keith-turner commented on code in PR #4042:
URL: https://github.com/apache/accumulo/pull/4042#discussion_r1420724383
##########
core/src/main/java/org/apache/accumulo/core/fate/Fate.java:
##########
@@ -68,25 +74,128 @@ public class Fate<T> {
private static final EnumSet<TStatus> FINISHED_STATES = EnumSet.of(FAILED,
SUCCESSFUL, UNKNOWN);
private final AtomicBoolean keepRunning = new AtomicBoolean(true);
+ private final BlockingQueue<Long> workQueue;
+ private final SignalCount idleWorkerCount = new SignalCount();
+ private final Thread workFinder;
public enum TxInfo {
TX_NAME, AUTO_CLEAN, EXCEPTION, RETURN_VALUE
}
+ private class SignalCount {
+ long count;
+
+ synchronized void increment() {
+ count++;
+ this.notifyAll();
+ }
+
+ synchronized void decrement() {
+ Preconditions.checkState(count > 0);
+ count--;
+ this.notifyAll();
+ }
+
+ synchronized void waitTillNonZero() {
+ while (count == 0 && keepRunning.get()) {
+ try {
+ wait(100);
+ } catch (InterruptedException e) {
+ Thread.currentThread().interrupt();
+ throw new IllegalStateException(e);
+ }
+ }
+ }
+
+ }
+
+ /**
+ * A single thread that finds transactions to work on and queues them up. Do
not want each worker
+ * thread going to the store and looking for work as it would place more
load on the store.
+ */
+ private class WorkFinder implements Runnable {
+
+ @Override
+ public void run() {
+
+ try {
+
+ while (keepRunning.get()) {
+
+ while (!workQueue.isEmpty() && keepRunning.get()) {
+ // wait till there is at least one worker that is looking for work
and the queue is
+ // empty
+ idleWorkerCount.waitTillNonZero();
+ }
Review Comment:
Before the LinkTransfer suggestion I had used SignalCount in two more places
in f67c53f. Did this to remove some of the usage of wait/notify in ZooStore
that was confusing. Was thinking that signal count makes the intent in the
code more clear.
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