Re: [patch] perchild.c (Re: setjmp/longjmp vs try/throw/catch)

2004-07-31 Thread Jeff Trawick 
On Wed, 21 Jul 2004 05:33:18 +0900 (JST), Tsuyoshi SASAMOTO
<[EMAIL PROTECTED]> wrote:

> And... in perchild.c, I found setjmp/longjmp is used unsafely
> (one jmpbuffer is shared by all threads).

(a) based on ancient experience, I'm surprised it doesn't use
SIGsetjmp()/SIGlongjmp(); event Apache 1.3 was smart enough to do that
(just not smart enough not to use longjmp in the first place ;) )

(b) I omitted the unrelated fix which was part of your patch; care to
provide an explanation?

Thanks,

Jeff

Re: [patch] perchild.c (Re: setjmp/longjmp vs try/throw/catch)

2004-07-20 Thread Jeff Trawick 
On Wed, 21 Jul 2004 05:33:18 +0900 (JST), Tsuyoshi SASAMOTO
<[EMAIL PROTECTED]> wrote:
> And... in perchild.c, I found setjmp/longjmp is used unsafely
> (one jmpbuffer is shared by all threads).

patch looks reasonable on first glance; I'll look further with the
intention of committing soon-ish; bother me privately in a few days if
I forget ;)

(thanks!)

Re: [patch] perchild.c (Re: setjmp/longjmp vs try/throw/catch)

2004-07-20 Thread Rici Lake 
On 20-Jul-04, at 3:33 PM, Tsuyoshi SASAMOTO wrote:
Please refer to this discussion about thread safety of setjmp/longjmp:
 
http://groups.google.com/groups? 
[EMAIL PROTECTED]

The signal-to-noise ratio in that thread is very low :)
It is clear that setjmp/longjmp are *not* signal-safe; furthermore,  
signals interact badly with threads. It is certainly not ok to use  
longjmp in a signal handler, since there is no way of knowing which  
thread a signal handler might be running in. This does not make  
setjmp/longjmp thread unsafe (IMHO).

As Posix memorably states, using longjmp with a jump buffer from a  
different thread context is a "questionable practice ... not worthy of  
standardization".

R.

[patch] perchild.c (Re: setjmp/longjmp vs try/throw/catch)

2004-07-20 Thread Tsuyoshi SASAMOTO 
>Switching to setjmp/longjmp does appear to work well with apache and gcc.
>But that leaves me wondering if I need to worry about thread-safety.
>Is using setjmp/longjmp with Worker or Windoze MPM asking for trouble?
>And if so, is there an alternative approach I could try?

Please refer to this discussion about thread safety of setjmp/longjmp:
http://groups.google.com/[EMAIL PROTECTED]


And... in perchild.c, I found setjmp/longjmp is used unsafely
(one jmpbuffer is shared by all threads).


Tsuyoshi SASAMOTO
[EMAIL PROTECTED]

--- httpd-2.0/server/mpm/experimental/perchild/perchild.c   Tue Mar 16 08:08:41 
2004
+++ httpd-2.0/server/mpm/experimental/perchild/perchild.c   Wed Jul 21 04:26:15 
2004
@@ -137,7 +137,7 @@
 static int requests_this_child;
 static int num_listensocks = 0;
 static ap_pod_t *pod;
-static jmp_buf jmpbuffer;
+static jmp_buf *jmpbuffers;
 
 struct child_info_t {
 uid_t uid;
@@ -617,7 +617,7 @@
 bodylen = strlen(body);
 
 headers = iov.iov_base;
-headerslen = body - headers;
+headerslen = body - 1 - headers;
 
 bucket = apr_bucket_heap_create(body, bodylen, NULL, alloc);
 APR_BRIGADE_INSERT_HEAD(bb, bucket);
@@ -758,7 +758,7 @@
 }
 }
 apr_thread_mutex_unlock(idle_thread_count_mutex);
-if (setjmp(jmpbuffer) != 1) {
+if (setjmp(jmpbuffers[thread_num]) != 1) {
 process_socket(ptrans, csd, conn_id, bucket_alloc);
 }
 else {
@@ -1668,6 +1668,8 @@
 }
 ap_child_table = (ap_ctable *)apr_pcalloc(p, server_limit * sizeof(ap_ctable));
 
+jmpbuffers = (jmp_buf *)apr_palloc(p, thread_limit * sizeof(jmp_buf));
+
 return OK;
 }
 
@@ -1704,7 +1706,7 @@
  ap_server_conf, "Could not pass request to proper "
  "child, request will not be honored.");
 }
-longjmp(jmpbuffer, 1); 
+longjmp(jmpbuffers[thread_num], 1); 
 }
 return OK;
 }