- Optimize out the version vector specific code (on the client)

sbodagala · sbodagala · commit 0da13a77977c · 2022-06-28T09:17:53.000Z
when the version vector feature is disabled.
diff --git a/fdbclient/DatabaseContext.h b/fdbclient/DatabaseContext.h
@@ -611,6 +611,14 @@ class DatabaseContext : public ReferenceCounted<DatabaseContext>, public FastAll
 	// Cache of the latest commit versions of storage servers.
 	VersionVector ssVersionVectorCache;
 
+	// Introduced mainly to optimize out the version vector related code (on the client side)
+	// when the version vector feature is disabled (on the server side).
+	// @param ssVersionVectorDelta version vector changes sent by GRV proxy
+	bool mayNeedToUpdateVersionVectorCache(const VersionVector& ssVersionVectorDelta) {
+		return (ssVersionVectorCache.getMaxVersion() != invalidVersion ||
+		        ssVersionVectorDelta.getMaxVersion() != invalidVersion);
+	}
+
 	// Adds or updates the specified (SS, TSS) pair in the TSS mapping (if not already present).
 	// Requests to the storage server will be duplicated to the TSS.
 	void addTssMapping(StorageServerInterface const& ssi, StorageServerInterface const& tssi);
diff --git a/fdbclient/NativeAPI.actor.cpp b/fdbclient/NativeAPI.actor.cpp
@@ -3474,10 +3474,12 @@ ACTOR Future<Version> waitForCommittedVersion(Database cx, Version version, Span
 					cx->minAcceptableReadVersion = std::min(cx->minAcceptableReadVersion, v.version);
 					if (v.midShardSize > 0)
 						cx->smoothMidShardSize.setTotal(v.midShardSize);
-					if (cx->isCurrentGrvProxy(v.proxyId)) {
-						cx->ssVersionVectorCache.applyDelta(v.ssVersionVectorDelta);
-					} else {
-						cx->ssVersionVectorCache.clear();
+					if (cx->mayNeedToUpdateVersionVectorCache(v.ssVersionVectorDelta)) {
+						if (cx->isCurrentGrvProxy(v.proxyId)) {
+							cx->ssVersionVectorCache.applyDelta(v.ssVersionVectorDelta);
+						} else {
+							cx->ssVersionVectorCache.clear();
+						}
 					}
 					if (v.version >= version)
 						return v.version;
@@ -3506,10 +3508,12 @@ ACTOR Future<Version> getRawVersion(Reference<TransactionState> trState) {
 			                                                     TransactionPriority::IMMEDIATE,
 			                                                     trState->cx->ssVersionVectorCache.getMaxVersion()),
 			                               trState->cx->taskID))) {
-				if (trState->cx->isCurrentGrvProxy(v.proxyId)) {
-					trState->cx->ssVersionVectorCache.applyDelta(v.ssVersionVectorDelta);
-				} else {
-					trState->cx->ssVersionVectorCache.clear();
+				if (trState->cx->mayNeedToUpdateVersionVectorCache(v.ssVersionVectorDelta)) {
+					if (trState->cx->isCurrentGrvProxy(v.proxyId)) {
+						trState->cx->ssVersionVectorCache.applyDelta(v.ssVersionVectorDelta);
+					} else {
+						trState->cx->ssVersionVectorCache.clear();
+					}
 				}
 				return v.version;
 			}
@@ -6640,10 +6644,12 @@ ACTOR Future<GetReadVersionReply> getConsistentReadVersion(SpanContext parentSpa
 						    "TransactionDebug", debugID.get().first(), "NativeAPI.getConsistentReadVersion.After");
 					ASSERT(v.version > 0);
 					cx->minAcceptableReadVersion = std::min(cx->minAcceptableReadVersion, v.version);
-					if (cx->isCurrentGrvProxy(v.proxyId)) {
-						cx->ssVersionVectorCache.applyDelta(v.ssVersionVectorDelta);
-					} else {
-						continue; // stale GRV reply, retry
+					if (cx->mayNeedToUpdateVersionVectorCache(v.ssVersionVectorDelta)) {
+						if (cx->isCurrentGrvProxy(v.proxyId)) {
+							cx->ssVersionVectorCache.applyDelta(v.ssVersionVectorDelta);
+						} else {
+							continue; // stale GRV reply, retry
+						}
 					}
 					return v;
 				}
@@ -6830,10 +6836,12 @@ ACTOR Future<Version> extractReadVersion(Reference<TransactionState> trState,
 	}
 
 	metadataVersion.send(rep.metadataVersion);
-	if (trState->cx->isCurrentGrvProxy(rep.proxyId)) {
-		trState->cx->ssVersionVectorCache.applyDelta(rep.ssVersionVectorDelta);
-	} else {
-		trState->cx->ssVersionVectorCache.clear();
+	if (trState->cx->mayNeedToUpdateVersionVectorCache(rep.ssVersionVectorDelta)) {
+		if (trState->cx->isCurrentGrvProxy(rep.proxyId)) {
+			trState->cx->ssVersionVectorCache.applyDelta(rep.ssVersionVectorDelta);
+		} else {
+			trState->cx->ssVersionVectorCache.clear();
+		}
 	}
 	return rep.version;
 }
