
 * 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.
 */
package net.morimekta.config.source;

import com.google.common.base.MoreObjects;
import net.morimekta.config.Config;
import net.morimekta.config.ConfigException;
import net.morimekta.config.format.ConfigParser;

import javax.annotation.Nonnull;
import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.UncheckedIOException;
import java.nio.file.Files;
import java.time.Clock;
import java.util.function.Supplier;

import static net.morimekta.config.util.ConfigUtil.getParserForName;

/**
 * File source for config objects.
 */
public class RefreshingFileConfigSupplier implements Supplier {
    private static final long UPDATE_CHECK_INTERVAL_MS = 1000;

    private final File         configFile;
    private final ConfigParser parser;
    private final Clock        clock;

    private long lastCheckTimestamp;
    private long lastModified;

    private Config config;

    public RefreshingFileConfigSupplier(@Nonnull File configFile) {
        this(configFile, getParserForName(configFile.getName()));
    }

    public RefreshingFileConfigSupplier(@Nonnull File configFile,
                                        @Nonnull ConfigParser format) {
        this(configFile, format, Clock.systemUTC());
    }

    public RefreshingFileConfigSupplier(@Nonnull File configFile,
                                        @Nonnull ConfigParser format,
                                        @Nonnull Clock clock) {
        this.clock = clock;
        this.configFile = configFile;
        this.parser = format;
    }

    @Override
    public synchronized Config get() {
        try {
            long now = clock.millis();
            if (config == null) {
                loadInternal();
                this.lastModified = Files.getLastModifiedTime(configFile.toPath())
                                         .toMillis();
                this.lastCheckTimestamp = now;
            } else if (now > (lastCheckTimestamp + UPDATE_CHECK_INTERVAL_MS)) {
                long modified = Files.getLastModifiedTime(configFile.toPath())
                                     .toMillis();
                if (modified > this.lastModified) {
                    loadInternal();
                    this.lastModified = modified;
                }
                this.lastCheckTimestamp = now;
            }
        } catch (IOException e) {
            throw new UncheckedIOException(e);
        }

        return config;
    }

    @Override
    public String toString() {
        return MoreObjects.toStringHelper(this)
                          .add("file", configFile)
                          .toString();
    }

    private void loadInternal() throws IOException, ConfigException {
        if (!configFile.exists()) {
            throw new ConfigException("No such config file: " + configFile.getCanonicalPath());
        }

        try (FileInputStream fis = new FileInputStream(configFile);
             BufferedInputStream bis = new BufferedInputStream(fis)) {
            this.config = parser.parse(bis);
        }
    }
}