zookeeper 원본 분석의 4 서버 (싱글) 처리 요청 절차
zookeeper 원본 분석 중 하나인 서버 시작 과정
여기서 zookeeper 서버의 시작 과정을 소개했습니다. 그 중에서 단기는 Zookeeper Server가 시작되고 집단은 QuorumPeer를 사용하여 시작됩니다. 그러면 이번에는 각각의 메시지 처리 과정을 분석합니다.
앞에서 보실 수 있습니다.
1. 독립 실행형 상태에서 NettyServerCnxnFactory에서 ZookeeperServer를 시작하여 메시지를 처리합니다. public synchronized void startup() {
if (sessionTracker == null) {
createSessionTracker();
}
startSessionTracker();
setupRequestProcessors();
registerJMX();
state = State.RUNNING;
notifyAll();
}
메시지 프로세서 호출은 다음과 같습니다. protected void setupRequestProcessors() {
RequestProcessor finalProcessor = new FinalRequestProcessor(this);
RequestProcessor syncProcessor = new SyncRequestProcessor(this,
finalProcessor);
((SyncRequestProcessor)syncProcessor).start();
firstProcessor = new PrepRequestProcessor(this, syncProcessor);
((PrepRequestProcessor)firstProcessor).start();
}
요청을 처리하기 위해 두 개의 메시지 프로세서를 시작하는 것을 보았습니다. 첫 번째 동기화 메시지 프로세서 예비 메시지 서버, 마지막 동기화 요청 프로세서와 비동기화 요청 프로세서입니다.
1.1 첫 번째 메시지 서버 프로세서 사전 메시지 서버 PrepRequestProcessor
@Override
public void run() {
try {
while (true) {
Request request = submittedRequests.take();
long traceMask = ZooTrace.CLIENT_REQUEST_TRACE_MASK;
if (request.type == OpCode.ping) {
traceMask = ZooTrace.CLIENT_PING_TRACE_MASK;
}
if (LOG.isTraceEnabled()) {
ZooTrace.logRequest(LOG, traceMask, 'P', request, "");
}
if (Request.requestOfDeath == request) {
break;
}
pRequest(request);
}
} catch (RequestProcessorException e) {
if (e.getCause() instanceof XidRolloverException) {
LOG.info(e.getCause().getMessage());
}
handleException(this.getName(), e);
} catch (Exception e) {
handleException(this.getName(), e);
}
LOG.info("PrepRequestProcessor exited loop!");
}
볼 수 있듯이while (true) 은 계속 순환 처리하는 과정으로 그 중에서 빨간색 부분은 처리하는 주체이다./**
* This method will be called inside the ProcessRequestThread, which is a
* singleton, so there will be a single thread calling this code.
*
* @param request
*/
protected void pRequest(Request request) throws RequestProcessorException {
// LOG.info("Prep>>> cxid = " + request.cxid + " type = " +
// request.type + " id = 0x" + Long.toHexString(request.sessionId));
request.setHdr(null);
request.setTxn(null);
try {
switch (request.type) {
case OpCode.createContainer:
case OpCode.create:
case OpCode.create2:
CreateRequest create2Request = new CreateRequest();
pRequest2Txn(request.type, zks.getNextZxid(), request, create2Request, true);
break;
case OpCode.deleteContainer:
case OpCode.delete:
DeleteRequest deleteRequest = new DeleteRequest();
pRequest2Txn(request.type, zks.getNextZxid(), request, deleteRequest, true);
break;
case OpCode.setData:
SetDataRequest setDataRequest = new SetDataRequest();
pRequest2Txn(request.type, zks.getNextZxid(), request, setDataRequest, true);
break;
case OpCode.reconfig:
ReconfigRequest reconfigRequest = new ReconfigRequest();
ByteBufferInputStream.byteBuffer2Record(request.request, reconfigRequest);
pRequest2Txn(request.type, zks.getNextZxid(), request, reconfigRequest, true);
break;
case OpCode.setACL:
SetACLRequest setAclRequest = new SetACLRequest();
pRequest2Txn(request.type, zks.getNextZxid(), request, setAclRequest, true);
break;
case OpCode.check:
CheckVersionRequest checkRequest = new CheckVersionRequest();
pRequest2Txn(request.type, zks.getNextZxid(), request, checkRequest, true);
break;
case OpCode.multi:
MultiTransactionRecord multiRequest = new MultiTransactionRecord();
try {
ByteBufferInputStream.byteBuffer2Record(request.request, multiRequest);
} catch(IOException e) {
request.setHdr(new TxnHeader(request.sessionId, request.cxid, zks.getNextZxid(),
Time.currentWallTime(), OpCode.multi));
throw e;
}
List<Txn> txns = new ArrayList<Txn>();
//Each op in a multi-op must have the same zxid!
long zxid = zks.getNextZxid();
KeeperException ke = null;
//Store off current pending change records in case we need to rollback
Map<String, ChangeRecord> pendingChanges = getPendingChanges(multiRequest);
for(Op op: multiRequest) {
Record subrequest = op.toRequestRecord();
int type;
Record txn;
/* If we've already failed one of the ops, don't bother
* trying the rest as we know it's going to fail and it
* would be confusing in the logfiles.
*/
if (ke != null) {
type = OpCode.error;
txn = new ErrorTxn(Code.RUNTIMEINCONSISTENCY.intValue());
}
/* Prep the request and convert to a Txn */
else {
try {
pRequest2Txn(op.getType(), zxid, request, subrequest, false);
type = request.getHdr().getType();
txn = request.getTxn();
} catch (KeeperException e) {
ke = e;
type = OpCode.error;
txn = new ErrorTxn(e.code().intValue());
LOG.info("Got user-level KeeperException when processing "
+ request.toString() + " aborting remaining multi ops."
+ " Error Path:" + e.getPath()
+ " Error:" + e.getMessage());
request.setException(e);
/* Rollback change records from failed multi-op */
rollbackPendingChanges(zxid, pendingChanges);
}
}
//FIXME: I don't want to have to serialize it here and then
// immediately deserialize in next processor. But I'm
// not sure how else to get the txn stored into our list.
ByteArrayOutputStream baos = new ByteArrayOutputStream();
BinaryOutputArchive boa = BinaryOutputArchive.getArchive(baos);
txn.serialize(boa, "request") ;
ByteBuffer bb = ByteBuffer.wrap(baos.toByteArray());
txns.add(new Txn(type, bb.array()));
}
request.setHdr(new TxnHeader(request.sessionId, request.cxid, zxid,
Time.currentWallTime(), request.type));
request.setTxn(new MultiTxn(txns));
break;
//create/close session don't require request record
case OpCode.createSession:
case OpCode.closeSession:
if (!request.isLocalSession()) {
pRequest2Txn(request.type, zks.getNextZxid(), request,
null, true);
}
break;
//All the rest don't need to create a Txn - just verify session
case OpCode.sync:
case OpCode.exists:
case OpCode.getData:
case OpCode.getACL:
case OpCode.getChildren:
case OpCode.getChildren2:
case OpCode.ping:
case OpCode.setWatches:
case OpCode.checkWatches:
case OpCode.removeWatches:
zks.sessionTracker.checkSession(request.sessionId,
request.getOwner());
break;
default:
LOG.warn("unknown type " + request.type);
break;
}
} catch (KeeperException e) {
if (request.getHdr() != null) {
request.getHdr().setType(OpCode.error);
request.setTxn(new ErrorTxn(e.code().intValue()));
}
LOG.info("Got user-level KeeperException when processing "
+ request.toString()
+ " Error Path:" + e.getPath()
+ " Error:" + e.getMessage());
request.setException(e);
} catch (Exception e) {
// log at error level as we are returning a marshalling
// error to the user
LOG.error("Failed to process " + request, e);
StringBuilder sb = new StringBuilder();
ByteBuffer bb = request.request;
if(bb != null){
bb.rewind();
while (bb.hasRemaining()) {
sb.append(Integer.toHexString(bb.get() & 0xff));
}
} else {
sb.append("request buffer is null");
}
LOG.error("Dumping request buffer: 0x" + sb.toString());
if (request.getHdr() != null) {
request.getHdr().setType(OpCode.error);
request.setTxn(new ErrorTxn(Code.MARSHALLINGERROR.intValue()));
}
}
request.zxid = zks.getZxid();
nextProcessor.processRequest(request);
}
이상한 논리를 배제합니다. 이 방법은 서로 다른 유형의request를 처리하는 것입니다. type에 따라 처리 지점을 선택하고 ProcessRequestThread 내부에서 이 방법을 호출합니다. 이것은 하나의 예이기 때문에 이 코드만 호출합니다.create 요청을 예로 들면 (빨간색 부분), 작업 메커니즘을 이해합니다. CreateRequest createRequest = (CreateRequest)record;
if (deserialize) {
ByteBufferInputStream.byteBuffer2Record(request.request, createRequest);
}
CreateMode createMode = CreateMode.fromFlag(createRequest.getFlags());
validateCreateRequest(createMode, request);
String path = createRequest.getPath();
String parentPath = validatePathForCreate(path, request.sessionId);
List<ACL> listACL = fixupACL(path, request.authInfo, createRequest.getAcl());
ChangeRecord parentRecord = getRecordForPath(parentPath);
checkACL(zks, parentRecord.acl, ZooDefs.Perms.CREATE, request.authInfo);
int parentCVersion = parentRecord.stat.getCversion();
if (createMode.isSequential()) {
path = path + String.format(Locale.ENGLISH, "%010d", parentCVersion);
}
validatePath(path, request.sessionId);
try {
if (getRecordForPath(path) != null) {
throw new KeeperException.NodeExistsException(path);
}
} catch (KeeperException.NoNodeException e) {
// ignore this one
}
boolean ephemeralParent = (parentRecord.stat.getEphemeralOwner() != 0) &&
(parentRecord.stat.getEphemeralOwner() != DataTree.CONTAINER_EPHEMERAL_OWNER);
if (ephemeralParent) {
throw new KeeperException.NoChildrenForEphemeralsException(path);
}
int newCversion = parentRecord.stat.getCversion()+1;
if (type == OpCode.createContainer) {
request.setTxn(new CreateContainerTxn(path, createRequest.getData(), listACL, newCversion));
} else {
request.setTxn(new CreateTxn(path, createRequest.getData(), listACL, createMode.isEphemeral(),
newCversion));
}
StatPersisted s = new StatPersisted();
if (createMode.isEphemeral()) {
s.setEphemeralOwner(request.sessionId);
}
parentRecord = parentRecord.duplicate(request.getHdr().getZxid());
parentRecord.childCount++;
parentRecord.stat.setCversion(newCversion);
addChangeRecord(parentRecord); addChangeRecord(new ChangeRecord(request.getHdr().getZxid(), path, s, 0, listACL));
break;
호출 방법, 변화 처리: private void addChangeRecord(ChangeRecord c) {
synchronized (zks.outstandingChanges) {
zks.outstandingChanges.add(c);
zks.outstandingChangesForPath.put(c.path, c);
}
}
계속 아래로 private void addChangeRecord(ChangeRecord c) {
synchronized (zks.outstandingChanges) {
zks.outstandingChanges.add(c);
zks.outstandingChangesForPath.put(c.path, c);
}
}
그 중에서 outstandingChanges는 ChangeRecord 그룹이고 outstandingChangesForPath는 맵의 ChangeRecord입니다. 다음과 같이 정의합니다.
final List outstandingChanges = new ArrayList();//this data structure must be accessed under the outstandingChanges lock final HashMap outstandingChangesForPath = new HashMap();
ChangeRecord는 PrepRP와 FinalRp가 정보를 공유할 수 있는 데이터 구조입니다. ChangeRecord(long zxid, String path, StatPersisted stat, int childCount,
List<ACL> acl) {
this.zxid = zxid;
this.path = path;
this.stat = stat;
this.childCount = childCount;
this.acl = acl;
}
1.2 먼저 동기화 요청 프로세서 Final Request Processor를 보십시오. 이 요청 프로세서는 실제로 요청된 모든 업무에 적용되고 모든 조회에 서비스를 제공합니다.그것은 보통 요청 처리의 마지막 (다음 메시지 프로세서가 없을 것) 에 있기 때문에 이름을 얻었다.그것은 어떻게 요청을 처리합니까?public void processRequest(Request request) {
if (LOG.isDebugEnabled()) {
LOG.debug("Processing request:: " + request);
}
// request.addRQRec(">final");
long traceMask = ZooTrace.CLIENT_REQUEST_TRACE_MASK;
if (request.type == OpCode.ping) {
traceMask = ZooTrace.SERVER_PING_TRACE_MASK;
}
if (LOG.isTraceEnabled()) {
ZooTrace.logRequest(LOG, traceMask, 'E', request, "");
}
ProcessTxnResult rc = null;
synchronized (zks.outstandingChanges) {
// Need to process local session requests
rc = zks.processTxn(request);
// request.hdr is set for write requests, which are the only ones
// that add to outstandingChanges.
if (request.getHdr() != null) {
TxnHeader hdr = request.getHdr();
Record txn = request.getTxn();
long zxid = hdr.getZxid();
while (!zks.outstandingChanges.isEmpty()
&& zks.outstandingChanges.get(0).zxid <= zxid) {
ChangeRecord cr = zks.outstandingChanges.remove(0);
if (cr.zxid < zxid) {
LOG.warn("Zxid outstanding " + cr.zxid
+ " is less than current " + zxid);
}
if (zks.outstandingChangesForPath.get(cr.path) == cr) {
zks.outstandingChangesForPath.remove(cr.path);
}
}
}
// do not add non quorum packets to the queue.
if (request.isQuorum()) { zks.getZKDatabase().addCommittedProposal(request); }
}
// ZOOKEEPER-558:
// In some cases the server does not close the connection (e.g., closeconn buffer
// was not being queued — ZOOKEEPER-558) properly. This happens, for example,
// when the client closes the connection. The server should still close the session, though.
// Calling closeSession() after losing the cnxn, results in the client close session response being dropped.
if (request.type == OpCode.closeSession && connClosedByClient(request)) {
// We need to check if we can close the session id.
// Sometimes the corresponding ServerCnxnFactory could be null because
// we are just playing diffs from the leader.
if (closeSession(zks.serverCnxnFactory, request.sessionId) ||
closeSession(zks.secureServerCnxnFactory, request.sessionId)) {
return;
}
}
if (request.cnxn == null) {
return;
}
ServerCnxn cnxn = request.cnxn;
String lastOp = "NA";
zks.decInProcess();
Code err = Code.OK;
Record rsp = null;
try {
if (request.getHdr() != null && request.getHdr().getType() == OpCode.error) {
/*
* When local session upgrading is disabled, leader will
* reject the ephemeral node creation due to session expire.
* However, if this is the follower that issue the request,
* it will have the correct error code, so we should use that
* and report to user
*/
if (request.getException() != null) {
throw request.getException();
} else {
throw KeeperException.create(KeeperException.Code
.get(((ErrorTxn) request.getTxn()).getErr()));
}
}
KeeperException ke = request.getException();
if (ke != null && request.type != OpCode.multi) {
throw ke;
}
if (LOG.isDebugEnabled()) {
LOG.debug("{}",request);
}
switch (request.type) {
case OpCode.ping: {
zks.serverStats().updateLatency(request.createTime);
lastOp = "PING";
cnxn.updateStatsForResponse(request.cxid, request.zxid, lastOp,
request.createTime, Time.currentElapsedTime());
cnxn.sendResponse(new ReplyHeader(-2,
zks.getZKDatabase().getDataTreeLastProcessedZxid(), 0), null, "response");
return;
}
case OpCode.createSession: {
zks.serverStats().updateLatency(request.createTime);
lastOp = "SESS";
cnxn.updateStatsForResponse(request.cxid, request.zxid, lastOp,
request.createTime, Time.currentElapsedTime());
zks.finishSessionInit(request.cnxn, true);
return;
}
case OpCode.multi: {
lastOp = "MULT";
rsp = new MultiResponse() ;
for (ProcessTxnResult subTxnResult : rc.multiResult) {
OpResult subResult ;
switch (subTxnResult.type) {
case OpCode.check:
subResult = new CheckResult();
break;
case OpCode.create:
subResult = new CreateResult(subTxnResult.path);
break;
case OpCode.create2:
case OpCode.createContainer:
subResult = new CreateResult(subTxnResult.path, subTxnResult.stat);
break;
case OpCode.delete:
case OpCode.deleteContainer:
subResult = new DeleteResult();
break;
case OpCode.setData:
subResult = new SetDataResult(subTxnResult.stat);
break;
case OpCode.error:
subResult = new ErrorResult(subTxnResult.err) ;
break;
default:
throw new IOException("Invalid type of op");
}
((MultiResponse)rsp).add(subResult);
}
break;
}
case OpCode.create: {
lastOp = "CREA";
rsp = new CreateResponse(rc.path);
err = Code.get(rc.err);
break;
}
case OpCode.create2:
case OpCode.createContainer: {
lastOp = "CREA";
rsp = new Create2Response(rc.path, rc.stat);
err = Code.get(rc.err);
break;
}
case OpCode.delete:
case OpCode.deleteContainer: {
lastOp = "DELE";
err = Code.get(rc.err);
break;
}
case OpCode.setData: {
lastOp = "SETD";
rsp = new SetDataResponse(rc.stat);
err = Code.get(rc.err);
break;
}
case OpCode.reconfig: {
lastOp = "RECO";
rsp = new GetDataResponse(((QuorumZooKeeperServer)zks).self.getQuorumVerifier().toString().getBytes(), rc.stat);
err = Code.get(rc.err);
break;
}
case OpCode.setACL: {
lastOp = "SETA";
rsp = new SetACLResponse(rc.stat);
err = Code.get(rc.err);
break;
}
case OpCode.closeSession: {
lastOp = "CLOS";
err = Code.get(rc.err);
break;
}
case OpCode.sync: {
lastOp = "SYNC";
SyncRequest syncRequest = new SyncRequest();
ByteBufferInputStream.byteBuffer2Record(request.request,
syncRequest);
rsp = new SyncResponse(syncRequest.getPath());
break;
}
case OpCode.check: {
lastOp = "CHEC";
rsp = new SetDataResponse(rc.stat);
err = Code.get(rc.err);
break;
}
case OpCode.exists: {
lastOp = "EXIS";
// TODO we need to figure out the security requirement for this!
ExistsRequest existsRequest = new ExistsRequest();
ByteBufferInputStream.byteBuffer2Record(request.request,
existsRequest);
String path = existsRequest.getPath();
if (path.indexOf('\0') != -1) {
throw new KeeperException.BadArgumentsException();
}
Stat stat = zks.getZKDatabase().statNode(path, existsRequest
.getWatch() ? cnxn : null);
rsp = new ExistsResponse(stat);
break;
}
case OpCode.getData: {
lastOp = "GETD";
GetDataRequest getDataRequest = new GetDataRequest();
ByteBufferInputStream.byteBuffer2Record(request.request,
getDataRequest);
DataNode n = zks.getZKDatabase().getNode(getDataRequest.getPath());
if (n == null) {
throw new KeeperException.NoNodeException();
}
Long aclL;
synchronized(n) {
aclL = n.acl;
}
PrepRequestProcessor.checkACL(zks, zks.getZKDatabase().convertLong(aclL),
ZooDefs.Perms.READ,
request.authInfo);
Stat stat = new Stat();
byte b[] = zks.getZKDatabase().getData(getDataRequest.getPath(), stat,
getDataRequest.getWatch() ? cnxn : null);
rsp = new GetDataResponse(b, stat);
break;
}
case OpCode.setWatches: {
lastOp = "SETW";
SetWatches setWatches = new SetWatches();
// XXX We really should NOT need this!!!!
request.request.rewind();
ByteBufferInputStream.byteBuffer2Record(request.request, setWatches);
long relativeZxid = setWatches.getRelativeZxid();
zks.getZKDatabase().setWatches(relativeZxid,
setWatches.getDataWatches(),
setWatches.getExistWatches(),
setWatches.getChildWatches(), cnxn);
break;
}
case OpCode.getACL: {
lastOp = "GETA";
GetACLRequest getACLRequest = new GetACLRequest();
ByteBufferInputStream.byteBuffer2Record(request.request,
getACLRequest);
Stat stat = new Stat();
List<ACL> acl =
zks.getZKDatabase().getACL(getACLRequest.getPath(), stat);
rsp = new GetACLResponse(acl, stat);
break;
}
case OpCode.getChildren: {
lastOp = "GETC";
GetChildrenRequest getChildrenRequest = new GetChildrenRequest();
ByteBufferInputStream.byteBuffer2Record(request.request,
getChildrenRequest);
DataNode n = zks.getZKDatabase().getNode(getChildrenRequest.getPath());
if (n == null) {
throw new KeeperException.NoNodeException();
}
Long aclG;
synchronized(n) {
aclG = n.acl;
}
PrepRequestProcessor.checkACL(zks, zks.getZKDatabase().convertLong(aclG),
ZooDefs.Perms.READ,
request.authInfo);
List<String> children = zks.getZKDatabase().getChildren(
getChildrenRequest.getPath(), null, getChildrenRequest
.getWatch() ? cnxn : null);
rsp = new GetChildrenResponse(children);
break;
}
case OpCode.getChildren2: {
lastOp = "GETC";
GetChildren2Request getChildren2Request = new GetChildren2Request();
ByteBufferInputStream.byteBuffer2Record(request.request,
getChildren2Request);
Stat stat = new Stat();
DataNode n = zks.getZKDatabase().getNode(getChildren2Request.getPath());
if (n == null) {
throw new KeeperException.NoNodeException();
}
Long aclG;
synchronized(n) {
aclG = n.acl;
}
PrepRequestProcessor.checkACL(zks, zks.getZKDatabase().convertLong(aclG),
ZooDefs.Perms.READ,
request.authInfo);
List<String> children = zks.getZKDatabase().getChildren(
getChildren2Request.getPath(), stat, getChildren2Request
.getWatch() ? cnxn : null);
rsp = new GetChildren2Response(children, stat);
break;
}
case OpCode.checkWatches: {
lastOp = "CHKW";
CheckWatchesRequest checkWatches = new CheckWatchesRequest();
ByteBufferInputStream.byteBuffer2Record(request.request,
checkWatches);
WatcherType type = WatcherType.fromInt(checkWatches.getType());
boolean containsWatcher = zks.getZKDatabase().containsWatcher(
checkWatches.getPath(), type, cnxn);
if (!containsWatcher) {
String msg = String.format(Locale.ENGLISH, "%s (type: %s)",
new Object[] { checkWatches.getPath(), type });
throw new KeeperException.NoWatcherException(msg);
}
break;
}
case OpCode.removeWatches: {
lastOp = "REMW";
RemoveWatchesRequest removeWatches = new RemoveWatchesRequest();
ByteBufferInputStream.byteBuffer2Record(request.request,
removeWatches);
WatcherType type = WatcherType.fromInt(removeWatches.getType());
boolean removed = zks.getZKDatabase().removeWatch(
removeWatches.getPath(), type, cnxn);
if (!removed) {
String msg = String.format(Locale.ENGLISH, "%s (type: %s)",
new Object[] { removeWatches.getPath(), type });
throw new KeeperException.NoWatcherException(msg);
}
break;
}
}
} catch (SessionMovedException e) {
// session moved is a connection level error, we need to tear
// down the connection otw ZOOKEEPER-710 might happen
// ie client on slow follower starts to renew session, fails
// before this completes, then tries the fast follower (leader)
// and is successful, however the initial renew is then
// successfully fwd/processed by the leader and as a result
// the client and leader disagree on where the client is most
// recently attached (and therefore invalid SESSION MOVED generated)
cnxn.sendCloseSession();
return;
} catch (KeeperException e) {
err = e.code();
} catch (Exception e) {
// log at error level as we are returning a marshalling
// error to the user
LOG.error("Failed to process " + request, e);
StringBuilder sb = new StringBuilder();
ByteBuffer bb = request.request;
bb.rewind();
while (bb.hasRemaining()) {
sb.append(Integer.toHexString(bb.get() & 0xff));
}
LOG.error("Dumping request buffer: 0x" + sb.toString());
err = Code.MARSHALLINGERROR;
}
long lastZxid = zks.getZKDatabase().getDataTreeLastProcessedZxid();
ReplyHeader hdr =
new ReplyHeader(request.cxid, lastZxid, err.intValue());
zks.serverStats().updateLatency(request.createTime);
cnxn.updateStatsForResponse(request.cxid, lastZxid, lastOp,
request.createTime, Time.currentElapsedTime());
try {
cnxn.sendResponse(hdr, rsp, "response");
if (request.type == OpCode.closeSession) {
cnxn.sendCloseSession();
}
} catch (IOException e) {
LOG.error("FIXMSG",e);
}
}
첫 번째, 공유된 outstandingChanges에 따라
트랜잭션 처리 후 세션 처리:private ProcessTxnResult processTxn(Request request, TxnHeader hdr,
Record txn) {
ProcessTxnResult rc;
int opCode = request != null ? request.type : hdr.getType();
long sessionId = request != null ? request.sessionId : hdr.getClientId();
if (hdr != null) {
rc = getZKDatabase().processTxn(hdr, txn);
} else {
rc = new ProcessTxnResult();
}
if (opCode == OpCode.createSession) {
if (hdr != null && txn instanceof CreateSessionTxn) {
CreateSessionTxn cst = (CreateSessionTxn) txn;
sessionTracker.addGlobalSession(sessionId, cst.getTimeOut());
} else if (request != null && request.isLocalSession()) {
request.request.rewind();
int timeout = request.request.getInt();
request.request.rewind();
sessionTracker.addSession(request.sessionId, timeout);
} else {
LOG.warn("*****>>>>> Got "
+ txn.getClass() + " "
+ txn.toString());
}
} else if (opCode == OpCode.closeSession) {
sessionTracker.removeSession(sessionId);
}
return rc;
}
트랜잭션 처리, 로컬과 데이터베이스의 다른 지점, DataTree 생성 노드 CreateTxn createTxn = (CreateTxn) txn;
rc.path = createTxn.getPath();
createNode(
createTxn.getPath(),
createTxn.getData(),
createTxn.getAcl(),
createTxn.getEphemeral() ? header.getClientId() : 0,
createTxn.getParentCVersion(),
header.getZxid(), header.getTime(), null);
break;
새 노드의 논리는 다음과 같습니다. /**
* Add a new node to the DataTree.
* @param path
* Path for the new node.
* @param data
* Data to store in the node.
* @param acl
* Node acls
* @param ephemeralOwner
* the session id that owns this node. -1 indicates this is not
* an ephemeral node.
* @param zxid
* Transaction ID
* @param time
* @param outputStat
* A Stat object to store Stat output results into.
* @throws NodeExistsException
* @throws NoNodeException
* @throws KeeperException
*/
public void createNode(final String path, byte data[], List<ACL> acl,
long ephemeralOwner, int parentCVersion, long zxid, long time, Stat outputStat)
throws KeeperException.NoNodeException,
KeeperException.NodeExistsException {
int lastSlash = path.lastIndexOf('/');
String parentName = path.substring(0, lastSlash);
String childName = path.substring(lastSlash + 1);
StatPersisted stat = new StatPersisted();
stat.setCtime(time);
stat.setMtime(time);
stat.setCzxid(zxid);
stat.setMzxid(zxid);
stat.setPzxid(zxid);
stat.setVersion(0);
stat.setAversion(0);
stat.setEphemeralOwner(ephemeralOwner);
DataNode parent = nodes.get(parentName);
if (parent == null) {
throw new KeeperException.NoNodeException();
}
synchronized (parent) {
Set<String> children = parent.getChildren();
if (children != null && children.contains(childName)) {
throw new KeeperException.NodeExistsException();
}
if (parentCVersion == -1) {
parentCVersion = parent.stat.getCversion();
parentCVersion++;
}
parent.stat.setCversion(parentCVersion);
parent.stat.setPzxid(zxid);
Long longval = convertAcls(acl);
DataNode child = new DataNode(data, longval, stat);
parent.addChild(childName);
nodes.put(path, child);
if (ephemeralOwner == CONTAINER_EPHEMERAL_OWNER) {
containers.add(path);
} else if (ephemeralOwner != 0) {
HashSet<String> list = ephemerals.get(ephemeralOwner);
if (list == null) {
list = new HashSet<String>();
ephemerals.put(ephemeralOwner, list);
}
synchronized (list) {
list.add(path);
}
}
if (outputStat != null) {
child.copyStat(outputStat);
}
}
// now check if its one of the zookeeper node child
if (parentName.startsWith(quotaZookeeper)) {
// now check if its the limit node
if (Quotas.limitNode.equals(childName)) {
// this is the limit node
// get the parent and add it to the trie
pTrie.addPath(parentName.substring(quotaZookeeper.length()));
}
if (Quotas.statNode.equals(childName)) {
updateQuotaForPath(parentName
.substring(quotaZookeeper.length()));
}
}
// also check to update the quotas for this node
String lastPrefix = getMaxPrefixWithQuota(path);
if(lastPrefix != null) {
// ok we have some match and need to update
updateCount(lastPrefix, 1);
updateBytes(lastPrefix, data == null ? 0 : data.length);
}
dataWatches.triggerWatch(path, Event.EventType.NodeCreated); childWatches.triggerWatch(parentName.equals("") ? "/" : parentName, Event.EventType.NodeChildrenChanged);
}
마지막 논리는 생성 노드와 하위 노드 변경 이벤트를 촉발하는 것이다. Set<Watcher> triggerWatch(String path, EventType type, Set<Watcher> supress) {
WatchedEvent e = new WatchedEvent(type,
KeeperState.SyncConnected, path);
HashSet<Watcher> watchers;
synchronized (this) {
watchers = watchTable.remove(path);
if (watchers == null || watchers.isEmpty()) {
if (LOG.isTraceEnabled()) {
ZooTrace.logTraceMessage(LOG,
ZooTrace.EVENT_DELIVERY_TRACE_MASK,
"No watchers for " + path);
}
return null;
}
for (Watcher w : watchers) {
HashSet<String> paths = watch2Paths.get(w);
if (paths != null) {
paths.remove(path);
}
}
}
for (Watcher w : watchers) {
if (supress != null && supress.contains(w)) {
continue;
}
w.process(e);
}
return watchers;
}
Watcher Manager는 정의된 Watcher를 호출하여 이벤트 처리를 합니다.
1.3. 비동기식 메시지 프로세서 SyncRequestProcessor 다시 보기@Override
public void run() {
try {
int logCount = 0;
// we do this in an attempt to ensure that not all of the servers
// in the ensemble take a snapshot at the same time
int randRoll = r.nextInt(snapCount/2);
while (true) {
Request si = null;
if (toFlush.isEmpty()) {
si = queuedRequests.take();
} else {
si = queuedRequests.poll();
if (si == null) {
flush(toFlush);
continue;
}
}
if (si == requestOfDeath) {
break;
}
if (si != null) {
// track the number of records written to the log
if (zks.getZKDatabase().append(si)) {
logCount++;
if (logCount > (snapCount / 2 + randRoll)) {
randRoll = r.nextInt(snapCount/2);
// roll the log
zks.getZKDatabase().rollLog();
// take a snapshot
if (snapInProcess != null && snapInProcess.isAlive()) {
LOG.warn("Too busy to snap, skipping");
} else {
snapInProcess = new ZooKeeperThread("Snapshot Thread") {
public void run() {
try {
zks.takeSnapshot();
} catch(Exception e) {
LOG.warn("Unexpected exception", e); } } }; snapInProcess.start();
}
logCount = 0;
}
} else if (toFlush.isEmpty()) {
// optimization for read heavy workloads
// iff this is a read, and there are no pending
// flushes (writes), then just pass this to the next
// processor
if (nextProcessor != null) {
nextProcessor.processRequest(si);
if (nextProcessor instanceof Flushable) {
((Flushable)nextProcessor).flush();
}
}
continue;
}
toFlush.add(si);
if (toFlush.size() > 1000) {
flush(toFlush);
}
}
}
} catch (Throwable t) {
handleException(this.getName(), t);
} finally{
running = false;
}
LOG.info("SyncRequestProcessor exited!");
}
비동기식 로그 및 스냅샷을 처리하고 ZooKeeperThread 스레드를 시작하여 스냅샷을 생성합니다. public void takeSnapshot(){
try {
txnLogFactory.save(zkDb.getDataTree(), zkDb.getSessionWithTimeOuts());
} catch (IOException e) {
LOG.error("Severe unrecoverable error, exiting", e);
// This is a severe error that we cannot recover from,
// so we need to exit
System.exit(10);
}
}
FileTxnSnapLog는 txtlog와 snapshot을 처리하는 데 도움을 주는 도구 클래스입니다. /**
* save the datatree and the sessions into a snapshot
* @param dataTree the datatree to be serialized onto disk
* @param sessionsWithTimeouts the sesssion timeouts to be
* serialized onto disk
* @throws IOException
*/
public void save(DataTree dataTree,
ConcurrentHashMap<Long, Integer> sessionsWithTimeouts)
throws IOException {
long lastZxid = dataTree.lastProcessedZxid;
File snapshotFile = new File(snapDir, Util.makeSnapshotName(lastZxid));
LOG.info("Snapshotting: 0x{} to {}", Long.toHexString(lastZxid),
snapshotFile);
snapLog.serialize(dataTree, sessionsWithTimeouts, snapshotFile);
}
파일로 영구화 /**
* serialize the datatree and session into the file snapshot
* @param dt the datatree to be serialized
* @param sessions the sessions to be serialized
* @param snapShot the file to store snapshot into
*/
public synchronized void serialize(DataTree dt, Map<Long, Integer> sessions, File snapShot)
throws IOException {
if (!close) {
OutputStream sessOS = new BufferedOutputStream(new FileOutputStream(snapShot));
CheckedOutputStream crcOut = new CheckedOutputStream(sessOS, new Adler32());
//CheckedOutputStream cout = new CheckedOutputStream()
OutputArchive oa = BinaryOutputArchive.getArchive(crcOut);
FileHeader header = new FileHeader(SNAP_MAGIC, VERSION, dbId);
serialize(dt,sessions,oa, header);
long val = crcOut.getChecksum().getValue();
oa.writeLong(val, "val");
oa.writeString("/", "path");
sessOS.flush();
crcOut.close();
sessOS.close();
}
}
이로써 전체 절차는 이미 끝났다.
2. 집단 상황에서
클러스터 상황은 단일 시스템과 약간 다릅니다. 클러스터에서 QuorumPeer를 사용하여 ServerCnxnFactory를 시작하고 로컬 주소를 바인딩합니다. @Override
public void start() {
LOG.info("binding to port " + localAddress);
parentChannel = bootstrap.bind(localAddress);
}
편폭에 한하여 뒤의 논리는 다음 편에서 상세하게 설명할 것이다.
작은 매듭
위의 코드 프로세스에서 우리는 서버 처리 요청이 Noi를 통해 처리하거나 프레임워크 Netty를 통해 처리하는 것을 알 수 있다. 요청은 먼저PrepRequestProcessor를 통해 요청을 받고 포장한 다음에 요청 유형에 따라 공유 데이터를 설정한다.그리고 SyncRequestProcessor를 통해 스냅샷과 사무 로그를 서열화하고 명령 형식에 따라db의 내용을 변경합니다. 로그와 스냅샷이 기록되지 않았을 때 다음 메시지 프로세서를 진행하지 않습니다.마지막으로 Final Request Processor를 호출하여 메시지 프로세서의 종결자로서 응답 메시지를 보내고 watcher의 프로세서를 터치합니다.
이 내용에 흥미가 있습니까?
현재 기사가 여러분의 문제를 해결하지 못하는 경우 AI 엔진은 머신러닝 분석(스마트 모델이 방금 만들어져 부정확한 경우가 있을 수 있음)을 통해 가장 유사한 기사를 추천합니다:
다양한 언어의 JSON
JSON은 Javascript 표기법을 사용하여 데이터 구조를 레이아웃하는 데이터 형식입니다.
그러나 Javascript가 코드에서 이러한 구조를 나타낼 수 있는 유일한 언어는 아닙니다.
저는 일반적으로 '객체'{}...
텍스트를 자유롭게 공유하거나 복사할 수 있습니다.하지만 이 문서의 URL은 참조 URL로 남겨 두십시오.
CC BY-SA 2.5, CC BY-SA 3.0 및 CC BY-SA 4.0에 따라 라이센스가 부여됩니다.
public synchronized void startup() {
if (sessionTracker == null) {
createSessionTracker();
}
startSessionTracker();
setupRequestProcessors();
registerJMX();
state = State.RUNNING;
notifyAll();
} protected void setupRequestProcessors() {
RequestProcessor finalProcessor = new FinalRequestProcessor(this);
RequestProcessor syncProcessor = new SyncRequestProcessor(this,
finalProcessor);
((SyncRequestProcessor)syncProcessor).start();
firstProcessor = new PrepRequestProcessor(this, syncProcessor);
((PrepRequestProcessor)firstProcessor).start();
} @Override
public void run() {
try {
while (true) {
Request request = submittedRequests.take();
long traceMask = ZooTrace.CLIENT_REQUEST_TRACE_MASK;
if (request.type == OpCode.ping) {
traceMask = ZooTrace.CLIENT_PING_TRACE_MASK;
}
if (LOG.isTraceEnabled()) {
ZooTrace.logRequest(LOG, traceMask, 'P', request, "");
}
if (Request.requestOfDeath == request) {
break;
}
pRequest(request);
}
} catch (RequestProcessorException e) {
if (e.getCause() instanceof XidRolloverException) {
LOG.info(e.getCause().getMessage());
}
handleException(this.getName(), e);
} catch (Exception e) {
handleException(this.getName(), e);
}
LOG.info("PrepRequestProcessor exited loop!");
}/**
* This method will be called inside the ProcessRequestThread, which is a
* singleton, so there will be a single thread calling this code.
*
* @param request
*/
protected void pRequest(Request request) throws RequestProcessorException {
// LOG.info("Prep>>> cxid = " + request.cxid + " type = " +
// request.type + " id = 0x" + Long.toHexString(request.sessionId));
request.setHdr(null);
request.setTxn(null);
try {
switch (request.type) {
case OpCode.createContainer:
case OpCode.create:
case OpCode.create2:
CreateRequest create2Request = new CreateRequest();
pRequest2Txn(request.type, zks.getNextZxid(), request, create2Request, true);
break;
case OpCode.deleteContainer:
case OpCode.delete:
DeleteRequest deleteRequest = new DeleteRequest();
pRequest2Txn(request.type, zks.getNextZxid(), request, deleteRequest, true);
break;
case OpCode.setData:
SetDataRequest setDataRequest = new SetDataRequest();
pRequest2Txn(request.type, zks.getNextZxid(), request, setDataRequest, true);
break;
case OpCode.reconfig:
ReconfigRequest reconfigRequest = new ReconfigRequest();
ByteBufferInputStream.byteBuffer2Record(request.request, reconfigRequest);
pRequest2Txn(request.type, zks.getNextZxid(), request, reconfigRequest, true);
break;
case OpCode.setACL:
SetACLRequest setAclRequest = new SetACLRequest();
pRequest2Txn(request.type, zks.getNextZxid(), request, setAclRequest, true);
break;
case OpCode.check:
CheckVersionRequest checkRequest = new CheckVersionRequest();
pRequest2Txn(request.type, zks.getNextZxid(), request, checkRequest, true);
break;
case OpCode.multi:
MultiTransactionRecord multiRequest = new MultiTransactionRecord();
try {
ByteBufferInputStream.byteBuffer2Record(request.request, multiRequest);
} catch(IOException e) {
request.setHdr(new TxnHeader(request.sessionId, request.cxid, zks.getNextZxid(),
Time.currentWallTime(), OpCode.multi));
throw e;
}
List<Txn> txns = new ArrayList<Txn>();
//Each op in a multi-op must have the same zxid!
long zxid = zks.getNextZxid();
KeeperException ke = null;
//Store off current pending change records in case we need to rollback
Map<String, ChangeRecord> pendingChanges = getPendingChanges(multiRequest);
for(Op op: multiRequest) {
Record subrequest = op.toRequestRecord();
int type;
Record txn;
/* If we've already failed one of the ops, don't bother
* trying the rest as we know it's going to fail and it
* would be confusing in the logfiles.
*/
if (ke != null) {
type = OpCode.error;
txn = new ErrorTxn(Code.RUNTIMEINCONSISTENCY.intValue());
}
/* Prep the request and convert to a Txn */
else {
try {
pRequest2Txn(op.getType(), zxid, request, subrequest, false);
type = request.getHdr().getType();
txn = request.getTxn();
} catch (KeeperException e) {
ke = e;
type = OpCode.error;
txn = new ErrorTxn(e.code().intValue());
LOG.info("Got user-level KeeperException when processing "
+ request.toString() + " aborting remaining multi ops."
+ " Error Path:" + e.getPath()
+ " Error:" + e.getMessage());
request.setException(e);
/* Rollback change records from failed multi-op */
rollbackPendingChanges(zxid, pendingChanges);
}
}
//FIXME: I don't want to have to serialize it here and then
// immediately deserialize in next processor. But I'm
// not sure how else to get the txn stored into our list.
ByteArrayOutputStream baos = new ByteArrayOutputStream();
BinaryOutputArchive boa = BinaryOutputArchive.getArchive(baos);
txn.serialize(boa, "request") ;
ByteBuffer bb = ByteBuffer.wrap(baos.toByteArray());
txns.add(new Txn(type, bb.array()));
}
request.setHdr(new TxnHeader(request.sessionId, request.cxid, zxid,
Time.currentWallTime(), request.type));
request.setTxn(new MultiTxn(txns));
break;
//create/close session don't require request record
case OpCode.createSession:
case OpCode.closeSession:
if (!request.isLocalSession()) {
pRequest2Txn(request.type, zks.getNextZxid(), request,
null, true);
}
break;
//All the rest don't need to create a Txn - just verify session
case OpCode.sync:
case OpCode.exists:
case OpCode.getData:
case OpCode.getACL:
case OpCode.getChildren:
case OpCode.getChildren2:
case OpCode.ping:
case OpCode.setWatches:
case OpCode.checkWatches:
case OpCode.removeWatches:
zks.sessionTracker.checkSession(request.sessionId,
request.getOwner());
break;
default:
LOG.warn("unknown type " + request.type);
break;
}
} catch (KeeperException e) {
if (request.getHdr() != null) {
request.getHdr().setType(OpCode.error);
request.setTxn(new ErrorTxn(e.code().intValue()));
}
LOG.info("Got user-level KeeperException when processing "
+ request.toString()
+ " Error Path:" + e.getPath()
+ " Error:" + e.getMessage());
request.setException(e);
} catch (Exception e) {
// log at error level as we are returning a marshalling
// error to the user
LOG.error("Failed to process " + request, e);
StringBuilder sb = new StringBuilder();
ByteBuffer bb = request.request;
if(bb != null){
bb.rewind();
while (bb.hasRemaining()) {
sb.append(Integer.toHexString(bb.get() & 0xff));
}
} else {
sb.append("request buffer is null");
}
LOG.error("Dumping request buffer: 0x" + sb.toString());
if (request.getHdr() != null) {
request.getHdr().setType(OpCode.error);
request.setTxn(new ErrorTxn(Code.MARSHALLINGERROR.intValue()));
}
}
request.zxid = zks.getZxid();
nextProcessor.processRequest(request);
} CreateRequest createRequest = (CreateRequest)record;
if (deserialize) {
ByteBufferInputStream.byteBuffer2Record(request.request, createRequest);
}
CreateMode createMode = CreateMode.fromFlag(createRequest.getFlags());
validateCreateRequest(createMode, request);
String path = createRequest.getPath();
String parentPath = validatePathForCreate(path, request.sessionId);
List<ACL> listACL = fixupACL(path, request.authInfo, createRequest.getAcl());
ChangeRecord parentRecord = getRecordForPath(parentPath);
checkACL(zks, parentRecord.acl, ZooDefs.Perms.CREATE, request.authInfo);
int parentCVersion = parentRecord.stat.getCversion();
if (createMode.isSequential()) {
path = path + String.format(Locale.ENGLISH, "%010d", parentCVersion);
}
validatePath(path, request.sessionId);
try {
if (getRecordForPath(path) != null) {
throw new KeeperException.NodeExistsException(path);
}
} catch (KeeperException.NoNodeException e) {
// ignore this one
}
boolean ephemeralParent = (parentRecord.stat.getEphemeralOwner() != 0) &&
(parentRecord.stat.getEphemeralOwner() != DataTree.CONTAINER_EPHEMERAL_OWNER);
if (ephemeralParent) {
throw new KeeperException.NoChildrenForEphemeralsException(path);
}
int newCversion = parentRecord.stat.getCversion()+1;
if (type == OpCode.createContainer) {
request.setTxn(new CreateContainerTxn(path, createRequest.getData(), listACL, newCversion));
} else {
request.setTxn(new CreateTxn(path, createRequest.getData(), listACL, createMode.isEphemeral(),
newCversion));
}
StatPersisted s = new StatPersisted();
if (createMode.isEphemeral()) {
s.setEphemeralOwner(request.sessionId);
}
parentRecord = parentRecord.duplicate(request.getHdr().getZxid());
parentRecord.childCount++;
parentRecord.stat.setCversion(newCversion);
addChangeRecord(parentRecord); addChangeRecord(new ChangeRecord(request.getHdr().getZxid(), path, s, 0, listACL));
break;
private void addChangeRecord(ChangeRecord c) {
synchronized (zks.outstandingChanges) {
zks.outstandingChanges.add(c);
zks.outstandingChangesForPath.put(c.path, c);
}
} private void addChangeRecord(ChangeRecord c) {
synchronized (zks.outstandingChanges) {
zks.outstandingChanges.add(c);
zks.outstandingChangesForPath.put(c.path, c);
}
}ChangeRecord는 PrepRP와 FinalRp가 정보를 공유할 수 있는 데이터 구조입니다.
ChangeRecord(long zxid, String path, StatPersisted stat, int childCount,
List<ACL> acl) {
this.zxid = zxid;
this.path = path;
this.stat = stat;
this.childCount = childCount;
this.acl = acl;
}1.2 먼저 동기화 요청 프로세서 Final Request Processor를 보십시오. 이 요청 프로세서는 실제로 요청된 모든 업무에 적용되고 모든 조회에 서비스를 제공합니다.그것은 보통 요청 처리의 마지막 (다음 메시지 프로세서가 없을 것) 에 있기 때문에 이름을 얻었다.그것은 어떻게 요청을 처리합니까?
public void processRequest(Request request) {
if (LOG.isDebugEnabled()) {
LOG.debug("Processing request:: " + request);
}
// request.addRQRec(">final");
long traceMask = ZooTrace.CLIENT_REQUEST_TRACE_MASK;
if (request.type == OpCode.ping) {
traceMask = ZooTrace.SERVER_PING_TRACE_MASK;
}
if (LOG.isTraceEnabled()) {
ZooTrace.logRequest(LOG, traceMask, 'E', request, "");
}
ProcessTxnResult rc = null;
synchronized (zks.outstandingChanges) {
// Need to process local session requests
rc = zks.processTxn(request);
// request.hdr is set for write requests, which are the only ones
// that add to outstandingChanges.
if (request.getHdr() != null) {
TxnHeader hdr = request.getHdr();
Record txn = request.getTxn();
long zxid = hdr.getZxid();
while (!zks.outstandingChanges.isEmpty()
&& zks.outstandingChanges.get(0).zxid <= zxid) {
ChangeRecord cr = zks.outstandingChanges.remove(0);
if (cr.zxid < zxid) {
LOG.warn("Zxid outstanding " + cr.zxid
+ " is less than current " + zxid);
}
if (zks.outstandingChangesForPath.get(cr.path) == cr) {
zks.outstandingChangesForPath.remove(cr.path);
}
}
}
// do not add non quorum packets to the queue.
if (request.isQuorum()) { zks.getZKDatabase().addCommittedProposal(request); }
}
// ZOOKEEPER-558:
// In some cases the server does not close the connection (e.g., closeconn buffer
// was not being queued — ZOOKEEPER-558) properly. This happens, for example,
// when the client closes the connection. The server should still close the session, though.
// Calling closeSession() after losing the cnxn, results in the client close session response being dropped.
if (request.type == OpCode.closeSession && connClosedByClient(request)) {
// We need to check if we can close the session id.
// Sometimes the corresponding ServerCnxnFactory could be null because
// we are just playing diffs from the leader.
if (closeSession(zks.serverCnxnFactory, request.sessionId) ||
closeSession(zks.secureServerCnxnFactory, request.sessionId)) {
return;
}
}
if (request.cnxn == null) {
return;
}
ServerCnxn cnxn = request.cnxn;
String lastOp = "NA";
zks.decInProcess();
Code err = Code.OK;
Record rsp = null;
try {
if (request.getHdr() != null && request.getHdr().getType() == OpCode.error) {
/*
* When local session upgrading is disabled, leader will
* reject the ephemeral node creation due to session expire.
* However, if this is the follower that issue the request,
* it will have the correct error code, so we should use that
* and report to user
*/
if (request.getException() != null) {
throw request.getException();
} else {
throw KeeperException.create(KeeperException.Code
.get(((ErrorTxn) request.getTxn()).getErr()));
}
}
KeeperException ke = request.getException();
if (ke != null && request.type != OpCode.multi) {
throw ke;
}
if (LOG.isDebugEnabled()) {
LOG.debug("{}",request);
}
switch (request.type) {
case OpCode.ping: {
zks.serverStats().updateLatency(request.createTime);
lastOp = "PING";
cnxn.updateStatsForResponse(request.cxid, request.zxid, lastOp,
request.createTime, Time.currentElapsedTime());
cnxn.sendResponse(new ReplyHeader(-2,
zks.getZKDatabase().getDataTreeLastProcessedZxid(), 0), null, "response");
return;
}
case OpCode.createSession: {
zks.serverStats().updateLatency(request.createTime);
lastOp = "SESS";
cnxn.updateStatsForResponse(request.cxid, request.zxid, lastOp,
request.createTime, Time.currentElapsedTime());
zks.finishSessionInit(request.cnxn, true);
return;
}
case OpCode.multi: {
lastOp = "MULT";
rsp = new MultiResponse() ;
for (ProcessTxnResult subTxnResult : rc.multiResult) {
OpResult subResult ;
switch (subTxnResult.type) {
case OpCode.check:
subResult = new CheckResult();
break;
case OpCode.create:
subResult = new CreateResult(subTxnResult.path);
break;
case OpCode.create2:
case OpCode.createContainer:
subResult = new CreateResult(subTxnResult.path, subTxnResult.stat);
break;
case OpCode.delete:
case OpCode.deleteContainer:
subResult = new DeleteResult();
break;
case OpCode.setData:
subResult = new SetDataResult(subTxnResult.stat);
break;
case OpCode.error:
subResult = new ErrorResult(subTxnResult.err) ;
break;
default:
throw new IOException("Invalid type of op");
}
((MultiResponse)rsp).add(subResult);
}
break;
}
case OpCode.create: {
lastOp = "CREA";
rsp = new CreateResponse(rc.path);
err = Code.get(rc.err);
break;
}
case OpCode.create2:
case OpCode.createContainer: {
lastOp = "CREA";
rsp = new Create2Response(rc.path, rc.stat);
err = Code.get(rc.err);
break;
}
case OpCode.delete:
case OpCode.deleteContainer: {
lastOp = "DELE";
err = Code.get(rc.err);
break;
}
case OpCode.setData: {
lastOp = "SETD";
rsp = new SetDataResponse(rc.stat);
err = Code.get(rc.err);
break;
}
case OpCode.reconfig: {
lastOp = "RECO";
rsp = new GetDataResponse(((QuorumZooKeeperServer)zks).self.getQuorumVerifier().toString().getBytes(), rc.stat);
err = Code.get(rc.err);
break;
}
case OpCode.setACL: {
lastOp = "SETA";
rsp = new SetACLResponse(rc.stat);
err = Code.get(rc.err);
break;
}
case OpCode.closeSession: {
lastOp = "CLOS";
err = Code.get(rc.err);
break;
}
case OpCode.sync: {
lastOp = "SYNC";
SyncRequest syncRequest = new SyncRequest();
ByteBufferInputStream.byteBuffer2Record(request.request,
syncRequest);
rsp = new SyncResponse(syncRequest.getPath());
break;
}
case OpCode.check: {
lastOp = "CHEC";
rsp = new SetDataResponse(rc.stat);
err = Code.get(rc.err);
break;
}
case OpCode.exists: {
lastOp = "EXIS";
// TODO we need to figure out the security requirement for this!
ExistsRequest existsRequest = new ExistsRequest();
ByteBufferInputStream.byteBuffer2Record(request.request,
existsRequest);
String path = existsRequest.getPath();
if (path.indexOf('\0') != -1) {
throw new KeeperException.BadArgumentsException();
}
Stat stat = zks.getZKDatabase().statNode(path, existsRequest
.getWatch() ? cnxn : null);
rsp = new ExistsResponse(stat);
break;
}
case OpCode.getData: {
lastOp = "GETD";
GetDataRequest getDataRequest = new GetDataRequest();
ByteBufferInputStream.byteBuffer2Record(request.request,
getDataRequest);
DataNode n = zks.getZKDatabase().getNode(getDataRequest.getPath());
if (n == null) {
throw new KeeperException.NoNodeException();
}
Long aclL;
synchronized(n) {
aclL = n.acl;
}
PrepRequestProcessor.checkACL(zks, zks.getZKDatabase().convertLong(aclL),
ZooDefs.Perms.READ,
request.authInfo);
Stat stat = new Stat();
byte b[] = zks.getZKDatabase().getData(getDataRequest.getPath(), stat,
getDataRequest.getWatch() ? cnxn : null);
rsp = new GetDataResponse(b, stat);
break;
}
case OpCode.setWatches: {
lastOp = "SETW";
SetWatches setWatches = new SetWatches();
// XXX We really should NOT need this!!!!
request.request.rewind();
ByteBufferInputStream.byteBuffer2Record(request.request, setWatches);
long relativeZxid = setWatches.getRelativeZxid();
zks.getZKDatabase().setWatches(relativeZxid,
setWatches.getDataWatches(),
setWatches.getExistWatches(),
setWatches.getChildWatches(), cnxn);
break;
}
case OpCode.getACL: {
lastOp = "GETA";
GetACLRequest getACLRequest = new GetACLRequest();
ByteBufferInputStream.byteBuffer2Record(request.request,
getACLRequest);
Stat stat = new Stat();
List<ACL> acl =
zks.getZKDatabase().getACL(getACLRequest.getPath(), stat);
rsp = new GetACLResponse(acl, stat);
break;
}
case OpCode.getChildren: {
lastOp = "GETC";
GetChildrenRequest getChildrenRequest = new GetChildrenRequest();
ByteBufferInputStream.byteBuffer2Record(request.request,
getChildrenRequest);
DataNode n = zks.getZKDatabase().getNode(getChildrenRequest.getPath());
if (n == null) {
throw new KeeperException.NoNodeException();
}
Long aclG;
synchronized(n) {
aclG = n.acl;
}
PrepRequestProcessor.checkACL(zks, zks.getZKDatabase().convertLong(aclG),
ZooDefs.Perms.READ,
request.authInfo);
List<String> children = zks.getZKDatabase().getChildren(
getChildrenRequest.getPath(), null, getChildrenRequest
.getWatch() ? cnxn : null);
rsp = new GetChildrenResponse(children);
break;
}
case OpCode.getChildren2: {
lastOp = "GETC";
GetChildren2Request getChildren2Request = new GetChildren2Request();
ByteBufferInputStream.byteBuffer2Record(request.request,
getChildren2Request);
Stat stat = new Stat();
DataNode n = zks.getZKDatabase().getNode(getChildren2Request.getPath());
if (n == null) {
throw new KeeperException.NoNodeException();
}
Long aclG;
synchronized(n) {
aclG = n.acl;
}
PrepRequestProcessor.checkACL(zks, zks.getZKDatabase().convertLong(aclG),
ZooDefs.Perms.READ,
request.authInfo);
List<String> children = zks.getZKDatabase().getChildren(
getChildren2Request.getPath(), stat, getChildren2Request
.getWatch() ? cnxn : null);
rsp = new GetChildren2Response(children, stat);
break;
}
case OpCode.checkWatches: {
lastOp = "CHKW";
CheckWatchesRequest checkWatches = new CheckWatchesRequest();
ByteBufferInputStream.byteBuffer2Record(request.request,
checkWatches);
WatcherType type = WatcherType.fromInt(checkWatches.getType());
boolean containsWatcher = zks.getZKDatabase().containsWatcher(
checkWatches.getPath(), type, cnxn);
if (!containsWatcher) {
String msg = String.format(Locale.ENGLISH, "%s (type: %s)",
new Object[] { checkWatches.getPath(), type });
throw new KeeperException.NoWatcherException(msg);
}
break;
}
case OpCode.removeWatches: {
lastOp = "REMW";
RemoveWatchesRequest removeWatches = new RemoveWatchesRequest();
ByteBufferInputStream.byteBuffer2Record(request.request,
removeWatches);
WatcherType type = WatcherType.fromInt(removeWatches.getType());
boolean removed = zks.getZKDatabase().removeWatch(
removeWatches.getPath(), type, cnxn);
if (!removed) {
String msg = String.format(Locale.ENGLISH, "%s (type: %s)",
new Object[] { removeWatches.getPath(), type });
throw new KeeperException.NoWatcherException(msg);
}
break;
}
}
} catch (SessionMovedException e) {
// session moved is a connection level error, we need to tear
// down the connection otw ZOOKEEPER-710 might happen
// ie client on slow follower starts to renew session, fails
// before this completes, then tries the fast follower (leader)
// and is successful, however the initial renew is then
// successfully fwd/processed by the leader and as a result
// the client and leader disagree on where the client is most
// recently attached (and therefore invalid SESSION MOVED generated)
cnxn.sendCloseSession();
return;
} catch (KeeperException e) {
err = e.code();
} catch (Exception e) {
// log at error level as we are returning a marshalling
// error to the user
LOG.error("Failed to process " + request, e);
StringBuilder sb = new StringBuilder();
ByteBuffer bb = request.request;
bb.rewind();
while (bb.hasRemaining()) {
sb.append(Integer.toHexString(bb.get() & 0xff));
}
LOG.error("Dumping request buffer: 0x" + sb.toString());
err = Code.MARSHALLINGERROR;
}
long lastZxid = zks.getZKDatabase().getDataTreeLastProcessedZxid();
ReplyHeader hdr =
new ReplyHeader(request.cxid, lastZxid, err.intValue());
zks.serverStats().updateLatency(request.createTime);
cnxn.updateStatsForResponse(request.cxid, lastZxid, lastOp,
request.createTime, Time.currentElapsedTime());
try {
cnxn.sendResponse(hdr, rsp, "response");
if (request.type == OpCode.closeSession) {
cnxn.sendCloseSession();
}
} catch (IOException e) {
LOG.error("FIXMSG",e);
}
}첫 번째, 공유된 outstandingChanges에 따라
트랜잭션 처리 후 세션 처리:
private ProcessTxnResult processTxn(Request request, TxnHeader hdr,
Record txn) {
ProcessTxnResult rc;
int opCode = request != null ? request.type : hdr.getType();
long sessionId = request != null ? request.sessionId : hdr.getClientId();
if (hdr != null) {
rc = getZKDatabase().processTxn(hdr, txn);
} else {
rc = new ProcessTxnResult();
}
if (opCode == OpCode.createSession) {
if (hdr != null && txn instanceof CreateSessionTxn) {
CreateSessionTxn cst = (CreateSessionTxn) txn;
sessionTracker.addGlobalSession(sessionId, cst.getTimeOut());
} else if (request != null && request.isLocalSession()) {
request.request.rewind();
int timeout = request.request.getInt();
request.request.rewind();
sessionTracker.addSession(request.sessionId, timeout);
} else {
LOG.warn("*****>>>>> Got "
+ txn.getClass() + " "
+ txn.toString());
}
} else if (opCode == OpCode.closeSession) {
sessionTracker.removeSession(sessionId);
}
return rc;
}트랜잭션 처리, 로컬과 데이터베이스의 다른 지점, DataTree 생성 노드
CreateTxn createTxn = (CreateTxn) txn;
rc.path = createTxn.getPath();
createNode(
createTxn.getPath(),
createTxn.getData(),
createTxn.getAcl(),
createTxn.getEphemeral() ? header.getClientId() : 0,
createTxn.getParentCVersion(),
header.getZxid(), header.getTime(), null);
break;새 노드의 논리는 다음과 같습니다.
/**
* Add a new node to the DataTree.
* @param path
* Path for the new node.
* @param data
* Data to store in the node.
* @param acl
* Node acls
* @param ephemeralOwner
* the session id that owns this node. -1 indicates this is not
* an ephemeral node.
* @param zxid
* Transaction ID
* @param time
* @param outputStat
* A Stat object to store Stat output results into.
* @throws NodeExistsException
* @throws NoNodeException
* @throws KeeperException
*/
public void createNode(final String path, byte data[], List<ACL> acl,
long ephemeralOwner, int parentCVersion, long zxid, long time, Stat outputStat)
throws KeeperException.NoNodeException,
KeeperException.NodeExistsException {
int lastSlash = path.lastIndexOf('/');
String parentName = path.substring(0, lastSlash);
String childName = path.substring(lastSlash + 1);
StatPersisted stat = new StatPersisted();
stat.setCtime(time);
stat.setMtime(time);
stat.setCzxid(zxid);
stat.setMzxid(zxid);
stat.setPzxid(zxid);
stat.setVersion(0);
stat.setAversion(0);
stat.setEphemeralOwner(ephemeralOwner);
DataNode parent = nodes.get(parentName);
if (parent == null) {
throw new KeeperException.NoNodeException();
}
synchronized (parent) {
Set<String> children = parent.getChildren();
if (children != null && children.contains(childName)) {
throw new KeeperException.NodeExistsException();
}
if (parentCVersion == -1) {
parentCVersion = parent.stat.getCversion();
parentCVersion++;
}
parent.stat.setCversion(parentCVersion);
parent.stat.setPzxid(zxid);
Long longval = convertAcls(acl);
DataNode child = new DataNode(data, longval, stat);
parent.addChild(childName);
nodes.put(path, child);
if (ephemeralOwner == CONTAINER_EPHEMERAL_OWNER) {
containers.add(path);
} else if (ephemeralOwner != 0) {
HashSet<String> list = ephemerals.get(ephemeralOwner);
if (list == null) {
list = new HashSet<String>();
ephemerals.put(ephemeralOwner, list);
}
synchronized (list) {
list.add(path);
}
}
if (outputStat != null) {
child.copyStat(outputStat);
}
}
// now check if its one of the zookeeper node child
if (parentName.startsWith(quotaZookeeper)) {
// now check if its the limit node
if (Quotas.limitNode.equals(childName)) {
// this is the limit node
// get the parent and add it to the trie
pTrie.addPath(parentName.substring(quotaZookeeper.length()));
}
if (Quotas.statNode.equals(childName)) {
updateQuotaForPath(parentName
.substring(quotaZookeeper.length()));
}
}
// also check to update the quotas for this node
String lastPrefix = getMaxPrefixWithQuota(path);
if(lastPrefix != null) {
// ok we have some match and need to update
updateCount(lastPrefix, 1);
updateBytes(lastPrefix, data == null ? 0 : data.length);
}
dataWatches.triggerWatch(path, Event.EventType.NodeCreated); childWatches.triggerWatch(parentName.equals("") ? "/" : parentName, Event.EventType.NodeChildrenChanged);
}마지막 논리는 생성 노드와 하위 노드 변경 이벤트를 촉발하는 것이다.
Set<Watcher> triggerWatch(String path, EventType type, Set<Watcher> supress) {
WatchedEvent e = new WatchedEvent(type,
KeeperState.SyncConnected, path);
HashSet<Watcher> watchers;
synchronized (this) {
watchers = watchTable.remove(path);
if (watchers == null || watchers.isEmpty()) {
if (LOG.isTraceEnabled()) {
ZooTrace.logTraceMessage(LOG,
ZooTrace.EVENT_DELIVERY_TRACE_MASK,
"No watchers for " + path);
}
return null;
}
for (Watcher w : watchers) {
HashSet<String> paths = watch2Paths.get(w);
if (paths != null) {
paths.remove(path);
}
}
}
for (Watcher w : watchers) {
if (supress != null && supress.contains(w)) {
continue;
}
w.process(e);
}
return watchers;
}Watcher Manager는 정의된 Watcher를 호출하여 이벤트 처리를 합니다.
1.3. 비동기식 메시지 프로세서 SyncRequestProcessor 다시 보기
@Override
public void run() {
try {
int logCount = 0;
// we do this in an attempt to ensure that not all of the servers
// in the ensemble take a snapshot at the same time
int randRoll = r.nextInt(snapCount/2);
while (true) {
Request si = null;
if (toFlush.isEmpty()) {
si = queuedRequests.take();
} else {
si = queuedRequests.poll();
if (si == null) {
flush(toFlush);
continue;
}
}
if (si == requestOfDeath) {
break;
}
if (si != null) {
// track the number of records written to the log
if (zks.getZKDatabase().append(si)) {
logCount++;
if (logCount > (snapCount / 2 + randRoll)) {
randRoll = r.nextInt(snapCount/2);
// roll the log
zks.getZKDatabase().rollLog();
// take a snapshot
if (snapInProcess != null && snapInProcess.isAlive()) {
LOG.warn("Too busy to snap, skipping");
} else {
snapInProcess = new ZooKeeperThread("Snapshot Thread") {
public void run() {
try {
zks.takeSnapshot();
} catch(Exception e) {
LOG.warn("Unexpected exception", e); } } }; snapInProcess.start();
}
logCount = 0;
}
} else if (toFlush.isEmpty()) {
// optimization for read heavy workloads
// iff this is a read, and there are no pending
// flushes (writes), then just pass this to the next
// processor
if (nextProcessor != null) {
nextProcessor.processRequest(si);
if (nextProcessor instanceof Flushable) {
((Flushable)nextProcessor).flush();
}
}
continue;
}
toFlush.add(si);
if (toFlush.size() > 1000) {
flush(toFlush);
}
}
}
} catch (Throwable t) {
handleException(this.getName(), t);
} finally{
running = false;
}
LOG.info("SyncRequestProcessor exited!");
}비동기식 로그 및 스냅샷을 처리하고 ZooKeeperThread 스레드를 시작하여 스냅샷을 생성합니다.
public void takeSnapshot(){
try {
txnLogFactory.save(zkDb.getDataTree(), zkDb.getSessionWithTimeOuts());
} catch (IOException e) {
LOG.error("Severe unrecoverable error, exiting", e);
// This is a severe error that we cannot recover from,
// so we need to exit
System.exit(10);
}
}FileTxnSnapLog는 txtlog와 snapshot을 처리하는 데 도움을 주는 도구 클래스입니다.
/**
* save the datatree and the sessions into a snapshot
* @param dataTree the datatree to be serialized onto disk
* @param sessionsWithTimeouts the sesssion timeouts to be
* serialized onto disk
* @throws IOException
*/
public void save(DataTree dataTree,
ConcurrentHashMap<Long, Integer> sessionsWithTimeouts)
throws IOException {
long lastZxid = dataTree.lastProcessedZxid;
File snapshotFile = new File(snapDir, Util.makeSnapshotName(lastZxid));
LOG.info("Snapshotting: 0x{} to {}", Long.toHexString(lastZxid),
snapshotFile);
snapLog.serialize(dataTree, sessionsWithTimeouts, snapshotFile);
}파일로 영구화
/**
* serialize the datatree and session into the file snapshot
* @param dt the datatree to be serialized
* @param sessions the sessions to be serialized
* @param snapShot the file to store snapshot into
*/
public synchronized void serialize(DataTree dt, Map<Long, Integer> sessions, File snapShot)
throws IOException {
if (!close) {
OutputStream sessOS = new BufferedOutputStream(new FileOutputStream(snapShot));
CheckedOutputStream crcOut = new CheckedOutputStream(sessOS, new Adler32());
//CheckedOutputStream cout = new CheckedOutputStream()
OutputArchive oa = BinaryOutputArchive.getArchive(crcOut);
FileHeader header = new FileHeader(SNAP_MAGIC, VERSION, dbId);
serialize(dt,sessions,oa, header);
long val = crcOut.getChecksum().getValue();
oa.writeLong(val, "val");
oa.writeString("/", "path");
sessOS.flush();
crcOut.close();
sessOS.close();
}
}이로써 전체 절차는 이미 끝났다.
2. 집단 상황에서
클러스터 상황은 단일 시스템과 약간 다릅니다. 클러스터에서 QuorumPeer를 사용하여 ServerCnxnFactory를 시작하고 로컬 주소를 바인딩합니다.
@Override
public void start() {
LOG.info("binding to port " + localAddress);
parentChannel = bootstrap.bind(localAddress);
}편폭에 한하여 뒤의 논리는 다음 편에서 상세하게 설명할 것이다.
작은 매듭
위의 코드 프로세스에서 우리는 서버 처리 요청이 Noi를 통해 처리하거나 프레임워크 Netty를 통해 처리하는 것을 알 수 있다. 요청은 먼저PrepRequestProcessor를 통해 요청을 받고 포장한 다음에 요청 유형에 따라 공유 데이터를 설정한다.그리고 SyncRequestProcessor를 통해 스냅샷과 사무 로그를 서열화하고 명령 형식에 따라db의 내용을 변경합니다. 로그와 스냅샷이 기록되지 않았을 때 다음 메시지 프로세서를 진행하지 않습니다.마지막으로 Final Request Processor를 호출하여 메시지 프로세서의 종결자로서 응답 메시지를 보내고 watcher의 프로세서를 터치합니다.
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현재 기사가 여러분의 문제를 해결하지 못하는 경우 AI 엔진은 머신러닝 분석(스마트 모델이 방금 만들어져 부정확한 경우가 있을 수 있음)을 통해 가장 유사한 기사를 추천합니다:
다양한 언어의 JSONJSON은 Javascript 표기법을 사용하여 데이터 구조를 레이아웃하는 데이터 형식입니다. 그러나 Javascript가 코드에서 이러한 구조를 나타낼 수 있는 유일한 언어는 아닙니다. 저는 일반적으로 '객체'{}...
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