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From: Peter Rehley <peter AT rehley DOT net>
Subject: Re: pthreads, cygwin and pthread_mutex_lock not blocking
Date: Thu, 2 Jun 2005 11:22:27 -0700
To: "Cygwin List'" <cygwin AT cygwin DOT com>
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Here is a patch to thread.cc that allows _lock to process signals.  The 
patch is against the 1.178 version of thread.cc found in cvs.

--- thread.cc.orig      Thu Jun  2 11:17:39 2005
+++ thread.cc   Thu Jun  2 11:20:00 2005
@@ -1543,8 +1543,24 @@
      }
    else
      {
-      WaitForSingleObject (win32_obj_id, INFINITE);
-      set_owner (self);
+      //WaitForSingleObject (win32_obj_id, INFINITE);
+      //set_owner (self);
+      bool loop = true;
+      do
+       switch (pthread::cancelable_wait (win32_obj_id, INFINITE, 
false, true))
+         {
+         case WAIT_OBJECT_0:
+            set_owner (self);
+            loop=false;
+           break;
+         case WAIT_SIGNALED:
+           _my_tls.call_signal_handler ();
+           break;
+         default:
+           // should never happen
+           return EINVAL;
+         }
+      while (loop);
      }

    return result;

On Jun 1, 2005, at 6:17 PM, Peter Rehley wrote:

> Here is the patch to pthread.h
>
> hummingbird:~/MontaVista/tmp prehley$ diff -u pthread.h.cygwin 
> pthread.h.new
> --- pthread.h.cygwin    Wed Jun  1 18:15:40 2005
> +++ pthread.h.new       Wed Jun  1 18:06:49 2005
> @@ -53,12 +53,12 @@
>  #define PTHREAD_MUTEX_RECURSIVE 0
>  #define PTHREAD_MUTEX_ERRORCHECK 1
>  #define PTHREAD_MUTEX_NORMAL 2
> -#define PTHREAD_MUTEX_DEFAULT PTHREAD_MUTEX_ERRORCHECK
> +#define PTHREAD_MUTEX_DEFAULT PTHREAD_MUTEX_NORMAL
>  /* this should be too low to ever be a valid address */
>  #define PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP (pthread_mutex_t)18
>  #define PTHREAD_NORMAL_MUTEX_INITIALIZER_NP (pthread_mutex_t)19
>  #define PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP (pthread_mutex_t)20
> -#define PTHREAD_MUTEX_INITIALIZER 
> PTHREAD_ERRORCHECK_MUTEX_INITIALIZER_NP
> +#define PTHREAD_MUTEX_INITIALIZER PTHREAD_NORMAL_MUTEX_INITIALIZER_NP
>  #define PTHREAD_ONCE_INIT { PTHREAD_MUTEX_INITIALIZER, 0 }
>  #define PTHREAD_PRIO_INHERIT
>  #define PTHREAD_PRIO_NONE
> @@ -202,4 +202,3 @@
>  #endif
>
>  #endif /* _PTHREAD_H */
> -
>
> On Jun 1, 2005, at 5:22 PM, Peter Rehley wrote:
>
>>
>>
>> On May 31, 2005, at 10:50 AM, David Rothenberger wrote:
>>
>>> On 5/31/2005 10:15 AM, Peter Rehley wrote:
>>>> Well, here is a simple test case, but turns out I wasn't using the 
>>>> latest version.  I was having the problem on 1.5.12,  I haven't 
>>>> been able to get a good build with cygwin 1.5.17-1.  It builds and 
>>>> I can run the install script, but when I put the dll in place I see 
>>>> the message "cygheap magic number mismatch detected", and gcc 
>>>> doesn't want to work.
>>>
>>> I had a similar problem (see 
>>> <http://cygwin.com/ml/cygwin/2005-05/msg01251.html>). It turned out 
>>> it was because I was using the latest release of binutils. Try 
>>> rolling back to the previous release.
>>>
>> Ok, I rolled binutils to 20041229, rebuilt and copied the new dll.  
>> It's having the same issue that I see in 1.5.12.  When I debug the 
>> program, I see that the signal is being sent, but it doesn't get 
>> executed.
>>
>> I've looked at the cygwin code, and I have noticed that the sleep 
>> (nanosleep) is calling pthread::cancelable_wait, and that will call 
>> WaitForMultipleObjects.  However, in pthread_mutex::_lock, it's only 
>> using WaitForSingleObject.  I'm wondering if something like 
>> WaitForMultipleObjects should be added to the lock function so that 
>> signals (SIGCHLD, in my case) can be handled.
>>
>> It's just a guess since I'm not an expert with this code.
>>
>> Enjoy,
>> Peter
>> -------------------------------
>> A Møøse once bit my sister
>>
>>
>> --
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>>
>>
>>
> Enjoy,
> Peter
> -------------------------------
> A Møøse once bit my sister
>
>
> --
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>
>
>
Enjoy,
Peter
-------------------------------
A Møøse once bit my sister


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