text: /*
   * MasterProxyServer.actor.cpp
   *
   * This source file is part of the FoundationDB open source project
   *
   * Copyright 2013-2018 Apple Inc. and the FoundationDB project authors
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  #include "flow/actorcompiler.h"
  #include "flow/ActorCollection.h"
  #include "fdbclient/MasterProxyInterface.h"
  #include "fdbclient/NativeAPI.h"
  #include "MasterInterface.h"
  #include "WorkerInterface.h"
  #include "WaitFailure.h"
  #include "Knobs.h"
  #include "ServerDBInfo.h"
  #include "LogSystem.h"
  #include "LogSystemDiskQueueAdapter.h"
  #include "IKeyValueStore.h"
  #include "fdbclient/SystemData.h"
  #include "fdbrpc/sim_validation.h"
  #include "fdbrpc/batcher.actor.h"
  #include "fdbclient/Notified.h"
  #include "fdbclient/KeyRangeMap.h"
  #include "ConflictSet.h"
  #include "flow/Stats.h"
  #include "ApplyMetadataMutation.h"
  #include "RecoveryState.h"
  #include "fdbclient/Atomic.h"
  #include "flow/TDMetric.actor.h"
  
  struct ProxyStats {
  	CounterCollection cc;
  	Counter txnStartIn, txnStartOut, txnStartBatch;
  	Counter txnSystemPriorityStartIn, txnSystemPriorityStartOut;
  	Counter txnBatchPriorityStartIn, txnBatchPriorityStartOut;
  	Counter txnDefaultPriorityStartIn, txnDefaultPriorityStartOut;
  	Counter txnCommitIn, txnCommitVersionAssigned, txnCommitResolving, txnCommitResolved, txnCommitOut, txnCommitOutSuccess;
  	Counter txnConflicts;
  	Counter commitBatchIn, commitBatchOut;
  	Counter mutationBytes;
  	Counter mutations;
  	Counter conflictRanges;
  	Version lastCommitVersionAssigned;
  
  	Future<Void> logger;
  
  	explicit ProxyStats(UID id, Version* pVersion, NotifiedVersion* pCommittedVersion, int64_t *commitBatchesMemBytesCountPtr)
  	  : cc("ProxyStats", id.toString()),
  		txnStartIn("TxnStartIn", cc), txnStartOut("TxnStartOut", cc), txnStartBatch("TxnStartBatch", cc), txnSystemPriorityStartIn("TxnSystemPriorityStartIn", cc), txnSystemPriorityStartOut("TxnSystemPriorityStartOut", cc), txnBatchPriorityStartIn("TxnBatchPriorityStartIn", cc), txnBatchPriorityStartOut("TxnBatchPriorityStartOut", cc),
  		txnDefaultPriorityStartIn("TxnDefaultPriorityStartIn", cc), txnDefaultPriorityStartOut("TxnDefaultPriorityStartOut", cc), txnCommitIn("TxnCommitIn", cc),	txnCommitVersionAssigned("TxnCommitVersionAssigned", cc), txnCommitResolving("TxnCommitResolving", cc), txnCommitResolved("TxnCommitResolved", cc), txnCommitOut("TxnCommitOut", cc),
  		txnCommitOutSuccess("TxnCommitOutSuccess", cc), txnConflicts("TxnConflicts", cc), commitBatchIn("CommitBatchIn", cc), commitBatchOut("CommitBatchOut", cc), mutationBytes("MutationBytes", cc), mutations("Mutations", cc), conflictRanges("ConflictRanges", cc), lastCommitVersionAssigned(0)
  	{
  		specialCounter(cc, "LastAssignedCommitVersion", [this](){return this->lastCommitVersionAssigned;});
  		specialCounter(cc, "Version", [pVersion](){return *pVersion; });
  		specialCounter(cc, "CommittedVersion", [pCommittedVersion](){ return pCommittedVersion->get(); });
  		specialCounter(cc, "CommitBatchesMemBytesCount", [commitBatchesMemBytesCountPtr]() { return *commitBatchesMemBytesCountPtr; });
  		logger = traceCounters("ProxyMetrics", id, SERVER_KNOBS->WORKER_LOGGING_INTERVAL, &cc, "ProxyMetrics");
  	}
  };
  
  ACTOR template <class T>
  Future<Void> forwardValue(Promise<T> out, Future<T> in)
  {
  	// Like forwardPromise, but throws on error
  	T t = wait(in);
  	out.send(t);
  	return Void();
  }
  
  int getBytes(Promise<Version> const& r) { return 0; }
  
  ACTOR Future<Void> getRate(UID myID, MasterInterface master, int64_t* inTransactionCount, double* outTransactionRate) {
  	state Future<Void> nextRequestTimer = Void();
  	state Future<Void> leaseTimeout = Never();
  	state Future<GetRateInfoReply> reply;
  	state int64_t lastTC = 0;
  
  	loop choose{
  		when(Void _ = wait(nextRequestTimer)) {
  			nextRequestTimer = Never();
  			reply = brokenPromiseToNever(master.getRateInfo.getReply(GetRateInfoRequest(myID, *inTransactionCount)));
  		}
  		when(GetRateInfoReply rep = wait(reply)) {
  			reply = Never();
  			*outTransactionRate = rep.transactionRate;
  			//TraceEvent("MasterProxyRate", myID).detail("Rate", rep.transactionRate).detail("Lease", rep.leaseDuration).detail("ReleasedTransactions", *inTransactionCount - lastTC);
  			lastTC = *inTransactionCount;
  			leaseTimeout = delay(rep.leaseDuration);
  			nextRequestTimer = delayJittered(rep.leaseDuration / 2);
  		}
  		when(Void _ = wait(leaseTimeout)) {
  			*outTransactionRate = 0;
  			//TraceEvent("MasterProxyRate", myID).detail("Rate", 0).detail("Lease", "Expired");
  			leaseTimeout = Never();
  		}
  	}
  }
  
  ACTOR Future<Void> queueTransactionStartRequests(std::priority_queue< std::pair<GetReadVersionRequest, int64_t>,
  	std::vector< std::pair<GetReadVersionRequest, int64_t> > > *transactionQueue,
  	FutureStream<GetReadVersionRequest> readVersionRequests,
  	PromiseStream<Void> GRVTimer, double *lastGRVTime,
  	double *GRVBatchTime, FutureStream<double> replyTimes,
  	ProxyStats* stats) {
  	state int64_t counter = 0;
  	loop choose{
  		when(GetReadVersionRequest req = waitNext(readVersionRequests)) {
  			if (req.debugID.present())
  				g_traceBatch.addEvent("TransactionDebug", req.debugID.get().first(), "MasterProxyServer.queueTransactionStartRequests.Before");
  
  			stats->txnStartIn += req.transactionCount;
  			if (req.priority() >= GetReadVersionRequest::PRIORITY_SYSTEM_IMMEDIATE)
  				stats->txnSystemPriorityStartIn += req.transactionCount;
  			else if (req.priority() >= GetReadVersionRequest::PRIORITY_DEFAULT)
  				stats->txnDefaultPriorityStartIn += req.transactionCount;
  			else
  				stats->txnBatchPriorityStartIn += req.transactionCount;
  
  			if (transactionQueue->empty()) {
  				if (now() - *lastGRVTime > *GRVBatchTime)
  					*lastGRVTime = now() - *GRVBatchTime;
  
  				forwardPromise(GRVTimer, delayJittered(*GRVBatchTime - (now() - *lastGRVTime), TaskProxyGRVTimer));
  			}
  
  			transactionQueue->push(std::make_pair(req, counter--));
  		}
  		// dynamic batching monitors reply latencies
  		when(double reply_latency = waitNext(replyTimes)) {
  			double target_latency = reply_latency * SERVER_KNOBS->START_TRANSACTION_BATCH_INTERVAL_LATENCY_FRACTION;
  			*GRVBatchTime = 
  				std::max(SERVER_KNOBS->START_TRANSACTION_BATCH_INTERVAL_MIN, 
  					std::min(SERVER_KNOBS->START_TRANSACTION_BATCH_INTERVAL_MAX, 
  						target_latency * SERVER_KNOBS->START_TRANSACTION_BATCH_INTERVAL_SMOOTHER_ALPHA + *GRVBatchTime * (1-SERVER_KNOBS->START_TRANSACTION_BATCH_INTERVAL_SMOOTHER_ALPHA)));
  		}
  	}
  }
  
  ACTOR void discardCommit(UID id, Future<LogSystemDiskQueueAdapter::CommitMessage> fcm, Future<Void> dummyCommitState) {
  	ASSERT(!dummyCommitState.isReady());
  	LogSystemDiskQueueAdapter::CommitMessage cm = wait(fcm);
  	TraceEvent("Discarding", id).detail("Count", cm.messages.size());
  	cm.acknowledge.send(Void());
  	ASSERT(dummyCommitState.isReady());
  }
  
  DESCR struct SingleKeyMutation {
  	Standalone<StringRef> shardBegin;
  	Standalone<StringRef> shardEnd;
  	int64_t tag1;
  	int64_t tag2;
  	int64_t tag3;
  };
  
  struct ProxyCommitData {
  	UID dbgid;
  	int64_t commitBatchesMemBytesCount;
  	ProxyStats stats;
  	MasterInterface master;
  	vector<ResolverInterface> resolvers;
  	LogSystemDiskQueueAdapter* logAdapter;
  	Reference<ILogSystem> logSystem;
  	IKeyValueStore* txnStateStore;
  	NotifiedVersion committedVersion; // Provided that this recovery has succeeded or will succeed, this version is fully committed (durable)
  	Version minKnownCommittedVersion; // No version smaller than this one will be used as the known committed version during recovery 
  	Version version;  // The version at which txnStateStore is up to date
  	Promise<Void> validState;  // Set once txnStateStore and version are valid
  	double lastVersionTime;
  	KeyRangeMap<std::set<Key>> vecBackupKeys;
  	uint64_t commitVersionRequestNumber;
  	uint64_t mostRecentProcessedRequestNumber;
  	KeyRangeMap<Deque<std::pair<Version,int>>> keyResolvers;
  	KeyRangeMap<ServerCacheInfo> keyInfo;
  	std::map<Key, applyMutationsData> uid_applyMutationsData;
  	bool firstProxy;
  	double lastCoalesceTime;
  	bool locked;
  
  	int64_t localCommitBatchesStarted;
  	NotifiedVersion latestLocalCommitBatchResolving;
  	NotifiedVersion latestLocalCommitBatchLogging;
  
  	PromiseStream<Void> commitBatchStartNotifications;
  	PromiseStream<Future<GetCommitVersionReply>> commitBatchVersions;  // 1:1 with commitBatchStartNotifications
  	RequestStream<GetReadVersionRequest> getConsistentReadVersion;
  	RequestStream<CommitTransactionRequest> commit;
  	Database cx;
  	EventMetricHandle<SingleKeyMutation> singleKeyMutationEvent;
  
  	std::map<UID, Reference<StorageInfo>> storageCache;
  	std::map<Tag, Version> tag_popped;
  
  	//The tag related to a storage server rarely change, so we keep a vector of tags for each key range to be slightly more CPU efficient.
  	//When a tag related to a storage server does change, we empty out all of these vectors to signify they must be repopulated.
  	//We do not repopulate them immediately to avoid a slow task.
  	const vector<Tag>& tagsForKey(StringRef key) {
  		auto& tags = keyInfo[key].tags;
  		if(!tags.size()) {
  			auto& r = keyInfo.rangeContaining(key).value();
  			for(auto info : r.src_info) {
  				r.tags.push_back(info->tag);
  			}
  			for(auto info : r.dest_info) {
  				r.tags.push_back(info->tag);
  			}
  			uniquify(r.tags);
  			return r.tags;
  		}
  		return tags;
  	}
  
  	ProxyCommitData(UID dbgid, MasterInterface master, RequestStream<GetReadVersionRequest> getConsistentReadVersion, Version recoveryTransactionVersion, RequestStream<CommitTransactionRequest> commit, Reference<AsyncVar<ServerDBInfo>> db, bool firstProxy)
  		: dbgid(dbgid), stats(dbgid, &version, &committedVersion, &commitBatchesMemBytesCount), master(master),
  			logAdapter(NULL), txnStateStore(NULL),
  			committedVersion(recoveryTransactionVersion), version(0), minKnownCommittedVersion(0),
  			lastVersionTime(0), commitVersionRequestNumber(1), mostRecentProcessedRequestNumber(0),
  			getConsistentReadVersion(getConsistentReadVersion), commit(commit), lastCoalesceTime(0),
  			localCommitBatchesStarted(0), locked(false), firstProxy(firstProxy),
  			cx(openDBOnServer(db, TaskDefaultEndpoint, true, true)), singleKeyMutationEvent(LiteralStringRef("SingleKeyMutation")),
  			commitBatchesMemBytesCount(0)
  	{}
  };
  
  struct ResolutionRequestBuilder {
  	ProxyCommitData* self;
  	vector<ResolveTransactionBatchRequest> requests;
  	vector<vector<int>> transactionResolverMap;
  	vector<CommitTransactionRef*> outTr;
  
  	ResolutionRequestBuilder( ProxyCommitData* self, Version version, Version prevVersion, Version lastReceivedVersion) : self(self), requests(self->resolvers.size()) {
  		for(auto& req : requests) {
  			req.prevVersion = prevVersion;
  			req.version = version;
  			req.lastReceivedVersion = lastReceivedVersion;
  		}
  	}
  
  	CommitTransactionRef& getOutTransaction(int resolver, Version read_snapshot) {
  		CommitTransactionRef *& out = outTr[resolver];
  		if (!out) {
  			ResolveTransactionBatchRequest& request = requests[resolver];
  			request.transactions.resize(request.arena, request.transactions.size() + 1);
  			out = &request.transactions.back();
  			out->read_snapshot = read_snapshot;
  		}
  		return *out;
  	}
  
  	void addTransaction(CommitTransactionRef& trIn, int transactionNumberInBatch) {
  		// SOMEDAY: There are a couple of unnecessary O( # resolvers ) steps here
  		outTr.assign(requests.size(), NULL);
  		ASSERT( transactionNumberInBatch >= 0 && transactionNumberInBatch < 32768 );
  
  		bool isTXNStateTransaction = false;
  		for (auto & m : trIn.mutations) {
  			if (m.type == MutationRef::SetVersionstampedKey) {
  				transformVersionstampMutation( m, &MutationRef::param1, requests[0].version, transactionNumberInBatch );
  				trIn.write_conflict_ranges.push_back( requests[0].arena, singleKeyRange( m.param1, requests[0].arena ) );
  			} else if (m.type == MutationRef::SetVersionstampedValue) {
  				transformVersionstampMutation( m, &MutationRef::param2, requests[0].version, transactionNumberInBatch );
  			}
  			if (isMetadataMutation(m)) {
  				isTXNStateTransaction = true;
  				getOutTransaction(0, trIn.read_snapshot).mutations.push_back(requests[0].arena, m);
  			}
  		}
  		for(auto& r : trIn.read_conflict_ranges) {
  			auto ranges = self->keyResolvers.intersectingRanges( r );
  			std::set<int> resolvers;
  			for(auto &ir : ranges) {
  				auto& version_resolver = ir.value();
  				for(int i = version_resolver.size()-1; i >= 0; i--) {
  					resolvers.insert(version_resolver[i].second);
  					if( version_resolver[i].first < trIn.read_snapshot )
  						break;
  				}
  			}
  			ASSERT(resolvers.size());
  			for(int resolver : resolvers)
  				getOutTransaction( resolver, trIn.read_snapshot ).read_conflict_ranges.push_back( requests[resolver].arena, r );
  		}
  		for(auto& r : trIn.write_conflict_ranges) {
  			auto ranges = self->keyResolvers.intersectingRanges( r );
  			std::set<int> resolvers;
  			for(auto &ir : ranges)
  				resolvers.insert(ir.value().back().second);
  			ASSERT(resolvers.size());
  			for(int resolver : resolvers)
  				getOutTransaction( resolver, trIn.read_snapshot ).write_conflict_ranges.push_back( requests[resolver].arena, r );
  		}
  		if (isTXNStateTransaction)
  			for (int r = 0; r<requests.size(); r++) {
  				int transactionNumberInRequest = &getOutTransaction(r, trIn.read_snapshot) - requests[r].transactions.begin();
  				requests[r].txnStateTransactions.push_back(requests[r].arena, transactionNumberInRequest);
  			}
  
  		vector<int> resolversUsed;
  		for (int r = 0; r<outTr.size(); r++)
  			if (outTr[r])
  				resolversUsed.push_back(r);
  		transactionResolverMap.push_back(std::move(resolversUsed));
  	}
  };
  
  ACTOR Future<Void> commitBatch(
  	ProxyCommitData* self,
  	vector<CommitTransactionRequest> trs,
  	double *commitBatchTime,
  	int currentBatchMemBytesCount)
  {
  	state int64_t localBatchNumber = ++self->localCommitBatchesStarted;
  	state LogPushData toCommit(self->logSystem);
  	state double t1 = now();
  	state Optional<UID> debugID;
  	state bool forceRecovery = false;
  
  	ASSERT(SERVER_KNOBS->MAX_READ_TRANSACTION_LIFE_VERSIONS <= SERVER_KNOBS->MAX_VERSIONS_IN_FLIGHT);  // since we are using just the former to limit the number of versions actually in flight!
  
  	// Active load balancing runs at a very high priority (to obtain accurate estimate of memory used by commit batches) so we need to downgrade here
  	Void _ = wait(delay(0, TaskProxyCommit));
  
  	self->lastVersionTime = t1;
  
  	++self->stats.commitBatchIn;
  
  	for (int t = 0; t<trs.size(); t++) {
  		if (trs[t].debugID.present()) {
  			if (!debugID.present())
  				debugID = g_nondeterministic_random->randomUniqueID();
  			g_traceBatch.addAttach("CommitAttachID", trs[t].debugID.get().first(), debugID.get().first());
  		}
  	}
  
  	if(localBatchNumber == 2 && !debugID.present() && self->firstProxy && !g_network->isSimulated()) {
  		debugID = g_random->randomUniqueID();
  		TraceEvent("SecondCommitBatch", self->dbgid).detail("DebugID", debugID.get());
  	}
  
  	if (debugID.present())
  		g_traceBatch.addEvent("CommitDebug", debugID.get().first(), "MasterProxyServer.commitBatch.Before");
  
  	if (trs.empty()) {
  		// We are sending an empty batch, so we have to trigger the version fetcher
  		self->commitBatchStartNotifications.send(Void());
  	}
  
  	/////// Phase 1: Pre-resolution processing (CPU bound except waiting for a version # which is separately pipelined and *should* be available by now (unless empty commit); ordered; currently atomic but could yield)
  	TEST(self->latestLocalCommitBatchResolving.get() < localBatchNumber-1); // Queuing pre-resolution commit processing 
  	Void _ = wait(self->latestLocalCommitBatchResolving.whenAtLeast(localBatchNumber-1));
  	Void _ = wait(yield());
  
  	if (debugID.present())
  		g_traceBatch.addEvent("CommitDebug", debugID.get().first(), "MasterProxyServer.commitBatch.GettingCommitVersion");
  
  	Future<GetCommitVersionReply> fVersionReply = waitNext(self->commitBatchVersions.getFuture());
  	GetCommitVersionReply versionReply = wait(fVersionReply);
  	self->mostRecentProcessedRequestNumber = versionReply.requestNum;
  
  	self->stats.txnCommitVersionAssigned += trs.size();
  	self->stats.lastCommitVersionAssigned = versionReply.version;
  
  	state Version commitVersion = versionReply.version;
  	state Version prevVersion = versionReply.prevVersion;
  
  	for(auto it : versionReply.resolverChanges) {
  		auto rs = self->keyResolvers.modify(it.range);
  		for(auto r = rs.begin(); r != rs.end(); ++r)
  			r->value().push_back(std::make_pair(versionReply.resolverChangesVersion,it.dest));
  	}
  
  	//TraceEvent("ProxyGotVer", self->dbgid).detail("Commit", commitVersion).detail("Prev", prevVersion);
  
  	if (debugID.present())
  		g_traceBatch.addEvent("CommitDebug", debugID.get().first(), "MasterProxyServer.commitBatch.GotCommitVersion");
  
  	ResolutionRequestBuilder requests( self, commitVersion, prevVersion, self->version );
  	int conflictRangeCount = 0;
  	for (int t = 0; t<trs.size(); t++) {
  		requests.addTransaction(trs[t].transaction, t);
  		conflictRangeCount += trs[t].transaction.read_conflict_ranges.size() + trs[t].transaction.write_conflict_ranges.size();
  		//TraceEvent("MPTransactionDump", self->dbgid).detail("Snapshot", trs[t].transaction.read_snapshot);
  		//for(auto& m : trs[t].transaction.mutations)
  		//	TraceEvent("MPTransactionsDump", self->dbgid).detail("Mutation", m.toString());
  	}
  	self->stats.conflictRanges += conflictRangeCount;
  
  	for (int r = 1; r<self->resolvers.size(); r++)
  		ASSERT(requests.requests[r].txnStateTransactions.size() == requests.requests[0].txnStateTransactions.size());
  
  	// Sending these requests is the fuzzy border between phase 1 and phase 2; it could conceivably overlap with resolution processing but is still using CPU
  	self->stats.txnCommitResolving += trs.size();
  	vector< Future<ResolveTransactionBatchReply> > replies;
  	for (int r = 0; r<self->resolvers.size(); r++) {
  		requests.requests[r].debugID = debugID;
  		replies.push_back(brokenPromiseToNever(self->resolvers[r].resolve.getReply(requests.requests[r], TaskProxyResolverReply)));
  	}
  
  	state vector<vector<int>> transactionResolverMap = std::move( requests.transactionResolverMap );
  
  	ASSERT(self->latestLocalCommitBatchResolving.get() == localBatchNumber-1);
  	self->latestLocalCommitBatchResolving.set(localBatchNumber);
  
  	/////// Phase 2: Resolution (waiting on the network; pipelined)
  	state vector<ResolveTransactionBatchReply> resolution = wait( getAll(replies) );
  
  	if (debugID.present())
  		g_traceBatch.addEvent("CommitDebug", debugID.get().first(), "MasterProxyServer.commitBatch.AfterResolution");
  
  	////// Phase 3: Post-resolution processing (CPU bound except for very rare situations; ordered; currently atomic but doesn't need to be)
  	TEST(self->latestLocalCommitBatchLogging.get() < localBatchNumber-1); // Queuing post-resolution commit processing 
  	Void _ = wait(self->latestLocalCommitBatchLogging.whenAtLeast(localBatchNumber-1));
  	Void _ = wait(yield());
  
  	self->stats.txnCommitResolved += trs.size();
  
  	if (debugID.present())
  		g_traceBatch.addEvent("CommitDebug", debugID.get().first(), "MasterProxyServer.commitBatch.ProcessingMutations");
  
  	state Arena arena;
  	state bool isMyFirstBatch = !self->version;
  	state Optional<Value> oldCoordinators = self->txnStateStore->readValue(coordinatorsKey).get();
  
  	//TraceEvent("ResolutionResult", self->dbgid).detail("Sequence", sequence).detail("Version", commitVersion).detail("StateMutationProxies", resolution[0].stateMutations.size()).detail("WaitForResolution", now()-t1).detail("R0Committed", resolution[0].committed.size())
  	//	.detail("Transactions", trs.size());
  
  	for(int r=1; r<resolution.size(); r++) {
  		ASSERT( resolution[r].stateMutations.size() == resolution[0].stateMutations.size() );
  		for(int s=0; s<resolution[r].stateMutations.size(); s++)
  			ASSERT( resolution[r].stateMutations[s].size() == resolution[0].stateMutations[s].size() );
  	}
  
  	// Compute and apply "metadata" effects of each other proxy's most recent batch
  	bool initialState = isMyFirstBatch;
  	state bool firstStateMutations = isMyFirstBatch;
  	state vector< std::pair<Future<LogSystemDiskQueueAdapter::CommitMessage>, Future<Void>> > storeCommits;
  	for (int versionIndex = 0; versionIndex < resolution[0].stateMutations.size(); versionIndex++) {
  		// self->logAdapter->setNextVersion( ??? );  << Ideally we would be telling the log adapter that the pushes in this commit will be in the version at which these state mutations were committed by another proxy, but at present we don't have that information here.  So the disk queue may be unnecessarily conservative about popping.
  
  		for (int transactionIndex = 0; transactionIndex < resolution[0].stateMutations[versionIndex].size() && !forceRecovery; transactionIndex++) {
  			bool committed = true;
  			for (int resolver = 0; resolver < resolution.size(); resolver++)
  				committed = committed && resolution[resolver].stateMutations[versionIndex][transactionIndex].committed;
  			if (committed)
  				applyMetadataMutations( self->dbgid, arena, resolution[0].stateMutations[versionIndex][transactionIndex].mutations, self->txnStateStore, NULL, &forceRecovery, self->logSystem, 0, &self->vecBackupKeys, &self->keyInfo, self->firstProxy ? &self->uid_applyMutationsData : NULL, self->commit, self->cx, &self->committedVersion, &self->storageCache, &self->tag_popped);
  			
  			if( resolution[0].stateMutations[versionIndex][transactionIndex].mutations.size() && firstStateMutations ) {
  				ASSERT(committed);
  				firstStateMutations = false;
  				forceRecovery = false;
  			}
  			//TraceEvent("MetadataTransaction", self->dbgid).detail("Committed", committed).detail("Mutations", resolution[0].stateMutations[versionIndex][transactionIndex].second.size()).detail("R1Mutations", resolution.back().stateMutations[versionIndex][transactionIndex].second.size());
  		}
  		//TraceEvent("MetadataBatch", self->dbgid).detail("Transactions", resolution[0].stateMutations[versionIndex].size());
  
  		// These changes to txnStateStore will be committed by the other proxy, so we simply discard the commit message
  		auto fcm = self->logAdapter->getCommitMessage();
  		storeCommits.push_back(std::make_pair(fcm, self->txnStateStore->commit()));
  		//discardCommit( dbgid, fcm, txnStateStore->commit() );
  
  		if (initialState) {
  			//TraceEvent("ResyncLog", dbgid);
  			initialState = false;
  			forceRecovery = false;
  			self->txnStateStore->resyncLog();
  
  			for (auto &p : storeCommits) {
  				ASSERT(!p.second.isReady());
  				p.first.get().acknowledge.send(Void());
  				ASSERT(p.second.isReady());
  			}
  			storeCommits.clear();
  		}
  	}
  
  	// Determine which transactions actually committed (conservatively) by combining results from the resolvers
  	state vector<uint8_t> committed(trs.size());
  	ASSERT(transactionResolverMap.size() == committed.size());
  	vector<int> nextTr(resolution.size());
  	for (int t = 0; t<trs.size(); t++) {
  		uint8_t commit = ConflictBatch::TransactionCommitted;
  		for (int r : transactionResolverMap[t])
  		{
  			commit = std::min(resolution[r].committed[nextTr[r]++], commit);
  		}
  		committed[t] = commit;
  	}
  	for (int r = 0; r<resolution.size(); r++)
  		ASSERT(nextTr[r] == resolution[r].committed.size());
  
  	self->logAdapter->setNextVersion(commitVersion);
  
  	state Optional<Key> lockedKey = self->txnStateStore->readValue(databaseLockedKey).get();
  	state bool locked = lockedKey.present() && lockedKey.get().size();
  
  	if(forceRecovery) {
  		Void _ = wait( Future<Void>(Never()) );
  	}
  
  	// This first pass through committed transactions deals with "metadata" effects (modifications of txnStateStore, changes to storage servers' responsibilities)
  	int t;
  	state int commitCount = 0;
  	for (t = 0; t < trs.size() && !forceRecovery; t++)
  	{
  		if (committed[t] == ConflictBatch::TransactionCommitted && (!locked || trs[t].isLockAware())) {
  			commitCount++;
  			applyMetadataMutations(self->dbgid, arena, trs[t].transaction.mutations, self->txnStateStore, &toCommit, &forceRecovery, self->logSystem, commitVersion+1, &self->vecBackupKeys, &self->keyInfo, self->firstProxy ? &self->uid_applyMutationsData : NULL, self->commit, self->cx, &self->committedVersion, &self->storageCache, &self->tag_popped);
  		}
  		if(firstStateMutations) {
  			ASSERT(committed[t] == ConflictBatch::TransactionCommitted);
  			firstStateMutations = false;
  			forceRecovery = false;
  		}
  	}
  	if (forceRecovery) {
  		for (; t<trs.size(); t++)
  			committed[t] = ConflictBatch::TransactionConflict;
  		TraceEvent(SevWarn, "RestartingTxnSubsystem", self->dbgid).detail("Stage", "AwaitCommit");
  	}
  
  	lockedKey = self->txnStateStore->readValue(databaseLockedKey).get();
  	state bool lockedAfter = lockedKey.present() && lockedKey.get().size();
  
  	auto fcm = self->logAdapter->getCommitMessage();
  	storeCommits.push_back(std::make_pair(fcm, self->txnStateStore->commit()));
  	self->version = commitVersion;
  	if (!self->validState.isSet()) self->validState.send(Void());
  	ASSERT(commitVersion);
  
  	if (!isMyFirstBatch && self->txnStateStore->readValue( coordinatorsKey ).get().get() != oldCoordinators.get()) {
  		Void _ = wait( brokenPromiseToNever( self->master.changeCoordinators.getReply( ChangeCoordinatorsRequest( self->txnStateStore->readValue( coordinatorsKey ).get().get() ) ) ) );
  		ASSERT(false);   // ChangeCoordinatorsRequest should always throw
  	}
  
  	// This second pass through committed transactions assigns the actual mutations to the appropriate storage servers' tags
  	int mutationCount = 0, mutationBytes = 0;
  	
  	state std::map<Key, MutationListRef> logRangeMutations;
  	state Arena logRangeMutationsArena;
  	state uint32_t v = commitVersion / CLIENT_KNOBS->LOG_RANGE_BLOCK_SIZE;
  
  	for (int t = 0; t<trs.size(); t++) {
  
  		if (committed[t] == ConflictBatch::TransactionCommitted && (!locked || trs[t].isLockAware())) {
  
  			for (auto m : trs[t].transaction.mutations) {
  				mutationCount++;
  				mutationBytes += m.expectedSize();
  				// Determine the set of tags (responsible storage servers) for the mutation, splitting it
  				// if necessary.  Serialize (splits of) the mutation into the message buffer and add the tags.
  
  				if (isSingleKeyMutation((MutationRef::Type) m.type)) {
  					auto& tags = self->tagsForKey(m.param1);
  	
  					if(self->singleKeyMutationEvent->enabled) {
  						KeyRangeRef shard = self->keyInfo.rangeContaining(m.param1).range();
  						self->singleKeyMutationEvent->tag1 = (int64_t)tags[0].id;
  						self->singleKeyMutationEvent->tag2 = (int64_t)tags[1].id;
  						self->singleKeyMutationEvent->tag3 = (int64_t)tags[2].id;
  						self->singleKeyMutationEvent->shardBegin = shard.begin;
  						self->singleKeyMutationEvent->shardEnd = shard.end;
  						self->singleKeyMutationEvent->log();
  					}
  
  					if (debugMutation("ProxyCommit", commitVersion, m))
  						TraceEvent("ProxyCommitTo", self->dbgid).detail("To", describe(tags)).detail("Mutation", m.toString()).detail("Version", commitVersion);
  					for (auto& tag : tags)
  						toCommit.addTag(tag);
  					toCommit.addTypedMessage(m);
  				}
  				else if (m.type == MutationRef::ClearRange) {
  					auto ranges = self->keyInfo.intersectingRanges(KeyRangeRef(m.param1, m.param2));
  					auto firstRange = ranges.begin();
  					++firstRange;
  					if (firstRange == ranges.end()) {
  						// Fast path
  						if (debugMutation("ProxyCommit", commitVersion, m))
  							TraceEvent("ProxyCommitTo", self->dbgid).detail("To", describe(ranges.begin().value().tags)).detail("Mutation", m.toString()).detail("Version", commitVersion);
  						
  						auto& tags = ranges.begin().value().tags;
  						if(!tags.size()) {
  							for( auto info : ranges.begin().value().src_info ) {
  								tags.push_back( info->tag );
  							}
  							for( auto info : ranges.begin().value().dest_info ) {
  								tags.push_back( info->tag );
  							}
  							uniquify(tags);
  						}
  						
  						for (auto& tag : tags)
  							toCommit.addTag(tag);
  					}
  					else {
  						TEST(true); //A clear range extends past a shard boundary
  						std::set<Tag> allSources;
  						for (auto r : ranges) {
  							auto& tags = r.value().tags;
  							if(!tags.size()) {
  								for( auto info : r.value().src_info ) {
  									tags.push_back(info->tag);
  								}
  								for( auto info : r.value().dest_info ) {
  									tags.push_back(info->tag);
  								}
  								uniquify(tags);
  							}
  							allSources.insert(tags.begin(), tags.end());
  						}
  						if (debugMutation("ProxyCommit", commitVersion, m))
  							TraceEvent("ProxyCommitTo", self->dbgid).detail("To", describe(allSources)).detail("Mutation", m.toString()).detail("Version", commitVersion);
  						for (auto& tag : allSources)
  							toCommit.addTag(tag);
  					}
  					toCommit.addTypedMessage(m);
  				}
  				else
  					UNREACHABLE();
  
  				// Check on backing up key, if backup ranges are defined and a normal key
  				if  ((self->vecBackupKeys.size() > 1) && normalKeys.contains(m.param1)) {
  
  					if (isAtomicOp((MutationRef::Type)m.type)) {
  						// Add the mutation to the relevant backup tag
  						for (auto backupName : self->vecBackupKeys[m.param1]) {
  							logRangeMutations[backupName].push_back_deep(logRangeMutationsArena, m);
  						}
  					}
  					else {
  						switch (m.type)
  						{
  							// Backup the mutation, if within a backup range
  						case MutationRef::Type::SetValue:
  							// Add the mutation to the relevant backup tag
  							for (auto backupName : self->vecBackupKeys[m.param1]) {
  								logRangeMutations[backupName].push_back_deep(logRangeMutationsArena, m);
  							}
  							break;
  
  						case MutationRef::Type::ClearRange:
  							{
  								KeyRangeRef mutationRange(m.param1, m.param2);
  								KeyRangeRef intersectionRange;
  
  								// Identify and add the intersecting ranges of the mutation to the array of mutations to serialize
  								for (auto backupRange : self->vecBackupKeys.intersectingRanges(mutationRange))
  								{
  									// Get the backup sub range
  									const auto&		backupSubrange = backupRange.range();
  
  									// Determine the intersecting range
  									intersectionRange = mutationRange & backupSubrange;
  
  									// Create the custom mutation for the specific backup tag
  									MutationRef		backupMutation(MutationRef::Type::ClearRange, intersectionRange.begin, intersectionRange.end);
  
  									// Add the mutation to the relevant backup tag
  									for (auto backupName : backupRange.value()) {
  										logRangeMutations[backupName].push_back_deep(logRangeMutationsArena, backupMutation);
  									}
  								}
  							}
  							break;
  
  						default:
  							UNREACHABLE();
  							break;
  						}
  					}
  				}
  			}
  		}
  	}
  
  	// Serialize and backup the mutations as a single mutation
  	if ((self->vecBackupKeys.size() > 1) && logRangeMutations.size()) {
  
  		Key			val;
  		MutationRef backupMutation;
  		uint32_t*	partBuffer = NULL;
  
  		// Serialize the log range mutations within the map
  		for (auto& logRangeMutation : logRangeMutations)
  		{
  			BinaryWriter wr(Unversioned());
  
  			// Serialize the log destination
  			wr.serializeBytes( logRangeMutation.first );
  
  			// Write the log keys and version information
  			wr << (uint8_t)hashlittle(&v, sizeof(v), 0);
  			wr << bigEndian64(commitVersion);
  
  			backupMutation.type = MutationRef::SetValue;
  			partBuffer = NULL;
  
  			val = BinaryWriter::toValue(logRangeMutation.second, IncludeVersion());
  
  			for (int part = 0; part * CLIENT_KNOBS->MUTATION_BLOCK_SIZE < val.size(); part++) {
  
  				// Assign the second parameter as the part
  				backupMutation.param2 = val.substr(part * CLIENT_KNOBS->MUTATION_BLOCK_SIZE,
  					std::min(val.size() - part * CLIENT_KNOBS->MUTATION_BLOCK_SIZE, CLIENT_KNOBS->MUTATION_BLOCK_SIZE));
  
  				// Write the last part of the mutation to the serialization, if the buffer is not defined
  				if (!partBuffer) {
  					// Serialize the part to the writer
  					wr << bigEndian32(part);
  
  					// Define the last buffer part
  					partBuffer = (uint32_t*) ((char*) wr.getData() + wr.getLength() - sizeof(uint32_t));
  				}
  				else {
  					*partBuffer = bigEndian32(part);
  				}
  
  				// Define the mutation type and and location
  				backupMutation.param1 = wr.toStringRef();
  				ASSERT( backupMutation.param1.startsWith(logRangeMutation.first) );  // We are writing into the configured destination
  					
  				auto& tags = self->tagsForKey(backupMutation.param1);
  				for (auto& tag : tags)
  					toCommit.addTag(tag);
  				toCommit.addTypedMessage(backupMutation);
  
  //				if (debugMutation("BackupProxyCommit", commitVersion, backupMutation)) {
  //					TraceEvent("BackupProxyCommitTo", self->dbgid).detail("To", describe(tags)).detail("BackupMutation", backupMutation.toString())
  //						.detail("BackupMutationSize", val.size()).detail("Version", commitVersion).detail("DestPath", printable(logRangeMutation.first))
  //						.detail("PartIndex", part).detail("PartIndexEndian", bigEndian32(part)).detail("PartData", printable(backupMutation.param1));
  //				}
  			}
  		}
  	}
  
  	self->stats.mutations += mutationCount;
  	self->stats.mutationBytes += mutationBytes;
  
  	// Storage servers mustn't make durable versions which are not fully committed (because then they are impossible to roll back)
  	// We prevent this by limiting the number of versions which are semi-committed but not fully committed to be less than the MVCC window
  	while (self->committedVersion.get() < commitVersion - SERVER_KNOBS->MAX_READ_TRANSACTION_LIFE_VERSIONS) {
  		// This should be *extremely* rare in the real world, but knob buggification should make it happen in simulation
  		TEST(true);  // Semi-committed pipeline limited by MVCC window
  		//TraceEvent("ProxyWaitingForCommitted", self->dbgid).detail("CommittedVersion", self->committedVersion.get()).detail("NeedToCommit", commitVersion);
  		choose{
  			when(Void _ = wait(self->committedVersion.whenAtLeast(commitVersion - SERVER_KNOBS->MAX_READ_TRANSACTION_LIFE_VERSIONS))) {
  				Void _ = wait(yield());
  				break; 
  			}
  			when(GetReadVersionReply v = wait(self->getConsistentReadVersion.getReply(GetReadVersionRequest(0, GetReadVersionRequest::PRIORITY_SYSTEM_IMMEDIATE | GetReadVersionRequest::FLAG_CAUSAL_READ_RISKY)))) {
  				if(v.version > self->committedVersion.get()) {
  					self->locked = v.locked;
  					self->committedVersion.set(v.version);
  				}
  				
  				if (self->committedVersion.get() < commitVersion - SERVER_KNOBS->MAX_READ_TRANSACTION_LIFE_VERSIONS)
  					Void _ = wait(delay(SERVER_KNOBS->PROXY_SPIN_DELAY));
  			}
  		}
  	}
  
  	state LogSystemDiskQueueAdapter::CommitMessage msg = wait(storeCommits.back().first); // Should just be doing yields
  
  	if (debugID.present())
  		g_traceBatch.addEvent("CommitDebug", debugID.get().first(), "MasterProxyServer.commitBatch.AfterStoreCommits");
  
  	// txnState (transaction subsystem state) tag: message extracted from log adapter
  	bool firstMessage = true;
  	for(auto m : msg.messages) {
  		if(firstMessage) {
  			toCommit.addTag(txsTag);
  		}
  		toCommit.addMessage(StringRef(m.begin(), m.size()), !firstMessage);
  		firstMessage = false;
  	}
  
  	if ( prevVersion && commitVersion - prevVersion < SERVER_KNOBS->MAX_VERSIONS_IN_FLIGHT/2 )
  		debug_advanceMaxCommittedVersion( UID(), commitVersion );  //< Is this valid?
  
  	//TraceEvent("ProxyPush", self->dbgid).detail("PrevVersion", prevVersion).detail("Version", commitVersion)
  	//	.detail("TransactionsSubmitted", trs.size()).detail("TransactionsCommitted", commitCount).detail("TxsPopTo", msg.popTo);
  
  	if ( prevVersion && commitVersion - prevVersion < SERVER_KNOBS->MAX_VERSIONS_IN_FLIGHT/2 )
  		debug_advanceMaxCommittedVersion(UID(), commitVersion);
  
  	Future<Version> loggingComplete = self->logSystem->push( prevVersion, commitVersion, self->committedVersion.get(), self->minKnownCommittedVersion, toCommit, debugID );
  
  	if (!forceRecovery) {
  		ASSERT(self->latestLocalCommitBatchLogging.get() == localBatchNumber-1);
  		self->latestLocalCommitBatchLogging.set(localBatchNumber);
  	}
  
  	/////// Phase 4: Logging (network bound; pipelined up to MAX_READ_TRANSACTION_LIFE_VERSIONS (limited by loop above))
  
  	try {
  		choose {
  			when(Version ver = wait(loggingComplete)) {
  				self->minKnownCommittedVersion = std::max(self->minKnownCommittedVersion, ver);
  			}
  			when(Void _ = wait(self->committedVersion.whenAtLeast( commitVersion+1 ))) {}
  		}
  	} catch(Error &e) {
  		if(e.code() == error_code_broken_promise) {
  			throw master_tlog_failed();
  		}
  		throw;
  	}
  	Void _ = wait(yield());
  
  	self->logSystem->pop(msg.popTo, txsTag);
  
  	/////// Phase 5: Replies (CPU bound; no particular order required, though ordered execution would be best for latency)
  	if ( prevVersion && commitVersion - prevVersion < SERVER_KNOBS->MAX_VERSIONS_IN_FLIGHT/2 )
  		debug_advanceMinCommittedVersion(UID(), commitVersion);
  
  	//TraceEvent("ProxyPushed", self->dbgid).detail("PrevVersion", prevVersion).detail("Version", commitVersion);
  	if (debugID.present())
  		g_traceBatch.addEvent("CommitDebug", debugID.get().first(), "MasterProxyServer.commitBatch.AfterLogPush");
  
  	for (auto &p : storeCommits) {
  		ASSERT(!p.second.isReady());
  		p.first.get().acknowledge.send(Void());
  		ASSERT(p.second.isReady());
  	}
  
  	TEST(self->committedVersion.get() > commitVersion);   // A later version was reported committed first
  	if( commitVersion > self->committedVersion.get() ) {
  		self->locked = lockedAfter;
  		self->committedVersion.set(commitVersion);
  	}
  
  	if (forceRecovery) {
  		TraceEvent(SevWarn, "RestartingTxnSubsystem", self->dbgid).detail("Stage", "ProxyShutdown");
  		throw worker_removed();
  	}
  
  	// Send replies to clients
  	for (int t = 0; t < trs.size(); t++)
  	{
  		if (committed[t] == ConflictBatch::TransactionCommitted && (!locked || trs[t].isLockAware())) {
  			ASSERT_WE_THINK(commitVersion != invalidVersion);
  			trs[t].reply.send(CommitID(commitVersion, t));
  		}
  		else if (committed[t] == ConflictBatch::TransactionTooOld)
  			trs[t].reply.sendError(transaction_too_old());
  		else
  			trs[t].reply.sendError(not_committed());
  	}
  
  	++self->stats.commitBatchOut;
  	self->stats.txnCommitOut += trs.size();
  	self->stats.txnConflicts += trs.size() - commitCount;
  	self->stats.txnCommitOutSuccess += commitCount;
  
  	if(now() - self->lastCoalesceTime > SERVER_KNOBS->RESOLVER_COALESCE_TIME) {
  		self->lastCoalesceTime = now();
  		int lastSize = self->keyResolvers.size();
  		auto rs = self->keyResolvers.ranges();
  		Version oldestVersion = prevVersion - SERVER_KNOBS->MAX_WRITE_TRANSACTION_LIFE_VERSIONS;
  		for(auto r = rs.begin(); r != rs.end(); ++r) {
  			while(r->value().size() > 1 && r->value()[1].first < oldestVersion)
  				r->value().pop_front();
  			if(r->value().size() && r->value().front().first < oldestVersion)
  				r->value().front().first = 0;
  		}
  		self->keyResolvers.coalesce(allKeys);
  		if(self->keyResolvers.size() != lastSize)
  			TraceEvent("KeyResolverSize", self->dbgid).detail("Size", self->keyResolvers.size());
  	}
  
  	// Dynamic batching for commits
  	double target_latency = (now() - t1) * SERVER_KNOBS->COMMIT_TRANSACTION_BATCH_INTERVAL_LATENCY_FRACTION;
  	*commitBatchTime = 
  		std::max(SERVER_KNOBS->COMMIT_TRANSACTION_BATCH_INTERVAL_MIN, 
  			std::min(SERVER_KNOBS->COMMIT_TRANSACTION_BATCH_INTERVAL_MAX, 
  				target_latency * SERVER_KNOBS->COMMIT_TRANSACTION_BATCH_INTERVAL_SMOOTHER_ALPHA + *commitBatchTime * (1-SERVER_KNOBS->COMMIT_TRANSACTION_BATCH_INTERVAL_SMOOTHER_ALPHA)));
  
  
  	self->commitBatchesMemBytesCount -= currentBatchMemBytesCount;
  	ASSERT_ABORT(self->commitBatchesMemBytesCount >= 0);
  	return Void();
  }
  
  
  ACTOR Future<GetReadVersionReply> getLiveCommittedVersion(ProxyCommitData* commitData, uint32_t flags, vector<MasterProxyInterface> *otherProxies, Optional<UID> debugID, int transactionCount, int systemTransactionCount, int defaultPriTransactionCount, int batchPriTransactionCount)
  {
  	// Returns a version which (1) is committed, and (2) is >= the latest version reported committed (by a commit response) when this request was sent
  	// (1) The version returned is the committedVersion of some proxy at some point before the request returns, so it is committed.
  	// (2) No proxy on our list reported committed a higher version before this request was received, because then its committedVersion would have been higher,
  	//     and no other proxy could have already committed anything without first ending the epoch
  	++commitData->stats.txnStartBatch;
  
  	state vector<Future<GetReadVersionReply>> proxyVersions;
  	for (auto const& p : *otherProxies)
  		proxyVersions.push_back(brokenPromiseToNever(p.getRawCommittedVersion.getReply(GetRawCommittedVersionRequest(debugID), TaskTLogConfirmRunningReply)));
  
  	if (!(flags&GetReadVersionRequest::FLAG_CAUSAL_READ_RISKY))
  	{
  		Void _ = wait(commitData->logSystem->confirmEpochLive(debugID));
  	}
  
  	if (debugID.present())
  		g_traceBatch.addEvent("TransactionDebug", debugID.get().first(), "MasterProxyServer.getLiveCommittedVersion.confirmEpochLive");
  
  	vector<GetReadVersionReply> versions = wait(getAll(proxyVersions));
  	GetReadVersionReply rep;
  	rep.version = commitData->committedVersion.get();
  	rep.locked = commitData->locked;
  	
  	for (auto v : versions) {
  		if(v.version > rep.version) {
  			rep = v;
  		}
  	}
  
  	if (debugID.present())
  		g_traceBatch.addEvent("TransactionDebug", debugID.get().first(), "MasterProxyServer.getLiveCommittedVersion.After");
  
  	commitData->stats.txnStartOut += transactionCount;
  	commitData->stats.txnSystemPriorityStartOut += systemTransactionCount;
  	commitData->stats.txnDefaultPriorityStartOut += defaultPriTransactionCount;
  	commitData->stats.txnBatchPriorityStartOut += batchPriTransactionCount;
  
  	return rep;
  }
  
  ACTOR Future<Void> fetchVersions(ProxyCommitData *commitData) {
  	loop {
  		Void _ = waitNext(commitData->commitBatchStartNotifications.getFuture());
  		GetCommitVersionRequest req(commitData->commitVersionRequestNumber++, commitData->mostRecentProcessedRequestNumber, commitData->dbgid);
  		commitData->commitBatchVersions.send(brokenPromiseToNever(commitData->master.getCommitVersion.getReply(req)));
  	}
  }
  
  ACTOR static Future<Void> transactionStarter(
  	MasterProxyInterface proxy,
  	MasterInterface master,
  	Reference<AsyncVar<ServerDBInfo>> db,
  	PromiseStream<Future<Void>> addActor,
  	ProxyCommitData* commitData
  	)
  {
  	state double lastGRVTime = 0;
  	state PromiseStream<Void> GRVTimer;
  	state double GRVBatchTime = SERVER_KNOBS->START_TRANSACTION_BATCH_INTERVAL_MIN;
  
  	state int64_t transactionCount = 0;
  	state double transactionBudget = 0;
  	state double transactionRate = 10;
  	state std::priority_queue<std::pair<GetReadVersionRequest, int64_t>, std::vector<std::pair<GetReadVersionRequest, int64_t>>> transactionQueue;
  	state vector<MasterProxyInterface> otherProxies;
  
  	state PromiseStream<double> replyTimes;
  	addActor.send(getRate(proxy.id(), master, &transactionCount, &transactionRate));
  	addActor.send(queueTransactionStartRequests(&transactionQueue, proxy.getConsistentReadVersion.getFuture(), GRVTimer, &lastGRVTime, &GRVBatchTime, replyTimes.getFuture(), &commitData->stats));
  
  	// Get a list of the other proxies that go together with us
  	while (std::find(db->get().client.proxies.begin(), db->get().client.proxies.end(), proxy) == db->get().client.proxies.end())
  		Void _ = wait(db->onChange());
  	for (MasterProxyInterface mp : db->get().client.proxies) {
  		if (mp != proxy)
  			otherProxies.push_back(mp);
  	}
  
  	ASSERT(db->get().recoveryState >= RecoveryState::ACCEPTING_COMMITS);  // else potentially we could return uncommitted read versions (since self->committedVersion is only a committed version if this recovery succeeds)
  
  	TraceEvent("ProxyReadyForTxnStarts", proxy.id());
  
  	loop{
  		Void _ = waitNext(GRVTimer.getFuture());
  		// Select zero or more transactions to start
  		double t = now();
  		double elapsed = std::min<double>(now() - lastGRVTime, SERVER_KNOBS->START_TRANSACTION_BATCH_INTERVAL_MAX);
  		lastGRVTime = t;
  
  		if(elapsed == 0) elapsed = 1e-15; // resolve a possible indeterminant multiplication with infinite transaction rate
  		double nTransactionsToStart = std::min(transactionRate * elapsed, SERVER_KNOBS->START_TRANSACTION_MAX_TRANSACTIONS_TO_START) + transactionBudget;
  
  		int transactionsStarted[2] = {0,0};
  		int systemTransactionsStarted[2] = {0,0};
  		int defaultPriTransactionsStarted[2] = { 0, 0 };
  		int batchPriTransactionsStarted[2] = { 0, 0 };
  
  		vector<vector<ReplyPromise<GetReadVersionReply>>> start(2);  // start[0] is transactions starting with !(flags&CAUSAL_READ_RISKY), start[1] is transactions starting with flags&CAUSAL_READ_RISKY
  		Optional<UID> debugID;
  
  		double leftToStart = 0;
  		while (!transactionQueue.empty()) {
  			auto& req = transactionQueue.top().first;
  			int tc = req.transactionCount;
  			leftToStart = nTransactionsToStart - transactionsStarted[0] - transactionsStarted[1];
  
  			bool startNext = tc < leftToStart || req.priority() >= GetReadVersionRequest::PRIORITY_SYSTEM_IMMEDIATE || tc * g_random->random01() < leftToStart - std::max(0.0, transactionBudget);
  			if (!startNext) break;
  
  			if (req.debugID.present()) {
  				if (!debugID.present()) debugID = g_nondeterministic_random->randomUniqueID();
  				g_traceBatch.addAttach("TransactionAttachID", req.debugID.get().first(), debugID.get().first());
  			}
  			start[req.flags & 1].push_back(std::move(req.reply));  static_assert(GetReadVersionRequest::FLAG_CAUSAL_READ_RISKY == 1, "Implementation dependent on flag value");
  
  			transactionsStarted[req.flags&1] += tc;
  			if (req.priority() >= GetReadVersionRequest::PRIORITY_SYSTEM_IMMEDIATE)
  				systemTransactionsStarted[req.flags & 1] += tc;
  			else if (req.priority() >= GetReadVersionRequest::PRIORITY_DEFAULT)
  				defaultPriTransactionsStarted[req.flags & 1] += tc;
  			else
  				batchPriTransactionsStarted[req.flags & 1] += tc;
  
  			transactionQueue.pop();
  		}
  
  		if (!transactionQueue.empty())
  			forwardPromise(GRVTimer, delayJittered(SERVER_KNOBS->START_TRANSACTION_BATCH_QUEUE_CHECK_INTERVAL, TaskProxyGRVTimer));
  
  		/*TraceEvent("GRVBatch", proxy.id())
  		.detail("Elapsed", elapsed)
  		.detail("NTransactionToStart", nTransactionsToStart)
  		.detail("TransactionRate", transactionRate)
  		.detail("TransactionQueueSize", transactionQueue.size())
  		.detail("NumTransactionsStarted", transactionsStarted[0] + transactionsStarted[1]) 
  		.detail("NumSystemTransactionsStarted", systemTransactionsStarted[0] + systemTransactionsStarted[1])
  		.detail("NumNonSystemTransactionsStarted", transactionsStarted[0] + transactionsStarted[1] - systemTransactionsStarted[0] - systemTransactionsStarted[1])
  		.detail("TransactionBudget", transactionBudget)
  		.detail("LastLeftToStart", leftToStart);*/
  
  		// dynamic batching
  		ReplyPromise<GetReadVersionReply> GRVReply;
  		if (start[0].size()){
  			start[0].push_back(GRVReply); // for now, base dynamic batching on the time for normal requests (not read_risky)
  			addActor.send(timeReply(GRVReply.getFuture(), replyTimes));
  		}
  
  		transactionCount += transactionsStarted[0] + transactionsStarted[1];
  		transactionBudget = std::max(std::min(nTransactionsToStart - transactionsStarted[0] - transactionsStarted[1], SERVER_KNOBS->START_TRANSACTION_MAX_BUDGET_SIZE), -SERVER_KNOBS->START_TRANSACTION_MAX_BUDGET_SIZE);
  		if (debugID.present())
  			g_traceBatch.addEvent("TransactionDebug", debugID.get().first(), "MasterProxyServer.masterProxyServerCore.Broadcast");
  		for (int i = 0; i<start.size(); i++) {
  			if (start[i].size()) {
  				addActor.send(broadcast(getLiveCommittedVersion(commitData, i, &otherProxies, debugID, transactionsStarted[i], systemTransactionsStarted[i], defaultPriTransactionsStarted[i], batchPriTransactionsStarted[i]), start[i]));
  			}
  		}
  	}
  }
  
  ACTOR static Future<Void> readRequestServer(
  	MasterProxyInterface proxy,
  	ProxyCommitData* commitData
  	)
  {
  	// Implement read-only parts of the proxy interface
  
  	// We can't respond to these requests until we have valid txnStateStore
  	Void _ = wait(commitData->validState.getFuture());
  
  	TraceEvent("ProxyReadyForReads", proxy.id());
  
  	loop {
  		choose{
  			when(GetKeyServerLocationsRequest req = waitNext(proxy.getKeyServersLocations.getFuture())) {
  				GetKeyServerLocationsReply rep;
  				if(!req.end.present()) {
  					auto r = req.reverse ? commitData->keyInfo.rangeContainingKeyBefore(req.begin) : commitData->keyInfo.rangeContaining(req.begin);
  					vector<StorageServerInterface> ssis;
  					ssis.reserve(r.value().src_info.size());
  					for(auto& it : r.value().src_info) {
  						ssis.push_back(it->interf);
  					}
  					rep.results.push_back(std::make_pair(r.range(), ssis));
  				} else if(!req.reverse) {
  					int count = 0;
  					for(auto r = commitData->keyInfo.rangeContaining(req.begin); r != commitData->keyInfo.ranges().end() && count < req.limit && r.begin() < req.end.get(); ++r) {
  						vector<StorageServerInterface> ssis;
  						ssis.reserve(r.value().src_info.size());
  						for(auto& it : r.value().src_info) {
  							ssis.push_back(it->interf);
  						}
  						rep.results.push_back(std::make_pair(r.range(), ssis));
  						count++;
  					}
  				} else {
  					int count = 0;
  					auto r = commitData->keyInfo.rangeContainingKeyBefore(req.end.get());
  					while( count < req.limit && req.begin < r.end() ) {
  						vector<StorageServerInterface> ssis;
  						ssis.reserve(r.value().src_info.size());
  						for(auto& it : r.value().src_info) {
  							ssis.push_back(it->interf);
  						}
  						rep.results.push_back(std::make_pair(r.range(), ssis));
  						if(r == commitData->keyInfo.ranges().begin()) {
  							break;
  						}
  						count++;
  						--r;
  					}
  				}
  				req.reply.send(rep);
  			}
  			when(GetStorageServerRejoinInfoRequest req = waitNext(proxy.getStorageServerRejoinInfo.getFuture())) {
  				if (commitData->txnStateStore->readValue(serverListKeyFor(req.id)).get().present()) {
  					GetStorageServerRejoinInfoReply rep;
  					rep.version = commitData->version;
  					rep.tag = decodeServerTagValue( commitData->txnStateStore->readValue(serverTagKeyFor(req.id)).get().get() );
  					Standalone<VectorRef<KeyValueRef>> history = commitData->txnStateStore->readRange(serverTagHistoryRangeFor(req.id)).get();
  					for(int i = history.size()-1; i >= 0; i-- ) {
  						rep.history.push_back(std::make_pair(decodeServerTagHistoryKey(history[i].key), decodeServerTagValue(history[i].value)));
  					}
  					auto localityKey = commitData->txnStateStore->readValue(tagLocalityListKeyFor(req.dcId)).get();
  					if( localityKey.present() ) {
  						rep.newLocality = false;
  						int8_t locality = decodeTagLocalityListValue(localityKey.get());
  						if(locality != rep.tag.locality) {
  							uint16_t tagId = 0;
  							std::vector<uint16_t> usedTags;
  							auto tagKeys = commitData->txnStateStore->readRange(serverTagKeys).get();
  							for( auto& kv : tagKeys ) {
  								Tag t = decodeServerTagValue( kv.value );
  								if(t.locality == locality) {
  									usedTags.push_back(t.id);
  								}
  							}
  							auto historyKeys = commitData->txnStateStore->readRange(serverTagHistoryKeys).get();
  							for( auto& kv : historyKeys ) {
  								Tag t = decodeServerTagValue( kv.value );
  								if(t.locality == locality) {
  									usedTags.push_back(t.id);
  								}
  							}
  							std::sort(usedTags.begin(), usedTags.end());
  
  							int usedIdx = 0;
  							for(; usedTags.size() > 0 && tagId <= usedTags.end()[-1]; tagId++) {
  								if(tagId < usedTags[usedIdx]) {
  									break;
  								} else {
  									usedIdx++;
  								}
  							}
  							rep.newTag = Tag(locality, tagId);
  						}
  					} else {
  						rep.newLocality = true;
  						int8_t maxTagLocality = 0;
  						auto localityKeys = commitData->txnStateStore->readRange(tagLocalityListKeys).get();
  						for( auto& kv : localityKeys ) {
  							maxTagLocality = std::max(maxTagLocality, decodeTagLocalityListValue( kv.value ));
  						}
  						rep.newTag = Tag(maxTagLocality+1,0);
  					}
  					req.reply.send(rep);
  				} else {
  					req.reply.sendError(worker_removed());
  				}
  			}
  		}
  		Void _ = wait(yield());
  	}
  }
  
  ACTOR Future<Void> masterProxyServerCore(
  	MasterProxyInterface proxy,
  	MasterInterface master,
  	Reference<AsyncVar<ServerDBInfo>> db,
  	LogEpoch epoch,
  	Version recoveryTransactionVersion,
  	bool firstProxy)
  {
  	state ProxyCommitData commitData(proxy.id(), master, proxy.getConsistentReadVersion, recoveryTransactionVersion, proxy.commit, db, firstProxy);
  
  	state Future<Sequence> sequenceFuture = (Sequence)0;
  	state PromiseStream< std::pair<vector<CommitTransactionRequest>, int> > batchedCommits;
  	state Future<Void> commitBatcher;
  	state Future<Void> lastCommitComplete = Void();
  
  	state PromiseStream<Future<Void>> addActor;
  	state Future<Void> onError = transformError( actorCollection(addActor.getFuture()), broken_promise(), master_tlog_failed() );
  	state double lastCommit = 0;
  	state std::set<Sequence> txnSequences;
  	state Sequence maxSequence = std::numeric_limits<Sequence>::max();
  	state double commitBatchInterval = SERVER_KNOBS->COMMIT_TRANSACTION_BATCH_INTERVAL_MIN;
  
  	addActor.send( fetchVersions(&commitData) );
  	addActor.send( waitFailureServer(proxy.waitFailure.getFuture()) );
  
  	//TraceEvent("ProxyInit1", proxy.id());
  
  	// Wait until we can load the "real" logsystem, since we don't support switching them currently
  	while (!(db->get().master.id() == master.id() && db->get().recoveryState >= RecoveryState::RECOVERY_TRANSACTION)) {
  		//TraceEvent("ProxyInit2", proxy.id()).detail("LSEpoch", db->get().logSystemConfig.epoch).detail("Need", epoch);
  		Void _ = wait(db->onChange());
  	}
  	state Future<Void> dbInfoChange = db->onChange();
  	//TraceEvent("ProxyInit3", proxy.id());
  
  	commitData.resolvers = db->get().resolvers;
  	ASSERT(commitData.resolvers.size() != 0);
  
  	auto rs = commitData.keyResolvers.modify(allKeys);
  	for(auto r = rs.begin(); r != rs.end(); ++r)
  		r->value().push_back(std::make_pair<Version,int>(0,0));
  
  	commitData.logSystem = ILogSystem::fromServerDBInfo(proxy.id(), db->get(), false, addActor);
  	commitData.logAdapter = new LogSystemDiskQueueAdapter(commitData.logSystem, txsTag, false);
  	commitData.txnStateStore = keyValueStoreLogSystem(commitData.logAdapter, proxy.id(), 2e9, true, true);
  
  	// ((SERVER_MEM_LIMIT * COMMIT_BATCHES_MEM_FRACTION_OF_TOTAL) / COMMIT_BATCHES_MEM_TO_TOTAL_MEM_SCALE_FACTOR) is only a approximate formula for limiting the memory used.
  	// COMMIT_BATCHES_MEM_TO_TOTAL_MEM_SCALE_FACTOR is an estimate based on experiments and not an accurate one.
  	state int64_t commitBatchesMemoryLimit = std::min(SERVER_KNOBS->COMMIT_BATCHES_MEM_BYTES_HARD_LIMIT, static_cast<int64_t>((SERVER_KNOBS->SERVER_MEM_LIMIT * SERVER_KNOBS->COMMIT_BATCHES_MEM_FRACTION_OF_TOTAL) / SERVER_KNOBS->COMMIT_BATCHES_MEM_TO_TOTAL_MEM_SCALE_FACTOR));
  	TraceEvent(SevInfo, "CommitBatchesMemoryLimit").detail("BytesLimit", commitBatchesMemoryLimit);
  
  	addActor.send(transactionStarter(proxy, master, db, addActor, &commitData));
  	addActor.send(readRequestServer(proxy, &commitData));
  
  	// wait for txnStateStore recovery
  	Optional<Value> _ = wait(commitData.txnStateStore->readValue(StringRef()));
  
  	int commitBatchByteLimit = 
  		(int)std::min<double>(SERVER_KNOBS->COMMIT_TRANSACTION_BATCH_BYTES_MAX, 
  			std::max<double>(SERVER_KNOBS->COMMIT_TRANSACTION_BATCH_BYTES_MIN, 
  				SERVER_KNOBS->COMMIT_TRANSACTION_BATCH_BYTES_SCALE_BASE * pow(db->get().client.proxies.size(), SERVER_KNOBS->COMMIT_TRANSACTION_BATCH_BYTES_SCALE_POWER)));
  	commitBatcher = batcher(batchedCommits, proxy.commit.getFuture(), SERVER_KNOBS->COMMIT_TRANSACTION_BATCH_INTERVAL_FROM_IDLE, &commitBatchInterval, SERVER_KNOBS->MAX_COMMIT_BATCH_INTERVAL, SERVER_KNOBS->COMMIT_TRANSACTION_BATCH_COUNT_MAX, commitBatchByteLimit, CLIENT_KNOBS->TRANSACTION_SIZE_LIMIT, commitData.commitBatchStartNotifications, &commitData.commitBatchesMemBytesCount, commitBatchesMemoryLimit, TaskProxyCommitBatcher, &commitData.stats.txnCommitIn);
  	loop choose{
  		when( Void _ = wait( dbInfoChange ) ) {
  			dbInfoChange = db->onChange();
  			if(db->get().master.id() == master.id() && db->get().recoveryState >= RecoveryState::RECOVERY_TRANSACTION) {
  				commitData.logSystem = ILogSystem::fromServerDBInfo(proxy.id(), db->get(), false, addActor);
  				for(auto it : commitData.tag_popped) {
  					commitData.logSystem->pop(it.second, it.first);
  				}
  			}
  		}
  		when(Void _ = wait(onError)) {}
  		when(std::pair<vector<CommitTransactionRequest>, int> batchedRequests = waitNext(batchedCommits.getFuture())) {
  			const vector<CommitTransactionRequest> &trs = batchedRequests.first;
  			int batchBytes = batchedRequests.second;
  			//TraceEvent("MasterProxyCTR", proxy.id()).detail("CommitTransactions", trs.size()).detail("TransactionRate", transactionRate).detail("TransactionQueue", transactionQueue.size()).detail("ReleasedTransactionCount", transactionCount);
  			if (trs.size() || (db->get().recoveryState >= RecoveryState::ACCEPTING_COMMITS && now() - lastCommit >= SERVER_KNOBS->MAX_COMMIT_BATCH_INTERVAL)) {
  				lastCommit = now();
  
  				if (trs.size() || lastCommitComplete.isReady()) {
  					lastCommitComplete = commitBatch(&commitData, trs, &commitBatchInterval, batchBytes);
  					addActor.send(lastCommitComplete);
  				}
  			}
  		}
  		when(GetRawCommittedVersionRequest req = waitNext(proxy.getRawCommittedVersion.getFuture())) {
  			//TraceEvent("ProxyGetRCV", proxy.id());
  			if (req.debugID.present())
  				g_traceBatch.addEvent("TransactionDebug", req.debugID.get().first(), "MasterProxyServer.masterProxyServerCore.GetRawCommittedVersion");
  			GetReadVersionReply rep;
  			rep.locked = commitData.locked;
  			rep.version = commitData.committedVersion.get();
  			req.reply.send(rep);
  		}
  		when(TxnStateRequest req = waitNext(proxy.txnState.getFuture())) {
  			state ReplyPromise<Void> reply = req.reply;
  			if(req.last) maxSequence = req.sequence + 1;
  			if (!txnSequences.count(req.sequence)) {
  				txnSequences.insert(req.sequence);
  				
  				ASSERT(!commitData.validState.isSet()); // Although we may receive the CommitTransactionRequest for the recovery transaction before all of the TxnStateRequest, we will not get a resolution result from any resolver until the master has submitted its initial (sequence 0) resolution request, which it doesn't do until we have acknowledged all TxnStateRequests
  
  				for(auto& kv : req.data)
  					commitData.txnStateStore->set(kv, &req.arena);
  				commitData.txnStateStore->commit(true);
  
  				if(txnSequences.size() == maxSequence) {
  					state KeyRange txnKeys = allKeys;
  					loop {
  						Void _ = wait(yield());
  						Standalone<VectorRef<KeyValueRef>> data = commitData.txnStateStore->readRange(txnKeys, SERVER_KNOBS->BUGGIFIED_ROW_LIMIT, SERVER_KNOBS->APPLY_MUTATION_BYTES).get();
  						if(!data.size()) break;
  						((KeyRangeRef&)txnKeys) = KeyRangeRef( keyAfter(data.back().key, txnKeys.arena()), txnKeys.end );
  
  						Standalone<VectorRef<MutationRef>> mutations;
  						std::vector<std::pair<MapPair<Key,ServerCacheInfo>,int>> keyInfoData;
  						vector<UID> src, dest;
  						Reference<StorageInfo> storageInfo;
  						ServerCacheInfo info;
  						for(auto &kv : data) {
  							if( kv.key.startsWith(keyServersPrefix) ) {
  								KeyRef k = kv.key.removePrefix(keyServersPrefix);
  								if(k != allKeys.end) {
  									decodeKeyServersValue(kv.value, src, dest);
  									info.tags.clear();
  									info.src_info.clear();
  									info.dest_info.clear();
  									for(auto& id : src) {
  										auto cacheItr = commitData.storageCache.find(id);
  										if(cacheItr == commitData.storageCache.end()) {
  											storageInfo = Reference<StorageInfo>( new StorageInfo() );
  											storageInfo->tag = decodeServerTagValue( commitData.txnStateStore->readValue( serverTagKeyFor(id) ).get().get() );
  											storageInfo->interf = decodeServerListValue( commitData.txnStateStore->readValue( serverListKeyFor(id) ).get().get() );
  											commitData.storageCache[id] = storageInfo;
  										} else {
  											storageInfo = cacheItr->second;
  										}
  										ASSERT(storageInfo->tag != invalidTag);
  										info.tags.push_back( storageInfo->tag );
  										info.src_info.push_back( storageInfo );
  									}
  									for(auto& id : dest) {
  										auto cacheItr = commitData.storageCache.find(id);
  										if(cacheItr == commitData.storageCache.end()) {
  											storageInfo = Reference<StorageInfo>( new StorageInfo() );
  											storageInfo->tag = decodeServerTagValue( commitData.txnStateStore->readValue( serverTagKeyFor(id) ).get().get() );
  											storageInfo->interf = decodeServerListValue( commitData.txnStateStore->readValue( serverListKeyFor(id) ).get().get() );
  											commitData.storageCache[id] = storageInfo;
  										} else {
  											storageInfo = cacheItr->second;
  										}
  										ASSERT(storageInfo->tag != invalidTag);
  										info.tags.push_back( storageInfo->tag );
  										info.dest_info.push_back( storageInfo );
  									}
  									uniquify(info.tags);
  									keyInfoData.push_back( std::make_pair(MapPair<Key,ServerCacheInfo>(k, info), 1) );
  								}
  							} else {
  								mutations.push_back(mutations.arena(), MutationRef(MutationRef::SetValue, kv.key, kv.value));
  							}
  						}
  						
  						//insert keyTag data separately from metadata mutations so that we can do one bulk insert which avoids a lot of map lookups.
  						commitData.keyInfo.rawInsert(keyInfoData); 
  
  						Arena arena;
  						bool confChanges;
  						applyMetadataMutations(commitData.dbgid, arena, mutations, commitData.txnStateStore, NULL, &confChanges, Reference<ILogSystem>(), 0, &commitData.vecBackupKeys, &commitData.keyInfo, commitData.firstProxy ? &commitData.uid_applyMutationsData : NULL, commitData.commit, commitData.cx, &commitData.committedVersion, &commitData.storageCache, &commitData.tag_popped, true );
  					}
  
  					auto lockedKey = commitData.txnStateStore->readValue(databaseLockedKey).get();
  					commitData.locked = lockedKey.present() && lockedKey.get().size();
  
  					commitData.txnStateStore->enableSnapshot();
  				}
  			}
  			reply.send(Void());
  			Void _ = wait(yield());
  		}
  	}
  }
  
  ACTOR Future<Void> checkRemoved(Reference<AsyncVar<ServerDBInfo>> db, uint64_t recoveryCount, MasterProxyInterface myInterface) {
  	loop{
  		if (db->get().recoveryCount >= recoveryCount && !std::count(db->get().client.proxies.begin(), db->get().client.proxies.end(), myInterface))
  		throw worker_removed();
  		Void _ = wait(db->onChange());
  	}
  }
  
  ACTOR Future<Void> masterProxyServer(
  	MasterProxyInterface proxy,
  	InitializeMasterProxyRequest req,
  	Reference<AsyncVar<ServerDBInfo>> db)
  {
  	try {
  		state Future<Void> core = masterProxyServerCore(proxy, req.master, db, req.recoveryCount, req.recoveryTransactionVersion, req.firstProxy);
  		loop choose{
  			when(Void _ = wait(core)) { return Void(); }
  			when(Void _ = wait(checkRemoved(db, req.recoveryCount, proxy))) {}
  		}
  	}
  	catch (Error& e) {
  		if (e.code() == error_code_actor_cancelled || e.code() == error_code_worker_removed || e.code() == error_code_tlog_stopped ||
  			e.code() == error_code_master_tlog_failed || e.code() == error_code_coordinators_changed || e.code() == error_code_coordinated_state_conflict ||
  			e.code() == error_code_new_coordinators_timed_out)
  		{
  			TraceEvent("MasterProxyTerminated", proxy.id()).error(e, true);
  			return Void();
  		}
  		throw;
  	}
  }
  