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https://issues.apache.org/jira/browse/SOLR-2878?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13144627#comment-13144627
]
Nick Veenhof commented on SOLR-2878:
------------------------------------
After loads of research and figuring out why it happened I found a
CharResponseWrapper that worked for getOutputStream also.
For archiving purposes I'd like to put the full class here :
With this class it all seems to work as it did before. Thanks for the pointer
on the CharResponseWrapper, I was not deep enough in the java servlets world to
understand that this CharResponseWrapper could have such an impact on the
response.
{code}
/**
*
*/
package clime.messadmin.filter;
import java.io.CharArrayWriter;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;
/**
* @author Cédrik LIME
*/
class CharResponseWrapper extends HttpServletResponseWrapper {
protected CharArrayWriter output;
protected ServletOutputStream stream = null;
protected PrintWriter writer = null;
static class CharOutputStream extends ServletOutputStream {
CharArrayWriter outstream;
public CharOutputStream(CharArrayWriter out) {
outstream = out;
}
/** {@inheritDoc} */
// @Override
public void write(int b) {
outstream.write(b);
}
public void write(String str) throws IOException {
outstream.write(str);
}
}
/** {@inheritDoc} */
// @Override
public String toString() {
return output.toString();
}
public char[] toCharArray() {
return (output.toCharArray());
}
public CharResponseWrapper(HttpServletResponse response) {
super(response);
output = new CharArrayWriter();
}
/** {@inheritDoc} */
// @Override
public synchronized PrintWriter getWriter() {
if (stream != null) {
throw new IllegalStateException("getOutputStream() has
already been called for this response");
}
if (writer == null) {
writer = new PrintWriter(output);
}
return writer;
}
/** {@inheritDoc} */
// @Override
public synchronized ServletOutputStream getOutputStream() {
if (writer != null) {
throw new IllegalStateException("getWriter() has
already been called for this response");
}
if (stream == null) {
stream = new CharOutputStream(output);
}
return stream;
}
}
{code}
> Regression in SolrDispatchFilter.java concerning the getOutputStream vs
> getWriter
> ---------------------------------------------------------------------------------
>
> Key: SOLR-2878
> URL: https://issues.apache.org/jira/browse/SOLR-2878
> Project: Solr
> Issue Type: Bug
> Components: Build, Response Writers
> Affects Versions: 3.4
> Environment: Any unix system, it's a global problem
> Reporter: Nick Veenhof
> Labels: filter, getOutputStream, getWriter, regression
> Fix For: 3.5, 4.0
>
>
> In solr 1.4 we used getWriter in the writeResponse for
> solrDispatchFilter::doFilter which invoked writeResponse.
> This code looked in summary like this :
> {code:title=solrDispatchFilter.java|borderStyle=solid}
> private void writeResponse(SolrQueryResponse solrRsp, ServletResponse
> response,
> QueryResponseWriter responseWriter, SolrQueryRequest solrReq, Method
> reqMethod)
> throws IOException {
> ...
> PrintWriter out = response.getWriter();
> responseWriter.write(out, solrReq, solrRsp);
> ...
> {code}
> In solr 3.x this has changed to something like this
> {code:title=solrDispatchFilter.java|borderStyle=solid}
> private void writeResponse(SolrQueryResponse solrRsp, ServletResponse
> response,
> QueryResponseWriter responseWriter, SolrQueryRequest solrReq, Method
> reqMethod)
> throws IOException {
> ...
> String charset = ContentStreamBase.getCharsetFromContentType(ct);
> Writer out = (charset == null || charset.equalsIgnoreCase("UTF-8"))
> ? new OutputStreamWriter(response.getOutputStream(), UTF8)
> : new OutputStreamWriter(response.getOutputStream(), charset);
> out = new FastWriter(out);
> responseWriter.write(out, solrReq, solrRsp);
> out.flush();
> ...
> {code}
> Now, when we add another filter that tries to modify the output it is being
> blocked by the out.flush().
> flush() is telling our outputstream that it can write directly to the
> destination (similar to the out.close()), since this normally happens
> automatically there shouldn't be a need to execute this flush.
> In our case this secondary filter is trying to add headers to the response
> object. When we were using getwriter() it was not closing the writer so we
> could still modify this output. Since the flush happens now we are no longer
> able to modify the headers accordingly.
> It would be an easy fix if the flush could be commented out and everything
> would work but that is not the case. The headers are working when this
> happens but there is no more output.
> When I modify both classes to use getWriter() everything is working as
> expected.
> This is a severe regression for our use of solr.
> Our code that is used in the filter
> {code:title=solrCustomFilter.java|borderStyle=solid}
> public void doFilter(ServletRequest req, ServletResponse res,FilterChain
> chain)
> throws IOException, ServletException {
> ...
> Writer out = new OutputStreamWriter(response.getOutputStream(), "UTF8");
> //auto flush
> out = new FastWriter(out);
> // convert to a chartext
> CharResponseWrapper wrapper = new CharResponseWrapper((HttpServletResponse)
> response);
> chain.doFilter(request, wrapper);
> String responseBody = wrapper.toString();
> //write the outgoing header. Only succeeds when flush of solrDispatchFilter
> is commented out
> response.addHeader("pragma", "somevalue;");
> out.write(responseBody);
> ...
> {code}
> Sources :
> {quote}
> SRV.5.5 Closure of Response Object
> When a response is closed, the container must immediately flush all remaining
> content in the response buffer to the client. The following events indicate
> that the servlet has satisfied the request and that the response object is to
> be closed:
> • The termination of the service method of the servlet.
> • The amount of content specified in the setContentLength method of the
> response has been written to the response.
> • The sendError method is called.
> • The sendRedirect method is called.
> {quote}
> Solr 1.4
> https://svn.apache.org/repos/asf/lucene/solr/branches/branch-1.4/src/webapp/src/org/apache/solr/servlet/SolrDispatchFilter.java
> Solr 3.4
> https://svn.apache.org/repos/asf/lucene/dev/branches/lucene_solr_3_4/solr/core/src/java/org/apache/solr/servlet/SolrDispatchFilter.java
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