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Date: Mon, 19 Nov 2001 12:47:05 -0800
From: Aaron Bannert <aaron@clove.org>
To: dev@httpd.apache.org, dev@apr.apache.org
Subject: Re: [2.0] does not compile without threads
Message-ID: <20011119124705.R18738@clove.org>
Mail-Followup-To: Aaron Bannert <aaron@clove.org>, dev@httpd.apache.org,
	dev@apr.apache.org
References: <20011119175440.A53500@deejai2.mch.fsc.net>
 <20011119091936.L18738@clove.org> <20011119200956.F3C5046DFD@koj.rkbloom.net>
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On Mon, Nov 19, 2001 at 12:09:56PM -0800, Ryan Bloom wrote:
> On Monday 19 November 2001 09:19 am, Aaron Bannert wrote:
> > What is the right way to handle this? I don't think we should we be
> > conditionally compiling declarations, only implementations. We can
> > either go for runtime errors (APR_ENOTIMPL) when functionality is
> > non-existant (--disable-threads), or we'll have to go around putting #if
> > blocks around all the code references.
> 
> We should always opt for compile time errors over run-time errors, because
> it makes the error easier to see and fix.  I would say, fix mod_ssl by #if'ing
> the code.

There are many other places where we make calls to the lock API without
checking APR_HAS_THREADS. I'm not so sure anymore that APR_HAS_THREADS
is even appropriate for the entire lock API (eg. crossprocess locks).

For the locks that do depend on a threading library (apr_thread_*_t)
how about we #error if the header was included but APR_HAS_THREADS
is not defined?

Something like this?

Index: apr_thread_mutex.h
===================================================================
RCS file: /home/cvs/apr/include/apr_thread_mutex.h,v
retrieving revision 1.4
diff -u -u -r1.4 apr_thread_mutex.h
--- apr_thread_mutex.h	2001/10/17 00:33:00	1.4
+++ apr_thread_mutex.h	2001/11/19 20:30:25
@@ -59,12 +59,14 @@
 #include "apr_pools.h"
 #include "apr_errno.h"
 
+#ifndef APR_HAS_THREADS
+#error Threads must be enabled to use the apr_thread_mutex.h interface
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif /* __cplusplus */
 
-#if APR_HAS_THREADS
-
 /**
  * @file apr_thread_mutex.h
  * @brief APR Thread Mutex Routines
@@ -127,8 +129,6 @@
  * @return apr_pool_t the pool
  */
 APR_POOL_DECLARE_ACCESSOR(thread_mutex);
-
-#endif
 
 #ifdef __cplusplus
 }