com.cloudera.hoop.fs.FSListStatus.java Source code

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Here is the source code for com.cloudera.hoop.fs.FSListStatus.java

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/*
 * Copyright (c) 2011, Cloudera, Inc. All Rights Reserved.
 *
 * Cloudera, Inc. 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
 *
 * This software 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.cloudera.hoop.fs;

import com.cloudera.hoop.HoopServer;
import com.cloudera.lib.service.Hadoop;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.PathFilter;
import org.json.simple.JSONArray;

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

/**
 * Executor that performs a list-status Hadoop files system operation.
 */
public class FSListStatus implements Hadoop.FileSystemExecutor<JSONArray>, PathFilter {
    private Path path;
    private PathFilter filter;

    /**
     * Creates a list-status executor.
     *
     * @param path the directory to retrieve the status of its contents.
     * @param filter glob filter to use.
     */
    public FSListStatus(String path, String filter) {
        this.path = new Path(path);
        this.filter = (filter == null) ? this : new GlobFilter(filter);
    }

    /**
     * Executes the filesystem operation.
     *
     * @param fs filesystem instance to use.
     * @return a JSONArray with the file status of the directory
     * contents.
     * @throws IOException thrown if an IO error occured.
     */
    @Override
    public JSONArray execute(FileSystem fs) throws IOException {
        FileStatus[] status = fs.listStatus(path, filter);
        String httpBaseUrl = HoopServer.get().getBaseUrl();
        return FSUtils.fileStatusToJSON(status, httpBaseUrl);
    }

    @Override
    public boolean accept(Path path) {
        return true;
    }

    /**
     * Cut&Paste of Hadoop FileSystem.GlobFilter (it is a private class).
     */
    private static class GlobFilter implements PathFilter {
        private Pattern regex;

        /**
         * 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 = ']';

        GlobFilter(String filePattern) {
            setRegex(filePattern);
        }

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

        void setRegex(String filePattern) {
            int len;
            int setOpen;
            int curlyOpen;
            boolean setRange;

            StringBuilder fileRegex = new StringBuilder();

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

            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);
            }
            regex = Pattern.compile(fileRegex.toString());
        }

        public boolean accept(Path path) {
            return regex.matcher(path.getName()).matches();
        }

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

}