ivandika3 commented on code in PR #9796:
URL: https://github.com/apache/ozone/pull/9796#discussion_r2850703353
##########
hadoop-ozone/ozone-manager/src/main/java/org/apache/hadoop/ozone/protocolPB/OzoneManagerProtocolServerSideTranslatorPB.java:
##########
@@ -216,44 +221,152 @@ public OMRequest getLastRequestToSubmit() {
private OMResponse submitReadRequestToOM(OMRequest request)
throws ServiceException {
- // Read from leader or followers using linearizable read
- if (ozoneManager.getConfig().isFollowerReadLocalLeaseEnabled() &&
- allowFollowerReadLocalLease(omRatisServer.getServerDivision(),
- ozoneManager.getConfig().getFollowerReadLocalLeaseLagLimit(),
- ozoneManager.getConfig().getFollowerReadLocalLeaseTimeMs())) {
- ozoneManager.getMetrics().incNumFollowerReadLocalLeaseSuccess();
+ if (request.getCmdType().equals(PrepareStatus)) {
+ // PrepareStatus is an OM request that only target a single OM node.
+ // Therefore, all PrepareStatus requests should be served immediately
without failover regardless
+ // of the OM node leadership or the read consistency. See
PrepareSubCommand.
+ // The implementation is not ideal, but exists for compatibility reason.
return handler.handleReadRequest(request);
- }
- // Get current OM's role
- RaftServerStatus raftServerStatus = omRatisServer.getLeaderStatus();
- // === 1. Follower linearizable read ===
- if (raftServerStatus == NOT_LEADER && omRatisServer.isLinearizableRead()) {
- ozoneManager.getMetrics().incNumLinearizableRead();
- return ozoneManager.getOmExecutionFlow().submit(request, false);
}
- // === 2. Leader local read (skip ReadIndex if allowed) ===
- if (raftServerStatus == LEADER_AND_READY ||
request.getCmdType().equals(PrepareStatus)) {
- if (ozoneManager.getConfig().isAllowLeaderSkipLinearizableRead()) {
- ozoneManager.getMetrics().incNumLeaderSkipLinearizableRead();
- // leader directly serves local committed data
+
+ if (!request.hasReadConsistencyHint() ||
!request.getReadConsistencyHint().hasReadConsistency() ||
+ request.getReadConsistencyHint().getReadConsistency() ==
UNKNOWN_READ_CONSISTENCY) {
+ // Read from leader or followers using linearizable read
+ if (ozoneManager.getConfig().isFollowerReadLocalLeaseEnabled() &&
+ allowFollowerReadLocalLease(omRatisServer.getServerDivision(),
+ ozoneManager.getConfig().getFollowerReadLocalLeaseLagLimit(),
+ ozoneManager.getConfig().getFollowerReadLocalLeaseTimeMs())) {
+ ozoneManager.getMetrics().incNumFollowerReadLocalLeaseSuccess();
return handler.handleReadRequest(request);
}
- // otherwise use linearizable path when enabled
- if (omRatisServer.isLinearizableRead()) {
+ // Get current OM's role
+ RaftServerStatus raftServerStatus = omRatisServer.getLeaderStatus();
+ // === 1. Follower linearizable read ===
+ if (raftServerStatus == NOT_LEADER &&
omRatisServer.isLinearizableRead()) {
ozoneManager.getMetrics().incNumLinearizableRead();
return ozoneManager.getOmExecutionFlow().submit(request, false);
}
+ // === 2. Leader local read (skip ReadIndex if allowed) ===
+ if (raftServerStatus == LEADER_AND_READY) {
+ if (ozoneManager.getConfig().isAllowLeaderSkipLinearizableRead()) {
+ ozoneManager.getMetrics().incNumLeaderSkipLinearizableRead();
+ // leader directly serves local committed data
+ return handler.handleReadRequest(request);
+ }
+ // otherwise use linearizable path when enabled
+ if (omRatisServer.isLinearizableRead()) {
+ ozoneManager.getMetrics().incNumLinearizableRead();
+ return ozoneManager.getOmExecutionFlow().submit(request, false);
+ }
- // fallback to local read
- return handler.handleReadRequest(request);
+ // fallback to local read
+ return handler.handleReadRequest(request);
+ } else {
+ throw createLeaderErrorException(raftServerStatus);
+ }
} else {
- throw createLeaderErrorException(raftServerStatus);
+ // If read consistency hint is specified, we should try to respect it
although
+ // there is no guarantee since it depends on the OM node configuration
(e.g.
+ // whether OM Raft server enables linearizable read).
+ ReadConsistencyHint readConsistencyHint =
request.getReadConsistencyHint();
+ ReadConsistencyProto readConsistency =
readConsistencyHint.getReadConsistency();
+ RaftServerStatus raftServerStatus;
+ switch (readConsistency) {
+ case LOCAL_LEASE:
+ raftServerStatus = omRatisServer.getLeaderStatus();
+ switch (raftServerStatus) {
+ case NOT_LEADER:
+ case LEADER_AND_NOT_READY:
+ if (!ozoneManager.getConfig().isFollowerReadLocalLeaseEnabled()) {
+ throw createLeaderErrorException(raftServerStatus);
+ }
+ LocalLeaseContext localLeaseContext =
readConsistencyHint.getLocalLeaseContext();
+ long localLeaseLagLimit = localLeaseContext.hasLagLimit() ?
+ localLeaseContext.getLagLimit() :
ozoneManager.getConfig().getFollowerReadLocalLeaseLagLimit();
+ long localLeaseLeaseTimeMs = localLeaseContext.hasLeaseTimeMs() ?
+ localLeaseContext.getLeaseTimeMs() :
ozoneManager.getConfig().getFollowerReadLocalLeaseTimeMs();
+ if (allowFollowerReadLocalLease(omRatisServer.getServerDivision(),
+ localLeaseLagLimit, localLeaseLeaseTimeMs)) {
+ ozoneManager.getMetrics().incNumFollowerReadLocalLeaseSuccess();
+ return handler.handleReadRequest(request);
+ }
+ // The LocalLease lag is too high, trigger failover
+ throw createLeaderErrorException(raftServerStatus);
+ case LEADER_AND_READY:
+ // Although local lease does not apply for leader (since leader is
always up-to-date)
+ // We still add the local lease metrics for compatibility reasons
+ ozoneManager.getMetrics().incNumFollowerReadLocalLeaseSuccess();
+ return handler.handleReadRequest(request);
+ default:
+ throw createUnknownRaftServerStatusException(raftServerStatus);
+ }
+ case LINEARIZABLE_LEADER_ONLY:
+ raftServerStatus = omRatisServer.getLeaderStatus();
+ switch (raftServerStatus) {
+ case NOT_LEADER:
+ case LEADER_AND_NOT_READY:
+ throw createLeaderErrorException(raftServerStatus);
+ case LEADER_AND_READY:
+ if (omRatisServer.isLinearizableRead()) {
+ ozoneManager.getMetrics().incNumLinearizableRead();
+ return ozoneManager.getOmExecutionFlow().submit(request, false);
+ } else {
+ // If linearizable read is not enabled, fallback to leader read
+ return handler.handleReadRequest(request);
+ }
+ default:
+ throw createUnknownRaftServerStatusException(raftServerStatus);
+ }
+ case LINEARIZABLE_ALLOW_FOLLOWER:
+ raftServerStatus = omRatisServer.getLeaderStatus();
+ switch (raftServerStatus) {
+ case LEADER_AND_NOT_READY:
+ throw createLeaderErrorException(raftServerStatus);
+ case NOT_LEADER:
+ if (omRatisServer.isLinearizableRead()) {
+ ozoneManager.getMetrics().incNumLinearizableRead();
+ return ozoneManager.getOmExecutionFlow().submit(request, false);
+ } else {
+ throw createLeaderErrorException(raftServerStatus);
+ }
+ case LEADER_AND_READY:
+ if (ozoneManager.getConfig().isAllowLeaderSkipLinearizableRead()) {
+ ozoneManager.getMetrics().incNumLeaderSkipLinearizableRead();
+ // leader directly serves local committed data
+ return handler.handleReadRequest(request);
+ }
+
+ // If the Raft server read option is not LINEARIZABLE, this will
+ // use leader read
+ if (omRatisServer.isLinearizableRead()) {
+ ozoneManager.getMetrics().incNumLinearizableRead();
+ }
+ return ozoneManager.getOmExecutionFlow().submit(request, false);
+ default:
+ throw createUnknownRaftServerStatusException(raftServerStatus);
+ }
+ case DEFAULT:
+ default:
+ raftServerStatus = omRatisServer.getLeaderStatus();
+ switch (raftServerStatus) {
+ case LEADER_AND_READY:
+ return handler.handleReadRequest(request);
+ case LEADER_AND_NOT_READY:
+ case NOT_LEADER:
+ throw createLeaderErrorException(raftServerStatus);
+ default:
+ throw createUnknownRaftServerStatusException(raftServerStatus);
+ }
+ }
}
}
- boolean allowFollowerReadLocalLease(Division ratisDivision, long
leaseLogLimit, long leaseTimeMsLimit) {
+ boolean allowFollowerReadLocalLease(Division ratisDivision, long
leaseLagLimit, long leaseTimeMsLimit) {
Review Comment:
Thanks for catching this, updated. The initial change was because of the
configuration which lead me to believe it's a typo.
##########
hadoop-ozone/ozonefs-hadoop2/src/main/java/org/apache/hadoop/fs/ozone/Hadoop27RpcTransport.java:
##########
@@ -46,6 +52,8 @@ public class Hadoop27RpcTransport implements OmTransport {
private final OzoneManagerProtocolPB rpcProxy;
private final HadoopRpcOMFailoverProxyProvider<OzoneManagerProtocolPB>
omFailoverProxyProvider;
+ private final boolean followerReadEnabled;
+ private final ReadConsistencyProto defaultLeaderReadConsistency;
Review Comment:
Thanks, updated.
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