foundationdb/fdbserver/OldTLogServer.actor.cpp

/*
 * OldTLogServer.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/Hash3.h"
#include "flow/Stats.h"
#include "flow/UnitTest.h"
#include "fdbclient/NativeAPI.h"
#include "fdbclient/Notified.h"
#include "fdbclient/KeyRangeMap.h"
#include "fdbclient/SystemData.h"
#include "fdbserver/WorkerInterface.h"
#include "fdbserver/TLogInterface.h"
#include "fdbserver/Knobs.h"
#include "fdbserver/IKeyValueStore.h"
#include "flow/ActorCollection.h"
#include "fdbrpc/FailureMonitor.h"
#include "fdbserver/IDiskQueue.h"
#include "fdbrpc/sim_validation.h"
#include "fdbserver/ServerDBInfo.h"
#include "fdbserver/LogSystem.h"
#include "fdbserver/WaitFailure.h"
#include "flow/actorcompiler.h"  // This must be the last #include.

using std::pair;
using std::make_pair;
using std::min;
using std::max;

namespace oldTLog {

	typedef int16_t OldTag;

	OldTag convertTag( Tag tag ) {
		if(tag == invalidTag) return invalidTagOld;
		if(tag == txsTag) return txsTagOld;
		ASSERT(tag.id >= 0);
		return tag.id;
	}

	Tag convertOldTag( OldTag tag ) {
		if(tag == invalidTagOld) return invalidTag;
		if(tag == txsTagOld) return txsTag;
		ASSERT(tag >= 0);
		return Tag(tagLocalityUpgraded, tag);
	}

	struct OldTagMessagesRef {
		OldTag tag;
		VectorRef<int> messageOffsets;

		OldTagMessagesRef() {}
		OldTagMessagesRef(Arena &a, const OldTagMessagesRef &from) : tag(from.tag), messageOffsets(a, from.messageOffsets) {}

		size_t expectedSize() const {
			return messageOffsets.expectedSize();
		}

		template <class Ar>
		void serialize(Ar& ar) {
			ar & tag & messageOffsets;
		}
	};

	struct TLogQueueEntryRef {
		UID id;
		Version version;
		Version knownCommittedVersion;
		StringRef messages;
		VectorRef< OldTagMessagesRef > tags;

		TLogQueueEntryRef() : version(0), knownCommittedVersion(0) {}
		TLogQueueEntryRef(Arena &a, TLogQueueEntryRef const &from)
		  : version(from.version), knownCommittedVersion(from.knownCommittedVersion), id(from.id), messages(a, from.messages), tags(a, from.tags) {
		}

		template <class Ar>
		void serialize(Ar& ar) {
			if( ar.protocolVersion() >= 0x0FDB00A460010001) {
				ar & version & messages & tags & knownCommittedVersion & id;
			} else if(ar.isDeserializing) {
				ar & version & messages & tags;
				knownCommittedVersion = 0;
				id = UID();
			}
		}
		size_t expectedSize() const {
			return messages.expectedSize() + tags.expectedSize();
		}
	};

	typedef Standalone<TLogQueueEntryRef> TLogQueueEntry;

	struct TLogQueue : public IClosable {
	public:
		TLogQueue( IDiskQueue* queue, UID dbgid ) : queue(queue), dbgid(dbgid) {}

		// Each packet in the queue is
		//    uint32_t payloadSize
		//    uint8_t payload[payloadSize]  (begins with uint64_t protocolVersion via IncludeVersion)
		//    uint8_t validFlag

		// TLogQueue is a durable queue of TLogQueueEntry objects with an interface similar to IDiskQueue

		// TLogQueue pushes (but not commits) are atomic - after commit fails to return, a prefix of entire calls to push are durable.  This is
		//    implemented on top of the weaker guarantee of IDiskQueue::commit (that a prefix of bytes is durable) using validFlag and by
		//    padding any incomplete packet with zeros after recovery.

		// Before calling push, pop, or commit, the user must call readNext() until it throws
		//    end_of_stream(). It may not be called again thereafter.
		Future<TLogQueueEntry> readNext() {
			return readNext( this );
		}

		void push( TLogQueueEntryRef const& qe ) {
			BinaryWriter wr( Unversioned() );  // outer framing is not versioned
			wr << uint32_t(0);
			IncludeVersion().write(wr);  // payload is versioned
			wr << qe;
			wr << uint8_t(1);
			*(uint32_t*)wr.getData() = wr.getLength() - sizeof(uint32_t) - sizeof(uint8_t);
			auto loc = queue->push( wr.toStringRef() );
			//TraceEvent("TLogQueueVersionWritten", dbgid).detail("Size", wr.getLength() - sizeof(uint32_t) - sizeof(uint8_t)).detail("Loc", loc);
			version_location[qe.version] = loc;
		}
		void pop( Version upTo ) {
			// Keep only the given and all subsequent version numbers
			// Find the first version >= upTo
			auto v = version_location.lower_bound(upTo);
			if (v == version_location.begin()) return;

			if(v == version_location.end()) {
				v = version_location.lastItem();
			}
			else {
				v.decrementNonEnd();
			}

			queue->pop( v->value );
			version_location.erase( version_location.begin(), v );  // ... and then we erase that previous version and all prior versions
		}
		Future<Void> commit() { return queue->commit(); }

		// Implements IClosable
		virtual Future<Void> getError() { return queue->getError(); }
		virtual Future<Void> onClosed() { return queue->onClosed(); }
		virtual void dispose() { queue->dispose(); delete this; }
		virtual void close() { queue->close(); delete this; }

	private:
		IDiskQueue* queue;
		Map<Version, IDiskQueue::location> version_location;  // For the version of each entry that was push()ed, the end location of the serialized bytes
		UID dbgid;

		ACTOR static Future<TLogQueueEntry> readNext( TLogQueue* self ) {
			state TLogQueueEntry result;
			state int zeroFillSize = 0;

			loop {
				Standalone<StringRef> h = wait( self->queue->readNext( sizeof(uint32_t) ) );
				if (h.size() != sizeof(uint32_t)) {
					if (h.size()) {
						TEST( true );  // Zero fill within size field
						int payloadSize = 0;
						memcpy(&payloadSize, h.begin(), h.size());
						zeroFillSize = sizeof(uint32_t)-h.size(); // zero fill the size itself
						zeroFillSize += payloadSize+1;  // and then the contents and valid flag
					}
					break;
				}

				state uint32_t payloadSize = *(uint32_t*)h.begin();
				ASSERT( payloadSize < (100<<20) );

				Standalone<StringRef> e = wait( self->queue->readNext( payloadSize+1 ) );
				if (e.size() != payloadSize+1) {
					TEST( true ); // Zero fill within payload
					zeroFillSize = payloadSize+1 - e.size();
					break;
				}

				if (e[payloadSize]) {
					Arena a = e.arena();
					ArenaReader ar( a, e.substr(0, payloadSize), IncludeVersion() );
					ar >> result;
					self->version_location[result.version] = self->queue->getNextReadLocation();
					return result;
				}
			}
			if (zeroFillSize) {
				TEST( true );  // Fixing a partial commit at the end of the tlog queue
				for(int i=0; i<zeroFillSize; i++)
					self->queue->push( StringRef((const uint8_t*)"",1) );
			}
			throw end_of_stream();
		}
	};

	////// Persistence format (for self->persistentData)

	// Immutable keys
	static const KeyValueRef persistFormat( LiteralStringRef( "Format" ), LiteralStringRef("FoundationDB/LogServer/2/3") );
	static const KeyRangeRef persistFormatReadableRange( LiteralStringRef("FoundationDB/LogServer/2/3"), LiteralStringRef("FoundationDB/LogServer/2/4") );
	static const KeyRangeRef persistRecoveryCountKeys = KeyRangeRef( LiteralStringRef( "DbRecoveryCount/" ), LiteralStringRef( "DbRecoveryCount0" ) );

	// Updated on updatePersistentData()
	static const KeyRangeRef persistCurrentVersionKeys = KeyRangeRef( LiteralStringRef( "version/" ), LiteralStringRef( "version0" ) );
	static const KeyRange persistTagMessagesKeys = prefixRange(LiteralStringRef("TagMsg/"));
	static const KeyRange persistTagPoppedKeys = prefixRange(LiteralStringRef("TagPop/"));

	static Key persistTagMessagesKey( UID id, OldTag tag, Version version ) {
		BinaryWriter wr( Unversioned() );
		wr.serializeBytes(persistTagMessagesKeys.begin);
		wr << id;
		wr << tag;
		wr << bigEndian64( version );
		return wr.toStringRef();
	}

	static Key persistTagPoppedKey( UID id, OldTag tag ) {
		BinaryWriter wr(Unversioned());
		wr.serializeBytes( persistTagPoppedKeys.begin );
		wr << id;
		wr << tag;
		return wr.toStringRef();
	}

	static Value persistTagPoppedValue( Version popped ) {
		return BinaryWriter::toValue( popped, Unversioned() );
	}

	static OldTag decodeTagPoppedKey( KeyRef id, KeyRef key ) {
		OldTag s;
		BinaryReader rd( key.removePrefix(persistTagPoppedKeys.begin).removePrefix(id), Unversioned() );
		rd >> s;
		return s;
	}

	static Version decodeTagPoppedValue( ValueRef value ) {
		return BinaryReader::fromStringRef<Version>( value, Unversioned() );
	}

	static StringRef stripTagMessagesKey( StringRef key ) {
		return key.substr( sizeof(UID) + sizeof(OldTag) + persistTagMessagesKeys.begin.size() );
	}

	static Version decodeTagMessagesKey( StringRef key ) {
		return bigEndian64( BinaryReader::fromStringRef<Version>( stripTagMessagesKey(key), Unversioned() ) );
	}

	struct TLogData : NonCopyable {
		AsyncTrigger newLogData;
		Deque<UID> queueOrder;
		std::map<UID, Reference<struct LogData>> id_data;

		UID dbgid;

		IKeyValueStore* persistentData;
		IDiskQueue* rawPersistentQueue;
		TLogQueue *persistentQueue;

		int64_t diskQueueCommitBytes;
		AsyncVar<bool> largeDiskQueueCommitBytes; //becomes true when diskQueueCommitBytes is greater than MAX_QUEUE_COMMIT_BYTES

		Reference<AsyncVar<ServerDBInfo>> dbInfo;

		NotifiedVersion queueCommitEnd;
		Version queueCommitBegin;
		AsyncTrigger newVersion;

		int64_t instanceID;
		int64_t bytesInput;
		int64_t bytesDurable;

		Version prevVersion;

		struct PeekTrackerData {
			std::map<int, Promise<Version>> sequence_version;
			double lastUpdate;
		};

		std::map<UID, PeekTrackerData> peekTracker;
		WorkerCache<TLogInterface> tlogCache;

		Future<Void> updatePersist; //SOMEDAY: integrate the recovery and update storage so that only one of them is committing to persistant data.

		PromiseStream<Future<Void>> sharedActors;
		bool terminated;

		TLogData(UID dbgid, IKeyValueStore* persistentData, IDiskQueue * persistentQueue, Reference<AsyncVar<ServerDBInfo>> const& dbInfo)
				: dbgid(dbgid), instanceID(g_random->randomUniqueID().first()),
				  persistentData(persistentData), rawPersistentQueue(persistentQueue), persistentQueue(new TLogQueue(persistentQueue, dbgid)),
				  dbInfo(dbInfo), queueCommitBegin(0), queueCommitEnd(0), prevVersion(0),
				  diskQueueCommitBytes(0), largeDiskQueueCommitBytes(false),
				  bytesInput(0), bytesDurable(0), updatePersist(Void()), terminated(false)
			{
			}
	};

	struct LogData : NonCopyable, public ReferenceCounted<LogData> {
		struct TagData {
			std::deque<std::pair<Version, LengthPrefixedStringRef>> version_messages;
			bool nothing_persistent;				// true means tag is *known* to have no messages in persistentData.  false means nothing.
			bool popped_recently;					// `popped` has changed since last updatePersistentData
			Version popped;				// see popped version tracking contract below
			bool update_version_sizes;

			TagData( Version popped, bool nothing_persistent, bool popped_recently, OldTag tag ) : nothing_persistent(nothing_persistent), popped(popped), popped_recently(popped_recently), update_version_sizes(tag != txsTagOld) {}

			TagData(TagData&& r) noexcept(true) : version_messages(std::move(r.version_messages)), nothing_persistent(r.nothing_persistent), popped_recently(r.popped_recently), popped(r.popped), update_version_sizes(r.update_version_sizes) {}
			void operator= (TagData&& r) noexcept(true) {
				version_messages = std::move(r.version_messages);
				nothing_persistent = r.nothing_persistent;
				popped_recently = r.popped_recently;
				popped = r.popped;
				update_version_sizes = r.update_version_sizes;
			}

			// Erase messages not needed to update *from* versions >= before (thus, messages with toversion <= before)
			ACTOR Future<Void> eraseMessagesBefore( TagData *self, Version before, int64_t* gBytesErased, Reference<LogData> tlogData, int taskID ) {
				while(!self->version_messages.empty() && self->version_messages.front().first < before) {
					Version version = self->version_messages.front().first;
					std::pair<int, int> &sizes = tlogData->version_sizes[version];
					int64_t messagesErased = 0;

					while(!self->version_messages.empty() && self->version_messages.front().first == version) {
						auto const& m = self->version_messages.front();
						++messagesErased;

						if(self->update_version_sizes) {
							sizes.first -= m.second.expectedSize();
						}

						self->version_messages.pop_front();
					}

					int64_t bytesErased = (messagesErased * sizeof(std::pair<Version, LengthPrefixedStringRef>) * SERVER_KNOBS->VERSION_MESSAGES_OVERHEAD_FACTOR_1024THS) >> 10;
					tlogData->bytesDurable += bytesErased;
					*gBytesErased += bytesErased;
					wait(yield(taskID));
				}

				return Void();
			}

			Future<Void> eraseMessagesBefore(Version before, int64_t* gBytesErased, Reference<LogData> tlogData, int taskID) {
				return eraseMessagesBefore(this, before, gBytesErased, tlogData, taskID);
			}
		};

		/*
		Popped version tracking contract needed by log system to implement ILogCursor::popped():

			- Log server tracks for each (possible) tag a popped_version
			Impl: TagData::popped (in memory) and persistTagPoppedKeys (in persistentData)
			- popped_version(tag) is <= the maximum version for which log server (or a predecessor) is ever asked to pop the tag
			Impl: Only increased by tLogPop() in response to either a pop request or recovery from a predecessor
			- popped_version(tag) is > the maximum version for which log server is unable to peek messages due to previous pops (on this server or a predecessor)
			Impl: Increased by tLogPop() atomically with erasing messages from memory; persisted by updatePersistentData() atomically with erasing messages from store; messages are not erased from queue where popped_version is not persisted
			- LockTLogReply returns all tags which either have messages, or which have nonzero popped_versions
			Impl: tag_data is present for all such tags
			- peek(tag, v) returns the popped_version for tag if that is greater than v
			Impl: Check tag_data->popped (after all waits)
		*/

		bool stopped, initialized;
		DBRecoveryCount recoveryCount;

		VersionMetricHandle persistentDataVersion, persistentDataDurableVersion;  // The last version number in the portion of the log (written|durable) to persistentData
		NotifiedVersion version, queueCommittedVersion;
		Version queueCommittingVersion;
		Version knownCommittedVersion;

		Deque<std::pair<Version, Standalone<VectorRef<uint8_t>>>> messageBlocks;
		Map< OldTag, TagData > tag_data;

		Map<Version, std::pair<int,int>> version_sizes;

		CounterCollection cc;
		Counter bytesInput;
		Counter bytesDurable;

		UID logId;
		Version newPersistentDataVersion;
		Future<Void> removed;
		TLogInterface tli;
		PromiseStream<Future<Void>> addActor;
		TLogData* tLogData;
		Promise<bool> recoverySuccessful;
		Future<Void> recovery;

		explicit LogData(TLogData* tLogData, TLogInterface interf) : tLogData(tLogData), knownCommittedVersion(0), tli(interf), logId(interf.id()),
				cc("TLog", interf.id().toString()),
				bytesInput("BytesInput", cc),
				bytesDurable("BytesDurable", cc),
				// These are initialized differently on init() or recovery
				recoveryCount(), stopped(false), initialized(false), queueCommittingVersion(0), newPersistentDataVersion(invalidVersion), recovery(Void())
		{
			startRole(Role::TRANSACTION_LOG,interf.id(), UID());

			persistentDataVersion.init(LiteralStringRef("TLog.PersistentDataVersion"), cc.id);
			persistentDataDurableVersion.init(LiteralStringRef("TLog.PersistentDataDurableVersion"), cc.id);
			version.initMetric(LiteralStringRef("TLog.Version"), cc.id);
			queueCommittedVersion.initMetric(LiteralStringRef("TLog.QueueCommittedVersion"), cc.id);

			specialCounter(cc, "Version", [this](){ return this->version.get(); });
			specialCounter(cc, "SharedBytesInput", [tLogData](){ return tLogData->bytesInput; });
			specialCounter(cc, "SharedBytesDurable", [tLogData](){ return tLogData->bytesDurable; });
			specialCounter(cc, "KvstoreBytesUsed", [tLogData](){ return tLogData->persistentData->getStorageBytes().used; });
			specialCounter(cc, "KvstoreBytesFree", [tLogData](){ return tLogData->persistentData->getStorageBytes().free; });
			specialCounter(cc, "KvstoreBytesAvailable", [tLogData](){ return tLogData->persistentData->getStorageBytes().available; });
			specialCounter(cc, "KvstoreBytesTotal", [tLogData](){ return tLogData->persistentData->getStorageBytes().total; });
			specialCounter(cc, "QueueDiskBytesUsed", [tLogData](){ return tLogData->rawPersistentQueue->getStorageBytes().used; });
			specialCounter(cc, "QueueDiskBytesFree", [tLogData](){ return tLogData->rawPersistentQueue->getStorageBytes().free; });
			specialCounter(cc, "QueueDiskBytesAvailable", [tLogData](){ return tLogData->rawPersistentQueue->getStorageBytes().available; });
			specialCounter(cc, "QueueDiskBytesTotal", [tLogData](){ return tLogData->rawPersistentQueue->getStorageBytes().total; });
		}

		~LogData() {
			tLogData->bytesDurable += bytesInput.getValue() - bytesDurable.getValue();
			TraceEvent("TLogBytesWhenRemoved", tli.id()).detail("SharedBytesInput", tLogData->bytesInput).detail("SharedBytesDurable", tLogData->bytesDurable).detail("LocalBytesInput", bytesInput.getValue()).detail("LocalBytesDurable", bytesDurable.getValue());

			ASSERT_ABORT(tLogData->bytesDurable <= tLogData->bytesInput);
			endRole(Role::TRANSACTION_LOG, tli.id(), "Error", true);

			if(!tLogData->terminated) {
				Key logIdKey = BinaryWriter::toValue(logId,Unversioned());
				tLogData->persistentData->clear( singleKeyRange(logIdKey.withPrefix(persistCurrentVersionKeys.begin)) );
				tLogData->persistentData->clear( singleKeyRange(logIdKey.withPrefix(persistRecoveryCountKeys.begin)) );
				Key msgKey = logIdKey.withPrefix(persistTagMessagesKeys.begin);
				tLogData->persistentData->clear( KeyRangeRef( msgKey, strinc(msgKey) ) );
				Key poppedKey = logIdKey.withPrefix(persistTagPoppedKeys.begin);
				tLogData->persistentData->clear( KeyRangeRef( poppedKey, strinc(poppedKey) ) );
			}
		}

		LogEpoch epoch() const { return recoveryCount; }
	};

	ACTOR Future<Void> tLogLock( TLogData* self, ReplyPromise< TLogLockResult > reply, Reference<LogData> logData ) {
		state Version stopVersion = logData->version.get();

		TEST(true); // TLog stopped by recovering master
		TEST( logData->stopped );
		TEST( !logData->stopped );

		TraceEvent("TLogStop", logData->logId).detail("Ver", stopVersion).detail("IsStopped", logData->stopped).detail("QueueCommitted", logData->queueCommittedVersion.get());

		logData->stopped = true;
		if(logData->recoverySuccessful.canBeSet()) {
			logData->recoverySuccessful.send(false);
		}

		// Lock once the current version has been committed
		wait( logData->queueCommittedVersion.whenAtLeast( stopVersion ) );

		ASSERT(stopVersion == logData->version.get());

		TLogLockResult result;
		result.end = stopVersion;
		result.knownCommittedVersion = logData->knownCommittedVersion;

		TraceEvent("TLogStop2", self->dbgid).detail("LogId", logData->logId).detail("Ver", stopVersion).detail("IsStopped", logData->stopped).detail("QueueCommitted", logData->queueCommittedVersion.get());


		reply.send( result );
		return Void();
	}

	void updatePersistentPopped( TLogData* self, Reference<LogData> logData, OldTag tag, LogData::TagData& data ) {
		if (!data.popped_recently) return;
		self->persistentData->set(KeyValueRef( persistTagPoppedKey(logData->logId, tag), persistTagPoppedValue(data.popped) ));
		data.popped_recently = false;

		if (data.nothing_persistent) return;

		self->persistentData->clear( KeyRangeRef(
			persistTagMessagesKey( logData->logId, tag, Version(0) ),
			persistTagMessagesKey( logData->logId, tag, data.popped ) ) );
		if (data.popped > logData->persistentDataVersion)
			data.nothing_persistent = true;
	}

	ACTOR Future<Void> updatePersistentData( TLogData* self, Reference<LogData> logData, Version newPersistentDataVersion ) {
		// PERSIST: Changes self->persistentDataVersion and writes and commits the relevant changes
		ASSERT( newPersistentDataVersion <= logData->version.get() );
		ASSERT( newPersistentDataVersion <= logData->queueCommittedVersion.get() );
		ASSERT( newPersistentDataVersion > logData->persistentDataVersion );
		ASSERT( logData->persistentDataVersion == logData->persistentDataDurableVersion );

		//TraceEvent("UpdatePersistentData", self->dbgid).detail("Seq", newPersistentDataSeq);

		state bool anyData = false;
		state Map<OldTag, LogData::TagData>::iterator tag;
		// For all existing tags
		for(tag = logData->tag_data.begin(); tag != logData->tag_data.end(); ++tag) {
			state Version currentVersion = 0;
			// Clear recently popped versions from persistentData if necessary
			updatePersistentPopped( self, logData, tag->key, tag->value );
			// Transfer unpopped messages with version numbers less than newPersistentDataVersion to persistentData
			state std::deque<std::pair<Version, LengthPrefixedStringRef>>::iterator msg = tag->value.version_messages.begin();
			while(msg != tag->value.version_messages.end() && msg->first <= newPersistentDataVersion) {
				currentVersion = msg->first;
				anyData = true;
				tag->value.nothing_persistent = false;
				BinaryWriter wr( Unversioned() );

				for(; msg != tag->value.version_messages.end() && msg->first == currentVersion; ++msg)
					wr << msg->second.toStringRef();

				self->persistentData->set( KeyValueRef( persistTagMessagesKey( logData->logId, tag->key, currentVersion ), wr.toStringRef() ) );

				Future<Void> f = yield(TaskUpdateStorage);
				if(!f.isReady()) {
					wait(f);
					msg = std::upper_bound(tag->value.version_messages.begin(), tag->value.version_messages.end(), std::make_pair(currentVersion, LengthPrefixedStringRef()), CompareFirst<std::pair<Version, LengthPrefixedStringRef>>());
				}
			}

			wait(yield(TaskUpdateStorage));
		}

		self->persistentData->set( KeyValueRef( BinaryWriter::toValue(logData->logId,Unversioned()).withPrefix(persistCurrentVersionKeys.begin), BinaryWriter::toValue(newPersistentDataVersion, Unversioned()) ) );
		logData->persistentDataVersion = newPersistentDataVersion;

		wait( self->persistentData->commit() ); // SOMEDAY: This seems to be running pretty often, should we slow it down???
		wait( delay(0, TaskUpdateStorage) );

		// Now that the changes we made to persistentData are durable, erase the data we moved from memory and the queue, increase bytesDurable accordingly, and update persistentDataDurableVersion.

		TEST(anyData);  // TLog moved data to persistentData
		logData->persistentDataDurableVersion = newPersistentDataVersion;

		for(tag = logData->tag_data.begin(); tag != logData->tag_data.end(); ++tag) {
			wait(tag->value.eraseMessagesBefore( newPersistentDataVersion+1, &self->bytesDurable, logData, TaskUpdateStorage ));
			wait(yield(TaskUpdateStorage));
		}

		logData->version_sizes.erase(logData->version_sizes.begin(), logData->version_sizes.lower_bound(logData->persistentDataDurableVersion));

		wait(yield(TaskUpdateStorage));

		while(!logData->messageBlocks.empty() && logData->messageBlocks.front().first <= newPersistentDataVersion) {
			int64_t bytesErased = int64_t(logData->messageBlocks.front().second.size()) * SERVER_KNOBS->TLOG_MESSAGE_BLOCK_OVERHEAD_FACTOR;
			logData->bytesDurable += bytesErased;
			self->bytesDurable += bytesErased;
			logData->messageBlocks.pop_front();
			wait(yield(TaskUpdateStorage));
		}

		if(logData->bytesDurable.getValue() > logData->bytesInput.getValue() || self->bytesDurable > self->bytesInput) {
			TraceEvent(SevError, "BytesDurableTooLarge", logData->logId).detail("SharedBytesInput", self->bytesInput).detail("SharedBytesDurable", self->bytesDurable).detail("LocalBytesInput", logData->bytesInput.getValue()).detail("LocalBytesDurable", logData->bytesDurable.getValue());
		}

		ASSERT(logData->bytesDurable.getValue() <= logData->bytesInput.getValue());
		ASSERT(self->bytesDurable <= self->bytesInput);

		if( self->queueCommitEnd.get() > 0 )
			self->persistentQueue->pop( newPersistentDataVersion+1 ); // SOMEDAY: this can cause a slow task (~0.5ms), presumably from erasing too many versions. Should we limit the number of versions cleared at a time?

		return Void();
	}

	// This function (and updatePersistentData, which is called by this function) run at a low priority and can soak up all CPU resources.
	// For this reason, they employ aggressive use of yields to avoid causing slow tasks that could introduce latencies for more important
	// work (e.g. commits).
	ACTOR Future<Void> updateStorage( TLogData* self ) {
		while(self->queueOrder.size() && !self->id_data.count(self->queueOrder.front())) {
			self->queueOrder.pop_front();
		}

		if(!self->queueOrder.size()) {
			wait( delay(BUGGIFY ? SERVER_KNOBS->BUGGIFY_TLOG_STORAGE_MIN_UPDATE_INTERVAL : SERVER_KNOBS->TLOG_STORAGE_MIN_UPDATE_INTERVAL, TaskUpdateStorage) );
			return Void();
		}

		state Reference<LogData> logData = self->id_data[self->queueOrder.front()];
		state Version prevVersion = 0;
		state Version nextVersion = 0;
		state int totalSize = 0;

		if(logData->stopped) {
			if (self->bytesInput - self->bytesDurable >= SERVER_KNOBS->TLOG_SPILL_THRESHOLD) {
				while(logData->persistentDataDurableVersion != logData->version.get()) {
					std::vector<std::pair<std::deque<std::pair<Version, LengthPrefixedStringRef>>::iterator, std::deque<std::pair<Version, LengthPrefixedStringRef>>::iterator>> iters;
					for(auto tag = logData->tag_data.begin(); tag != logData->tag_data.end(); ++tag)
						iters.push_back(std::make_pair(tag->value.version_messages.begin(), tag->value.version_messages.end()));

					nextVersion = 0;
					while( totalSize < SERVER_KNOBS->UPDATE_STORAGE_BYTE_LIMIT || nextVersion <= logData->persistentDataVersion ) {
						nextVersion = logData->version.get();
						for( auto &it : iters )
							if(it.first != it.second)
								nextVersion = std::min( nextVersion, it.first->first + 1 );

						if(nextVersion == logData->version.get())
							break;

						for( auto &it : iters ) {
							while (it.first != it.second && it.first->first < nextVersion) {
								totalSize += it.first->second.expectedSize();
								++it.first;
							}
						}
					}

					wait( logData->queueCommittedVersion.whenAtLeast( nextVersion ) );
					wait( delay(0, TaskUpdateStorage) );

					//TraceEvent("TlogUpdatePersist", self->dbgid).detail("LogId", logData->logId).detail("NextVersion", nextVersion).detail("Version", logData->version.get()).detail("PersistentDataDurableVer", logData->persistentDataDurableVersion).detail("QueueCommitVer", logData->queueCommittedVersion.get()).detail("PersistDataVer", logData->persistentDataVersion);
					if (nextVersion > logData->persistentDataVersion) {
						self->updatePersist = updatePersistentData(self, logData, nextVersion);
						wait( self->updatePersist );
					} else {
						wait( delay(BUGGIFY ? SERVER_KNOBS->BUGGIFY_TLOG_STORAGE_MIN_UPDATE_INTERVAL : SERVER_KNOBS->TLOG_STORAGE_MIN_UPDATE_INTERVAL, TaskUpdateStorage) );
					}

					if( logData->removed.isReady() ) {
						break;
					}
				}

				if(logData->persistentDataDurableVersion == logData->version.get()) {
					self->queueOrder.pop_front();
				}
				wait( delay(0.0, TaskUpdateStorage) );
			} else {
				wait( delay(BUGGIFY ? SERVER_KNOBS->BUGGIFY_TLOG_STORAGE_MIN_UPDATE_INTERVAL : SERVER_KNOBS->TLOG_STORAGE_MIN_UPDATE_INTERVAL, TaskUpdateStorage) );
			}
		}
		else if(logData->initialized) {
			ASSERT(self->queueOrder.size() == 1);
			state Map<Version, std::pair<int, int>>::iterator sizeItr = logData->version_sizes.begin();
			while( totalSize < SERVER_KNOBS->UPDATE_STORAGE_BYTE_LIMIT && sizeItr != logData->version_sizes.end()
					&& (logData->bytesInput.getValue() - logData->bytesDurable.getValue() - totalSize >= SERVER_KNOBS->TLOG_SPILL_THRESHOLD || sizeItr->value.first == 0) )
			{
				wait( yield(TaskUpdateStorage) );

				++sizeItr;
				nextVersion = sizeItr == logData->version_sizes.end() ? logData->version.get() : sizeItr->key;

				state Map<OldTag, LogData::TagData>::iterator tag;
				for(tag = logData->tag_data.begin(); tag != logData->tag_data.end(); ++tag) {
					auto it = std::lower_bound(tag->value.version_messages.begin(), tag->value.version_messages.end(), std::make_pair(prevVersion, LengthPrefixedStringRef()), CompareFirst<std::pair<Version, LengthPrefixedStringRef>>());
					for(; it != tag->value.version_messages.end() && it->first < nextVersion; ++it) {
						totalSize += it->second.expectedSize();
					}

					wait(yield(TaskUpdateStorage));
				}

				prevVersion = nextVersion;
			}

			nextVersion = std::max<Version>(nextVersion, logData->persistentDataVersion);

			//TraceEvent("UpdateStorageVer", logData->logId).detail("NextVersion", nextVersion).detail("PersistentDataVersion", logData->persistentDataVersion).detail("TotalSize", totalSize);

			wait( logData->queueCommittedVersion.whenAtLeast( nextVersion ) );
			wait( delay(0, TaskUpdateStorage) );

			if (nextVersion > logData->persistentDataVersion) {
				self->updatePersist = updatePersistentData(self, logData, nextVersion);
				wait( self->updatePersist );
			}

			if( totalSize < SERVER_KNOBS->UPDATE_STORAGE_BYTE_LIMIT ) {
				wait( delay(BUGGIFY ? SERVER_KNOBS->BUGGIFY_TLOG_STORAGE_MIN_UPDATE_INTERVAL : SERVER_KNOBS->TLOG_STORAGE_MIN_UPDATE_INTERVAL, TaskUpdateStorage) );
			}
			else {
				//recovery wants to commit to persistant data when updatePersistentData is not active, this delay ensures that immediately after
				//updatePersist returns another one has not been started yet.
				wait( delay(0.0, TaskUpdateStorage) );
			}
		} else {
			wait( delay(BUGGIFY ? SERVER_KNOBS->BUGGIFY_TLOG_STORAGE_MIN_UPDATE_INTERVAL : SERVER_KNOBS->TLOG_STORAGE_MIN_UPDATE_INTERVAL, TaskUpdateStorage) );
		}
		return Void();
	}

	ACTOR Future<Void> updateStorageLoop( TLogData* self ) {
		wait(delay(0, TaskUpdateStorage));

		loop {
			wait( updateStorage(self) );
		}
	}

	void commitMessages( Reference<LogData> self, Version version, Arena arena, StringRef messages, VectorRef< OldTagMessagesRef > tags, int64_t& bytesInput) {
		// SOMEDAY: This method of copying messages is reasonably memory efficient, but it's still a lot of bytes copied.  Find a
		// way to do the memory allocation right as we receive the messages in the network layer.

		int64_t addedBytes = 0;
		int64_t expectedBytes = 0;

		if(!messages.size()) {
			return;
		}

		StringRef messages1;  // the first block of messages, if they aren't all stored contiguously.  otherwise empty

		// Grab the last block in the blocks list so we can share its arena
		// We pop all of the elements of it to create a "fresh" vector that starts at the end of the previous vector
		Standalone<VectorRef<uint8_t>> block;
		if(self->messageBlocks.empty()) {
			block = Standalone<VectorRef<uint8_t>>();
			block.reserve(block.arena(), std::max<int64_t>(SERVER_KNOBS->TLOG_MESSAGE_BLOCK_BYTES, messages.size()));
		}
		else {
			block = self->messageBlocks.back().second;
		}

		block.pop_front(block.size());

		// If the current batch of messages doesn't fit entirely in the remainder of the last block in the list
		if(messages.size() + block.size() > block.capacity()) {
			// Find how many messages will fit
			LengthPrefixedStringRef r((uint32_t*)messages.begin());
			uint8_t const* end = messages.begin() + block.capacity() - block.size();
			while(r.toStringRef().end() <= end) {
				r = LengthPrefixedStringRef( (uint32_t*)r.toStringRef().end() );
			}

			// Fill up the rest of this block
			int bytes = (uint8_t*)r.getLengthPtr()-messages.begin();
			if (bytes) {
				TEST(true); // Splitting commit messages across multiple blocks
				messages1 = StringRef(block.end(), bytes);
				block.append(block.arena(), messages.begin(), bytes);
				self->messageBlocks.push_back( std::make_pair(version, block) );
				addedBytes += int64_t(block.size()) * SERVER_KNOBS->TLOG_MESSAGE_BLOCK_OVERHEAD_FACTOR;
				messages = messages.substr(bytes);
			}

			// Make a new block
			block = Standalone<VectorRef<uint8_t>>();
			block.reserve(block.arena(), std::max<int64_t>(SERVER_KNOBS->TLOG_MESSAGE_BLOCK_BYTES, messages.size()));
		}

		// Copy messages into block
		ASSERT(messages.size() <= block.capacity() - block.size());
		block.append(block.arena(), messages.begin(), messages.size());
		self->messageBlocks.push_back( std::make_pair(version, block) );
		addedBytes += int64_t(block.size()) * SERVER_KNOBS->TLOG_MESSAGE_BLOCK_OVERHEAD_FACTOR;
		messages = StringRef(block.end()-messages.size(), messages.size());

		for(auto tag = tags.begin(); tag != tags.end(); ++tag) {
			int64_t tagMessages = 0;

			auto tsm = self->tag_data.find(tag->tag);
			if (tsm == self->tag_data.end()) {
				tsm = self->tag_data.insert( mapPair(std::move(OldTag(tag->tag)), LogData::TagData(Version(0), true, true, tag->tag) ), false );
			}

			if (version >= tsm->value.popped) {
				for(int m = 0; m < tag->messageOffsets.size(); ++m) {
					int offs = tag->messageOffsets[m];
					uint8_t const* p = offs < messages1.size() ? messages1.begin() + offs : messages.begin() + offs - messages1.size();
					tsm->value.version_messages.push_back(std::make_pair(version, LengthPrefixedStringRef((uint32_t*)p)));
					if(tsm->value.version_messages.back().second.expectedSize() > SERVER_KNOBS->MAX_MESSAGE_SIZE) {
						TraceEvent(SevWarnAlways, "LargeMessage").detail("Size", tsm->value.version_messages.back().second.expectedSize());
					}
					if (tag->tag != txsTagOld)
						expectedBytes += tsm->value.version_messages.back().second.expectedSize();

					++tagMessages;
				}
			}

			// The factor of VERSION_MESSAGES_OVERHEAD is intended to be an overestimate of the actual memory used to store this data in a std::deque.
			// In practice, this number is probably something like 528/512 ~= 1.03, but this could vary based on the implementation.
			// There will also be a fixed overhead per std::deque, but its size should be trivial relative to the size of the TLog
			// queue and can be thought of as increasing the capacity of the queue slightly.
			addedBytes += (tagMessages * sizeof(std::pair<Version, LengthPrefixedStringRef>) * SERVER_KNOBS->VERSION_MESSAGES_OVERHEAD_FACTOR_1024THS) >> 10;
		}

		self->version_sizes[version] = make_pair(expectedBytes, expectedBytes);
		self->bytesInput += addedBytes;
		bytesInput += addedBytes;

		//TraceEvent("TLogPushed", self->dbgid).detail("Bytes", addedBytes).detail("MessageBytes", messages.size()).detail("Tags", tags.size()).detail("ExpectedBytes", expectedBytes).detail("MCount", mCount).detail("TCount", tCount);
	}

	Version poppedVersion( Reference<LogData> self, OldTag tag) {
		auto mapIt = self->tag_data.find(tag);
		if (mapIt == self->tag_data.end())
			return Version(0);
		return mapIt->value.popped;
	}

	std::deque<std::pair<Version, LengthPrefixedStringRef>> & get_version_messages( Reference<LogData> self, OldTag tag ) {
		auto mapIt = self->tag_data.find(tag);
		if (mapIt == self->tag_data.end()) {
			static std::deque<std::pair<Version, LengthPrefixedStringRef>> empty;
			return empty;
		}
		return mapIt->value.version_messages;
	};

	ACTOR Future<Void> tLogPop( TLogData* self, TLogPopRequest req, Reference<LogData> logData ) {
		OldTag oldTag = convertTag(req.tag);
		auto ti = logData->tag_data.find(oldTag);
		if (ti == logData->tag_data.end()) {
			ti = logData->tag_data.insert( mapPair(oldTag, LogData::TagData(req.to, true, true, oldTag)) );
		} else if (req.to > ti->value.popped) {
			ti->value.popped = req.to;
			ti->value.popped_recently = true;
			//if (to.epoch == self->epoch())
			if ( req.to > logData->persistentDataDurableVersion )
				wait(ti->value.eraseMessagesBefore( req.to, &self->bytesDurable, logData, TaskTLogPop ));
		}

		req.reply.send(Void());
		return Void();
	}

	void peekMessagesFromMemory( Reference<LogData> self, TLogPeekRequest const& req, BinaryWriter& messages, Version& endVersion ) {
		OldTag oldTag = convertTag(req.tag);
		ASSERT( !messages.getLength() );

		auto& deque = get_version_messages(self, oldTag);
		Version begin = std::max( req.begin, self->persistentDataDurableVersion+1 );
		auto it = std::lower_bound(deque.begin(), deque.end(), std::make_pair(begin, LengthPrefixedStringRef()), CompareFirst<std::pair<Version, LengthPrefixedStringRef>>());

		Version currentVersion = -1;
		for(; it != deque.end(); ++it) {
			if(it->first != currentVersion) {
				if (messages.getLength() >= SERVER_KNOBS->DESIRED_TOTAL_BYTES) {
					endVersion = it->first;
					//TraceEvent("TLogPeekMessagesReached2", self->dbgid);
					break;
				}

				currentVersion = it->first;
				messages << int32_t(-1) << currentVersion;
			}

			BinaryReader rd( it->second.getLengthPtr(), it->second.expectedSize()+4, Unversioned() );
			while(!rd.empty()) {
				int32_t messageLength;
				uint32_t subVersion;
				rd >> messageLength >> subVersion;
				messageLength += sizeof(uint16_t) + sizeof(Tag);
				messages << messageLength << subVersion << uint16_t(1) << req.tag;
				messageLength -= (sizeof(subVersion) + sizeof(uint16_t) + sizeof(Tag));
				messages.serializeBytes(rd.readBytes(messageLength), messageLength);
			}
		}
	}

	ACTOR Future<Void> tLogPeekMessages( TLogData* self, TLogPeekRequest req, Reference<LogData> logData ) {
		state BinaryWriter messages(Unversioned());
		state BinaryWriter messages2(Unversioned());
		state int sequence = -1;
		state UID peekId;
		state OldTag oldTag = convertTag(req.tag);

		if(req.sequence.present()) {
			try {
				peekId = req.sequence.get().first;
				sequence = req.sequence.get().second;
				if(sequence > 0) {
					auto& trackerData = self->peekTracker[peekId];
					trackerData.lastUpdate = now();
					Version ver = wait(trackerData.sequence_version[sequence].getFuture());
					req.begin = ver;
					wait(yield());
				}
			} catch( Error &e ) {
				if(e.code() == error_code_timed_out) {
					req.reply.sendError(timed_out());
					return Void();
				} else {
					throw;
				}
			}
		}

		if( req.returnIfBlocked && logData->version.get() < req.begin ) {
			req.reply.sendError(end_of_stream());
			return Void();
		}

		//TraceEvent("TLogPeekMessages0", self->dbgid).detail("ReqBeginEpoch", req.begin.epoch).detail("ReqBeginSeq", req.begin.sequence).detail("Epoch", self->epoch()).detail("PersistentDataSeq", self->persistentDataSequence).detail("Tag1", printable(req.tag1)).detail("Tag2", printable(req.tag2));
		// Wait until we have something to return that the caller doesn't already have
		if( logData->version.get() < req.begin ) {
			wait( logData->version.whenAtLeast( req.begin ) );
			wait( delay(SERVER_KNOBS->TLOG_PEEK_DELAY, g_network->getCurrentTask()) );
		}

		state Version endVersion = logData->version.get() + 1;

		//grab messages from disk
		//TraceEvent("TLogPeekMessages", self->dbgid).detail("ReqBeginEpoch", req.begin.epoch).detail("ReqBeginSeq", req.begin.sequence).detail("Epoch", self->epoch()).detail("PersistentDataSeq", self->persistentDataSequence).detail("Tag1", printable(req.tag1)).detail("Tag2", printable(req.tag2));
		if( req.begin <= logData->persistentDataDurableVersion ) {
			// Just in case the durable version changes while we are waiting for the read, we grab this data from memory.  We may or may not actually send it depending on
			// whether we get enough data from disk.
			// SOMEDAY: Only do this if an initial attempt to read from disk results in insufficient data and the required data is no longer in memory
			// SOMEDAY: Should we only send part of the messages we collected, to actually limit the size of the result?

			peekMessagesFromMemory( logData, req, messages2, endVersion );

			Standalone<VectorRef<KeyValueRef>> kvs = wait(
				self->persistentData->readRange(KeyRangeRef(
					persistTagMessagesKey(logData->logId, oldTag, req.begin),
					persistTagMessagesKey(logData->logId, oldTag, logData->persistentDataDurableVersion + 1)), SERVER_KNOBS->DESIRED_TOTAL_BYTES, SERVER_KNOBS->DESIRED_TOTAL_BYTES));

			//TraceEvent("TLogPeekResults", self->dbgid).detail("ForAddress", req.reply.getEndpoint().address).detail("Tag1Results", s1).detail("Tag2Results", s2).detail("Tag1ResultsLim", kv1.size()).detail("Tag2ResultsLim", kv2.size()).detail("Tag1ResultsLast", kv1.size() ? printable(kv1[0].key) : "").detail("Tag2ResultsLast", kv2.size() ? printable(kv2[0].key) : "").detail("Limited", limited).detail("NextEpoch", next_pos.epoch).detail("NextSeq", next_pos.sequence).detail("NowEpoch", self->epoch()).detail("NowSeq", self->sequence.getNextSequence());

			for (auto &kv : kvs) {
				auto ver = decodeTagMessagesKey(kv.key);
				messages << int32_t(-1) << ver;

				BinaryReader rd( kv.value, Unversioned() );
				while(!rd.empty()) {
					int32_t messageLength;
					uint32_t subVersion;
					rd >> messageLength >> subVersion;
					messageLength += sizeof(uint16_t) + sizeof(Tag);
					messages << messageLength << subVersion << uint16_t(1) << req.tag;
					messageLength -= (sizeof(subVersion) + sizeof(uint16_t) + sizeof(Tag));
					messages.serializeBytes(rd.readBytes(messageLength), messageLength);
				}
			}

			if (kvs.expectedSize() >= SERVER_KNOBS->DESIRED_TOTAL_BYTES)
				endVersion = decodeTagMessagesKey(kvs.end()[-1].key) + 1;
			else
				messages.serializeBytes( messages2.toStringRef() );
		} else {
			peekMessagesFromMemory( logData, req, messages, endVersion );
			//TraceEvent("TLogPeekResults", self->dbgid).detail("ForAddress", req.reply.getEndpoint().address).detail("MessageBytes", messages.getLength()).detail("NextEpoch", next_pos.epoch).detail("NextSeq", next_pos.sequence).detail("NowSeq", self->sequence.getNextSequence());
		}

		Version poppedVer = poppedVersion(logData, oldTag);

		TLogPeekReply reply;
		reply.maxKnownVersion = logData->version.get();
		reply.minKnownCommittedVersion = 0;
		if(poppedVer > req.begin) {
			reply.popped = poppedVer;
			reply.end = poppedVer;
		} else {
			reply.messages = messages.toStringRef();
			reply.end = endVersion;
		}
		//TraceEvent("TlogPeek", self->dbgid).detail("LogId", logData->logId).detail("EndVer", reply.end).detail("MsgBytes", reply.messages.expectedSize()).detail("ForAddress", req.reply.getEndpoint().address);

		if(req.sequence.present()) {
			auto& trackerData = self->peekTracker[peekId];
			trackerData.lastUpdate = now();
			auto& sequenceData = trackerData.sequence_version[sequence+1];
			if(sequenceData.isSet()) {
				if(sequenceData.getFuture().get() != reply.end) {
					TEST(true); //tlog peek second attempt ended at a different version
					req.reply.sendError(timed_out());
					return Void();
				}
			} else {
				sequenceData.send(reply.end);
			}
			reply.begin = req.begin;
		}

		req.reply.send( reply );
		return Void();
	}

	ACTOR Future<Void> doQueueCommit( TLogData* self, Reference<LogData> logData ) {
		state Version ver = logData->version.get();
		state Version commitNumber = self->queueCommitBegin+1;
		self->queueCommitBegin = commitNumber;
		logData->queueCommittingVersion = ver;

		Future<Void> c = self->persistentQueue->commit();
		self->diskQueueCommitBytes = 0;
		self->largeDiskQueueCommitBytes.set(false);

		wait(c);
		wait(self->queueCommitEnd.whenAtLeast(commitNumber-1));

		//Calling check_yield instead of yield to avoid a destruction ordering problem in simulation
		if(g_network->check_yield(g_network->getCurrentTask())) {
			wait(delay(0, g_network->getCurrentTask()));
		}

		ASSERT( ver > logData->queueCommittedVersion.get() );

		logData->queueCommittedVersion.set(ver);
		self->queueCommitEnd.set(commitNumber);

		//TraceEvent("TLogCommitDurable", self->dbgid).detail("Version", ver);

		return Void();
	}

	ACTOR Future<Void> commitQueue( TLogData* self ) {
		state Reference<LogData> logData;

		loop {
			bool foundCount = 0;
			for(auto it : self->id_data) {
				if(!it.second->stopped) {
					 logData = it.second;
					 foundCount++;
				}
			}

			ASSERT(foundCount < 2);
			if(!foundCount) {
				wait( self->newLogData.onTrigger() );
				continue;
			}

			TraceEvent("CommitQueueNewLog", self->dbgid).detail("LogId", logData->logId).detail("Version", logData->version.get()).detail("Committing", logData->queueCommittingVersion).detail("Commmitted", logData->queueCommittedVersion.get());

			loop {
				if(logData->stopped && logData->version.get() == std::max(logData->queueCommittingVersion, logData->queueCommittedVersion.get())) {
					wait( logData->queueCommittedVersion.whenAtLeast(logData->version.get() ) );
					break;
				}

				choose {
					when(wait( logData->version.whenAtLeast( std::max(logData->queueCommittingVersion, logData->queueCommittedVersion.get()) + 1 ) ) ) {
						while( self->queueCommitBegin != self->queueCommitEnd.get() && !self->largeDiskQueueCommitBytes.get() ) {
							wait( self->queueCommitEnd.whenAtLeast(self->queueCommitBegin) || self->largeDiskQueueCommitBytes.onChange() );
						}
						self->sharedActors.send(doQueueCommit(self, logData));
					}
					when(wait(self->newLogData.onTrigger())) {}
				}
			}
		}
	}

	ACTOR Future<Void> rejoinMasters( TLogData* self, TLogInterface tli, DBRecoveryCount recoveryCount, Future<Void> registerWithMaster ) {
		state UID lastMasterID(0,0);
		loop {
			auto const& inf = self->dbInfo->get();
			bool isDisplaced = !std::count( inf.priorCommittedLogServers.begin(), inf.priorCommittedLogServers.end(), tli.id() );
			isDisplaced = isDisplaced && inf.recoveryCount >= recoveryCount && inf.recoveryState != RecoveryState::UNINITIALIZED;

			if(isDisplaced) {
				for(auto& log : inf.logSystemConfig.tLogs) {
					 if( std::count( log.tLogs.begin(), log.tLogs.end(), tli.id() ) ) {
						isDisplaced = false;
						break;
					 }
				}
			}
			if(isDisplaced) {
				for(auto& old : inf.logSystemConfig.oldTLogs) {
					for(auto& log : old.tLogs) {
						 if( std::count( log.tLogs.begin(), log.tLogs.end(), tli.id() ) ) {
							isDisplaced = false;
							break;
						 }
					}
				}
			}
			if ( isDisplaced )
			{
				TraceEvent("TLogDisplaced", tli.id()).detail("Reason", "DBInfoDoesNotContain").detail("RecoveryCount", recoveryCount).detail("InfRecoveryCount", inf.recoveryCount).detail("RecoveryState", (int)inf.recoveryState)
					.detail("LogSysConf", describe(inf.logSystemConfig.tLogs)).detail("PriorLogs", describe(inf.priorCommittedLogServers)).detail("OldLogGens", inf.logSystemConfig.oldTLogs.size());
				if (BUGGIFY) wait( delay( SERVER_KNOBS->BUGGIFY_WORKER_REMOVED_MAX_LAG * g_random->random01() ) );
				throw worker_removed();
			}

			if( registerWithMaster.isReady() ) {
				if ( self->dbInfo->get().master.id() != lastMasterID) {
					// The TLogRejoinRequest is needed to establish communications with a new master, which doesn't have our TLogInterface
					TLogRejoinRequest req;
					req.myInterface = tli;
					TraceEvent("TLogRejoining", self->dbgid).detail("Master", self->dbInfo->get().master.id());
					choose {
						when ( bool success = wait( brokenPromiseToNever( self->dbInfo->get().master.tlogRejoin.getReply( req ) ) ) ) {
							if (success)
								lastMasterID = self->dbInfo->get().master.id();
						}
						when ( wait( self->dbInfo->onChange() ) ) { }
					}
				} else {
					wait( self->dbInfo->onChange() );
				}
			} else {
				wait( registerWithMaster || self->dbInfo->onChange() );
			}
		}
	}

	ACTOR Future<Void> cleanupPeekTrackers( TLogData* self ) {
		loop {
			double minTimeUntilExpiration = SERVER_KNOBS->PEEK_TRACKER_EXPIRATION_TIME;
			auto it = self->peekTracker.begin();
			while(it != self->peekTracker.end()) {
				double timeUntilExpiration = it->second.lastUpdate + SERVER_KNOBS->PEEK_TRACKER_EXPIRATION_TIME - now();
				if(timeUntilExpiration < 1.0e-6) {
					for(auto seq : it->second.sequence_version) {
						if(!seq.second.isSet()) {
							seq.second.sendError(timed_out());
						}
					}
					it = self->peekTracker.erase(it);
				} else {
					minTimeUntilExpiration = std::min(minTimeUntilExpiration, timeUntilExpiration);
					++it;
				}
			}

			wait( delay(minTimeUntilExpiration) );
		}
	}

	void getQueuingMetrics( TLogData* self, TLogQueuingMetricsRequest const& req ) {
		TLogQueuingMetricsReply reply;
		reply.localTime = now();
		reply.instanceID = self->instanceID;
		reply.bytesInput = self->bytesInput;
		reply.bytesDurable = self->bytesDurable;
		reply.storageBytes = self->persistentData->getStorageBytes();
		reply.v = self->prevVersion;
		req.reply.send( reply );
	}

	ACTOR Future<Void> serveTLogInterface( TLogData* self, TLogInterface tli, Reference<LogData> logData, PromiseStream<Void> warningCollectorInput ) {
		loop choose {
			when( TLogPeekRequest req = waitNext( tli.peekMessages.getFuture() ) ) {
				logData->addActor.send( tLogPeekMessages( self, req, logData ) );
			}
			when( TLogPopRequest req = waitNext( tli.popMessages.getFuture() ) ) {
				logData->addActor.send( tLogPop( self, req, logData ) );
			}
			when( TLogCommitRequest req = waitNext( tli.commit.getFuture() ) ) {
				ASSERT(logData->stopped);
				req.reply.sendError( tlog_stopped() );
			}
			when( ReplyPromise< TLogLockResult > reply = waitNext( tli.lock.getFuture() ) ) {
				logData->addActor.send( tLogLock(self, reply, logData) );
			}
			when (TLogQueuingMetricsRequest req = waitNext(tli.getQueuingMetrics.getFuture())) {
				getQueuingMetrics(self, req);
			}
			when (TLogConfirmRunningRequest req = waitNext(tli.confirmRunning.getFuture())){
				if (req.debugID.present() ) {
					UID tlogDebugID = g_nondeterministic_random->randomUniqueID();
					g_traceBatch.addAttach("TransactionAttachID", req.debugID.get().first(), tlogDebugID.first());
					g_traceBatch.addEvent("TransactionDebug", tlogDebugID.first(), "TLogServer.TLogConfirmRunningRequest");
				}
				ASSERT(logData->stopped);
				req.reply.sendError( tlog_stopped() );
			}
		}
	}

	void removeLog( TLogData* self, Reference<LogData> logData ) {
		TraceEvent("TLogRemoved", logData->logId).detail("Input", logData->bytesInput.getValue()).detail("Durable", logData->bytesDurable.getValue());
		logData->stopped = true;
		if(logData->recoverySuccessful.canBeSet()) {
			logData->recoverySuccessful.send(false);
		}

		logData->addActor = PromiseStream<Future<Void>>(); //there could be items still in the promise stream if one of the actors threw an error immediately
		self->id_data.erase(logData->logId);

		if(self->id_data.size()) {
			return;
		} else {
			throw worker_removed();
		}
	}

	ACTOR Future<Void> tLogCore( TLogData* self, Reference<LogData> logData ) {
		if(logData->removed.isReady()) {
			wait(delay(0)); //to avoid iterator invalidation in restorePersistentState when removed is already ready
			ASSERT(logData->removed.isError());

			if(logData->removed.getError().code() != error_code_worker_removed) {
				throw logData->removed.getError();
			}

			removeLog(self, logData);
			return Void();
		}

		TraceEvent("NewLogData", self->dbgid).detail("LogId", logData->logId);
		logData->initialized = true;
		self->newLogData.trigger();

		state PromiseStream<Void> warningCollectorInput;
		state Future<Void> warningCollector = timeoutWarningCollector( warningCollectorInput.getFuture(), 1.0, "TLogQueueCommitSlow", self->dbgid );
		state Future<Void> error = actorCollection( logData->addActor.getFuture() );

		logData->addActor.send( logData->recovery );
		logData->addActor.send( waitFailureServer(logData->tli.waitFailure.getFuture()) );
		logData->addActor.send( logData->removed );
		//FIXME: update tlogMetrics to include new information, or possibly only have one copy for the shared instance
		logData->addActor.send( traceCounters("TLogMetrics", logData->logId, SERVER_KNOBS->STORAGE_LOGGING_DELAY, &logData->cc, logData->logId.toString() + "/TLogMetrics"));
		logData->addActor.send( serveTLogInterface(self, logData->tli, logData, warningCollectorInput) );

		try {
			wait( error );
			throw internal_error();
		} catch( Error &e ) {
			if( e.code() != error_code_worker_removed )
				throw;

			removeLog(self, logData);
			return Void();
		}
	}

	ACTOR Future<Void> restorePersistentState( TLogData* self, LocalityData locality ) {
		state double startt = now();
		state Reference<LogData> logData;
		state KeyRange tagKeys;
		// PERSIST: Read basic state from persistentData; replay persistentQueue but don't erase it

		TraceEvent("TLogRestorePersistentState", self->dbgid);

		IKeyValueStore *storage = self->persistentData;
		state Future<Optional<Value>> fFormat = storage->readValue(persistFormat.key);
		state Future<Standalone<VectorRef<KeyValueRef>>> fVers = storage->readRange(persistCurrentVersionKeys);
		state Future<Standalone<VectorRef<KeyValueRef>>> fRecoverCounts = storage->readRange(persistRecoveryCountKeys);

		// FIXME: metadata in queue?

		wait( waitForAll( (vector<Future<Optional<Value>>>(), fFormat ) ) );
		wait( waitForAll( (vector<Future<Standalone<VectorRef<KeyValueRef>>>>(), fVers, fRecoverCounts) ) );

		if (fFormat.get().present() && !persistFormatReadableRange.contains( fFormat.get().get() )) {
			TraceEvent(SevError, "UnsupportedDBFormat", self->dbgid).detail("Format", printable(fFormat.get().get())).detail("Expected", persistFormat.value.toString());
			throw worker_recovery_failed();
		}

		if (!fFormat.get().present()) {
			Standalone<VectorRef<KeyValueRef>> v = wait( self->persistentData->readRange( KeyRangeRef(StringRef(), LiteralStringRef("\xff")), 1 ) );
			if (!v.size()) {
				TEST(true); // The DB is completely empty, so it was never initialized.  Delete it.
				throw worker_removed();
			} else {
				// This should never happen
				TraceEvent(SevError, "NoDBFormatKey", self->dbgid).detail("FirstKey", printable(v[0].key));
				ASSERT( false );
				throw worker_recovery_failed();
			}
		}

		state std::vector<Future<ErrorOr<Void>>> removed;

		ASSERT(fVers.get().size() == fRecoverCounts.get().size());

		state int idx = 0;
		state Promise<Void> registerWithMaster;
		for(idx = 0; idx < fVers.get().size(); idx++) {
			state KeyRef rawId = fVers.get()[idx].key.removePrefix(persistCurrentVersionKeys.begin);
			UID id1 = BinaryReader::fromStringRef<UID>( rawId, Unversioned() );
			UID id2 = BinaryReader::fromStringRef<UID>( fRecoverCounts.get()[idx].key.removePrefix(persistRecoveryCountKeys.begin), Unversioned() );
			ASSERT(id1 == id2);

			TLogInterface recruited(id1, self->dbgid, locality);
			recruited.initEndpoints();

			DUMPTOKEN( recruited.peekMessages );
			DUMPTOKEN( recruited.popMessages );
			DUMPTOKEN( recruited.commit );
			DUMPTOKEN( recruited.lock );
			DUMPTOKEN( recruited.getQueuingMetrics );
			DUMPTOKEN( recruited.confirmRunning );

			logData = Reference<LogData>( new LogData(self, recruited) );
			logData->stopped = true;
			self->id_data[id1] = logData;

			Version ver = BinaryReader::fromStringRef<Version>( fVers.get()[idx].value, Unversioned() );
			logData->persistentDataVersion = ver;
			logData->persistentDataDurableVersion = ver;
			logData->version.set(ver);
			logData->recoveryCount = BinaryReader::fromStringRef<DBRecoveryCount>( fRecoverCounts.get()[idx].value, Unversioned() );
			logData->removed = rejoinMasters(self, recruited, logData->recoveryCount, registerWithMaster.getFuture());
			removed.push_back(errorOr(logData->removed));

			TraceEvent("TLogRestorePersistentStateVer", id1).detail("Ver", ver);

			// Restore popped keys.  Pop operations that took place after the last (committed) updatePersistentDataVersion might be lost, but
			// that is fine because we will get the corresponding data back, too.
			tagKeys = prefixRange( rawId.withPrefix(persistTagPoppedKeys.begin) );
			loop {
				if(logData->removed.isReady()) break;
				Standalone<VectorRef<KeyValueRef>> data = wait( self->persistentData->readRange( tagKeys, BUGGIFY ? 3 : 1<<30, 1<<20 ) );
				if (!data.size()) break;
				((KeyRangeRef&)tagKeys) = KeyRangeRef( keyAfter(data.back().key, tagKeys.arena()), tagKeys.end );

				for(auto &kv : data) {
					OldTag tag = decodeTagPoppedKey(rawId, kv.key);
					Version popped = decodeTagPoppedValue(kv.value);
					TraceEvent("TLogRestorePop", logData->logId).detail("Tag", tag).detail("To", popped);
					ASSERT( logData->tag_data.find(tag) == logData->tag_data.end() );
					logData->tag_data.insert( mapPair( tag, LogData::TagData( popped, false, false, tag )) );
				}
			}
		}

		state Future<Void> allRemoved = waitForAll(removed);
		state Version lastVer = 0;
		state UID lastId = UID(1,1); //initialized so it will not compare equal to a default UID
		state double recoverMemoryLimit = SERVER_KNOBS->TARGET_BYTES_PER_TLOG + SERVER_KNOBS->SPRING_BYTES_TLOG;
		if (BUGGIFY) recoverMemoryLimit = std::max<double>(SERVER_KNOBS->BUGGIFY_RECOVER_MEMORY_LIMIT, SERVER_KNOBS->TLOG_SPILL_THRESHOLD);
	
		try {
			loop {
				if(allRemoved.isReady()) {
					TEST(true); //all tlogs removed during queue recovery
					throw worker_removed();
				}
				choose {
					when( TLogQueueEntry qe = wait( self->persistentQueue->readNext() ) ) {
						if(!self->queueOrder.size() || self->queueOrder.back() != qe.id) self->queueOrder.push_back(qe.id);
						if(qe.id != lastId) {
							lastId = qe.id;
							auto it = self->id_data.find(qe.id);
							if(it != self->id_data.end()) {
								logData = it->second;
							} else {
								logData = Reference<LogData>();
							}
						} else {
							ASSERT( qe.version >= lastVer );
							lastVer = qe.version;
						}

						//TraceEvent("TLogRecoveredQE", self->dbgid).detail("LogId", qe.id).detail("Ver", qe.version).detail("MessageBytes", qe.messages.size()).detail("Tags", qe.tags.size())
						//	.detail("Tag0", qe.tags.size() ? qe.tags[0].tag : invalidTag).detail("Version", logData->version.get());

						if(logData) {
							logData->knownCommittedVersion = std::max(logData->knownCommittedVersion, qe.knownCommittedVersion);
							if( qe.version > logData->version.get() ) {
								commitMessages(logData, qe.version, qe.arena(), qe.messages, qe.tags, self->bytesInput);
								logData->version.set( qe.version );
								logData->queueCommittedVersion.set( qe.version );

								while (self->bytesInput - self->bytesDurable >= recoverMemoryLimit) {
									TEST(true);  // Flush excess data during TLog queue recovery
									TraceEvent("FlushLargeQueueDuringRecovery", self->dbgid).detail("BytesInput", self->bytesInput).detail("BytesDurable", self->bytesDurable).detail("Version", logData->version.get()).detail("PVer", logData->persistentDataVersion);

									choose {
										when( wait( updateStorage(self) ) ) {}
										when( wait( allRemoved ) ) { throw worker_removed(); }
									}
								}
							}
						}
					}
					when( wait( allRemoved ) ) { throw worker_removed(); }
				}
			}
		} catch (Error& e) {
			if (e.code() != error_code_end_of_stream) throw;
		}

		TraceEvent("TLogRestorePersistentStateDone", self->dbgid).detail("Took", now()-startt);
		TEST( now()-startt >= 1.0 );  // TLog recovery took more than 1 second

		for(auto it : self->id_data) {
			if(it.second->queueCommittedVersion.get() == 0) {
				TraceEvent("TLogZeroVersion", self->dbgid).detail("LogId", it.first);
				it.second->queueCommittedVersion.set(it.second->version.get());
			}
			self->sharedActors.send( tLogCore( self, it.second ) );
		}

		if(registerWithMaster.canBeSet()) registerWithMaster.send(Void());
		return Void();
	}

	ACTOR Future<Void> tLog( IKeyValueStore* persistentData, IDiskQueue* persistentQueue, Reference<AsyncVar<ServerDBInfo>> db, LocalityData locality, UID tlogId )
	{
		state TLogData self( tlogId, persistentData, persistentQueue, db );
		state Future<Void> error = actorCollection( self.sharedActors.getFuture() );

		TraceEvent("SharedTlog", tlogId);

		try {
			wait( restorePersistentState( &self, locality ) );
			
			self.sharedActors.send( cleanupPeekTrackers(&self) );
			self.sharedActors.send( commitQueue(&self) );
			self.sharedActors.send( updateStorageLoop(&self) );

			wait( error );
			throw internal_error();
		} catch (Error& e) {
			TraceEvent("TLogError", tlogId).error(e, true);

			for( auto& it : self.id_data ) {
				if(it.second->recoverySuccessful.canBeSet()) {
					it.second->recoverySuccessful.send(false);
				}
			}

			throw;
		}
	}
}