MSM用MemcachedBackupSessionManager类替换了StandardManager
1 MSM通过两个Valve拦截Request请求实现了对Session的操作
RequestTrackingHostValve RequestTrackingContextValve
这两个Valve是在startInternal()方法中加载的 如下代码
_trackingHostValve = new RequestTrackingHostValve(_requestUriIgnorePattern, sessionCookieName, this, _statistics, _enabled, _currentRequest);
_manager.getContainer().getParent().getPipeline().addValve(_trackingHostValve);
_trackingContextValve = new RequestTrackingContextValve(sessionCookieName, this);
_manager.getContainer().getPipeline().addValve( _trackingContextValve );
先看RequestTrackingHostValve做了什么？
@Override
public void invoke( final Request request, final Response response ) throws IOException, ServletException {
final String requestId = getURIWithQueryString( request );
if(!_enabled.get() || !_msmContext.equals(request.getContext())) {
getNext().invoke( request, response );
} else if ( _ignorePattern != null && _ignorePattern.matcher( requestId ).matches() ) {
if(_log.isDebugEnabled()) {
_log.debug( ">>>>>> Ignoring: " + requestId + " (requestedSessionId "+ request.getRequestedSessionId() +") ==================" );
}
try {
storeRequestThreadLocal( request );
request.setNote(REQUEST_IGNORED, Boolean.TRUE);
getNext().invoke( request, response );
} finally {
if(request.getNote(REQUEST_PROCESSED) == Boolean.TRUE) {
final String sessionId = getSessionId(request, response);
if(sessionId != null) {
_sessionBackupService.requestFinished(sessionId, requestId);
}
}
resetRequestThreadLocal();
}
if(_log.isDebugEnabled()) {
_log.debug( "<<<<<< Ignored: " + requestId + " ==================" );
}
} else {
request.setNote(REQUEST_PROCESS, Boolean.TRUE);
if ( _log.isDebugEnabled() ) {
_log.debug( ">>>>>> Request starting: " + requestId + " (requestedSessionId "+ request.getRequestedSessionId() +") ==================" );
}
//请求开始，注意这里并没有从memcached获取session，而是在用户调用request.getSession()才从memcached获取
try {
storeRequestThreadLocal( request ); //保存request到ThreadLocal
getNext().invoke( request, response ); //调用下一个Valve
} finally {
final Boolean sessionIdChanged = (Boolean) request.getNote(SESSION_ID_CHANGED);
//在请求结束时保存session到memcached
backupSession( request, response, sessionIdChanged == null ? false : sessionIdChanged.booleanValue() );
resetRequestThreadLocal();
}
if ( _log.isDebugEnabled() ) {
logDebugRequestSessionCookie( request );
logDebugResponseCookie( response );
_log.debug( "<<<<<< Request finished: " + requestId + " ==================" );
}
}
}