MVTableEngine: concurrency

h2/src/main/org/h2/mvstore/db/TransactionStore.java

@@ -103,7 +103,7 @@ public class TransactionStore {
         init();
     }
 
-    private void init() {
+    private synchronized void init() {
         String s = settings.get(LAST_TRANSACTION_ID);
         if (s != null) {
             lastTransactionId = Long.parseLong(s);
@@ -115,18 +115,21 @@ public class TransactionStore {
                     DataUtils.ERROR_TRANSACTION_CORRUPT,
                     "Last transaction not stored");
         }
+        synchronized (undoLog) {
             if (undoLog.size() > 0) {
                 long[] key = undoLog.firstKey();
                 firstOpenTransaction = key[0];
             }
         }
+    }
 
     /**
      * Get the list of unclosed transactions that have pending writes.
      *
      * @return the list of transactions (sorted by id)
      */
-    public synchronized List<Transaction> getOpenTransactions() {
+    public List<Transaction> getOpenTransactions() {
+        synchronized (undoLog) {
             ArrayList<Transaction> list = New.arrayList();
             long[] key = undoLog.firstKey();
             while (key != null) {
@@ -150,6 +153,7 @@ public class TransactionStore {
             }
             return list;
         }
+    }
 
     /**
      * Close the transaction store.
@@ -187,7 +191,7 @@ public class TransactionStore {
      *
      * @param t the transaction
      */
-    void storeTransaction(Transaction t) {
+    synchronized void storeTransaction(Transaction t) {
         if (t.getStatus() == Transaction.STATUS_PREPARED || t.getName() != null) {
             Object[] v = { t.getStatus(), t.getName() };
             preparedTransactions.put(t.getId(), v);
@@ -209,7 +213,9 @@ public class TransactionStore {
         commitIfNeeded();
         long[] undoKey = { t.getId(), logId };
         Object[] log = new Object[] { opType, mapId, key, oldValue };
+        synchronized (undoLog) {
             undoLog.put(undoKey, log);
+        }
         if (firstOpenTransaction == -1 || t.getId() < firstOpenTransaction) {
             firstOpenTransaction = t.getId();
         }
@@ -225,6 +231,7 @@ public class TransactionStore {
         if (store.isClosed()) {
             return;
         }
+        synchronized (undoLog) {
             for (long logId = 0; logId < maxLogId; logId++) {
                 commitIfNeeded();
                 long[] undoKey = new long[] { t.getId(), logId };
@@ -246,10 +253,11 @@ public class TransactionStore {
                 }
                 undoLog.remove(undoKey);
             }
+        }
         endTransaction(t);
     }
 
-    private MVMap<Object, VersionedValue> openMap(int mapId) {
+    private synchronized MVMap<Object, VersionedValue> openMap(int mapId) {
         // TODO open map by id if possible
         Map<String, String> meta = store.getMetaMap();
         String m = meta.get("map." + mapId);
@@ -277,6 +285,7 @@ public class TransactionStore {
         if (transactionId < firstOpenTransaction) {
             return false;
         }
+        synchronized (undoLog) {
             if (firstOpenTransaction == -1) {
                 if (undoLog.size() == 0) {
                     return false;
@@ -295,13 +304,14 @@ public class TransactionStore {
             key = undoLog.higherKey(key);
             return key != null && key[0] == transactionId;
         }
+    }
 
     /**
      * End this transaction
      *
      * @param t the transaction
      */
-    void endTransaction(Transaction t) {
+    synchronized void endTransaction(Transaction t) {
         if (t.getStatus() == Transaction.STATUS_PREPARED) {
             preparedTransactions.remove(t.getId());
         }
@@ -322,6 +332,7 @@ public class TransactionStore {
      * @param toLogId the log id to roll back to
      */
     void rollbackTo(Transaction t, long maxLogId, long toLogId) {
+        synchronized (undoLog) {
             for (long logId = maxLogId - 1; logId >= toLogId; logId--) {
                 commitIfNeeded();
                 long[] undoKey = new long[] { t.getId(), logId };
@@ -342,6 +353,7 @@ public class TransactionStore {
                 undoLog.remove(undoKey);
             }
         }
+    }
 
     /**
      * Get the changes of the given transaction, starting from the latest log id
@@ -363,6 +375,7 @@ public class TransactionStore {
             }
 
             private void fetchNext() {
+                synchronized (undoLog) {
                     while (logId >= toLogId) {
                         Object[] op = undoLog.get(new long[] {
                                 t.getId(), logId });
@@ -382,6 +395,7 @@ public class TransactionStore {
                             return;
                         }
                     }
+                }
                 current = null;
             }
 
@@ -958,10 +972,12 @@ public class TransactionStore {
                 }
                 // get the value before the uncommitted transaction
                 long[] x = new long[] { tx, logId };
+                synchronized (transaction.store.undoLog) {
                     Object[] d = transaction.store.undoLog.get(x);
                     data = (VersionedValue) d[3];
                 }
             }
+        }
 
 
         /**

h2/src/test/org/h2/test/TestAll.java

@@ -680,10 +680,7 @@ kill -9 `jps -l | grep "org.h2.test." | cut -d " " -f 1`
         new TestRandomCompare().runTest(this);
         new TestKillRestart().runTest(this);
         new TestKillRestartMulti().runTest(this);
-        if (!mvStore) {
-            // concurrent modification of the undoLog 
         new TestMultiThreaded().runTest(this);
-        }
         new TestOuterJoins().runTest(this);
         new TestNestedJoins().runTest(this);