hadoop中服务端重要内部类的代码阅读
/近来看了些58的一个沈剑的架构文章，觉得很是一般，就是把网络上常见的一些模型，自己写一些小例子，博取一些还对网络不了解的人的赞赏。其实文章没有交代出什么东西来，支付宝那么大的架构肯定不是分几个库就分出来的。其中的中间件肯定不会告诉你，那都是集结了许多人的智慧才开发出来的。你比如无论是梁飞开发的dubbo，还是毕玄-林昊开发的HSF，除了这两个知名的人，后面还有一个开发小组的。我们要想进阶，只有不断阅读优秀的代码，和含有先进思想的代码才会写出高质量的代码，这东西就像憋尿一样，水喝多了，尿自然就有了。
这里通读一下hadoop的源码，首先今天的这个类是Server类，因为这里涉及到了通信，序列化，线程操作，一致性，服务端最重要的一些特点在这个类都展现的淋漓尽致。所以我决定从这个类开始看。Server类里有几个重要的模块，一个是Responder，一个是Listener，还有一个是Connection，分别对应着返回线程，监听客户端连接线程，还有就是连接，着三个内部类基本贯穿了他们之间的操作。Listener中又有一个内部类Reader用于读取连接中传来的内容。
/** Listens on the socket. Creates jobs for the handler threads*/
private class Listener extends Thread {
//这个就是nio操作中的频道，并且选择器用来监听这个频道中传来的事件，如果有读取操作
//的键值，他就从这个事件中读取相应的数据
private ServerSocketChannel acceptChannel = null; //the accept channel
private Selector selector = null; //the selector that we use for the server
private Reader[] readers = null;
private int currentReader = 0;
private InetSocketAddress address; //the address we bind at
private int backlogLength = conf.getInt(
CommonConfigurationKeysPublic.IPC_SERVER_LISTEN_QUEUE_SIZE_KEY,
CommonConfigurationKeysPublic.IPC_SERVER_LISTEN_QUEUE_SIZE_DEFAULT);
public Listener() throws IOException {
address = new InetSocketAddress(bindAddress, port);
// Create a new server socket and set to non blocking mode
acceptChannel = ServerSocketChannel.open();
//设置为非阻塞 no-blocking
acceptChannel.configureBlocking(false);
//最常见的监听端口操作
// Bind the server socket to the local host and port
bind(acceptChannel.socket(), address, backlogLength, conf, portRangeConfig);
port = acceptChannel.socket().getLocalPort(); //Could be an ephemeral port
// create a selector;
selector= Selector.open();
readers = new Reader[readThreads];
for (int i = 0; i < readThreads; i++) {
Reader reader = new Reader(
"Socket Reader #" + (i + 1) + " for port " + port);
readers[i] = reader;
reader.start();
}
// Register accepts on the server socket with the selector.
acceptChannel.register(selector, SelectionKey.OP_ACCEPT);
this.setName("IPC Server listener on " + port);
this.setDaemon(true);
}
private class Reader extends Thread {
final private BlockingQueue<Connection> pendingConnections;
private final Selector readSelector;
Reader(String name) throws IOException {
super(name);
this.pendingConnections =
new LinkedBlockingQueue<Connection>(readerPendingConnectionQueue);
this.readSelector = Selector.open();
}
@Override
public void run() {
//Reader线程，一直循环着读取
LOG.info("Starting " + Thread.currentThread().getName());
try {
doRunLoop();
} finally {
try {
readSelector.close();
} catch (IOException ioe) {
LOG.error("Error closing read selector in " + Thread.currentThread().getName(), ioe);
}
}
}
private synchronized void doRunLoop() {
while (running) {
SelectionKey key = null;
try {
// consume as many connections as currently queued to avoid
// unbridled acceptance of connections that starves the select
//避免无尽的连接，只读取当前数量的连接
int size = pendingConnections.size();
for (int i=size; i>0; i--) {
Connection conn = pendingConnections.take();
conn.channel.register(readSelector, SelectionKey.OP_READ, conn);
}
readSelector.select();
Iterator<SelectionKey> iter = readSelector.selectedKeys().iterator();
while (iter.hasNext()) {
key = iter.next();
iter.remove();
if (key.isValid()) {
if (key.isReadable()) {
doRead(key);
}
}
key = null;
}
} catch (InterruptedException e) {
if (running) { // unexpected -- log it
LOG.info(Thread.currentThread().getName() + " unexpectedly interrupted", e);
}
} catch (IOException ex) {
LOG.error("Error in Reader", ex);
}
}
}
/**
* Updating the readSelector while it's being used is not thread-safe,
* so the connection must be queued. The reader will drain the queue
* and update its readSelector before performing the next select
*/
public void addConnection(Connection conn) throws InterruptedException {
pendingConnections.put(conn);
readSelector.wakeup();
}
void shutdown() {
assert !running;
readSelector.wakeup();
try {
join();
} catch (InterruptedException ie) {
Thread.currentThread().interrupt();
}
}
}
@Override
public void run() {
LOG.info(Thread.currentThread().getName() + ": starting");
SERVER.set(Server.this);
connectionManager.startIdleScan();
while (running) {
SelectionKey key = null;
try {
getSelector().select();
Iterator<SelectionKey> iter = getSelector().selectedKeys().iterator();
while (iter.hasNext()) {
key = iter.next();
iter.remove();
try {
if (key.isValid()) {
if (key.isAcceptable())
//这里是Listener这个线程的主方法，就是不断读取当前频道内的selectedKey，
如果有连接过来的连接，则接受这个连接。
doAccept(key);
}
} catch (IOException e) {
}
key = null;
}
} catch (OutOfMemoryError e) {
// we can run out of memory if we have too many threads
// log the event and sleep for a minute and give
// some thread(s) a chance to finish
LOG.warn("Out of Memory in server select", e);
closeCurrentConnection(key, e);
connectionManager.closeIdle(true);
try { Thread.sleep(60000); } catch (Exception ie) {}
} catch (Exception e) {
closeCurrentConnection(key, e);
}
}
LOG.info("Stopping " + Thread.currentThread().getName());
synchronized (this) {
try {
acceptChannel.close();
selector.close();
} catch (IOException e) { }
selector= null;
acceptChannel= null;
// close all connections
connectionManager.stopIdleScan();
connectionManager.closeAll();
}
}
private void closeCurrentConnection(SelectionKey key, Throwable e) {
if (key != null) {
Connection c = (Connection)key.attachment();
if (c != null) {
closeConnection(c);
c = null;
}
}
}
InetSocketAddress getAddress() {
return (InetSocketAddress)acceptChannel.socket().getLocalSocketAddress();
}
//Listener的主方法其实是是，监听线程主要在处理连接
void doAccept(SelectionKey key) throws InterruptedException, IOException, OutOfMemoryError {
ServerSocketChannel server = (ServerSocketChannel) key.channel();
SocketChannel channel;
while ((channel = server.accept()) != null) {
channel.configureBlocking(false);
channel.socket().setTcpNoDelay(tcpNoDelay);
channel.socket().setKeepAlive(true);
Reader reader = getReader();
Connection c = connectionManager.register(channel);
key.attach(c); // so closeCurrentConnection can get the object
reader.addConnection(c);
}
}
void doRead(SelectionKey key) throws InterruptedException {
int count = 0;
Connection c = (Connection)key.attachment();
if (c == null) {
return;
}
c.setLastContact(Time.now());
try {
//读-处理这个方法在内部类connection中实现的，下面就会看到。
count = c.readAndProcess();
} catch (InterruptedException ieo) {
LOG.info(Thread.currentThread().getName() + ": readAndProcess caught InterruptedException", ieo);
throw ieo;
} catch (Exception e) {
// a WrappedRpcServerException is an exception that has been sent
// to the client, so the stacktrace is unnecessary; any other
// exceptions are unexpected internal server errors and thus the
// stacktrace should be logged
LOG.info(Thread.currentThread().getName() + ": readAndProcess from client " +
c.getHostAddress() + " threw exception [" + e + "]",
(e instanceof WrappedRpcServerException) ? null : e);
count = -1; //so that the (count < 0) block is executed
}
if (count < 0) {
closeConnection(c);
c = null;
}
else {
c.setLastContact(Time.now());
}
}
synchronized void doStop() {
if (selector != null) {
selector.wakeup();
Thread.yield();
}
if (acceptChannel != null) {
try {
acceptChannel.socket().close();
} catch (IOException e) {
LOG.info(Thread.currentThread().getName() + ":Exception in closing listener socket. " + e);
}
}
for (Reader r : readers) {
r.shutdown();
}
}
synchronized Selector getSelector() { return selector; }
// The method that will return the next reader to work with
// Simplistic implementation of round robin for now
Reader getReader() {
currentReader = (currentReader + 1) % readers.length;
return readers[currentReader];
}
}
读取管道内的数据，就是在内部类connection中实现的，下面阅读一下connection类。
/** Reads calls from a connection and queues them for handling. */
public class Connection {
private boolean connectionHeaderRead = false; // connection header is read?
private boolean connectionContextRead = false; //if connection context that
//follows connection header is read
private SocketChannel channel;
private ByteBuffer data;
private ByteBuffer dataLengthBuffer;
//call也是一个内部类，用于调取rpc
private LinkedList<Call> responseQueue;
private volatile int rpcCount = 0; // number of outstanding rpcs
private long lastContact;
private int dataLength;
private Socket socket;
// Cache the remote host & port info so that even if the socket is
// disconnected, we can say where it used to connect to.
private String hostAddress;
private int remotePort;
private InetAddress addr;
//ipc连接（inter-process-communication协议，用protobuf生成的类
IpcConnectionContextProto connectionContext;
String protocolName;
SaslServer saslServer;
private AuthMethod authMethod;
private AuthProtocol authProtocol;
//安全sasl连接
private boolean saslContextEstablished;
private ByteBuffer connectionHeaderBuf = null;
private ByteBuffer unwrappedData;
private ByteBuffer unwrappedDataLengthBuffer;
private int serviceClass;
UserGroupInformation user = null;
public UserGroupInformation attemptingUser = null; // user name before auth
// Fake 'call' for failed authorization response
private final Call authFailedCall = new Call(AUTHORIZATION_FAILED_CALL_ID,
RpcConstants.INVALID_RETRY_COUNT, null, this);
private ByteArrayOutputStream authFailedResponse = new ByteArrayOutputStream();
private final Call saslCall = new Call(AuthProtocol.SASL.callId,
RpcConstants.INVALID_RETRY_COUNT, null, this);
private final ByteArrayOutputStream saslResponse = new ByteArrayOutputStream();
private boolean sentNegotiate = false;
private boolean useWrap = false;
//与监听中的ServerSocketChannel是两个类
public Connection(SocketChannel channel, long lastContact) {
this.channel = channel;
this.lastContact = lastContact;
this.data = null;
this.dataLengthBuffer = ByteBuffer.allocate(4);
this.unwrappedData = null;
this.unwrappedDataLengthBuffer = ByteBuffer.allocate(4);
this.socket = channel.socket();
this.addr = socket.getInetAddress();
if (addr == null) {
this.hostAddress = "*Unknown*";
} else {
this.hostAddress = addr.getHostAddress();
}
this.remotePort = socket.getPort();
this.responseQueue = new LinkedList<Call>();
if (socketSendBufferSize != 0) {
try {
socket.setSendBufferSize(socketSendBufferSize);
} catch (IOException e) {
LOG.warn("Connection: unable to set socket send buffer size to " +
socketSendBufferSize);
}
}
}
@Override
public String toString() {
return getHostAddress() + ":" + remotePort;
}
public String getHostAddress() {
return hostAddress;
}
public InetAddress getHostInetAddress() {
return addr;
}
public void setLastContact(long lastContact) {
this.lastContact = lastContact;
}
public long getLastContact() {
return lastContact;
}
//如果没有明显的rpc，返回true，rpcCount为0
/* Return true if the connection has no outstanding rpc */
private boolean isIdle() {
return rpcCount == 0;
}
/* Decrement the outstanding RPC count */
private void decRpcCount() {
rpcCount--;
}
/* Increment the outstanding RPC count */
private void incRpcCount() {
rpcCount++;
}
private UserGroupInformation getAuthorizedUgi(String authorizedId)
throws InvalidToken, AccessControlException {
if (authMethod == AuthMethod.TOKEN) {
TokenIdentifier tokenId = SaslRpcServer.getIdentifier(authorizedId,
secretManager);
UserGroupInformation ugi = tokenId.getUser();
if (ugi == null) {
throw new AccessControlException(
"Can't retrieve username from tokenIdentifier.");
}
ugi.addTokenIdentifier(tokenId);
return ugi;
} else {
return UserGroupInformation.createRemoteUser(authorizedId, authMethod);
}
}
private void saslReadAndProcess(DataInputStream dis) throws
WrappedRpcServerException, IOException, InterruptedException {
final RpcSaslProto saslMessage =
decodeProtobufFromStream(RpcSaslProto.newBuilder(), dis);
switch (saslMessage.getState()) {
case WRAP: {
if (!saslContextEstablished || !useWrap) {
throw new WrappedRpcServerException(
RpcErrorCodeProto.FATAL_INVALID_RPC_HEADER,
new SaslException("Server is not wrapping data"));
}
// loops over decoded data and calls processOneRpc
unwrapPacketAndProcessRpcs(saslMessage.getToken().toByteArray());
break;
}
default:
saslProcess(saslMessage);
}
}
private Throwable getCauseForInvalidToken(IOException e) {
Throwable cause = e;
while (cause != null) {
if (cause instanceof RetriableException) {
return cause;
} else if (cause instanceof StandbyException) {
return cause;
} else if (cause instanceof InvalidToken) {
//hadoop的方法限制sasl的回调给返回无效的token，但是有些服务需要抛出其他异常
// FIXME: hadoop method signatures are restricting the SASL
// callbacks to only returning InvalidToken, but some services
// need to throw other exceptions (ex. NN + StandyException),
// so for now we'll tunnel the real exceptions via an
// InvalidToken's cause which normally is not set
if (cause.getCause() != null) {
cause = cause.getCause();
}
return cause;
}
cause = cause.getCause();
}
return e;
}
private void saslProcess(RpcSaslProto saslMessage)
throws WrappedRpcServerException, IOException, InterruptedException {
if (saslContextEstablished) {
throw new WrappedRpcServerException(
RpcErrorCodeProto.FATAL_INVALID_RPC_HEADER,
new SaslException("Negotiation is already complete"));
}
RpcSaslProto saslResponse = null;
try {
try {
saslResponse = processSaslMessage(saslMessage);
} catch (IOException e) {
rpcMetrics.incrAuthenticationFailures();
// attempting user could be null
AUDITLOG.warn(AUTH_FAILED_FOR + this.toString() + ":"
+ attemptingUser + " (" + e.getLocalizedMessage() + ")");
throw (IOException) getCauseForInvalidToken(e);
}
if (saslServer != null && saslServer.isComplete()) {
if (LOG.isDebugEnabled()) {
LOG.debug("SASL server context established. Negotiated QoP is "
+ saslServer.getNegotiatedProperty(Sasl.QOP));
}
user = getAuthorizedUgi(saslServer.getAuthorizationID());
if (LOG.isDebugEnabled()) {
LOG.debug("SASL server successfully authenticated client: " + user);
}
rpcMetrics.incrAuthenticationSuccesses();
AUDITLOG.info(AUTH_SUCCESSFUL_FOR + user);
saslContextEstablished = true;
}
} catch (WrappedRpcServerException wrse) { // don't re-wrap
throw wrse;
} catch (IOException ioe) {
throw new WrappedRpcServerException(
RpcErrorCodeProto.FATAL_UNAUTHORIZED, ioe);
}
// send back response if any, may throw IOException
if (saslResponse != null) {
doSaslReply(saslResponse);
}
// do NOT enable wrapping until the last auth response is sent
if (saslContextEstablished) {
String qop = (String) saslServer.getNegotiatedProperty(Sasl.QOP);
// SASL wrapping is only used if the connection has a QOP, and
// the value is not auth. ex. auth-int & auth-priv
useWrap = (qop != null && !"auth".equalsIgnoreCase(qop));
}
}
private RpcSaslProto processSaslMessage(RpcSaslProto saslMessage)
throws IOException, InterruptedException {
final RpcSaslProto saslResponse;
final SaslState state = saslMessage.getState(); // required
switch (state) {
case NEGOTIATE: {
if (sentNegotiate) {
throw new AccessControlException(
"Client already attempted negotiation");
}
saslResponse = buildSaslNegotiateResponse();
// simple-only server negotiate response is success which client
// interprets as switch to simple
if (saslResponse.getState() == SaslState.SUCCESS) {
switchToSimple();
}
break;
}
case INITIATE: {
if (saslMessage.getAuthsCount() != 1) {
throw new SaslException("Client mechanism is malformed");
}
// verify the client requested an advertised authType
SaslAuth clientSaslAuth = saslMessage.getAuths(0);
if (!negotiateResponse.getAuthsList().contains(clientSaslAuth)) {
if (sentNegotiate) {
throw new AccessControlException(
clientSaslAuth.getMethod() + " authentication is not enabled."
+ " Available:" + enabledAuthMethods);
}
saslResponse = buildSaslNegotiateResponse();
break;
}
authMethod = AuthMethod.valueOf(clientSaslAuth.getMethod());
// abort SASL for SIMPLE auth, server has already ensured that
// SIMPLE is a legit option above. we will send no response
if (authMethod == AuthMethod.SIMPLE) {
switchToSimple();
saslResponse = null;
break;
}
// sasl server for tokens may already be instantiated
if (saslServer == null || authMethod != AuthMethod.TOKEN) {
saslServer = createSaslServer(authMethod);
}
saslResponse = processSaslToken(saslMessage);
break;
}
case RESPONSE: {
saslResponse = processSaslToken(saslMessage);
break;
}
default:
throw new SaslException("Client sent unsupported state " + state);
}
return saslResponse;
}
private RpcSaslProto processSaslToken(RpcSaslProto saslMessage)
throws SaslException {
if (!saslMessage.hasToken()) {
throw new SaslException("Client did not send a token");
}
byte[] saslToken = saslMessage.getToken().toByteArray();
if (LOG.isDebugEnabled()) {
LOG.debug("Have read input token of size " + saslToken.length
+ " for processing by saslServer.evaluateResponse()");
}
saslToken = saslServer.evaluateResponse(saslToken);
return buildSaslResponse(
saslServer.isComplete() ? SaslState.SUCCESS : SaslState.CHALLENGE,
saslToken);
}
private void switchToSimple() {
// disable SASL and blank out any SASL server
authProtocol = AuthProtocol.NONE;
saslServer = null;
}
private RpcSaslProto buildSaslResponse(SaslState state, byte[] replyToken) {
if (LOG.isDebugEnabled()) {
LOG.debug("Will send " + state + " token of size "
+ ((replyToken != null) ? replyToken.length : null)
+ " from saslServer.");
}
RpcSaslProto.Builder response = RpcSaslProto.newBuilder();
response.setState(state);
if (replyToken != null) {
response.setToken(ByteString.copyFrom(replyToken));
}
return response.build();
}
private void doSaslReply(Message message) throws IOException {
if (LOG.isDebugEnabled()) {
LOG.debug("Sending sasl message "+message);
}
setupResponse(saslResponse, saslCall,
RpcStatusProto.SUCCESS, null,
new RpcResponseWrapper(message), null, null);
responder.doRespond(saslCall);
}
private void doSaslReply(Exception ioe) throws IOException {
setupResponse(authFailedResponse, authFailedCall,
RpcStatusProto.FATAL, RpcErrorCodeProto.FATAL_UNAUTHORIZED,
null, ioe.getClass().getName(), ioe.getLocalizedMessage());
responder.doRespond(authFailedCall);
}
private void disposeSasl() {
if (saslServer != null) {
try {
saslServer.dispose();
} catch (SaslException ignored) {
}
}
}
private void checkDataLength(int dataLength) throws IOException {
if (dataLength < 0) {
String error = "Unexpected data length " + dataLength +
"!! from " + getHostAddress();
LOG.warn(error);
throw new IOException(error);
} else if (dataLength > maxDataLength) {
String error = "Requested data length " + dataLength +
" is longer than maximum configured RPC length " +
maxDataLength + ". RPC came from " + getHostAddress();
LOG.warn(error);
throw new IOException(error);
}
}
public int readAndProcess()
throws WrappedRpcServerException, IOException, InterruptedException {
while (true) {
/* Read at most one RPC. If the header is not read completely yet
* then iterate until we read first RPC or until there is no data left.
最多读一个rpc，如果头部没有被读完整，那么迭代直到读到第一个rpc，或者没有数据剩下
*/
int count = -1;
if (dataLengthBuffer.remaining() > 0) {
//从管道里读取
count = channelRead(channel, dataLengthBuffer);
if (count < 0 || dataLengthBuffer.remaining() > 0)
return count;
}
if (!connectionHeaderRead) {
//Every connection is expected to send the header.
if (connectionHeaderBuf == null) {
connectionHeaderBuf = ByteBuffer.allocate(3);
}
count = channelRead(channel, connectionHeaderBuf);
if (count < 0 || connectionHeaderBuf.remaining() > 0) {
return count;
}
int version = connectionHeaderBuf.get(0);
// TODO we should add handler for service class later
this.setServiceClass(connectionHeaderBuf.get(1));
dataLengthBuffer.flip();
// Check if it looks like the user is hitting an IPC port
// with an HTTP GET - this is a common error, so we can
// send back a simple string indicating as much.
if (HTTP_GET_BYTES.equals(dataLengthBuffer)) {
setupHttpRequestOnIpcPortResponse();
return -1;
}
if (!RpcConstants.HEADER.equals(dataLengthBuffer)
|| version != CURRENT_VERSION) {
//Warning is ok since this is not supposed to happen.
LOG.warn("Incorrect header or version mismatch from " +
hostAddress + ":" + remotePort +
" got version " + version +
" expected version " + CURRENT_VERSION);
setupBadVersionResponse(version);
return -1;
}
// this may switch us into SIMPLE
authProtocol = initializeAuthContext(connectionHeaderBuf.get(2));
dataLengthBuffer.clear();
connectionHeaderBuf = null;
connectionHeaderRead = true;
continue;
}
if (data == null) {
dataLengthBuffer.flip();
dataLength = dataLengthBuffer.getInt();
checkDataLength(dataLength);
data = ByteBuffer.allocate(dataLength);
}
//从频道中读取数据的函数
count = channelRead(channel, data);
if (data.remaining() == 0) {
dataLengthBuffer.clear();
data.flip();
boolean isHeaderRead = connectionContextRead;
processOneRpc(data.array());
data = null;
if (!isHeaderRead) {
continue;
}
}
return count;
}
}
//这里面定义了几个认证协议
private AuthProtocol initializeAuthContext(int authType)
throws IOException {
AuthProtocol authProtocol = AuthProtocol.valueOf(authType);
if (authProtocol == null) {
IOException ioe = new IpcException("Unknown auth protocol:" + authType);
doSaslReply(ioe);
throw ioe;
}
boolean isSimpleEnabled = enabledAuthMethods.contains(AuthMethod.SIMPLE);
switch (authProtocol) {
case NONE: {
// don't reply if client is simple and server is insecure
if (!isSimpleEnabled) {
IOException ioe = new AccessControlException(
"SIMPLE authentication is not enabled."
+ " Available:" + enabledAuthMethods);
doSaslReply(ioe);
throw ioe;
}
break;
}
default: {
break;
}
}
return authProtocol;
}
private RpcSaslProto buildSaslNegotiateResponse()
throws IOException, InterruptedException {
RpcSaslProto negotiateMessage = negotiateResponse;
// accelerate token negotiation by sending initial challenge
// in the negotiation response
if (enabledAuthMethods.contains(AuthMethod.TOKEN)) {
saslServer = createSaslServer(AuthMethod.TOKEN);
byte[] challenge = saslServer.evaluateResponse(new byte[0]);
RpcSaslProto.Builder negotiateBuilder =
RpcSaslProto.newBuilder(negotiateResponse);
negotiateBuilder.getAuthsBuilder(0) // TOKEN is always first
.setChallenge(ByteString.copyFrom(challenge));
negotiateMessage = negotiateBuilder.build();
}
sentNegotiate = true;
return negotiateMessage;
}
private SaslServer createSaslServer(AuthMethod authMethod)
throws IOException, InterruptedException {
final Map<String,?> saslProps =
saslPropsResolver.getServerProperties(addr);
return new SaslRpcServer(authMethod).create(this, saslProps, secretManager);
}
/**
* Try to set up the response to indicate that the client version
* is incompatible with the server. This can contain special-case
* code to speak enough of past IPC protocols to pass back
* an exception to the caller.
* @param clientVersion the version the caller is using
* @throws IOException
*/
//设置去告诉客户端版本是否与服务端兼容
private void setupBadVersionResponse(int clientVersion) throws IOException {
String errMsg = "Server IPC version " + CURRENT_VERSION +
" cannot communicate with client version " + clientVersion;
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
if (clientVersion >= 9) {
// Versions >>9 understand the normal response
Call fakeCall = new Call(-1, RpcConstants.INVALID_RETRY_COUNT, null,
this);
setupResponse(buffer, fakeCall,
RpcStatusProto.FATAL, RpcErrorCodeProto.FATAL_VERSION_MISMATCH,
null, VersionMismatch.class.getName(), errMsg);
responder.doRespond(fakeCall);
} else if (clientVersion >= 3) {
Call fakeCall = new Call(-1, RpcConstants.INVALID_RETRY_COUNT, null,
this);
// Versions 3 to 8 use older response
setupResponseOldVersionFatal(buffer, fakeCall,
null, VersionMismatch.class.getName(), errMsg);
responder.doRespond(fakeCall);
} else if (clientVersion == 2) { // Hadoop 0.18.3
Call fakeCall = new Call(0, RpcConstants.INVALID_RETRY_COUNT, null,
this);
DataOutputStream out = new DataOutputStream(buffer);
out.writeInt(0); // call ID
out.writeBoolean(true); // error
WritableUtils.writeString(out, VersionMismatch.class.getName());
WritableUtils.writeString(out, errMsg);
fakeCall.setResponse(ByteBuffer.wrap(buffer.toByteArray()));
responder.doRespond(fakeCall);
}
}
private void setupHttpRequestOnIpcPortResponse() throws IOException {
Call fakeCall = new Call(0, RpcConstants.INVALID_RETRY_COUNT, null, this);
fakeCall.setResponse(ByteBuffer.wrap(
RECEIVED_HTTP_REQ_RESPONSE.getBytes()));
responder.doRespond(fakeCall);
}
/** Reads the connection context following the connection header
* @param dis - DataInputStream from which to read the header
* @throws WrappedRpcServerException - if the header cannot be
* deserialized, or the user is not authorized
*/
//这个函数是读取连接中头部下面的内容上下文，从DataInputStream中读取
private void processConnectionContext(DataInputStream dis)
throws WrappedRpcServerException {
// allow only one connection context during a session
if (connectionContextRead) {
throw new WrappedRpcServerException(
RpcErrorCodeProto.FATAL_INVALID_RPC_HEADER,
"Connection context already processed");
}
//从流中解码protobuf协议的内容上下文
connectionContext = decodeProtobufFromStream(
IpcConnectionContextProto.newBuilder(), dis);
protocolName = connectionContext.hasProtocol() ? connectionContext
.getProtocol() : null;
//得到用户组，接下来认证是否有权限
UserGroupInformation protocolUser = ProtoUtil.getUgi(connectionContext);
if (saslServer == null) {
user = protocolUser;
} else {
// user is authenticated
user.setAuthenticationMethod(authMethod);
//Now we check if this is a proxy user case. If the protocol user is
//different from the 'user', it is a proxy user scenario. However,
//this is not allowed if user authenticated with DIGEST.
if ((protocolUser != null)
&& (!protocolUser.getUserName().equals(user.getUserName()))) {
if (authMethod == AuthMethod.TOKEN) {
// Not allowed to doAs if token authentication is used
throw new WrappedRpcServerException(
RpcErrorCodeProto.FATAL_UNAUTHORIZED,
new AccessControlException("Authenticated user (" + user
+ ") doesn't match what the client claims to be ("
+ protocolUser + ")"));
} else {
// Effective user can be different from authenticated user
// for simple auth or kerberos auth
// The user is the real user. Now we create a proxy user
UserGroupInformation realUser = user;
user = UserGroupInformation.createProxyUser(protocolUser
.getUserName(), realUser);
}
}
}
authorizeConnection();
// don't set until after authz because connection isn't established
connectionContextRead = true;
}
/**
* Process a wrapped RPC Request - unwrap the SASL packet and process
* each embedded RPC request
* @param buf - SASL wrapped request of one or more RPCs
* @throws IOException - SASL packet cannot be unwrapped
* @throws InterruptedException
*/
private void unwrapPacketAndProcessRpcs(byte[] inBuf)
throws WrappedRpcServerException, IOException, InterruptedException {
if (LOG.isDebugEnabled()) {
LOG.debug("Have read input token of size " + inBuf.length
+ " for processing by saslServer.unwrap()");
}
inBuf = saslServer.unwrap(inBuf, 0, inBuf.length);
ReadableByteChannel ch = Channels.newChannel(new ByteArrayInputStream(
inBuf));
// Read all RPCs contained in the inBuf, even partial ones
while (true) {
int count = -1;
if (unwrappedDataLengthBuffer.remaining() > 0) {
count = channelRead(ch, unwrappedDataLengthBuffer);
if (count <= 0 || unwrappedDataLengthBuffer.remaining() > 0)
return;
}
if (unwrappedData == null) {
unwrappedDataLengthBuffer.flip();
int unwrappedDataLength = unwrappedDataLengthBuffer.getInt();
unwrappedData = ByteBuffer.allocate(unwrappedDataLength);
}
count = channelRead(ch, unwrappedData);
if (count <= 0 || unwrappedData.remaining() > 0)
return;
if (unwrappedData.remaining() == 0) {
unwrappedDataLengthBuffer.clear();
unwrappedData.flip();
processOneRpc(unwrappedData.array());
unwrappedData = null;
}
}
}
/**
* Process an RPC Request - handle connection setup and decoding of
* request into a Call
* @param buf - contains the RPC request header and the rpc request
* @throws IOException - internal error that should not be returned to
* client, typically failure to respond to client
* @throws WrappedRpcServerException - an exception to be sent back to
* the client that does not require verbose logging by the
* Listener thread
* @throws InterruptedException
*/
//如理rpc请求
private void processOneRpc(byte[] buf)
throws IOException, WrappedRpcServerException, InterruptedException {
int callId = -1;
int retry = RpcConstants.INVALID_RETRY_COUNT;
try {
final DataInputStream dis =
new DataInputStream(new ByteArrayInputStream(buf));
final RpcRequestHeaderProto header =
decodeProtobufFromStream(RpcRequestHeaderProto.newBuilder(), dis);
callId = header.getCallId();
retry = header.getRetryCount();
if (LOG.isDebugEnabled()) {
LOG.debug(" got #" + callId);
}
checkRpcHeaders(header);
if (callId < 0) { // callIds typically used during connection setup
processRpcOutOfBandRequest(header, dis);
} else if (!connectionContextRead) {
throw new WrappedRpcServerException(
RpcErrorCodeProto.FATAL_INVALID_RPC_HEADER,
"Connection context not established");
} else {
processRpcRequest(header, dis);
}
} catch (WrappedRpcServerException wrse) { // inform client of error
Throwable ioe = wrse.getCause();
final Call call = new Call(callId, retry, null, this);
setupResponse(authFailedResponse, call,
RpcStatusProto.FATAL, wrse.getRpcErrorCodeProto(), null,
ioe.getClass().getName(), ioe.getMessage());
responder.doRespond(call);
throw wrse;
}
}
/**
* Verify RPC header is valid
* @param header - RPC request header
* @throws WrappedRpcServerException - header contains invalid values
*/
//头部要有几个部分，rpc操作，rpc种类
private void checkRpcHeaders(RpcRequestHeaderProto header)
throws WrappedRpcServerException {
if (!header.hasRpcOp()) {
String err = " IPC Server: No rpc op in rpcRequestHeader";
throw new WrappedRpcServerException(
RpcErrorCodeProto.FATAL_INVALID_RPC_HEADER, err);
}
if (header.getRpcOp() !=
RpcRequestHeaderProto.OperationProto.RPC_FINAL_PACKET) {
String err = "IPC Server does not implement rpc header operation" +
header.getRpcOp();
throw new WrappedRpcServerException(
RpcErrorCodeProto.FATAL_INVALID_RPC_HEADER, err);
}
// If we know the rpc kind, get its class so that we can deserialize
// (Note it would make more sense to have the handler deserialize but
// we continue with this original design.
if (!header.hasRpcKind()) {
String err = " IPC Server: No rpc kind in rpcRequestHeader";
throw new WrappedRpcServerException(
RpcErrorCodeProto.FATAL_INVALID_RPC_HEADER, err);
}
}
/**
* Process an RPC Request - the connection headers and context must
* have been already read
* @param header - RPC request header
* @param dis - stream to request payload
* @throws WrappedRpcServerException - due to fatal rpc layer issues such
* as invalid header or deserialization error. In this case a RPC fatal
* status response will later be sent back to client.
* @throws InterruptedException
*/
//处理rpc请求
private void processRpcRequest(RpcRequestHeaderProto header,
DataInputStream dis) throws WrappedRpcServerException,
InterruptedException {
Class<? extends Writable> rpcRequestClass =
getRpcRequestWrapper(header.getRpcKind());
if (rpcRequestClass == null) {
LOG.warn("Unknown rpc kind " + header.getRpcKind() +
" from client " + getHostAddress());
final String err = "Unknown rpc kind in rpc header" +
header.getRpcKind();
throw new WrappedRpcServerException(
RpcErrorCodeProto.FATAL_INVALID_RPC_HEADER, err);
}
//writable接口是hadoop中所有可序列化实体中需要实现的
Writable rpcRequest;
try {
//Read the rpc request
rpcRequest = ReflectionUtils.newInstance(rpcRequestClass, conf);
rpcRequest.readFields(dis);
} catch (Throwable t) {
// includes runtime exception from newInstance
LOG.warn("Unable to read call parameters for client " +
getHostAddress() + "on connection protocol " +
this.protocolName + " for rpcKind " + header.getRpcKind(), t);
String err = "IPC server unable to read call parameters: "+ t.getMessage();
throw new WrappedRpcServerException(
RpcErrorCodeProto.FATAL_DESERIALIZING_REQUEST, err);
}
Call call = new Call(header.getCallId(), header.getRetryCount(),
rpcRequest, this, ProtoUtil.convert(header.getRpcKind()), header
.getClientId().toByteArray());
callQueue.put(call); // queue the call; maybe blocked here
incRpcCount(); // Increment the rpc count
}
/**
* Establish RPC connection setup by negotiating SASL if required, then
* reading and authorizing the connection header
* @param header - RPC header
* @param dis - stream to request payload
* @throws WrappedRpcServerException - setup failed due to SASL
* negotiation failure, premature or invalid connection context,
* or other state errors
* @throws IOException - failed to send a response back to the client
* @throws InterruptedException
*/
//简历rpc连接，被sasl协议搭建的，然后读取认证连接头
private void processRpcOutOfBandRequest(RpcRequestHeaderProto header,
DataInputStream dis) throws WrappedRpcServerException, IOException,
InterruptedException {
final int callId = header.getCallId();
if (callId == CONNECTION_CONTEXT_CALL_ID) {
// SASL must be established prior to connection context
if (authProtocol == AuthProtocol.SASL && !saslContextEstablished) {
throw new WrappedRpcServerException(
RpcErrorCodeProto.FATAL_INVALID_RPC_HEADER,
"Connection header sent during SASL negotiation");
}
// read and authorize the user
//读取认证用户
processConnectionContext(dis);
} else if (callId == AuthProtocol.SASL.callId) {
// if client was switched to simple, ignore first SASL message
if (authProtocol != AuthProtocol.SASL) {
throw new WrappedRpcServerException(
RpcErrorCodeProto.FATAL_INVALID_RPC_HEADER,
"SASL protocol not requested by client");
}
saslReadAndProcess(dis);
} else if (callId == PING_CALL_ID) {
LOG.debug("Received ping message");
} else {
throw new WrappedRpcServerException(
RpcErrorCodeProto.FATAL_INVALID_RPC_HEADER,
"Unknown out of band call #" + callId);
}
}
/**
* Authorize proxy users to access this server
* @throws WrappedRpcServerException - user is not allowed to proxy
*/
private void authorizeConnection() throws WrappedRpcServerException {
try {
// If auth method is TOKEN, the token was obtained by the
// real user for the effective user, therefore not required to
// authorize real user. doAs is allowed only for simple or kerberos
// authentication
//如果认证方法是token，这个token要被一个真实有效地的用户获取
if (user != null && user.getRealUser() != null
&& (authMethod != AuthMethod.TOKEN)) {
ProxyUsers.authorize(user, this.getHostAddress());
}
authorize(user, protocolName, getHostInetAddress());
if (LOG.isDebugEnabled()) {
LOG.debug("Successfully authorized " + connectionContext);
}
rpcMetrics.incrAuthorizationSuccesses();
} catch (AuthorizationException ae) {
LOG.info("Connection from " + this
+ " for protocol " + connectionContext.getProtocol()
+ " is unauthorized for user " + user);
rpcMetrics.incrAuthorizationFailures();
throw new WrappedRpcServerException(
RpcErrorCodeProto.FATAL_UNAUTHORIZED, ae);
}
}
/**
* Decode the a protobuf from the given input stream
* @param builder - Builder of the protobuf to decode
* @param dis - DataInputStream to read the protobuf
* @return Message - decoded protobuf
* @throws WrappedRpcServerException - deserialization failed
*/
@SuppressWarnings("unchecked")
//解码流
private <T extends Message> T decodeProtobufFromStream(Builder builder,
DataInputStream dis) throws WrappedRpcServerException {
try {
builder.mergeDelimitedFrom(dis);
return (T)builder.build();
} catch (Exception ioe) {
Class<?> protoClass = builder.getDefaultInstanceForType().getClass();
throw new WrappedRpcServerException(
RpcErrorCodeProto.FATAL_DESERIALIZING_REQUEST,
"Error decoding " + protoClass.getSimpleName() + ": "+ ioe);
}
}
/**
* Get service class for connection
* @return the serviceClass
*/
public int getServiceClass() {
return serviceClass;
}
/**
* Set service class for connection
* @param serviceClass the serviceClass to set
*/
public void setServiceClass(int serviceClass) {
this.serviceClass = serviceClass;
}
//同步关闭方法
private synchronized void close() {
disposeSasl();
data = null;
dataLengthBuffer = null;
if (!channel.isOpen())
return;
try {socket.shutdownOutput();} catch(Exception e) {
LOG.debug("Ignoring socket shutdown exception", e);
}
if (channel.isOpen()) {
try {channel.close();} catch(Exception e) {}
}
try {socket.close();} catch(Exception e) {}
}
}
这里面的序列化用了protobuf，还有一些具体的头，rpc体的设置。