ibessonov commented on code in PR #5670:
URL: https://github.com/apache/ignite-3/pull/5670#discussion_r2054574123
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modules/metastorage/src/main/java/org/apache/ignite/internal/metastorage/server/ReadOperationForCompactionTracker.java:
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@@ -48,56 +50,82 @@ public class ReadOperationForCompactionTracker {
private final AtomicLong longOperationIdGenerator = new AtomicLong();
- /** Generates the next read operation ID. Thread-safe. */
- public long generateReadOperationId() {
- return longOperationIdGenerator.getAndIncrement();
+ /**
+ * Token to stop tracking the read operation.
+ *
+ * @see #track(long, LongSupplier, LongSupplier)
+ */
+ @FunctionalInterface
+ public interface TrackingToken extends AutoCloseable {
+ @Override
+ void close();
}
/**
* Starts tracking the completion of a read operation on its lowest
estimation for revision upper bound.
*
- * <p>Method is expected not to be called more than once for the same
arguments.</p>
- *
* <p>Expected usage pattern:</p>
* <pre><code>
- * Object readOperationId = ...;
* int operationRevision = ...;
*
- * tracker.track(readOperationId, operationRevision);
- *
- * try {
+ * try (var token = tracker.track(operationRevision,
storage::revision, storage::getCompactionRevision)) {
* doReadOperation(...);
- * } finally {
- * tracker.untrack(readOperationId, operationRevision);
* }
* </code></pre>
*
- * @see #untrack(Object, long)
+ * @see TrackingToken
*/
- public void track(Object readOperationId, long operationRevision) {
- var key = new ReadOperationKey(readOperationId, operationRevision);
+ public TrackingToken track(
+ long operationRevision, LongSupplier latestRevision, LongSupplier
compactedRevision
+ ) throws CompactedException {
+ long operationId = longOperationIdGenerator.getAndIncrement();
+
+ while (true) {
+ // "operationRevision" parameter is immutable, because we might
need it on a next iteration.
+ // If it is asked to track the latest revision, we receive it
right here from the corresponding supplier.
+ long currentOperationRevision = operationRevision ==
MetaStorageManager.LATEST_REVISION
+ ? latestRevision.getAsLong()
+ : operationRevision;
+
+ // Value from compacted revision supplier can only grow. We only
use it for upper bound checks, so it's safe to read it every
+ // time instead of caching it. It applies to all usages of the
supplier.
+ if (currentOperationRevision <= compactedRevision.getAsLong()) {
+ // Latest revision can never be compacted. If for some reason
it already is, we should retry until it is not.
Review Comment:
I'll rephrase that
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