From 4cee88c43846ea3236814636259fae43c8d63de7 Mon Sep 17 00:00:00 2001
From: Otis Gospodnetic <otis@apache.org>
Date: Fri, 21 Jun 2002 14:57:46 +0000
Subject: [PATCH] - Added the ability to disable creation of locks on the file
 system, in order   to allow Lucene to be used on read-only media.   To
 disable lock creation set 'disableLocks' system property to 'true'. PR:
 Obtained from: Submitted by: Reviewed by:

git-svn-id: https://svn.apache.org/repos/asf/lucene/java/trunk@149782 13f79535-47bb-0310-9956-ffa450edef68
---
 TODO.txt                                      |  6 ++----
 .../org/apache/lucene/store/FSDirectory.java  | 21 ++++++++++++++++---
 2 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/TODO.txt b/TODO.txt
index aa5dd7da65c..21911189299 100644
--- a/TODO.txt
+++ b/TODO.txt
@@ -32,10 +32,8 @@ $Revision$
   http://nagoya.apache.org/eyebrowse/ReadMsg?listName=lucene-dev@jakarta.apache.org&msgId=114749
   http://nagoya.apache.org/eyebrowse/ReadMsg?listName=lucene-dev@jakarta.apache.org&msgId=114757
 
-- Add to FSDirectory the ability to specify where lock files live and
-  to disable the use of lock files altogether (for read-only media).
-  c.f.
-  http://nagoya.apache.org/eyebrowse/BrowseList?listName=lucene-user@jakarta.apache.org&by=thread&from=57011
+- Add to FSDirectory the ability to disable the use of lock files altogether (for read-only media).
+  Status: COMPLETED
 
 - Add some requested methods:
     String[] Document.getValues(String fieldName);
diff --git a/src/java/org/apache/lucene/store/FSDirectory.java b/src/java/org/apache/lucene/store/FSDirectory.java
index e06a854380b..c604dc4383f 100644
--- a/src/java/org/apache/lucene/store/FSDirectory.java
+++ b/src/java/org/apache/lucene/store/FSDirectory.java
@@ -77,6 +77,8 @@ final public class FSDirectory extends Directory {
    * require Java 1.2.  Instead we use refcounts...  */
   private static final Hashtable DIRECTORIES = new Hashtable();
 
+  private static final boolean DISABLE_LOCKS = Boolean.getBoolean("disableLocks");
+
   /** Returns the directory instance for the named location.
    * 
    * <p>Directories are cached, so that, for a given canonical path, the same
@@ -211,18 +213,31 @@ final public class FSDirectory extends Directory {
     return new FSInputStream(new File(directory, name));
   }
 
-  /** Construct a {@link Lock}.
+  /**
+   * Constructs a {@link Lock} with the specified name.
+   * If JDK 1.1 is used the lock file is not really made.
+   * If system property <I>disableLocks</I> has the value of 'true'
+   * the lock will not be created.  Assigning this property any other value
+   * will <B>not</B> prevent creation of locks.
+   * <BR>
+   * This is useful for using Lucene on read-only medium, such as CD-ROM.
+   *
    * @param name the name of the lock file
+   * @return an instance of <code>Lock</code> holding the lock
    */
   public final Lock makeLock(String name) {
     final File lockFile = new File(directory, name);
     return new Lock() {
 	public boolean obtain() throws IOException {
-          if (Constants.JAVA_1_1) return true;    // locks disabled in jdk 1.1
+          if (Constants.JAVA_1_1)
+	      return true;    // locks disabled in jdk 1.1
+	  if (DISABLE_LOCKS)
+	      return true;
           return lockFile.createNewFile();
 	}
 	public void release() {
-          if (Constants.JAVA_1_1) return;         // locks disabled in jdk 1.1
+          if (Constants.JAVA_1_1)
+	      return;         // locks disabled in jdk 1.1
 	  lockFile.delete();
 	}
 	public String toString() {