From: James Ahlborn <jtahlborn@yahoo.com>
Date: Tue, 26 Sep 2006 15:01:38 +0000 (+0000)
Subject: read index entries on demand
X-Git-Tag: rel_1_1_7~3
X-Git-Url: https://source.dussan.org/?a=commitdiff_plain;h=584802a0b811edc57fc5f423dc07f258cdede362;p=jackcess.git

read index entries on demand


git-svn-id: https://svn.code.sf.net/p/jackcess/code/jackcess/trunk@126 f203690c-595d-4dc9-a70b-905162fa7fd2
---

diff --git a/src/java/com/healthmarketscience/jackcess/Index.java b/src/java/com/healthmarketscience/jackcess/Index.java
index 602bd5f..3f18a33 100644
--- a/src/java/com/healthmarketscience/jackcess/Index.java
+++ b/src/java/com/healthmarketscience/jackcess/Index.java
@@ -189,7 +189,7 @@ public class Index implements Comparable<Index> {
   /** Number of rows in the index */
   private int _rowCount;
   private JetFormat _format;
-  private SortedSet<Entry> _entries = new TreeSet<Entry>();
+  private SortedSet<Entry> _entries;
   /** Map of columns to flags */
   private Map<Column, Byte> _columns = new LinkedHashMap<Column, Byte>();
   private PageChannel _pageChannel;
@@ -199,6 +199,9 @@ public class Index implements Comparable<Index> {
   private String _name;
   /** is this index a primary key */
   private boolean _primaryKey;
+  /** <code>true</code> if the index entries have been initialized,
+      <code>false</code> otherwise */
+  private boolean _initialized;
   /** FIXME, for now, we can't write multi-page indexes or indexes using the funky primary key compression scheme */
   boolean _readOnly;
   
@@ -238,7 +241,44 @@ public class Index implements Comparable<Index> {
     return Collections.unmodifiableCollection(_columns.keySet());
   }
 
+  /**
+   * Returns the number of index entries in the index.  Only called by unit
+   * tests.
+   * <p>
+   * Forces index initialization.
+   */
+  int getEntryCount()
+    throws IOException
+  {
+    initialize();
+    return _entries.size();
+  }
+  
+  public boolean isInitialized() {
+    return _initialized;
+  }
+
+  /**
+   * Forces initialization of this index (actual parsing of index pages).
+   * normally, the index will not be initialized until the entries are
+   * actually needed.
+   */
+  public void initialize() throws IOException {
+    if(!_initialized) {
+      readIndexEntries();
+      _initialized = true;
+    }
+  }
+
+  /**
+   * Writes the current index state to the database.
+   * <p>
+   * Forces index initialization.
+   */
   public void update() throws IOException {
+    // make sure we've parsed the entries
+    initialize();
+    
     if(_readOnly) {
       throw new UnsupportedOperationException(
           "FIXME cannot write indexes of this type yet");
@@ -287,12 +327,12 @@ public class Index implements Comparable<Index> {
   }
   
   /**
-   * Read this index in from a tableBuffer
+   * Read the index info from a tableBuffer
    * @param tableBuffer table definition buffer to read from initial info
    * @param availableColumns Columns that this index may use
    */
   public void read(ByteBuffer tableBuffer, List<Column> availableColumns)
-  throws IOException
+    throws IOException
   {
     for (int i = 0; i < MAX_COLUMNS; i++) {
       short columnNumber = tableBuffer.getShort();
@@ -304,6 +344,16 @@ public class Index implements Comparable<Index> {
     tableBuffer.getInt(); //Forward past Unknown
     _pageNumber = tableBuffer.getInt();
     tableBuffer.position(tableBuffer.position() + 10);  //Forward past other stuff
+  }
+
+  /**
+   * Reads the actual index entries.
+   */
+  private void readIndexEntries()
+    throws IOException
+  {
+    _entries = new TreeSet<Entry>();
+    
     ByteBuffer indexPage = _pageChannel.createPageBuffer();
 
     // find first leaf page
@@ -340,7 +390,6 @@ public class Index implements Comparable<Index> {
         break;
       }
     }
-
   }
 
   /**
@@ -437,6 +486,9 @@ public class Index implements Comparable<Index> {
   
   /**
    * Add a row to this index
+   * <p>
+   * Forces index initialization.
+   * 
    * @param row Row to add
    * @param pageNumber Page number on which the row is stored
    * @param rowNumber Row number at which the row is stored
@@ -444,6 +496,9 @@ public class Index implements Comparable<Index> {
   public void addRow(Object[] row, int pageNumber, byte rowNumber)
     throws IOException
   {
+    // make sure we've parsed the entries
+    initialize();
+    
     _entries.add(new Entry(row, pageNumber, rowNumber));
   }
 
@@ -455,6 +510,7 @@ public class Index implements Comparable<Index> {
     rtn.append("\n\tPage number: " + _pageNumber);
     rtn.append("\n\tIs Primary Key: " + _primaryKey);
     rtn.append("\n\tColumns: " + _columns);
+    rtn.append("\n\tInitialized: " + _initialized);
     rtn.append("\n\tEntries: " + _entries);
     rtn.append("\n\n");
     return rtn.toString();
diff --git a/test/src/java/com/healthmarketscience/jackcess/IndexTest.java b/test/src/java/com/healthmarketscience/jackcess/IndexTest.java
index 33967bb..d8307a9 100644
--- a/test/src/java/com/healthmarketscience/jackcess/IndexTest.java
+++ b/test/src/java/com/healthmarketscience/jackcess/IndexTest.java
@@ -43,7 +43,6 @@ public class IndexTest extends TestCase {
   }
   
   public void testByteCodeComparator() {
-    // FIXME, writeme
     byte[] b0 = null;
     byte[] b1 = new byte[]{(byte)0x00};
     byte[] b2 = new byte[]{(byte)0x00, (byte)0x00};
@@ -99,7 +98,10 @@ public class IndexTest extends TestCase {
     File origFile = new File("test/data/compIndexTest.mdb");
     Database db = Database.open(origFile);
     Table t = db.getTable("Table1");
+    Index index = t.getIndexes().get(0);
+    assertFalse(index.isInitialized());
     assertEquals(512, countRows(t));
+    assertEquals(512, index.getEntryCount());
     db.close();
 
     // copy to temp file and attemp to edit