svn commit: r1462386 - /hbase/branches/0.95/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RegionMergeRequest.java

[enis]

Author: enis
Date: Fri Mar 29 02:47:26 2013
New Revision: 1462386

URL: http://svn.apache.org/r1462386
Log:
HBASE-7977 Online merge should acquire table lock

Modified:
    
hbase/branches/0.95/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RegionMergeRequest.java

Modified: 
hbase/branches/0.95/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RegionMergeRequest.java
URL: 
http://svn.apache.org/viewvc/hbase/branches/0.95/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RegionMergeRequest.java?rev=1462386&r1=1462385&r2=1462386&view=diff
==============================================================================
--- 
hbase/branches/0.95/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RegionMergeRequest.java
 (original)
+++ 
hbase/branches/0.95/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RegionMergeRequest.java
 Fri Mar 29 02:47:26 2013
@@ -24,6 +24,7 @@ import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.classification.InterfaceAudience;
 import org.apache.hadoop.hbase.RemoteExceptionHandler;
+import org.apache.hadoop.hbase.master.TableLockManager.TableLock;
 import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
 import org.apache.hadoop.util.StringUtils;
 
@@ -39,6 +40,7 @@ class RegionMergeRequest implements Runn
   private final HRegion region_b;
   private final HRegionServer server;
   private final boolean forcible;
+  private TableLock tableLock;
 
   RegionMergeRequest(HRegion a, HRegion b, HRegionServer hrs, boolean 
forcible) {
     Preconditions.checkNotNull(hrs);
@@ -65,6 +67,18 @@ class RegionMergeRequest implements Runn
       final long startTime = EnvironmentEdgeManager.currentTimeMillis();
       RegionMergeTransaction mt = new RegionMergeTransaction(region_a,
           region_b, forcible);
+
+      //acquire a shared read lock on the table, so that table schema 
modifications
+      //do not happen concurrently
+      tableLock = 
server.getTableLockManager().readLock(region_a.getTableDesc().getName()
+          , "MERGE_REGIONS:" + region_a.getRegionNameAsString() + ", " + 
region_b.getRegionNameAsString());
+      try {
+        tableLock.acquire();
+      } catch (IOException ex) {
+        tableLock = null;
+        throw ex;
+      }
+
       // If prepare does not return true, for some reason -- logged inside in
       // the prepare call -- we are not ready to merge just now. Just return.
       if (!mt.prepare(this.server)) return;
@@ -107,6 +121,19 @@ class RegionMergeRequest implements Runn
       LOG.error("Merge failed " + this,
           RemoteExceptionHandler.checkIOException(ex));
       server.checkFileSystem();
+    } finally {
+      releaseTableLock();
+    }
+  }
+
+  protected void releaseTableLock() {
+    if (this.tableLock != null) {
+      try {
+        this.tableLock.release();
+      } catch (IOException ex) {
+        LOG.warn("Could not release the table lock", ex);
+        //TODO: if we get here, and not abort RS, this lock will never be 
released
+      }
     }
   }
 }