Author: sshafroi
Date: 2008-06-10 12:01:45 +0200 (Tue, 10 Jun 2008)
New Revision: 6684
Modified:
trunk/war/src/main/java/no/sesat/search/http/filters/SiteLocatorFilter.java
Log:
Issue SKER4321: (Load reducing filter that handles only current and last
request from client)
Implementation:
- A request comes inn, if there is less then max number on the stack then push
it, else return 409. (max number = 5)
- If the current thread's request is the same request as the one at the top of
the stack, then execute it. If not then wait for a minimum time to see if our
request is at the top of the stack. If this is not the case we return a 409.
(timeout = 5000ms)
Modified:
trunk/war/src/main/java/no/sesat/search/http/filters/SiteLocatorFilter.java
===================================================================
--- trunk/war/src/main/java/no/sesat/search/http/filters/SiteLocatorFilter.java
2008-06-10 08:18:44 UTC (rev 6683)
+++ trunk/war/src/main/java/no/sesat/search/http/filters/SiteLocatorFilter.java
2008-06-10 10:01:45 UTC (rev 6684)
@@ -30,13 +30,9 @@
import java.util.Enumeration;
import java.util.Locale;
import java.util.Properties;
+import java.util.Stack;
import java.util.UUID;
import java.text.MessageFormat;
-import java.util.concurrent.TimeUnit;
-import java.util.concurrent.locks.Lock;
-import java.util.concurrent.locks.ReentrantLock;
-import javax.enterprise.deploy.model.J2eeApplicationObject;
-import javax.enterprise.deploy.model.J2eeApplicationObject;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
@@ -55,8 +51,8 @@
import no.sesat.search.site.config.UrlResourceLoader;
import no.sesat.search.site.Site;
import no.sesat.search.datamodel.DataModel;
-import no.sesat.search.site.config.ResourceLoadException;
import no.sesat.search.view.FindResource;
+
import org.apache.commons.lang.StringEscapeUtils;
import org.apache.commons.lang.time.StopWatch;
import org.apache.log4j.Logger;
@@ -89,7 +85,11 @@
private static final String UNKNOWN = "unknown";
+ private static final String USER_REQUEST_STACK = "userRequestStack";
+ private static final long WAIT_TIME = 5000;
+ private static final int REQUEST_QUEUE_SIZE = 5;
+
// Any request coming into Sesat with /conf/ is immediately returned as a
404.
// It should have been directed to a skin.
private static final String CONFIGURATION_RESOURCE= "/conf/";
@@ -385,44 +385,50 @@
// Protected -----------------------------------------------------
// Private -------------------------------------------------------
+ private static void doChainFilter(final FilterChain chain, final
ServletRequest request,
+ final ServletResponse response) throws IOException,
ServletException {
+ if (request instanceof HttpServletRequest) {
+ HttpSession session = ((HttpServletRequest) request).getSession();
- private static void doChainFilter(
- final FilterChain chain,
- final ServletRequest request,
- final ServletResponse response) throws IOException,
ServletException{
+ Stack<ServletRequest> stack = (Stack<ServletRequest>)
session.getAttribute(USER_REQUEST_STACK);
+ if (null == stack) {
+ stack = new Stack<ServletRequest>();
+ session.setAttribute(USER_REQUEST_STACK, stack);
+ }
- Lock lock = request instanceof HttpServletRequest
- ? (Lock)
((HttpServletRequest)request).getSession().getAttribute("userLock")
- : new ReentrantLock();
+ if (stack.size() > REQUEST_QUEUE_SIZE) {
+ if (response instanceof HttpServletResponse) {
+ LOG.warn(" -- response 409 (More then " +
REQUEST_QUEUE_SIZE + " request in queue)");
+ ((HttpServletResponse)
response).sendError(HttpServletResponse.SC_CONFLICT);
+ }
+ } else {
+ stack.push(request);
- if(null == lock){
- lock = new ReentrantLock();
-
((HttpServletRequest)request).getSession().setAttribute("userLock", lock);
- }
-
- // datamodel is NOT request-safe. all the user's requests must execute
in sequence!
- // ten seconds is enough to wait.
- boolean done = false;
- try{
- if( lock.tryLock(10, TimeUnit.SECONDS) ){
- try{
- // request will be processed by search-portal
- LOG.info("Incoming! Duck!");
- chain.doFilter(request, response);
- done = true;
- }finally{
- lock.unlock();
+ long start = System.currentTimeMillis();
+ synchronized (session) {
+ long timeLeft = WAIT_TIME - (System.currentTimeMillis() -
start);
+ while (stack.peek() != request && timeLeft > 0) {
+ try {
+ session.wait(timeLeft);
+ timeLeft = WAIT_TIME - (System.currentTimeMillis()
- start);
+ } catch (InterruptedException e) {
+ LOG.error(e);
+ timeLeft = -1;
+ }
+ }
+ if (timeLeft >= 0) {
+ chain.doFilter(request, response);
+ } else {
+ LOG.warn(" -- response 409 (Timeout: Waited " +
(WAIT_TIME - timeLeft) + " ms. )");
+ ((HttpServletResponse)
response).sendError(HttpServletResponse.SC_CONFLICT);
+ }
+ stack.pop();
+ session.notifyAll();
}
}
- }catch(InterruptedException ie){
- LOG.warn("The duck got trucked", ie);
+ } else {
+ chain.doFilter(request, response);
}
-
- if(!done && response instanceof HttpServletResponse){
- // failed to get lock in time
- LOG.warn(" -- response 409");
-
((HttpServletResponse)response).sendError(HttpServletResponse.SC_CONFLICT);
- }
}
static String getRequestId(final ServletRequest servletRequest){
@@ -654,6 +660,5 @@
public int getStatus(){
return status;
}
-
}
}
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