jvrao commented on a change in pull request #205: Issue 208: Improve ledger
fence logic
URL: https://github.com/apache/bookkeeper/pull/205#discussion_r124808898
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File path:
bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/LedgerDescriptorImpl.java
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@@ -81,6 +85,52 @@ ByteBuf getExplicitLac() {
return ledgerStorage.getExplicitLac(ledgerId);
}
+ synchronized SettableFuture<Boolean> fenceAndLogInJournal(Journal journal)
throws IOException {
+ boolean success = this.setFenced();
+ if(success) {
+ // fenced for first time, we should add the key to journal ensure
we can rebuild.
+ return logFenceEntryInJournal(journal);
+ } else {
+ // If we reach here, it means this ledger has been fenced before.
+ // However, fencing might still be in progress.
+ if(logFenceResult == null || fenceEntryPersisted.get()){
+ // Either ledger's fenced state is recovered from Journal
+ // Or Log fence entry in Journal succeed
+ SettableFuture<Boolean> result = SettableFuture.create();
+ result.set(true);
+ return result;
+ } else if (logFenceResult.isDone()) {
+ // We failed to log fence entry in Journal, try again.
+ return logFenceEntryInJournal(journal);
+ }
+ // Fencing is in progress
+ return logFenceResult;
+ }
+ }
+
+ /**
+ * Log the fence ledger entry in Journal so that we can rebuild the state.
+ * @param journal log the fence entry in the Journal
+ * @return A future which will be satisfied when add entry to journal
complete
+ */
+ private SettableFuture<Boolean> logFenceEntryInJournal(Journal journal) {
+ SettableFuture<Boolean> result;
+ synchronized (this) {
+ result = logFenceResult = SettableFuture.create();
Review comment:
When logFenceEntryInJournal is called in line 104, the else case says we
have object logFenceResult already. Why are we creating another logFenceResult
here???
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