[modwsgi] [patch] handle write errors more gracefully

[James Brown]

If a client goes away while mod_wsgi is writing (causing ap_pass_brigate to 
fail), it currently raises an IOError, which causes an entry in Apache's 
error log. There is some code that tries to detect disconnects and 
optionally log a debug statement instead, but it doesn't work very well.

Additionally, if the client goes away during a write, the ap_bucket_brigade 
is never cleaned up.

I believe that the attached patch will resolve both issues.

-- 
You received this message because you are subscribed to the Google Groups 
"modwsgi" group.
To view this discussion on the web visit 
https://groups.google.com/d/msg/modwsgi/-/8rrFFT2NNNQJ.
To post to this group, send email to modwsgi@googlegroups.com.
To unsubscribe from this group, send email to 
modwsgi+unsubscr...@googlegroups.com.
For more options, visit this group at 
http://groups.google.com/group/modwsgi?hl=en.


--- mod_wsgi~/mod_wsgi.c	2012-04-19 12:12:43.000000000 -0700
+++ mod_wsgi/mod_wsgi.c	2012-04-19 12:15:28.012541540 -0700
@@ -3311,7 +3311,16 @@
         Py_END_ALLOW_THREADS
 
         if (rv != APR_SUCCESS) {
-            PyErr_SetString(PyExc_IOError, "failed to write data");
+            Py_BEGIN_ALLOW_THREADS
+            apr_brigade_cleanup(self->bb);
+            Py_END_ALLOW_THREADS
+            if (!exception_when_aborted) {
+                ap_log_rerror(APLOG_MARK, WSGI_LOG_DEBUG(0), r,
+                              "mod_wsgi (pid=%d): failed to write data (client closed connection?).",
+                              getpid());
+            }
+            else
+                PyErr_SetString(PyExc_IOError, "failed to write data");
             return 0;
         }
 
@@ -3331,7 +3340,13 @@
         Py_END_ALLOW_THREADS
 
         if (n == -1) {
-            PyErr_SetString(PyExc_IOError, "failed to write data");
+            if (!exception_when_aborted) {
+                ap_log_rerror(APLOG_MARK, WSGI_LOG_DEBUG(0), r,
+                              "mod_wsgi (pid=%d): failed to write data (client closed connection?).",
+                              getpid());
+            }
+            else
+                PyErr_SetString(PyExc_IOError, "failed to write data");
             return 0;
         }