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Posted to commits@zookeeper.apache.org by iv...@apache.org on 2012/03/14 17:11:55 UTC

svn commit: r1300616 - in /zookeeper/bookkeeper/trunk: CHANGES.txt bookkeeper-server/pom.xml bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/FileSystemUpgrade.java bookkeeper-server/src/main/java/org/apache/bookkeeper/util/HardLink.java

Author: ivank
Date: Wed Mar 14 16:11:54 2012
New Revision: 1300616

URL: http://svn.apache.org/viewvc?rev=1300616&view=rev
Log:
BOOKKEEPER-185: Remove bookkeeper-server dependency on hadoop-common (ivank)

Added:
    zookeeper/bookkeeper/trunk/bookkeeper-server/src/main/java/org/apache/bookkeeper/util/HardLink.java
Modified:
    zookeeper/bookkeeper/trunk/CHANGES.txt
    zookeeper/bookkeeper/trunk/bookkeeper-server/pom.xml
    zookeeper/bookkeeper/trunk/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/FileSystemUpgrade.java

Modified: zookeeper/bookkeeper/trunk/CHANGES.txt
URL: http://svn.apache.org/viewvc/zookeeper/bookkeeper/trunk/CHANGES.txt?rev=1300616&r1=1300615&r2=1300616&view=diff
==============================================================================
--- zookeeper/bookkeeper/trunk/CHANGES.txt (original)
+++ zookeeper/bookkeeper/trunk/CHANGES.txt Wed Mar 14 16:11:54 2012
@@ -52,6 +52,8 @@ Trunk (unreleased changes)
 
         BOOKKEEPER-180: bookie server doesn't quit when running out of disk space (sijie via ivank)
 
+        BOOKKEEPER-185: Remove bookkeeper-server dependency on hadoop-common (ivank)
+
       hedwig-server/
       
         BOOKKEEPER-140: Hub server doesn't subscribe remote region correctly when a region is down. (Sijie Gou via ivank)

Modified: zookeeper/bookkeeper/trunk/bookkeeper-server/pom.xml
URL: http://svn.apache.org/viewvc/zookeeper/bookkeeper/trunk/bookkeeper-server/pom.xml?rev=1300616&r1=1300615&r2=1300616&view=diff
==============================================================================
--- zookeeper/bookkeeper/trunk/bookkeeper-server/pom.xml (original)
+++ zookeeper/bookkeeper/trunk/bookkeeper-server/pom.xml Wed Mar 14 16:11:54 2012
@@ -81,185 +81,6 @@
       <artifactId>commons-io</artifactId>
       <version>2.1</version>
     </dependency>
-    <dependency>
-      <groupId>org.apache.hadoop</groupId>
-      <artifactId>hadoop-common</artifactId>
-      <version>0.23.1</version>
-      <exclusions>
-	<exclusion>
-	  <groupId>com.google.guava</groupId>
-	  <artifactId>guava</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>com.google.guava</groupId>
-	  <artifactId>guava</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>org.apache.commons</groupId>
-	  <artifactId>commons-math</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>xmlenc</groupId>
-	  <artifactId>xmlenc</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>commons-httpclient</groupId>
-	  <artifactId>commons-httpclient</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>commons-codec</groupId>
-	  <artifactId>commons-codec</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>commons-net</groupId>
-	  <artifactId>commons-net</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>javax.servlet</groupId>
-	  <artifactId>servlet-api</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>org.mortbay.jetty</groupId>
-	  <artifactId>jetty</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>org.mortbay.jetty</groupId>
-	  <artifactId>jetty-util</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>asm</groupId>
-	  <artifactId>asm</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>com.sun.jersey</groupId>
-	  <artifactId>jersey-core</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>com.sun.jersey</groupId>
-	  <artifactId>jersey-json</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>com.sun.jersey</groupId>
-	  <artifactId>jersey-server</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>tomcat</groupId>
-	  <artifactId>jasper-compiler</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>tomcat</groupId>
-	  <artifactId>jasper-runtime</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>javax.servlet.jsp</groupId>
-	  <artifactId>jsp-api</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>commons-el</groupId>
-	  <artifactId>commons-el</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>commons-logging</groupId>
-	  <artifactId>commons-logging</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>commons-logging</groupId>
-	  <artifactId>commons-logging-api</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>log4j</groupId>
-	  <artifactId>log4j</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>net.java.dev.jets3t</groupId>
-	  <artifactId>jets3t</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>org.apache.mina</groupId>
-	  <artifactId>mina-core</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>org.apache.ftpserver</groupId>
-	  <artifactId>ftplet-api</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>org.apache.ftpserver</groupId>
-	  <artifactId>ftpserver-core</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>org.apache.ftpserver</groupId>
-	  <artifactId>ftpserver-deprecated</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>junit</groupId>
-	  <artifactId>junit</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>commons-lang</groupId>
-	  <artifactId>commons-lang</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>commons-collections</groupId>
-	  <artifactId>commons-collections</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>commons-configuration</groupId>
-	  <artifactId>commons-configuration</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>hsqldb</groupId>
-	  <artifactId>hsqldb</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>org.slf4j</groupId>
-	  <artifactId>slf4j-api</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>org.slf4j</groupId>
-	  <artifactId>slf4j-log4j12</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>org.eclipse.jdt</groupId>
-	  <artifactId>core</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>oro</groupId>
-	  <artifactId>oro</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>org.codehaus.jackson</groupId>
-	  <artifactId>jackson-mapper-asl</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>org.aspectj</groupId>
-	  <artifactId>aspectjrt</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>org.apache.avro</groupId>
-	  <artifactId>avro</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>org.apache.avro</groupId>
-	  <artifactId>avro-ipc</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>net.sf.kosmosfs</groupId>
-	  <artifactId>kfs</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>com.google.protobuf</groupId>
-	  <artifactId>protobuf-java</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>org.apache.hadoop</groupId>
-	  <artifactId>hadoop-auth</artifactId>
-	</exclusion>
-	<exclusion>
-	  <groupId>com.googlecode.json-simple</groupId>
-	  <artifactId>json-simple</artifactId>
-	</exclusion>
-      </exclusions>
-    </dependency>
     <!--
 	Annoying dependency we need to include because
 	zookeeper uses log4j and so we transatively do, but

Modified: zookeeper/bookkeeper/trunk/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/FileSystemUpgrade.java
URL: http://svn.apache.org/viewvc/zookeeper/bookkeeper/trunk/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/FileSystemUpgrade.java?rev=1300616&r1=1300615&r2=1300616&view=diff
==============================================================================
--- zookeeper/bookkeeper/trunk/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/FileSystemUpgrade.java (original)
+++ zookeeper/bookkeeper/trunk/bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/FileSystemUpgrade.java Wed Mar 14 16:11:54 2012
@@ -21,7 +21,7 @@
 
 package org.apache.bookkeeper.bookie;
 
-import org.apache.hadoop.fs.HardLink;
+import org.apache.bookkeeper.util.HardLink;
 
 import org.apache.commons.io.FileUtils;
 import org.apache.commons.cli.BasicParser;

Added: zookeeper/bookkeeper/trunk/bookkeeper-server/src/main/java/org/apache/bookkeeper/util/HardLink.java
URL: http://svn.apache.org/viewvc/zookeeper/bookkeeper/trunk/bookkeeper-server/src/main/java/org/apache/bookkeeper/util/HardLink.java?rev=1300616&view=auto
==============================================================================
--- zookeeper/bookkeeper/trunk/bookkeeper-server/src/main/java/org/apache/bookkeeper/util/HardLink.java (added)
+++ zookeeper/bookkeeper/trunk/bookkeeper-server/src/main/java/org/apache/bookkeeper/util/HardLink.java Wed Mar 14 16:11:54 2012
@@ -0,0 +1,665 @@
+/**
+ * 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.
+ */
+/* Copied wholesale from hadoop-common 0.23.1
+package org.apache.hadoop.fs;
+*/
+package org.apache.bookkeeper.util;
+
+import java.io.BufferedReader;
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.Arrays;
+
+/**
+ * Class for creating hardlinks.
+ * Supports Unix/Linux, WinXP/2003/Vista via Cygwin, and Mac OS X.
+ * 
+ * The HardLink class was formerly a static inner class of FSUtil,
+ * and the methods provided were blatantly non-thread-safe.
+ * To enable volume-parallel Update snapshots, we now provide static 
+ * threadsafe methods that allocate new buffer string arrays
+ * upon each call.  We also provide an API to hardlink all files in a
+ * directory with a single command, which is up to 128 times more 
+ * efficient - and minimizes the impact of the extra buffer creations.
+ */
+public class HardLink { 
+
+  public enum OSType {
+    OS_TYPE_UNIX,
+    OS_TYPE_WINXP,
+    OS_TYPE_SOLARIS,
+    OS_TYPE_MAC
+  }
+  
+  public static OSType osType;
+  private static HardLinkCommandGetter getHardLinkCommand;
+  
+  public final LinkStats linkStats; //not static
+  
+  //initialize the command "getters" statically, so can use their 
+  //methods without instantiating the HardLink object
+  static { 
+    osType = getOSType();
+    if (osType == OSType.OS_TYPE_WINXP) {
+      // Windows
+      getHardLinkCommand = new HardLinkCGWin();
+    } else {
+      // Unix
+      getHardLinkCommand = new HardLinkCGUnix();
+      //override getLinkCountCommand for the particular Unix variant
+      //Linux is already set as the default - {"stat","-c%h", null}
+      if (osType == OSType.OS_TYPE_MAC) {
+        String[] linkCountCmdTemplate = {"stat","-f%l", null};
+        HardLinkCGUnix.setLinkCountCmdTemplate(linkCountCmdTemplate);
+      } else if (osType == OSType.OS_TYPE_SOLARIS) {
+        String[] linkCountCmdTemplate = {"ls","-l", null};
+        HardLinkCGUnix.setLinkCountCmdTemplate(linkCountCmdTemplate);        
+      }
+    }
+  }
+
+  public HardLink() {
+    linkStats = new LinkStats();
+  }
+  
+  static private OSType getOSType() {
+    String osName = System.getProperty("os.name");
+    if (osName.contains("Windows") &&
+            (osName.contains("XP") 
+            || osName.contains("2003") 
+            || osName.contains("Vista")
+            || osName.contains("Windows_7")
+            || osName.contains("Windows 7") 
+            || osName.contains("Windows7"))) {
+      return OSType.OS_TYPE_WINXP;
+    }
+    else if (osName.contains("SunOS") 
+            || osName.contains("Solaris")) {
+       return OSType.OS_TYPE_SOLARIS;
+    }
+    else if (osName.contains("Mac")) {
+       return OSType.OS_TYPE_MAC;
+    }
+    else {
+      return OSType.OS_TYPE_UNIX;
+    }
+  }
+  
+  /**
+   * This abstract class bridges the OS-dependent implementations of the 
+   * needed functionality for creating hardlinks and querying link counts.
+   * The particular implementation class is chosen during 
+   * static initialization phase of the HardLink class.
+   * The "getter" methods construct shell command strings for various purposes.
+   */
+  private static abstract class HardLinkCommandGetter {
+
+    /**
+     * Get the command string needed to hardlink a bunch of files from
+     * a single source directory into a target directory.  The source directory
+     * is not specified here, but the command will be executed using the source
+     * directory as the "current working directory" of the shell invocation.
+     * 
+     * @param fileBaseNames - array of path-less file names, relative
+     *            to the source directory
+     * @param linkDir - target directory where the hardlinks will be put
+     * @return - an array of Strings suitable for use as a single shell command
+     *            with {@link Runtime.exec()}
+     * @throws IOException - if any of the file or path names misbehave
+     */
+    abstract String[] linkMult(String[] fileBaseNames, File linkDir) 
+                          throws IOException;
+    
+    /**
+     * Get the command string needed to hardlink a single file
+     */
+    abstract String[] linkOne(File file, File linkName) throws IOException;
+    
+    /**
+     * Get the command string to query the hardlink count of a file
+     */
+    abstract String[] linkCount(File file) throws IOException;
+    
+    /**
+     * Calculate the total string length of the shell command
+     * resulting from execution of linkMult, plus the length of the
+     * source directory name (which will also be provided to the shell)
+     * 
+     * @param fileDir - source directory, parent of fileBaseNames
+     * @param fileBaseNames - array of path-less file names, relative
+     *            to the source directory
+     * @param linkDir - target directory where the hardlinks will be put
+     * @return - total data length (must not exceed maxAllowedCmdArgLength)
+     * @throws IOException
+     */
+    abstract int getLinkMultArgLength(
+                     File fileDir, String[] fileBaseNames, File linkDir) 
+                     throws IOException;
+    
+    /**
+     * Get the maximum allowed string length of a shell command on this OS,
+     * which is just the documented minimum guaranteed supported command
+     * length - aprx. 32KB for Unix, and 8KB for Windows.
+     */
+    abstract int getMaxAllowedCmdArgLength(); 
+  }
+  
+  /**
+   * Implementation of HardLinkCommandGetter class for Unix
+   */
+  static class HardLinkCGUnix extends HardLinkCommandGetter {
+    private static String[] hardLinkCommand = {"ln", null, null};
+    private static String[] hardLinkMultPrefix = {"ln"};
+    private static String[] hardLinkMultSuffix = {null};
+    private static String[] getLinkCountCommand = {"stat","-c%h", null};
+    //Unix guarantees at least 32K bytes cmd length.
+    //Subtract another 64b to allow for Java 'exec' overhead
+    private static final int maxAllowedCmdArgLength = 32*1024 - 65;
+    
+    private static synchronized 
+    void setLinkCountCmdTemplate(String[] template) {
+      //May update this for specific unix variants, 
+      //after static initialization phase
+      getLinkCountCommand = template;
+    }
+    
+    /*
+     * @see org.apache.hadoop.fs.HardLink.HardLinkCommandGetter#linkOne(java.io.File, java.io.File)
+     */
+    @Override
+    String[] linkOne(File file, File linkName) 
+    throws IOException {
+      String[] buf = new String[hardLinkCommand.length];
+      System.arraycopy(hardLinkCommand, 0, buf, 0, hardLinkCommand.length);
+      //unix wants argument order: "ln <existing> <new>"
+      buf[1] = makeShellPath(file); 
+      buf[2] = makeShellPath(linkName);
+      return buf;
+    }
+    
+    /*
+     * @see org.apache.hadoop.fs.HardLink.HardLinkCommandGetter#linkMult(java.lang.String[], java.io.File)
+     */
+    @Override
+    String[] linkMult(String[] fileBaseNames, File linkDir) 
+    throws IOException {
+      String[] buf = new String[fileBaseNames.length 
+                                + hardLinkMultPrefix.length 
+                                + hardLinkMultSuffix.length];
+      int mark=0;
+      System.arraycopy(hardLinkMultPrefix, 0, buf, mark, 
+                       hardLinkMultPrefix.length);
+      mark += hardLinkMultPrefix.length;
+      System.arraycopy(fileBaseNames, 0, buf, mark, fileBaseNames.length);
+      mark += fileBaseNames.length;
+      buf[mark] = makeShellPath(linkDir);
+      return buf;
+    }
+    
+    /*
+     * @see org.apache.hadoop.fs.HardLink.HardLinkCommandGetter#linkCount(java.io.File)
+     */
+    @Override
+    String[] linkCount(File file) 
+    throws IOException {
+      String[] buf = new String[getLinkCountCommand.length];
+      System.arraycopy(getLinkCountCommand, 0, buf, 0, 
+                       getLinkCountCommand.length);
+      buf[getLinkCountCommand.length - 1] = makeShellPath(file);
+      return buf;
+    }
+    
+    /*
+     * @see org.apache.hadoop.fs.HardLink.HardLinkCommandGetter#getLinkMultArgLength(java.io.File, java.lang.String[], java.io.File)
+     */
+    @Override
+    int getLinkMultArgLength(File fileDir, String[] fileBaseNames, File linkDir) 
+    throws IOException{
+      int sum = 0;
+      for (String x : fileBaseNames) {
+        // add 1 to account for terminal null or delimiter space
+        sum += 1 + ((x == null) ? 0 : x.length());
+      }
+      sum += 2 + makeShellPath(fileDir).length()
+             + makeShellPath(linkDir).length();
+      //add the fixed overhead of the hardLinkMult prefix and suffix
+      sum += 3; //length("ln") + 1
+      return sum;
+    }
+    
+    /*
+     * @see org.apache.hadoop.fs.HardLink.HardLinkCommandGetter#getMaxAllowedCmdArgLength()
+     */
+    @Override
+    int getMaxAllowedCmdArgLength() {
+      return maxAllowedCmdArgLength;
+    }
+  }
+  
+  
+  /**
+   * Implementation of HardLinkCommandGetter class for Windows
+   * 
+   * Note that the linkCount shell command for Windows is actually
+   * a Cygwin shell command, and depends on ${cygwin}/bin
+   * being in the Windows PATH environment variable, so
+   * stat.exe can be found.
+   */
+  static class HardLinkCGWin extends HardLinkCommandGetter {
+    //The Windows command getter impl class and its member fields are
+    //package-private ("default") access instead of "private" to assist 
+    //unit testing (sort of) on non-Win servers
+
+    static String[] hardLinkCommand = {
+                        "fsutil","hardlink","create", null, null};
+    static String[] hardLinkMultPrefix = {
+                        "cmd","/q","/c","for", "%f", "in", "("};
+    static String   hardLinkMultDir = "\\%f";
+    static String[] hardLinkMultSuffix = {
+                        ")", "do", "fsutil", "hardlink", "create", null, 
+                        "%f", "1>NUL"};
+    static String[] getLinkCountCommand = {"stat","-c%h", null};
+    //Windows guarantees only 8K - 1 bytes cmd length.
+    //Subtract another 64b to allow for Java 'exec' overhead
+    static final int maxAllowedCmdArgLength = 8*1024 - 65;
+
+    /*
+     * @see org.apache.hadoop.fs.HardLink.HardLinkCommandGetter#linkOne(java.io.File, java.io.File)
+     */
+    @Override
+    String[] linkOne(File file, File linkName) 
+    throws IOException {
+      String[] buf = new String[hardLinkCommand.length];
+      System.arraycopy(hardLinkCommand, 0, buf, 0, hardLinkCommand.length);
+      //windows wants argument order: "create <new> <existing>"
+      buf[4] = file.getCanonicalPath(); 
+      buf[3] = linkName.getCanonicalPath();
+      return buf;
+    }
+    
+    /*
+     * @see org.apache.hadoop.fs.HardLink.HardLinkCommandGetter#linkMult(java.lang.String[], java.io.File)
+     */
+    @Override
+    String[] linkMult(String[] fileBaseNames, File linkDir) 
+    throws IOException {
+      String[] buf = new String[fileBaseNames.length 
+                                + hardLinkMultPrefix.length 
+                                + hardLinkMultSuffix.length];
+      String td = linkDir.getCanonicalPath() + hardLinkMultDir;
+      int mark=0;
+      System.arraycopy(hardLinkMultPrefix, 0, buf, mark, 
+                       hardLinkMultPrefix.length);
+      mark += hardLinkMultPrefix.length;
+      System.arraycopy(fileBaseNames, 0, buf, mark, fileBaseNames.length);
+      mark += fileBaseNames.length;
+      System.arraycopy(hardLinkMultSuffix, 0, buf, mark, 
+                       hardLinkMultSuffix.length);
+      mark += hardLinkMultSuffix.length;
+      buf[mark - 3] = td;
+      return buf;
+    }
+    
+    /*
+     * @see org.apache.hadoop.fs.HardLink.HardLinkCommandGetter#linkCount(java.io.File)
+     */
+    @Override
+    String[] linkCount(File file) 
+    throws IOException {
+      String[] buf = new String[getLinkCountCommand.length];
+      System.arraycopy(getLinkCountCommand, 0, buf, 0, 
+                       getLinkCountCommand.length);
+      //The linkCount command is actually a Cygwin shell command,
+      //not a Windows shell command, so we should use "makeShellPath()"
+      //instead of "getCanonicalPath()".  However, that causes another
+      //shell exec to "cygpath.exe", and "stat.exe" actually can handle
+      //DOS-style paths (it just prints a couple hundred bytes of warning
+      //to stderr), so we use the more efficient "getCanonicalPath()".
+      buf[getLinkCountCommand.length - 1] = file.getCanonicalPath();
+      return buf;
+    }
+    
+    /*
+     * @see org.apache.hadoop.fs.HardLink.HardLinkCommandGetter#getLinkMultArgLength(java.io.File, java.lang.String[], java.io.File)
+     */
+    @Override
+    int getLinkMultArgLength(File fileDir, String[] fileBaseNames, File linkDir) 
+    throws IOException {
+      int sum = 0;
+      for (String x : fileBaseNames) {
+        // add 1 to account for terminal null or delimiter space
+        sum += 1 + ((x == null) ? 0 : x.length());
+      }
+      sum += 2 + fileDir.getCanonicalPath().length() +
+               linkDir.getCanonicalPath().length();
+      //add the fixed overhead of the hardLinkMult command 
+      //(prefix, suffix, and Dir suffix)
+      sum += ("cmd.exe /q /c for %f in ( ) do "
+              + "fsutil hardlink create \\%f %f 1>NUL ").length();
+      return sum;
+    }
+    
+    /*
+     * @see org.apache.hadoop.fs.HardLink.HardLinkCommandGetter#getMaxAllowedCmdArgLength()
+     */
+    @Override
+    int getMaxAllowedCmdArgLength() {
+      return maxAllowedCmdArgLength;
+    }
+  }
+  
+  
+  /**
+   * Calculate the nominal length of all contributors to the total 
+   * commandstring length, including fixed overhead of the OS-dependent 
+   * command.  It's protected rather than private, to assist unit testing,
+   * but real clients are not expected to need it -- see the way 
+   * createHardLinkMult() uses it internally so the user doesn't need to worry
+   * about it.
+   * 
+   * @param fileDir - source directory, parent of fileBaseNames
+   * @param fileBaseNames - array of path-less file names, relative
+   *            to the source directory
+   * @param linkDir - target directory where the hardlinks will be put
+   * @return - total data length (must not exceed maxAllowedCmdArgLength)
+   * @throws IOException
+   */
+  protected static int getLinkMultArgLength(
+          File fileDir, String[] fileBaseNames, File linkDir) 
+  throws IOException {
+    return getHardLinkCommand.getLinkMultArgLength(fileDir, 
+          fileBaseNames, linkDir);
+  }
+  
+  /**
+   * Return this private value for use by unit tests.
+   * Shell commands are not allowed to have a total string length
+   * exceeding this size.
+   */
+  protected static int getMaxAllowedCmdArgLength() {
+    return getHardLinkCommand.getMaxAllowedCmdArgLength();
+  }
+  
+  /*
+   * ****************************************************
+   * Complexity is above.  User-visible functionality is below
+   * ****************************************************
+   */
+
+  /**
+   * Creates a hardlink 
+   * @param file - existing source file
+   * @param linkName - desired target link file
+   */
+  public static void createHardLink(File file, File linkName) 
+  throws IOException {
+    if (file == null) {
+      throw new IOException(
+          "invalid arguments to createHardLink: source file is null");
+    }
+    if (linkName == null) {
+      throw new IOException(
+          "invalid arguments to createHardLink: link name is null");
+    }
+	  // construct and execute shell command
+    String[] hardLinkCommand = getHardLinkCommand.linkOne(file, linkName);
+    Process process = Runtime.getRuntime().exec(hardLinkCommand);
+    try {
+      if (process.waitFor() != 0) {
+        String errMsg = new BufferedReader(new InputStreamReader(
+            process.getInputStream())).readLine();
+        if (errMsg == null)  errMsg = "";
+        String inpMsg = new BufferedReader(new InputStreamReader(
+            process.getErrorStream())).readLine();
+        if (inpMsg == null)  inpMsg = "";
+        throw new IOException(errMsg + inpMsg);
+      }
+    } catch (InterruptedException e) {
+      throw new IOException(e);
+    } finally {
+      process.destroy();
+    }
+  }
+
+  /**
+   * Creates hardlinks from multiple existing files within one parent
+   * directory, into one target directory.
+   * @param parentDir - directory containing source files
+   * @param fileBaseNames - list of path-less file names, as returned by 
+   *                        parentDir.list()
+   * @param linkDir - where the hardlinks should be put.  It must already exist.
+   * 
+   * If the list of files is too long (overflows maxAllowedCmdArgLength),
+   * we will automatically split it into multiple invocations of the
+   * underlying method.
+   */
+  public static void createHardLinkMult(File parentDir, String[] fileBaseNames, 
+      File linkDir) throws IOException {
+    //This is the public method all non-test clients are expected to use.
+    //Normal case - allow up to maxAllowedCmdArgLength characters in the cmd
+    createHardLinkMult(parentDir, fileBaseNames, linkDir, 
+                       getHardLinkCommand.getMaxAllowedCmdArgLength());
+  }
+
+  /*
+   * Implements {@link createHardLinkMult} with added variable  "maxLength",
+   * to ease unit testing of the auto-splitting feature for long lists.
+   * Likewise why it returns "callCount", the number of sub-arrays that
+   * the file list had to be split into.
+   * Non-test clients are expected to call the public method instead.
+   */
+  protected static int createHardLinkMult(File parentDir, 
+      String[] fileBaseNames, File linkDir, int maxLength) 
+  throws IOException {
+    if (parentDir == null) {
+      throw new IOException(
+          "invalid arguments to createHardLinkMult: parent directory is null");
+    }
+    if (linkDir == null) {
+      throw new IOException(
+          "invalid arguments to createHardLinkMult: link directory is null");
+    }
+    if (fileBaseNames == null) {
+      throw new IOException(
+          "invalid arguments to createHardLinkMult: "
+          + "filename list can be empty but not null");
+    }
+    if (fileBaseNames.length == 0) {
+      //the OS cmds can't handle empty list of filenames, 
+      //but it's legal, so just return.
+      return 0; 
+    }
+    if (!linkDir.exists()) {
+      throw new FileNotFoundException(linkDir + " not found.");
+    }
+
+    //if the list is too long, split into multiple invocations
+    int callCount = 0;
+    if (getLinkMultArgLength(parentDir, fileBaseNames, linkDir) > maxLength
+          && fileBaseNames.length > 1) {
+      String[] list1 = Arrays.copyOf(fileBaseNames, fileBaseNames.length/2);
+      callCount += createHardLinkMult(parentDir, list1, linkDir, maxLength);
+      String[] list2 = Arrays.copyOfRange(fileBaseNames, fileBaseNames.length/2,
+          fileBaseNames.length);
+      callCount += createHardLinkMult(parentDir, list2, linkDir, maxLength);  
+      return callCount;
+    } else {
+      callCount = 1;
+    }
+    
+    // construct and execute shell command
+    String[] hardLinkCommand = getHardLinkCommand.linkMult(fileBaseNames, 
+        linkDir);
+    Process process = Runtime.getRuntime().exec(hardLinkCommand, null, 
+        parentDir);
+    try {
+      if (process.waitFor() != 0) {
+        String errMsg = new BufferedReader(new InputStreamReader(
+            process.getInputStream())).readLine();
+        if (errMsg == null)  errMsg = "";
+        String inpMsg = new BufferedReader(new InputStreamReader(
+            process.getErrorStream())).readLine();
+        if (inpMsg == null)  inpMsg = "";
+        throw new IOException(errMsg + inpMsg);
+      }
+    } catch (InterruptedException e) {
+      throw new IOException(e);
+    } finally {
+      process.destroy();
+    }
+    return callCount;
+  }
+
+   /**
+   * Retrieves the number of links to the specified file.
+   */
+  public static int getLinkCount(File fileName) throws IOException {
+    if (fileName == null) {
+      throw new IOException(
+          "invalid argument to getLinkCount: file name is null");
+    }
+    if (!fileName.exists()) {
+      throw new FileNotFoundException(fileName + " not found.");
+    }
+
+    // construct and execute shell command
+    String[] cmd = getHardLinkCommand.linkCount(fileName);
+    String inpMsg = null;
+    String errMsg = null;
+    int exitValue = -1;
+    BufferedReader in = null;
+    BufferedReader err = null;
+
+    Process process = Runtime.getRuntime().exec(cmd);
+    try {
+      exitValue = process.waitFor();
+      in = new BufferedReader(new InputStreamReader(
+                                  process.getInputStream()));
+      inpMsg = in.readLine();
+      err = new BufferedReader(new InputStreamReader(
+                                   process.getErrorStream()));
+      errMsg = err.readLine();
+      if (inpMsg == null || exitValue != 0) {
+        throw createIOException(fileName, inpMsg, errMsg, exitValue, null);
+      }
+      if (osType == OSType.OS_TYPE_SOLARIS) {
+        String[] result = inpMsg.split("\\s+");
+        return Integer.parseInt(result[1]);
+      } else {
+        return Integer.parseInt(inpMsg);
+      }
+    } catch (NumberFormatException e) {
+      throw createIOException(fileName, inpMsg, errMsg, exitValue, e);
+    } catch (InterruptedException e) {
+      throw createIOException(fileName, inpMsg, errMsg, exitValue, e);
+    } finally {
+      process.destroy();
+      if (in != null) in.close();
+      if (err != null) err.close();
+    }
+  }
+  
+  /* Create an IOException for failing to get link count. */
+  private static IOException createIOException(File f, String message,
+      String error, int exitvalue, Exception cause) {
+    
+    final String winErrMsg = "; Windows errors in getLinkCount are often due "
+         + "to Cygwin misconfiguration";
+
+    final String s = "Failed to get link count on file " + f
+        + ": message=" + message
+        + "; error=" + error
+        + ((osType == OSType.OS_TYPE_WINXP) ? winErrMsg : "")
+        + "; exit value=" + exitvalue;
+    return (cause == null) ? new IOException(s) : new IOException(s, cause);
+  }
+  
+  
+  /**
+   * HardLink statistics counters and methods.
+   * Not multi-thread safe, obviously.
+   * Init is called during HardLink instantiation, above.
+   * 
+   * These are intended for use by knowledgeable clients, not internally, 
+   * because many of the internal methods are static and can't update these
+   * per-instance counters.
+   */
+  public static class LinkStats {
+    public int countDirs = 0; 
+    public int countSingleLinks = 0; 
+    public int countMultLinks = 0; 
+    public int countFilesMultLinks = 0; 
+    public int countEmptyDirs = 0; 
+    public int countPhysicalFileCopies = 0;
+  
+    public void clear() {
+      countDirs = 0; 
+      countSingleLinks = 0; 
+      countMultLinks = 0; 
+      countFilesMultLinks = 0; 
+      countEmptyDirs = 0; 
+      countPhysicalFileCopies = 0;
+    }
+    
+    public String report() {
+      return "HardLinkStats: " + countDirs + " Directories, including " 
+      + countEmptyDirs + " Empty Directories, " 
+      + countSingleLinks 
+      + " single Link operations, " + countMultLinks 
+      + " multi-Link operations, linking " + countFilesMultLinks 
+      + " files, total " + (countSingleLinks + countFilesMultLinks) 
+      + " linkable files.  Also physically copied " 
+      + countPhysicalFileCopies + " other files.";
+    }
+  }
+
+  /**
+   * Convert a os-native filename to a path that works for the shell.
+   * @param filename The filename to convert
+   * @return The unix pathname
+   * @throws IOException on windows, there can be problems with the subprocess
+   */
+  public static String makeShellPath(File file) throws IOException {
+    String filename = file.getCanonicalPath();
+    if (System.getProperty("os.name").startsWith("Windows")) {
+      BufferedReader r = null;
+      try {
+        ProcessBuilder pb = new ProcessBuilder("cygpath", "-u", filename);
+        Process p = pb.start();
+        int err = p.waitFor();
+        if (err != 0) {
+            throw new IOException("Couldn't resolve path "
+                                  + filename + "(" + err + ")");
+        }
+        r = new BufferedReader(new InputStreamReader(p.getInputStream()));
+        return r.readLine();
+      } catch (InterruptedException ie) {
+        throw new IOException("Couldn't resolve path " + filename, ie);
+      } finally {
+        if (r != null) {
+          r.close();
+        }
+      }
+    } else {
+      return filename;
+    }
+  }
+}
+