Bug 150852 - Improve BufferedRandomInputStream # seek() functionalityR3_2_1R32x_v20060814

Bug 150516 - BufferedRandomInputStream doesn't buffer correctly

2 files changed, 37 insertions, 12 deletions

diff --git a/bundles/org.eclipse.equinox.registry/META-INF/MANIFEST.MF b/bundles/org.eclipse.equinox.registry/META-INF/MANIFEST.MF
index 0b774836e..24ccadd6f 100644
--- a/bundles/org.eclipse.equinox.registry/META-INF/MANIFEST.MF
+++ b/bundles/org.eclipse.equinox.registry/META-INF/MANIFEST.MF
@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %pluginName
 Bundle-SymbolicName: org.eclipse.equinox.registry; singleton:=true
-Bundle-Version: 3.2.0.qualifier
+Bundle-Version: 3.2.1.qualifier
 Bundle-Localization: plugin
 Export-Package: org.eclipse.core.internal.registry;x-friends:="org.eclipse.core.runtime",
  org.eclipse.core.internal.registry.osgi;x-friends:="org.eclipse.core.runtime",
diff --git a/bundles/org.eclipse.equinox.registry/src/org/eclipse/core/internal/registry/BufferedRandomInputStream.java b/bundles/org.eclipse.equinox.registry/src/org/eclipse/core/internal/registry/BufferedRandomInputStream.java
index a19c8619f..db0abec13 100644
--- a/bundles/org.eclipse.equinox.registry/src/org/eclipse/core/internal/registry/BufferedRandomInputStream.java
+++ b/bundles/org.eclipse.equinox.registry/src/org/eclipse/core/internal/registry/BufferedRandomInputStream.java
@@ -21,6 +21,16 @@ public class BufferedRandomInputStream extends InputStream {
 	private String filePath; // Canonical path to the underlying file used for logging
 	private int buffer_size; // Current size of the buffer 
 	private int buffer_pos; // Current read position in the buffer
+	/**
+	 * The absolute position in the file where the buffered region starts.
+	 */
+	private long buffer_start = 0;
+
+	/**
+	 * The current value of the RAF's file pointer.
+	 */
+	private long file_pointer;
+
 	private byte buffer[];
 
 	public BufferedRandomInputStream(File file) throws IOException {
@@ -31,17 +41,21 @@ public class BufferedRandomInputStream extends InputStream {
 		filePath = file.getCanonicalPath();
 		inputFile = new RandomAccessFile(file, "r"); //$NON-NLS-1$
 		buffer = new byte[bufferSize];
+		file_pointer = 0;
 		resetBuffer();
 	}
 
-	private void resetBuffer() throws IOException {
+	private void resetBuffer() {
 		buffer_pos = 0;
 		buffer_size = 0;
+		buffer_start = 0;
 	}
 
 	private int fillBuffer() throws IOException {
 		buffer_pos = 0;
+		buffer_start = file_pointer;
 		buffer_size = inputFile.read(buffer, 0, buffer.length);
+		file_pointer += buffer_size;
 		return buffer_size;
 	}
 
@@ -55,17 +69,20 @@ public class BufferedRandomInputStream extends InputStream {
 
 	public int read(byte b[], int off, int len) throws IOException {
 		int available = buffer_size - buffer_pos;
+		if (available < 0)
+			return -1;
+		//the buffer contains all the bytes we need, so copy over and return
 		if (len <= available) {
 			System.arraycopy(buffer, buffer_pos, b, off, len);
 			buffer_pos += len;
 			return len;
 		}
-
-		// Use portion remaining in the buffer and read the rest from file
+		// Use portion remaining in the buffer
 		System.arraycopy(buffer, buffer_pos, b, off, available);
-		int read = inputFile.read(b, off + available, len - available);
-		fillBuffer(); // nothing left in the buffer, fill it with the next chunk
-		return available + read;
+		if (fillBuffer() <= 0)
+			return available;
+		//recursive call to read again until we have the bytes we need
+		return available + read(b, off + available, len - available);
 	}
 
 	public long skip(long n) throws IOException {
@@ -76,10 +93,11 @@ public class BufferedRandomInputStream extends InputStream {
 		if (n <= available) {
 			buffer_pos += n;
 			return n;
-		} else {
-			resetBuffer();
-			return available + inputFile.skipBytes((int) (n - available));
 		}
+		resetBuffer();
+		final int skipped = inputFile.skipBytes((int) (n - available));
+		file_pointer += skipped;
+		return available + skipped;
 	}
 
 	public int available() throws IOException {
@@ -104,8 +122,15 @@ public class BufferedRandomInputStream extends InputStream {
 	 * @throws IOException
 	 */
 	public void seek(long pos) throws IOException {
-		inputFile.seek(pos);
-		resetBuffer();
+		if (pos >= buffer_start && pos < buffer_start + buffer_size) {
+			//seeking within the current buffer
+			buffer_pos = (int) (pos - buffer_start);
+		} else {
+			//seeking outside the buffer - just discard the buffer
+			inputFile.seek(pos);
+			file_pointer = pos;
+			resetBuffer();
+		}
 	}
 
 	/**