From b98349fd0cadf2f0c17dad9cbcf9fea312ec2684 Mon Sep 17 00:00:00 2001
From: "Brian S. O'Neill" <bronee@gmail.com>
Date: Wed, 30 Apr 2008 18:08:10 +0000
Subject: Recover from potential deadlocks against repositories with coarse
 locks.

---
 .../com/amazon/carbonado/layout/LayoutFactory.java | 35 +++++++++++++++++++++-
 1 file changed, 34 insertions(+), 1 deletion(-)

(limited to 'src/main/java/com/amazon/carbonado/layout')

diff --git a/src/main/java/com/amazon/carbonado/layout/LayoutFactory.java b/src/main/java/com/amazon/carbonado/layout/LayoutFactory.java
index d7bf3da..1b2f0fc 100644
--- a/src/main/java/com/amazon/carbonado/layout/LayoutFactory.java
+++ b/src/main/java/com/amazon/carbonado/layout/LayoutFactory.java
@@ -29,10 +29,14 @@ import java.util.Map;
 import org.cojen.util.SoftValuedHashMap;
 
 import com.amazon.carbonado.Cursor;
+import com.amazon.carbonado.FetchDeadlockException;
 import com.amazon.carbonado.FetchException;
 import com.amazon.carbonado.FetchNoneException;
+import com.amazon.carbonado.FetchTimeoutException;
 import com.amazon.carbonado.IsolationLevel;
+import com.amazon.carbonado.PersistDeadlockException;
 import com.amazon.carbonado.PersistException;
+import com.amazon.carbonado.PersistTimeoutException;
 import com.amazon.carbonado.Repository;
 import com.amazon.carbonado.RepositoryException;
 import com.amazon.carbonado.Storable;
@@ -98,9 +102,16 @@ public class LayoutFactory implements LayoutCapability {
         ResyncCapability resyncCap = null;
 
         // Try to insert metadata up to three times.
+        boolean top = true;
         loadLayout: for (int retryCount = 3;;) {
             try {
-                Transaction txn = mRepository.enterTopTransaction(IsolationLevel.READ_COMMITTED);
+                Transaction txn;
+                if (top) {
+                    txn = mRepository.enterTopTransaction(IsolationLevel.READ_COMMITTED);
+                } else {
+                    txn = mRepository.enterTransaction(IsolationLevel.READ_COMMITTED);
+                }
+
                 txn.setForUpdate(true);
                 try {
                     // If type represents a new generation, then a new layout needs to
@@ -185,6 +196,28 @@ public class LayoutFactory implements LayoutCapability {
                 // before each retry.
                 retryCount = e.backoff(e, retryCount, 1000);
                 resyncCap = mRepository.getCapability(ResyncCapability.class);
+            } catch (FetchException e) {
+                if (e instanceof FetchDeadlockException || e instanceof FetchTimeoutException) {
+                    // Might be caused by coarse locks. Switch to nested
+                    // transaction to share the locks.
+                    if (top) {
+                        top = false;
+                        retryCount = e.backoff(e, retryCount, 100);
+                        continue;
+                    }
+                }
+                throw e;
+            } catch (PersistException e) {
+                if (e instanceof PersistDeadlockException || e instanceof PersistTimeoutException){
+                    // Might be caused by coarse locks. Switch to nested
+                    // transaction to share the locks.
+                    if (top) {
+                        top = false;
+                        retryCount = e.backoff(e, retryCount, 100);
+                        continue;
+                    }
+                }
+                throw e;
             }
         }
 
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