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[Bigdata-commit] SF.net SVN: bigdata:[3865] branches/QUADS_QUERY_BRANCH/bigdata/src
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From: <tho...@us...> - 2010-11-02 12:43:23
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Revision: 3865
http://bigdata.svn.sourceforge.net/bigdata/?rev=3865&view=rev
Author: thompsonbry
Date: 2010-11-02 12:43:16 +0000 (Tue, 02 Nov 2010)
Log Message:
-----------
https://sourceforge.net/apps/trac/bigdata/ticket/187
I've updated the javadoc for ITransactionService#newTx(long) to indicate that the given timestamp may lie in the future. I've updated AbstractTransactionService? to hand back nextTimestamp() for a read-only transaction request when the given timestamp is in the future. I've updated TestTransactionService? to test this behavior for read-only and read-write tx (nothing had to be changed to support the latter). I've updated test_newTx_readOnly_timestampInFuture to request a timestamp which is known to be in the future and to verify that a read-only tx was assigned.
These edits are self-consistent, but the tx semantics really ought to be reviewed in more depth, e.g., as part of https://sourceforge.net/apps/trac/bigdata/ticket/145 or when adding full-distributed read-write tx support to the database.
Modified Paths:
--------------
branches/QUADS_QUERY_BRANCH/bigdata/src/java/com/bigdata/journal/ITransactionService.java
branches/QUADS_QUERY_BRANCH/bigdata/src/java/com/bigdata/service/AbstractTransactionService.java
branches/QUADS_QUERY_BRANCH/bigdata/src/test/com/bigdata/journal/TestTransactionService.java
Modified: branches/QUADS_QUERY_BRANCH/bigdata/src/java/com/bigdata/journal/ITransactionService.java
===================================================================
--- branches/QUADS_QUERY_BRANCH/bigdata/src/java/com/bigdata/journal/ITransactionService.java 2010-11-02 12:42:22 UTC (rev 3864)
+++ branches/QUADS_QUERY_BRANCH/bigdata/src/java/com/bigdata/journal/ITransactionService.java 2010-11-02 12:43:16 UTC (rev 3865)
@@ -152,9 +152,6 @@
* @return The unique transaction identifier.
*
* @throws IllegalStateException
- * if the requested timestamp is greater than
- * {@link #getLastCommitTime()}.
- * @throws IllegalStateException
* if the requested timestamp is for a commit point that is no
* longer preserved by the database (the resources for that
* commit point have been released).
@@ -164,6 +161,9 @@
* @todo specialize exception for a timestamp that is no longer preserved
* and for one that is in the future?
*/
+// * @throws IllegalStateException
+// * if the requested timestamp is greater than
+// * {@link #getLastCommitTime()}.
public long newTx(long timestamp) throws IOException;
/**
Modified: branches/QUADS_QUERY_BRANCH/bigdata/src/java/com/bigdata/service/AbstractTransactionService.java
===================================================================
--- branches/QUADS_QUERY_BRANCH/bigdata/src/java/com/bigdata/service/AbstractTransactionService.java 2010-11-02 12:42:22 UTC (rev 3864)
+++ branches/QUADS_QUERY_BRANCH/bigdata/src/java/com/bigdata/service/AbstractTransactionService.java 2010-11-02 12:43:16 UTC (rev 3865)
@@ -625,6 +625,8 @@
private volatile long lastTimestamp;
/**
+ * {@inheritDoc}
+ * <p>
* Note: There is an upper bound of one read-write transaction that may be
* created per millisecond (the resolution of {@link #nextTimestamp()}) and
* requests for new read-write transactions contend with other requests for
@@ -1234,21 +1236,21 @@
final long lastCommitTime = getLastCommitTime();
-// if (timestamp > lastCommitTime) {
- if (timestamp > lastTimestamp) {
-
- /*
- * You can't request a historical read for a timestamp which has not
- * yet been issued by this service!
- */
+// if (timestamp > lastTimestamp) {
+//
+// /*
+// * You can't request a historical read for a timestamp which has not
+// * yet been issued by this service!
+// */
+//
+// throw new IllegalStateException(
+// "Timestamp is in the future: timestamp=" + timestamp
+// + ", lastCommitTime=" + lastCommitTime
+// + ", lastTimestamp=" + lastTimestamp);
+//
+// } else
+ if (timestamp == lastCommitTime) {
- throw new IllegalStateException(
- "Timestamp is in the future: timestamp=" + timestamp
- + ", lastCommitTime=" + lastCommitTime
- + ", lastTimestamp=" + lastTimestamp);
-
- } else if (timestamp == lastCommitTime) {
-
/*
* Special case. We just return the next timestamp.
*
@@ -1325,12 +1327,23 @@
if (commitTime == -1L) {
/*
- * @todo I believe that this can only arise when there are no commit
- * points in the log.
+ * There are no commit points in the log.
+ *
+ * Note: Just return the next timestamp. It is guaranteed to be GT
+ * the desired commit time (which does not exist) and LT the next
+ * commit point.
*/
- throw new RuntimeException(
- "No data for that commit time: timestamp=" + timestamp);
+ return nextTimestamp();
+
+// /*
+// * Note: I believe that this can only arise when there are no commit
+// * points in the log. The thrown exception is per the top-level api
+// * for ITransactionService#newTx(long).
+// */
+// throw new IllegalStateException(
+// "No data for that commit time: timestamp=" + timestamp);
+
}
/*
Modified: branches/QUADS_QUERY_BRANCH/bigdata/src/test/com/bigdata/journal/TestTransactionService.java
===================================================================
--- branches/QUADS_QUERY_BRANCH/bigdata/src/test/com/bigdata/journal/TestTransactionService.java 2010-11-02 12:42:22 UTC (rev 3864)
+++ branches/QUADS_QUERY_BRANCH/bigdata/src/test/com/bigdata/journal/TestTransactionService.java 2010-11-02 12:43:16 UTC (rev 3865)
@@ -270,8 +270,15 @@
@Override
public long nextTimestamp() {
- super.nextTimestamp () ;
- return super.nextTimestamp () ;
+ // skip at least one millisecond.
+ super.nextTimestamp();
+
+ /*
+ * Invoke the behavior on the base class, which has a side-effect on
+ * the private [lastTimestamp] method.
+ */
+ return super.nextTimestamp();
+
}
}
@@ -889,33 +896,96 @@
}
}
+
+ /**
+ * Verify the behavior of the {@link AbstractTransactionService} when there
+ * are no commit points and a read-only transaction is requested. Since
+ * there are no commit points, the transaction service will return the next
+ * timestamp. That value will be GT the requested timestamp and LT any
+ * commit point (all commit points are in the future).
+ */
+ public void test_newTx_nothingCommitted_readOnlyTx() {
+ final MockTransactionService service = newFixture();
+
+ try {
+
+ /*
+ * Note: The commit time log is empty.
+ */
+ final long timestamp = service.nextTimestamp();
+
+ /*
+ * Request a read-only view which is in the past based on the
+ * transaction server's clock. However, there are no commit points
+ * which cover that timestamp since there are no commit points in
+ * the database.
+ */
+ service.newTx(timestamp - 1);
+
+ } finally {
+
+ service.destroy();
+
+ }
+
+ }
+
/**
- * Verify that you can not create a read-only transaction using a timestamp
- * that is in the future.
+ * Verify the behavior of the {@link AbstractTransactionService} when there
+ * are no commit points and a read-write transaction is requested. You can
+ * always obtain a read-write transaction, even when there are no commit
+ * points on the database.
*/
- public void test_newTx_readOnly_timestampInFuture() {
+ public void test_newTx_nothingCommitted_readWriteTx() {
final MockTransactionService service = newFixture();
try {
/*
- * Note: The commit time log is empty so anything is in the future.
+ * Note: The commit time log is empty.
*/
+ service.newTx(ITx.UNISOLATED);
+
+ } finally {
- try {
- /**
- * FIXME Modified to be compatible with changes made to AbstractTransactionService, revision 3804.
- * @see <a href="https://sourceforge.net/apps/trac/bigdata/ticket/187">Trac 187</a>
- */
-// service.newTx(10);
- service.newTx(service.nextTimestamp () + 10);
- fail("Expecting: "+IllegalStateException.class);
- } catch(IllegalStateException ex) {
- log.info("Ignoring expected exception: "+ex);
- }
+ service.destroy();
+
+ }
+
+ }
+
+ /**
+ * Verify that you can create a read-only transaction using a timestamp that
+ * is in the future. A commit point is generated and a read-only tx is
+ * requested which is beyond that commit point. The returned tx will be
+ * assigned using nextTimestamp() which is guaranteed to be less than the
+ * next commit point on the database (which in this case would be the first
+ * commit point as well).
+ */
+ public void test_newTx_readOnly_timestampInFuture() {
+
+ final MockTransactionService service = newFixture();
+
+ try {
+
+ // request a timestamp.
+ final long timestamp1 = service.nextTimestamp();
+ // make that timestamp a valid commit time.
+ service.notifyCommit(timestamp1);
+
+// try {
+ // request a timestamp in the future.
+ final long tx = service.newTx(timestamp1 * 2);
+ System.err.println("ts="+timestamp1);
+ System.err.println("tx="+tx);
+// fail("Expecting: "+IllegalStateException.class);
+// } catch(IllegalStateException ex) {
+// log.info("Ignoring expected exception: "+ex);
+// }
+
} finally {
service.destroy();
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