tomcat源码分析系列之请求处理---关门打狗
上回我们把请求放进来了，这回我们关上门，好好修理修理它，不折腾它一番，休想轻易出去。
要关门打狗，先得知道房子在哪才行啊，上回我们说到proces的处理被委托到Http11Processor类，它就是这套房子！Http11Processor的process方法，就是这间屋子：
/**
* Process pipelined HTTP requests on the specified socket.
*
* @param socketWrapper Socket from which the HTTP requests will be read
* and the HTTP responses will be written.
*
* @throws IOException error during an I/O operation
*/
@Override
public SocketState process(SocketWrapper<Socket> socketWrapper)
throws IOException {
RequestInfo rp = request.getRequestProcessor();
//第一阶段
rp.setStage(org.apache.coyote.Constants.STAGE_PARSE);
// Setting up the I/O
this.socket = socketWrapper;
inputBuffer.setInputStream(socket.getSocket().getInputStream());
outputBuffer.setOutputStream(socket.getSocket().getOutputStream());
// Error flag
error = false;
keepAlive = true;
if (maxKeepAliveRequests > 0) {
socketWrapper.decrementKeepAlive();
}
int soTimeout = endpoint.getSoTimeout();
int threadRatio = -1;
// These may return zero or negative values
// Only calculate a thread ratio when both are >0 to ensure we get a
// sensible result
if (endpoint.getCurrentThreadsBusy() >0 &&
endpoint.getMaxThreads() >0) {
threadRatio = (endpoint.getCurrentThreadsBusy() * 100)
/ endpoint.getMaxThreads();
}
// Disable keep-alive if we are running low on threads
if (threadRatio > getDisableKeepAlivePercentage()) {
socketWrapper.setKeepAliveLeft(0);
}
try {
socket.getSocket().setSoTimeout(soTimeout);
} catch (Throwable t) {
ExceptionUtils.handleThrowable(t);
log.debug(sm.getString("http11processor.socket.timeout"), t);
error = true;
}
boolean keptAlive = socketWrapper.isKeptAlive();
while (!error && keepAlive && !endpoint.isPaused()) {
// Parsing the request header
try {
int standardTimeout = 0;
if (keptAlive) {
if (keepAliveTimeout > 0) {
standardTimeout = keepAliveTimeout;
} else if (soTimeout > 0) {
standardTimeout = soTimeout;
}
}
/*
* When there is no data in the buffer and this is not the first
* request on this connection and timeouts are being used the
* first read for this request may need a different timeout to
* take account of time spent waiting for a processing thread.
*
* This is a little hacky but better than exposing the socket
* and the timeout info to the InputBuffer
*/
if (inputBuffer.lastValid == 0 &&
socketWrapper.getLastAccess() > -1 &&
standardTimeout > 0) {
long queueTime = System.currentTimeMillis() -
socketWrapper.getLastAccess();
int firstReadTimeout;
if (queueTime >= standardTimeout) {
// Queued for longer than timeout but there might be
// data so use shortest possible timeout
firstReadTimeout = 1;
} else {
// Cast is safe since queueTime must be less than
// standardTimeout which is an int
firstReadTimeout = standardTimeout - (int) queueTime;
}
socket.getSocket().setSoTimeout(firstReadTimeout);
if (!inputBuffer.fill()) {
throw new EOFException(sm.getString("iib.eof.error"));
}
}
if (standardTimeout > 0) {
socket.getSocket().setSoTimeout(standardTimeout);
}
/**前面一堆道具，这里正式开始 这是用来读取Http头的，只是用来读取头的哦，
* 它负责将二进制流解析到对应的头部 后面我们会放出次方法的实现
**/
inputBuffer.parseRequestLine(false);
if (endpoint.isPaused()) {
// 503 - Service unavailable
response.setStatus(503);
adapter.log(request, response, 0);
error = true;
} else {
request.setStartTime(System.currentTimeMillis());
keptAlive = true;
if (disableUploadTimeout) {
socket.getSocket().setSoTimeout(soTimeout);
} else {
socket.getSocket().setSoTimeout(connectionUploadTimeout);
}
/**走到这真坎坷，赶紧把到手的狗处理了吧--先处理头、脚
* 先把头部转化了
**/
inputBuffer.parseHeaders();
}
} catch (IOException e) {
error = true;
break;
} catch (Throwable t) {
ExceptionUtils.handleThrowable(t);
if (log.isDebugEnabled()) {
log.debug(sm.getString("http11processor.header.parse"), t);
}
// 400 - Bad Request
response.setStatus(400);
adapter.log(request, response, 0);
error = true;
}
if (!error) {
// Setting up filters, and parse some request headers
//第二阶段
rp.setStage(org.apache.coyote.Constants.STAGE_PREPARE);
try {
/**拔毛----预处理请求，解析一些协议上的东西，稍后放出方法**/
prepareRequest();
} catch (Throwable t) {
ExceptionUtils.handleThrowable(t);
if (log.isDebugEnabled()) {
log.debug(sm.getString("http11processor.request.prepare"), t);
}
// 400 - Internal Server Error
response.setStatus(400);
adapter.log(request, response, 0);
error = true;
}
}
if (socketWrapper.getKeepAliveLeft() == 0) {
keepAlive = false;
}
// Process the request in the adapter
if (!error) {
try {
//第三阶段
rp.setStage(org.apache.coyote.Constants.STAGE_SERVICE);
//核心处理：去除内脏，烹饪…… 处理请求体 这里又涉及到很多知识了，在下节详细介绍这个过程
adapter.service(request, response);
// Handle when the response was committed before a serious
// error occurred. Throwing a ServletException should both
// set the status to 500 and set the errorException.
// If we fail here, then the response is likely already
// committed, so we can't try and set headers.
if(keepAlive && !error) { // Avoid checking twice.
error = response.getErrorException() != null ||
(!isAsync() &&
statusDropsConnection(response.getStatus()));
}
} catch (InterruptedIOException e) {
error = true;
} catch (Throwable t) {
ExceptionUtils.handleThrowable(t);
log.error(sm.getString("http11processor.request.process"), t);
// 500 - Internal Server Error
response.setStatus(500);
adapter.log(request, response, 0);
error = true;
}
}
// Finish the handling of the request
try {
//第四阶段
rp.setStage(org.apache.coyote.Constants.STAGE_ENDINPUT);
// If we know we are closing the connection, don't drain input.
// This way uploading a 100GB file doesn't tie up the thread
// if the servlet has rejected it.
if(error && !isAsync())
inputBuffer.setSwallowInput(false);
if (!isAsync())
//结束烹饪，结束请求
endRequest();
} catch (Throwable t) {
ExceptionUtils.handleThrowable(t);
log.error(sm.getString("http11processor.request.finish"), t);
// 500 - Internal Server Error
response.setStatus(500);
adapter.log(request, response, 0);
error = true;
}
try {
//第五阶段
rp.setStage(org.apache.coyote.Constants.STAGE_ENDOUTPUT);
} catch (Throwable t) {
ExceptionUtils.handleThrowable(t);
log.error(sm.getString("http11processor.response.finish"), t);
error = true;
}
// If there was an error, make sure the request is counted as
// and error, and update the statistics counter
if (error) {
response.setStatus(500);
}
//收尾阶段：将狗肉盛盘 更新统计数据
request.updateCounters();
//第六阶段 收尾阶段：收拾后厨 清楚数据，等待下一个请求，计数器
rp.setStage(org.apache.coyote.Constants.STAGE_KEEPALIVE);
// Don't reset the param - we'll see it as ended. Next request
// will reset it
// thrA.setParam(null);
// Next request
if (!isAsync() || error) {
inputBuffer.nextRequest();
outputBuffer.nextRequest();
}
// If we don't have a pipe-lined request allow this thread to be
// used by another connection
if (isAsync() || error || inputBuffer.lastValid == 0) {
break;
}
if (maxKeepAliveRequests > 0) {
socketWrapper.decrementKeepAlive();
}
}
//第七阶段：收工 上狗肉
rp.setStage(org.apache.coyote.Constants.STAGE_ENDED);
if (error || endpoint.isPaused()) {
return SocketState.CLOSED;
} else if (isAsync()) {
return SocketState.LONG;
} else {
if (!keepAlive) {
return SocketState.CLOSED;
} else {
return SocketState.OPEN;
}
}
}
这个过程还是挺复杂的（你以为吃顿狗肉这么容易？），分七个阶段：
第一阶段：处理头部，可能抛503和400异常；
第二阶段：预处理请求体，主要解析请求的部分header和解析url，可能抛400异常；
第三阶段：处理请求（最核心的阶段），可能抛500异常；
第四阶段：结束请求，可能抛500异常；
第五阶段：更新统计计数，可能抛500异常；
第六阶段：整理线程，准备接受下一个请求；
第七阶段：结束
走完这七步，香喷喷的狗肉就上桌了！！
，不过先别动筷子，我们还要补上前面提到的几个方法：
处理头部：
/**
* Read the request line. This function is meant to be used during the
* HTTP request header parsing. Do NOT attempt to read the request body
* using it.
*
* @throws IOException If an exception occurs during the underlying socket
* read operations, or if the given buffer is not big enough to accommodate
* the whole line.
*/
@Override
public boolean parseRequestLine(boolean useAvailableDataOnly)
throws IOException {
int start = 0;
//
// Skipping blank lines
//
byte chr = 0;
do {
// Read new bytes if needed
if (pos >= lastValid) {
if (!fill())
throw new EOFException(sm.getString("iib.eof.error"));
}
chr = buf[pos++];
} while ((chr == Constants.CR) || (chr == Constants.LF));
pos--;
// Mark the current buffer position
start = pos;
//
// Reading the method name
// Method name is always US-ASCII
//
boolean space = false;
while (!space) {
// Read new bytes if needed
if (pos >= lastValid) {
if (!fill())
throw new EOFException(sm.getString("iib.eof.error"));
}
// Spec says no CR or LF in method name
if (buf[pos] == Constants.CR || buf[pos] == Constants.LF) {
throw new IllegalArgumentException(
sm.getString("iib.invalidmethod"));
}
// Spec says single SP but it also says be tolerant of HT
if (buf[pos] == Constants.SP || buf[pos] == Constants.HT) {
space = true;
request.method().setBytes(buf, start, pos - start);
}
pos++;
}
// Spec says single SP but also says be tolerant of multiple and/or HT
while (space) {
// Read new bytes if needed
if (pos >= lastValid) {
if (!fill())
throw new EOFException(sm.getString("iib.eof.error"));
}
if (buf[pos] == Constants.SP || buf[pos] == Constants.HT) {
pos++;
} else {
space = false;
}
}
// Mark the current buffer position
start = pos;
int end = 0;
int questionPos = -1;
//
// Reading the URI
//
boolean eol = false;
while (!space) {
// Read new bytes if needed
if (pos >= lastValid) {
if (!fill())
throw new EOFException(sm.getString("iib.eof.error"));
}
// Spec says single SP but it also says be tolerant of HT
if (buf[pos] == Constants.SP || buf[pos] == Constants.HT) {
space = true;
end = pos;
} else if ((buf[pos] == Constants.CR)
|| (buf[pos] == Constants.LF)) {
// HTTP/0.9 style request
eol = true;
space = true;
end = pos;
} else if ((buf[pos] == Constants.QUESTION)
&& (questionPos == -1)) {
questionPos = pos;
}
pos++;
}
request.unparsedURI().setBytes(buf, start, end - start);
if (questionPos >= 0) {
request.queryString().setBytes(buf, questionPos + 1,
end - questionPos - 1);
request.requestURI().setBytes(buf, start, questionPos - start);
} else {
request.requestURI().setBytes(buf, start, end - start);
}
// Spec says single SP but also says be tolerant of multiple and/or HT
while (space) {
// Read new bytes if needed
if (pos >= lastValid) {
if (!fill())
throw new EOFException(sm.getString("iib.eof.error"));
}
if (buf[pos] == Constants.SP || buf[pos] == Constants.HT) {
pos++;
} else {
space = false;
}
}
// Mark the current buffer position
start = pos;
end = 0;
//
// Reading the protocol
// Protocol is always US-ASCII
//
while (!eol) {
// Read new bytes if needed
if (pos >= lastValid) {
if (!fill())
throw new EOFException(sm.getString("iib.eof.error"));
}
if (buf[pos] == Constants.CR) {
end = pos;
} else if (buf[pos] == Constants.LF) {
if (end == 0)
end = pos;
eol = true;
}
pos++;
}
if ((end - start) > 0) {
request.protocol().setBytes(buf, start, end - start);
} else {
request.protocol().setString("");
}
return true;
}
这个方法没什么好说，接下来看
/**
* Parse an HTTP header.
*
* @return false after reading a blank line (which indicates that the
* HTTP header parsing is done
*/
@SuppressWarnings("null") // headerValue cannot be null
public boolean parseHeader()
throws IOException {
//
// Check for blank line
//
byte chr = 0;
while (true) {
// Read new bytes if needed
if (pos >= lastValid) {
if (!fill())
throw new EOFException(sm.getString("iib.eof.error"));
}
chr = buf[pos];
if ((chr == Constants.CR) || (chr == Constants.LF)) {
if (chr == Constants.LF) {
pos++;
return false;
}
} else {
break;
}
pos++;
}
// Mark the current buffer position
int start = pos;
//
// Reading the header name
// Header name is always US-ASCII
//
boolean colon = false;
MessageBytes headerValue = null;
while (!colon) {
// Read new bytes if needed
if (pos >= lastValid) {
if (!fill())
throw new EOFException(sm.getString("iib.eof.error"));
}
if (buf[pos] == Constants.COLON) {
colon = true;
headerValue = headers.addValue(buf, start, pos - start);
} else if (!HTTP_TOKEN_CHAR[buf[pos]]) {
// If a non-token header is detected, skip the line and
// ignore the header
skipLine(start);
return true;
}
chr = buf[pos];
if ((chr >= Constants.A) && (chr <= Constants.Z)) {
buf[pos] = (byte) (chr - Constants.LC_OFFSET);
}
pos++;
}
// Mark the current buffer position
start = pos;
int realPos = pos;
//
// Reading the header value (which can be spanned over multiple lines)
//
boolean eol = false;
boolean validLine = true;
while (validLine) {
boolean space = true;
// Skipping spaces
while (space) {
// Read new bytes if needed
if (pos >= lastValid) {
if (!fill())
throw new EOFException(sm.getString("iib.eof.error"));
}
if ((buf[pos] == Constants.SP) || (buf[pos] == Constants.HT)) {
pos++;
} else {
space = false;
}
}
int lastSignificantChar = realPos;
// Reading bytes until the end of the line
while (!eol) {
// Read new bytes if needed
if (pos >= lastValid) {
if (!fill())
throw new EOFException(sm.getString("iib.eof.error"));
}
if (buf[pos] == Constants.CR) {
// Skip
} else if (buf[pos] == Constants.LF) {
eol = true;
} else if (buf[pos] == Constants.SP) {
buf[realPos] = buf[pos];
realPos++;
} else {
buf[realPos] = buf[pos];
realPos++;
lastSignificantChar = realPos;
}
pos++;
}
realPos = lastSignificantChar;
// Checking the first character of the new line. If the character
// is a LWS, then it's a multiline header
// Read new bytes if needed
if (pos >= lastValid) {
if (!fill())
throw new EOFException(sm.getString("iib.eof.error"));
}
chr = buf[pos];
if ((chr != Constants.SP) && (chr != Constants.HT)) {
validLine = false;
} else {
eol = false;
// Copying one extra space in the buffer (since there must
// be at least one space inserted between the lines)
buf[realPos] = chr;
realPos++;
}
}
// Set the header value
headerValue.setBytes(buf, start, realPos - start);
return true;
}
/**
* After reading the request headers, we have to setup the request filters.
*/
protected void prepareRequest() {
http11 = true;
http09 = false;
contentDelimitation = false;
expectation = false;
prepareRequestInternal();
if (endpoint.isSSLEnabled()) {
request.scheme().setString("https");
}
MessageBytes protocolMB = request.protocol();
if (protocolMB.equals(Constants.HTTP_11)) {
http11 = true;
protocolMB.setString(Constants.HTTP_11);
} else if (protocolMB.equals(Constants.HTTP_10)) {
http11 = false;
keepAlive = false;
protocolMB.setString(Constants.HTTP_10);
} else if (protocolMB.equals("")) {
// HTTP/0.9
http09 = true;
http11 = false;
keepAlive = false;
} else {
// Unsupported protocol
http11 = false;
error = true;
// Send 505; Unsupported HTTP version
if (getLog().isDebugEnabled()) {
getLog().debug(sm.getString("http11processor.request.prepare")+
" Unsupported HTTP version \""+protocolMB+"\"");
}
response.setStatus(505);
adapter.log(request, response, 0);
}
MessageBytes methodMB = request.method();
if (methodMB.equals(Constants.GET)) {
methodMB.setString(Constants.GET);
} else if (methodMB.equals(Constants.POST)) {
methodMB.setString(Constants.POST);
}
MimeHeaders headers = request.getMimeHeaders();
// Check connection header
MessageBytes connectionValueMB = headers.getValue("connection");
if (connectionValueMB != null) {
ByteChunk connectionValueBC = connectionValueMB.getByteChunk();
if (findBytes(connectionValueBC, Constants.CLOSE_BYTES) != -1) {
keepAlive = false;
} else if (findBytes(connectionValueBC,
Constants.KEEPALIVE_BYTES) != -1) {
keepAlive = true;
}
}
MessageBytes expectMB = null;
if (http11)
expectMB = headers.getValue("expect");
if ((expectMB != null)
&& (expectMB.indexOfIgnoreCase("100-continue", 0) != -1)) {
getInputBuffer().setSwallowInput(false);
expectation = true;
}
// Check user-agent header
if ((restrictedUserAgents != null) && ((http11) || (keepAlive))) {
MessageBytes userAgentValueMB = headers.getValue("user-agent");
// Check in the restricted list, and adjust the http11
// and keepAlive flags accordingly
if(userAgentValueMB != null) {
String userAgentValue = userAgentValueMB.toString();
if (restrictedUserAgents != null &&
restrictedUserAgents.matcher(userAgentValue).matches()) {
http11 = false;
keepAlive = false;
}
}
}
// Check for a full URI (including protocol://host:port/)
ByteChunk uriBC = request.requestURI().getByteChunk();
if (uriBC.startsWithIgnoreCase("http", 0)) {
int pos = uriBC.indexOf("://", 0, 3, 4);
int uriBCStart = uriBC.getStart();
int slashPos = -1;
if (pos != -1) {
byte[] uriB = uriBC.getBytes();
slashPos = uriBC.indexOf('/', pos + 3);
if (slashPos == -1) {
slashPos = uriBC.getLength();
// Set URI as "/"
request.requestURI().setBytes
(uriB, uriBCStart + pos + 1, 1);
} else {
request.requestURI().setBytes
(uriB, uriBCStart + slashPos,
uriBC.getLength() - slashPos);
}
MessageBytes hostMB = headers.setValue("host");
hostMB.setBytes(uriB, uriBCStart + pos + 3,
slashPos - pos - 3);
}
}
// Input filter setup
InputFilter[] inputFilters = getInputBuffer().getFilters();
// Parse transfer-encoding header
MessageBytes transferEncodingValueMB = null;
if (http11)
transferEncodingValueMB = headers.getValue("transfer-encoding");
if (transferEncodingValueMB != null) {
String transferEncodingValue = transferEncodingValueMB.toString();
// Parse the comma separated list. "identity" codings are ignored
int startPos = 0;
int commaPos = transferEncodingValue.indexOf(',');
String encodingName = null;
while (commaPos != -1) {
encodingName = transferEncodingValue.substring
(startPos, commaPos).toLowerCase(Locale.ENGLISH).trim();
if (!addInputFilter(inputFilters, encodingName)) {
// Unsupported transfer encoding
error = true;
// 501 - Unimplemented
response.setStatus(501);
adapter.log(request, response, 0);
}
startPos = commaPos + 1;
commaPos = transferEncodingValue.indexOf(',', startPos);
}
encodingName = transferEncodingValue.substring(startPos)
.toLowerCase(Locale.ENGLISH).trim();
if (!addInputFilter(inputFilters, encodingName)) {
// Unsupported transfer encoding
error = true;
// 501 - Unimplemented
if (getLog().isDebugEnabled()) {
getLog().debug(sm.getString("http11processor.request.prepare")+
" Unsupported transfer encoding \""+encodingName+"\"");
}
response.setStatus(501);
adapter.log(request, response, 0);
}
}
// Parse content-length header
long contentLength = request.getContentLengthLong();
if (contentLength >= 0 && !contentDelimitation) {
getInputBuffer().addActiveFilter
(inputFilters[Constants.IDENTITY_FILTER]);
contentDelimitation = true;
}
MessageBytes valueMB = headers.getValue("host");
// Check host header
if (http11 && (valueMB == null)) {
error = true;
// 400 - Bad request
if (getLog().isDebugEnabled()) {
getLog().debug(sm.getString("http11processor.request.prepare")+
" host header missing");
}
response.setStatus(400);
adapter.log(request, response, 0);
}
parseHost(valueMB);
if (!contentDelimitation) {
// If there's no content length
// (broken HTTP/1.0 or HTTP/1.1), assume
// the client is not broken and didn't send a body
getInputBuffer().addActiveFilter
(inputFilters[Constants.VOID_FILTER]);
contentDelimitation = true;
}
// Advertise sendfile support through a request attribute
if (endpoint.getUseSendfile()) {
request.setAttribute("org.apache.tomcat.sendfile.support",
Boolean.TRUE);
}
// Advertise comet support through a request attribute
if (endpoint.getUseComet()) {
request.setAttribute("org.apache.tomcat.comet.support",
Boolean.TRUE);
}
// Advertise comet timeout support
if (endpoint.getUseCometTimeout()) {
request.setAttribute("org.apache.tomcat.comet.timeout.support",
Boolean.TRUE);
}
}
这几个方法没什么好说，感兴趣就看一下就行了。