Github user keith-turner commented on a diff in the pull request:
https://github.com/apache/accumulo/pull/60#discussion_r48749879
--- Diff:
server/tserver/src/main/java/org/apache/accumulo/tserver/tablet/Scanner.java ---
@@ -38,100 +40,126 @@
private ScanDataSource isolatedDataSource;
private boolean sawException = false;
private boolean scanClosed = false;
+ protected Semaphore scannerSemaphore;
Scanner(Tablet tablet, Range range, ScanOptions options) {
this.tablet = tablet;
this.range = range;
this.options = options;
+ scannerSemaphore = new Semaphore(1, true);
}
- public synchronized ScanBatch read() throws IOException,
TabletClosedException {
-
- if (sawException)
- throw new IllegalStateException("Tried to use scanner after
exception occurred.");
+ public ScanBatch read() throws IOException, TabletClosedException {
if (scanClosed)
--- End diff --
Below is from the semaphore javadoc. Reading that is sounds like there is
no guarantee of seeing a change to `scanClosed` until after `acquire()`.
```
Memory consistency effects: Actions in a thread prior to calling a
"release" method such as release() happen-before actions following a successful
"acquire" method such as acquire() in another thread.
```
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at [email protected] or file a JIRA ticket
with INFRA.
---
