diff options
| -rw-r--r-- | docs/CarbonadoGuide.odt | bin | 56032 -> 56398 bytes | |||
| -rw-r--r-- | docs/CarbonadoGuide.pdf | bin | 417058 -> 432918 bytes | |||
| -rw-r--r-- | src/main/java/com/amazon/carbonado/IsolationLevel.java | 13 | ||||
| -rw-r--r-- | src/main/java/com/amazon/carbonado/OptimisticLockException.java | 2 | ||||
| -rw-r--r-- | src/main/java/com/amazon/carbonado/repo/jdbc/JDBCRepository.java | 6 |
5 files changed, 21 insertions, 0 deletions
diff --git a/docs/CarbonadoGuide.odt b/docs/CarbonadoGuide.odt Binary files differindex d6b977b..3530801 100644 --- a/docs/CarbonadoGuide.odt +++ b/docs/CarbonadoGuide.odt diff --git a/docs/CarbonadoGuide.pdf b/docs/CarbonadoGuide.pdf Binary files differindex 20f763f..56414db 100644 --- a/docs/CarbonadoGuide.pdf +++ b/docs/CarbonadoGuide.pdf diff --git a/src/main/java/com/amazon/carbonado/IsolationLevel.java b/src/main/java/com/amazon/carbonado/IsolationLevel.java index 5f963b2..7571205 100644 --- a/src/main/java/com/amazon/carbonado/IsolationLevel.java +++ b/src/main/java/com/amazon/carbonado/IsolationLevel.java @@ -26,6 +26,7 @@ package com.amazon.carbonado; * <li>{@link #READ_UNCOMMITTED}
* <li>{@link #READ_COMMITTED}
* <li>{@link #REPEATABLE_READ}
+ * <li>{@link #SNAPSHOT}
* <li>{@link #SERIALIZABLE}
* </ul>
*
@@ -35,6 +36,11 @@ package com.amazon.carbonado; * iteration. It releases locks during iteration rather than holding on to them
* until the transaction exits.
*
+ * <p>{@code SNAPSHOT} isolation is special in that it uses multiversion
+ * concurrency control (MVCC). A commit may fail with an {@link
+ * OptimisticLockException}. Few repositories are expected to support this
+ * level, however.
+ *
* @author Brian S O'Neill
* @see Repository#enterTransaction(IsolationLevel)
* @see Transaction
@@ -73,6 +79,13 @@ public enum IsolationLevel { /**
* Indicates that dirty reads, non-repeatable reads and phantom reads are
+ * prevented. Commits can still fail however, as snapshot isolation avoids
+ * using locks.
+ */
+ SNAPSHOT,
+
+ /**
+ * Indicates that dirty reads, non-repeatable reads and phantom reads are
* prevented. Phantoms are records returned as a result of a search, but
* which were not seen by the same transaction when the identical search
* criteria was previously used. For example, another transaction may have
diff --git a/src/main/java/com/amazon/carbonado/OptimisticLockException.java b/src/main/java/com/amazon/carbonado/OptimisticLockException.java index 2a782d1..b4a43de 100644 --- a/src/main/java/com/amazon/carbonado/OptimisticLockException.java +++ b/src/main/java/com/amazon/carbonado/OptimisticLockException.java @@ -21,6 +21,8 @@ package com.amazon.carbonado; /**
* An OptimisticLockException is thrown if the {@link Repository} is using
* optimistic locking for concurrency control, and lock aquisition failed.
+ * This exception may also be thrown if multiversion concurrency control (MVCC)
+ * is being used and the commit fails.
*
* @author Brian S O'Neill
*/
diff --git a/src/main/java/com/amazon/carbonado/repo/jdbc/JDBCRepository.java b/src/main/java/com/amazon/carbonado/repo/jdbc/JDBCRepository.java index 6e53354..97be915 100644 --- a/src/main/java/com/amazon/carbonado/repo/jdbc/JDBCRepository.java +++ b/src/main/java/com/amazon/carbonado/repo/jdbc/JDBCRepository.java @@ -92,6 +92,9 @@ public class JDBCRepository return Connection.TRANSACTION_READ_COMMITTED;
case REPEATABLE_READ:
return Connection.TRANSACTION_REPEATABLE_READ;
+ case SNAPSHOT:
+ // TODO: not accurate for all databases.
+ return Connection.TRANSACTION_SERIALIZABLE;
case SERIALIZABLE:
return Connection.TRANSACTION_SERIALIZABLE;
}
@@ -117,6 +120,9 @@ public class JDBCRepository case REPEATABLE_READ:
desiredLevel = IsolationLevel.SERIALIZABLE;
break;
+ case SNAPSHOT:
+ desiredLevel = IsolationLevel.SERIALIZABLE;
+ break;
case SERIALIZABLE: default:
return null;
}
|