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Don't hold the underlying file/channel open for longer than necessary. #7

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merged 1 commit into from
Aug 27, 2014
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Don't hold the underlying file/channel open for longer than necessary. #7

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51 changes: 24 additions & 27 deletions src/main/java/com/maxmind/db/BufferHolder.java
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Original file line number Diff line number Diff line change
@@ -1,7 +1,6 @@
package com.maxmind.db;

import java.io.ByteArrayOutputStream;
import java.io.Closeable;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
Expand All @@ -12,21 +11,33 @@

import com.maxmind.db.Reader.FileMode;

final class BufferHolder implements Closeable {
// DO NOT PASS THESE OUTSIDE THIS CLASS. Doing so will remove thread
// safety.
final class BufferHolder {
// DO NOT PASS OUTSIDE THIS CLASS. Doing so will remove thread safety.
private final ByteBuffer buffer;
private final RandomAccessFile raf;
private final FileChannel fc;

BufferHolder(File database, FileMode mode) throws IOException {
this.raf = new RandomAccessFile(database, "r");
this.fc = this.raf.getChannel();
if (mode == FileMode.MEMORY) {
this.buffer = ByteBuffer.wrap(new byte[(int) this.fc.size()]);
this.fc.read(this.buffer);
} else {
this.buffer = this.fc.map(MapMode.READ_ONLY, 0, this.fc.size());
final RandomAccessFile file = new RandomAccessFile(database, "r");
boolean threw = true;
try {
final FileChannel channel = file.getChannel();
if (mode == FileMode.MEMORY) {
this.buffer = ByteBuffer.wrap(new byte[(int) channel.size()]);
channel.read(this.buffer);
} else {
this.buffer = channel.map(MapMode.READ_ONLY, 0, channel.size());
}
threw = false;
} finally {
try {
// Also closes the underlying channel.
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Is this documented somewhere? My Google searches suggest that this may depend on the implementation.

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The documentation for RandomAccessFile.close() has included the following since Java 1.4:

If this file has an associated channel then the channel is closed as well.

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Thanks. 👍 I must have totally glossed over that.

file.close();
} catch (final IOException e) {
// If an exception was underway when we entered the finally block,
// don't stomp over it due to an error closing the file and channel.
if (!threw) {
throw e;
}
}
}
}

Expand All @@ -52,15 +63,11 @@ final class BufferHolder implements Closeable {
baos.write(bytes, 0, br);
}
this.buffer = ByteBuffer.wrap(baos.toByteArray());
this.raf = null;
this.fc = null;
}

// This is just to ease unit testing
BufferHolder(ByteBuffer buffer) {
this.buffer = buffer;
this.raf = null;
this.fc = null;
}

/*
Expand All @@ -70,14 +77,4 @@ final class BufferHolder implements Closeable {
synchronized ByteBuffer get() {
return this.buffer.duplicate();
}

@Override
public void close() throws IOException {
if (this.fc != null) {
this.fc.close();
}
if (this.raf != null) {
this.raf.close();
}
}
}
2 changes: 1 addition & 1 deletion src/main/java/com/maxmind/db/Reader.java
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Expand Up @@ -241,6 +241,6 @@ Metadata getMetadata() {
*/
@Override
public void close() throws IOException {
this.bufferHolder.close();
// Nothing to do for now.
}
}
45 changes: 20 additions & 25 deletions src/test/java/com/maxmind/db/PointerTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -20,37 +20,32 @@ public void testWithPointers() throws InvalidDatabaseException,
File file = new File(PointerTest.class.getResource(
"/maxmind-db/test-data/maps-with-pointers.raw").toURI());
BufferHolder ptf = new BufferHolder(file, FileMode.MEMORY);
try {
Decoder decoder = new Decoder(ptf.get(), 0);
Decoder decoder = new Decoder(ptf.get(), 0);

ObjectMapper om = new ObjectMapper();
ObjectMapper om = new ObjectMapper();

ObjectNode map = om.createObjectNode();
map.put("long_key", "long_value1");
assertEquals(map, decoder.decode(0).getNode());
ObjectNode map = om.createObjectNode();
map.put("long_key", "long_value1");
assertEquals(map, decoder.decode(0).getNode());

map = om.createObjectNode();
map.put("long_key", "long_value2");
assertEquals(map, decoder.decode(22).getNode());
map = om.createObjectNode();
map.put("long_key", "long_value2");
assertEquals(map, decoder.decode(22).getNode());

map = om.createObjectNode();
map.put("long_key2", "long_value1");
assertEquals(map, decoder.decode(37).getNode());
map = om.createObjectNode();
map.put("long_key2", "long_value1");
assertEquals(map, decoder.decode(37).getNode());

map = om.createObjectNode();
map.put("long_key2", "long_value2");
assertEquals(map, decoder.decode(50).getNode());
map = om.createObjectNode();
map.put("long_key2", "long_value2");
assertEquals(map, decoder.decode(50).getNode());

map = om.createObjectNode();
map.put("long_key", "long_value1");
assertEquals(map, decoder.decode(55).getNode());

map = om.createObjectNode();
map.put("long_key2", "long_value2");
assertEquals(map, decoder.decode(57).getNode());
} finally {
ptf.close();
}
map = om.createObjectNode();
map.put("long_key", "long_value1");
assertEquals(map, decoder.decode(55).getNode());

map = om.createObjectNode();
map.put("long_key2", "long_value2");
assertEquals(map, decoder.decode(57).getNode());
}
}