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HBASE-2646 Compaction requests should be prioritized to prevent blocking; remove of hbase-3038 added by mistake 

git-svn-id: https://svn.apache.org/repos/asf/hbase/trunk@1002020 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Michael Stack 2010-09-28 05:29:29 +00:00
parent f4ac670a42
commit 8032206236
1 changed files with 9 additions and 34 deletions
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43
src/main/java/org/apache/hadoop/hbase/regionserver/wal/SequenceFileLogReader.java
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@ -20,7 +20,7 @@
package org.apache.hadoop.hbase.regionserver.wal; package org.apache.hadoop.hbase.regionserver.wal;
import java.io.FilterInputStream; import java.io.EOFException;
import java.io.IOException; import java.io.IOException;
import java.lang.Class; import java.lang.Class;
import java.lang.reflect.Constructor; import java.lang.reflect.Constructor;
@ -78,43 +78,18 @@ public class SequenceFileLogReader implements HLog.Reader {
this.length = l; this.length = l;
} }
// This section can be confusing. It is specific to how HDFS works.
// Let me try to break it down. This is the problem:
//
// 1. HDFS DataNodes update the NameNode about a filename's length
// on block boundaries or when a file is closed. Therefore,
// if an RS dies, then the NN's fs.getLength() can be out of date
// 2. this.in.available() would work, but it returns int &
// therefore breaks for files > 2GB (happens on big clusters)
// 3. DFSInputStream.getFileLength() gets the actual length from the DNs
// 4. DFSInputStream is wrapped 2 levels deep : this.in.in
//
// So, here we adjust getPos() using getFileLength() so the
// SequenceFile.Reader constructor (aka: first invocation) comes out
// with the correct end of the file:
// this.end = in.getPos() + length;
@Override @Override
public long getPos() throws IOException { public long getPos() throws IOException {
if (this.firstGetPosInvocation) { if (this.firstGetPosInvocation) {
this.firstGetPosInvocation = false; this.firstGetPosInvocation = false;
long adjust = 0; // Tell a lie. We're doing this just so that this line up in
// SequenceFile.Reader constructor comes out with the correct length
try { // on the file:
Field fIn = FilterInputStream.class.getDeclaredField("in"); // this.end = in.getPos() + length;
fIn.setAccessible(true); long available = this.in.available();
Object realIn = fIn.get(this.in); // Length gets added up in the SF.Reader constructor so subtract the
long realLength = ((Long)realIn.getClass(). // difference. If available < this.length, then return this.length.
getMethod("getFileLength", new Class<?> []{}). return available >= this.length? available - this.length: this.length;
invoke(realIn, new Object []{})).longValue();
assert(realLength >= this.length);
adjust = realLength - this.length;
} catch(Exception e) {
SequenceFileLogReader.LOG.warn(
"Error while trying to get accurate file length. " +
"Truncation / data loss may occur if RegionServers die.", e);
}
return adjust + super.getPos();
} }
return super.getPos(); return super.getPos();
} }