com.google.caliper.util.Util.java Source code

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Here is the source code for com.google.caliper.util.Util.java

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/*
 * Copyright (C) 2011 Google 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.google.caliper.util;

import com.google.common.collect.ImmutableBiMap;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Maps;
import com.google.common.io.ByteSource;
import com.google.common.io.Closer;
import com.google.common.io.Resources;

import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Member;
import java.lang.reflect.Modifier;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;

public final class Util {
    private Util() {
    }

    // Users have no idea that nested classes are identified with '$', not '.', so if class lookup
    // fails try replacing the last . with $.
    public static Class<?> lenientClassForName(String className) throws ClassNotFoundException {
        try {
            // TODO: consider whether any control over class loader is really needed here
            // (forName(className, true, Thread.currentThread().getContextClassLoader())?)
            return Class.forName(className);
        } catch (ClassNotFoundException ignored) {
            // try replacing the last dot with a $, in case that helps
            // example: tutorial.Tutorial.Benchmark1 becomes tutorial.Tutorial$Benchmark1
            // amusingly, the $ character means three different things in this one line alone
            String newName = className.replaceFirst("\\.([^.]+)$", "\\$$1");
            return Class.forName(newName);
        }
    }

    public static ImmutableMap<String, String> loadProperties(ByteSource is) throws IOException {
        Properties props = new Properties();
        Closer closer = Closer.create();
        InputStream in = closer.register(is.openStream());
        try {
            props.load(in);
        } finally {
            closer.close();
        }
        return Maps.fromProperties(props);
    }

    public static ByteSource resourceSupplier(final Class<?> c, final String name) {
        return Resources.asByteSource(c.getResource(name));
    }

    public static <T> ImmutableMap<String, T> prefixedSubmap(Map<String, T> props, String prefix) {
        ImmutableMap.Builder<String, T> submapBuilder = ImmutableMap.builder();
        for (Map.Entry<String, T> entry : props.entrySet()) {
            String name = entry.getKey();
            if (name.startsWith(prefix)) {
                submapBuilder.put(name.substring(prefix.length()), entry.getValue());
            }
        }
        return submapBuilder.build();
    }

    public static boolean isPublic(Member member) {
        return Modifier.isPublic(member.getModifiers());
    }

    public static boolean isStatic(Member member) {
        return Modifier.isStatic(member.getModifiers());
    }

    private static final long FORCE_GC_TIMEOUT_SECS = 2;

    public static void forceGc() {
        System.gc();
        System.runFinalization();
        final CountDownLatch latch = new CountDownLatch(1);
        new Object() {
            @Override
            protected void finalize() {
                latch.countDown();
            }
        };
        System.gc();
        System.runFinalization();
        try {
            latch.await(FORCE_GC_TIMEOUT_SECS, TimeUnit.SECONDS);
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        }
    }

    public static <T> ImmutableBiMap<T, String> assignNames(Set<T> items) {
        ImmutableList<T> itemList = ImmutableList.copyOf(items);
        ImmutableBiMap.Builder<T, String> itemNamesBuilder = ImmutableBiMap.builder();
        for (int i = 0; i < itemList.size(); i++) {
            itemNamesBuilder.put(itemList.get(i), generateUniqueName(i));
        }
        return itemNamesBuilder.build();
    }

    private static String generateUniqueName(int index) {
        if (index < 26) {
            return String.valueOf((char) ('A' + index));
        } else {
            return generateUniqueName(index / 26 - 1) + generateUniqueName(index % 26);
        }
    }
}