org.apache.drill.exec.store.sys.local.LocalPStore.java Source code

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Here is the source code for org.apache.drill.exec.store.sys.local.LocalPStore.java

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/**
 * 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 org.apache.drill.exec.store.sys.local;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import java.util.Map.Entry;

import org.apache.commons.io.IOUtils;
import org.apache.drill.exec.store.sys.PStore;
import org.apache.drill.exec.store.sys.PStoreConfig;

import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;

public class LocalPStore<V> implements PStore<V> {
    static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(LocalPStore.class);

    private final File basePath;
    private final PStoreConfig<V> config;
    private static final String SUFFIX = ".sys.drill";

    public LocalPStore(File base, PStoreConfig<V> config) {
        super();
        this.basePath = new File(base, config.getName());
        if (!basePath.exists()) {
            basePath.mkdirs();
        }
        this.config = config;
    }

    @Override
    public Iterator<Entry<String, V>> iterator() {
        String[] f = basePath.list();
        if (f == null)
            return Collections.emptyIterator();
        List<String> files = Lists.newArrayList();
        for (String s : f) {
            if (s.endsWith(SUFFIX)) {
                files.add(s.substring(0, s.length() - SUFFIX.length()));
            }
        }

        return new Iter(files.iterator());
    }

    private File p(String name) throws IOException {
        Preconditions.checkArgument(!name.contains("/") && !name.contains(":") && !name.contains(".."));

        File f = new File(basePath, name + SUFFIX);
        // do this to check file name.
        f.getCanonicalPath();
        return f;
    }

    @Override
    public V get(String key) {
        try (InputStream is = new FileInputStream(p(key))) {
            return config.getSerializer().deserialize(IOUtils.toByteArray(is));
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public void put(String key, V value) {
        try (OutputStream os = new FileOutputStream(p(key))) {
            IOUtils.write(config.getSerializer().serialize(value), os);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public boolean putIfAbsent(String key, V value) {
        try {
            File f = p(key);
            if (f.exists()) {
                return false;
            } else {
                put(key, value);
                return true;
            }
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public void delete(String key) {
        try {
            p(key).delete();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    private class Iter implements Iterator<Entry<String, V>> {

        private Iterator<String> keys;
        private String current;

        public Iter(Iterator<String> keys) {
            super();
            this.keys = keys;
        }

        @Override
        public boolean hasNext() {
            return keys.hasNext();
        }

        @Override
        public Entry<String, V> next() {
            current = keys.next();
            return new DeferredEntry(current);
        }

        @Override
        public void remove() {
            delete(current);
            keys.remove();
        }

        private class DeferredEntry implements Entry<String, V> {

            private String name;

            public DeferredEntry(String name) {
                super();
                this.name = name;
            }

            @Override
            public String getKey() {
                return name;
            }

            @Override
            public V getValue() {
                return get(name);
            }

            @Override
            public V setValue(V value) {
                throw new UnsupportedOperationException();
            }

        }
    }
}