replication/src/main/java/org/apache/falcon/replication/FilteredCopyListing.java

/**
 * 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.falcon.replication;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.security.Credentials;
import org.apache.hadoop.tools.DistCpOptions;
import org.apache.hadoop.tools.SimpleCopyListing;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.regex.Pattern;

/**
 * An implementation of CopyListing that overrides the default behavior by suppressing file
 * availabilityFlag and copies that in the last so downstream apps depending on data
 * availability will work correctly.
 */
public class FilteredCopyListing extends SimpleCopyListing {
    private static final Logger LOG = LoggerFactory.getLogger(FilteredCopyListing.class);

    /**
     * Default pattern character: Escape any special meaning.
     */
    private static final char PAT_ESCAPE = '\\';
    /**
     * Default pattern character: Any single character.
     */
    private static final char PAT_ANY = '.';
    /**
     * Default pattern character: Character set close.
     */
    private static final char PAT_SET_CLOSE = ']';

    private String availabilityFlag;

    private Pattern regex;

    protected FilteredCopyListing(Configuration configuration, Credentials credentials) {
        super(configuration, credentials);
        availabilityFlag = configuration.get("falcon.feed.availability.flag");
        try {
            regex = getRegEx(configuration.get("falcon.include.path", "").trim());
            LOG.info("Inclusion pattern = {}", configuration.get("falcon.include.path"));
            LOG.info("Regex pattern = {}", regex);
        } catch (IOException e) {
            throw new IllegalArgumentException("Unable to build regex for "
                    + configuration.get("falcon.include.path", ""));
        }
    }

    @Override
    protected boolean shouldCopy(Path path, DistCpOptions options) {
        return shouldCopy(path);
    }

    /**
     * From hadoop 2.8.0 onwards, the function signature has been changed to not use DistCpOptions.
     * hence added another function that works with the new implementation.
     *
     * Preserving previous implementation as well for backward compatibility.
     */
    protected boolean shouldCopy(Path path) {
        if (path.getName().equals(availabilityFlag)) {
            return false;
        }
        return regex == null || regex.matcher(path.toString()).find();
    }

    private static boolean isJavaRegexSpecialChar(char pChar) {
        return pChar == '.' || pChar == '$' || pChar == '(' || pChar == ')'
                || pChar == '|' || pChar == '+';
    }

    public static Pattern getRegEx(String filePattern) throws IOException {
        int len;
        int setOpen;
        int curlyOpen;
        boolean setRange;

        StringBuilder fileRegex = new StringBuilder();

        // Validate the pattern
        len = filePattern.length();
        if (len == 0) {
            return null;
        }

        setOpen = 0;
        setRange = false;
        curlyOpen = 0;

        for (int i = 0; i < len; i++) {
            char pCh;

            // Examine a single pattern character
            pCh = filePattern.charAt(i);
            if (pCh == PAT_ESCAPE) {
                fileRegex.append(pCh);
                i++;
                if (i >= len) {
                    error("An escaped character does not present", filePattern, i);
                }
                pCh = filePattern.charAt(i);
            } else if (isJavaRegexSpecialChar(pCh)) {
                fileRegex.append(PAT_ESCAPE);
            } else if (pCh == '*') {
                fileRegex.append(PAT_ANY);
            } else if (pCh == '?') {
                pCh = PAT_ANY;
            } else if (pCh == '{') {
                fileRegex.append('(');
                pCh = '(';
                curlyOpen++;
            } else if (pCh == ',' && curlyOpen > 0) {
                fileRegex.append(")|");
                pCh = '(';
            } else if (pCh == '}' && curlyOpen > 0) {
                // End of a group
                curlyOpen--;
                fileRegex.append(")");
                pCh = ')';
            } else if (pCh == '[' && setOpen == 0) {
                setOpen++;
            // } else if (pCh == '^' && setOpen > 0) {
            } else if (pCh == '-' && setOpen > 0) {
                // Character set range
                setRange = true;
            } else if (pCh == PAT_SET_CLOSE && setRange) {
                // Incomplete character set range
                error("Incomplete character set range", filePattern, i);
            } else if (pCh == PAT_SET_CLOSE && setOpen > 0) {
                // End of a character set
                if (setOpen < 2) {
                    error("Unexpected end of set", filePattern, i);
                }
                setOpen = 0;
            } else if (setOpen > 0) {
                // Normal character, or the end of a character set range
                setOpen++;
                setRange = false;
            }
            fileRegex.append(pCh);
        }

        // Check for a well-formed pattern
        if (setOpen > 0 || setRange || curlyOpen > 0) {
            // Incomplete character set or character range
            error("Expecting set closure character or end of range, or }",
                    filePattern, len);
        }
        return Pattern.compile("(" + fileRegex.toString() + "/)|(" + fileRegex.toString() + "$)");
    }

    private static void error(String s, String pattern, int pos) throws IOException {
        throw new IOException("Illegal file pattern: "
                + s + " for glob " + pattern + " at " + pos);
    }

    @Override
    public long getBytesToCopy() {
        return super.getBytesToCopy();
    }

    @Override
    public long getNumberOfPaths() {
        return super.getNumberOfPaths();
    }
}