From: Jarkko Hietaniemi <jhi@iki.fi>
Date: Thu, 28 Sep 2006 12:40:04 +0000 (+0300)
Subject: reentr reshuffle
X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=commitdiff_plain;h=832a833bda7470a7163fbdbf0c6029513869c248;p=p5sagit%2Fp5-mst-13.2.git

reentr reshuffle
Message-ID: <451B9874.7060000@iki.fi>

p4raw-id: //depot/perl@28896
---

diff --git a/pod/perlembed.pod b/pod/perlembed.pod
index 9523e1f..41028f8 100644
--- a/pod/perlembed.pod
+++ b/pod/perlembed.pod
@@ -915,6 +915,8 @@ C<-Dusemultiplicity> option otherwise some interpreter variables may
 not be initialized correctly between consecutive runs and your
 application may crash.
 
+See also L<perlxs/Thread-aware system interfaces>.
+
 Using C<-Dusethreads -Duseithreads> rather than C<-Dusemultiplicity>
 is more appropriate if you intend to run multiple interpreters
 concurrently in different threads, because it enables support for
diff --git a/pod/perlxs.pod b/pod/perlxs.pod
index e6f1862..6d14bae 100644
--- a/pod/perlxs.pod
+++ b/pod/perlxs.pod
@@ -2025,6 +2025,23 @@ Note that these macros will only work together within the I<same> source
 file; that is, a dMY_CTX in one source file will access a different structure
 than a dMY_CTX in another source file.
 
+=head2 Thread-aware system interfaces
+
+Starting from Perl 5.8, in C/C++ level Perl knows how to wrap
+system/library interfaces that have thread-aware versions
+(e.g. getpwent_r()) into frontend macros (e.g. getpwent()) that
+correctly handle the multithreaded interaction with the Perl
+interpreter.  This will happen transparently, the only thing
+you need to do is to instantiate a Perl interpreter.
+
+This wrapping happens always when compiling Perl core source
+(PERL_CORE is defined) or the Perl core extensions (PERL_EXT is
+defined).  When compiling XS code outside of Perl core the wrapping
+does not take place.  Note, however, that intermixing the _r-forms
+(as Perl compiled for multithreaded operation will do) and the _r-less
+forms is neither well-defined (inconsistent results, data corruption,
+or even crashes become more likely), nor is it very portable.
+
 =head1 EXAMPLES
 
 File C<RPC.xs>: Interface to some ONC+ RPC bind library functions.
diff --git a/reentr.pl b/reentr.pl
index 13cf4d1..9edc7ad 100644
--- a/reentr.pl
+++ b/reentr.pl
@@ -61,13 +61,29 @@ print <<EOF;
 #ifndef REENTR_H
 #define REENTR_H
 
+/* If compiling for a threaded perl, we will macro-wrap the system/library
+ * interfaces (e.g. getpwent()) which have threaded versions
+ * (e.g. getpwent_r()), which will handle things correctly for
+ * the Perl interpreter, but otherwise (for XS) the wrapping does
+ * not take place.  See L<perlxs/Thread-aware system interfaces>.
+ */
+
+#ifndef PERL_REENTR_API
+# if defined(PERL_CORE) || defined(PERL_EXT)
+#  define PERL_REENTR_API 1
+# else
+#  define PERL_REENTR_API 0
+# endif
+#endif
+
 #ifdef USE_REENTRANT_API
  
 /* Deprecations: some platforms have the said reentrant interfaces
  * but they are declared obsolete and are not to be used.  Often this
  * means that the platform has threadsafed the interfaces (hopefully).
  * All this is OS version dependent, so we are of course fooling ourselves.
- * If you know of more deprecations on some platforms, please add your own. */
+ * If you know of more deprecations on some platforms, please add your own
+ * (by editing reentr.pl, mind!) */
 
 #ifdef __hpux
 #   undef HAS_CRYPT_R
@@ -547,7 +563,7 @@ EOF
 	    push @size, <<EOF;
 #   if defined(HAS_SYSCONF) && defined($sc) && !defined(__GLIBC__)
 	PL_reentrant_buffer->$sz = sysconf($sc);
-	if (PL_reentrant_buffer->$sz == -1)
+	if (PL_reentrant_buffer->$sz == (size_t) -1)
 		PL_reentrant_buffer->$sz = REENTRANTUSUALSIZE;
 #   else
 #       if defined(__osf__) && defined(__alpha) && defined(SIABUFSIZ)
@@ -634,6 +650,7 @@ EOF
 	push @wrap, $ifdef;
 
 	push @wrap, <<EOF;
+#  if defined(PERL_REENTR_API) && (PERL_REENTR_API == 1)
 #   undef $func
 EOF
 
@@ -698,6 +715,7 @@ EOF
 			 } split '', $b;
 		$w = ", $w" if length $v;
 	    }
+
 	    my $call = "${func}_r($v$w)";
 
             # Must make OpenBSD happy
@@ -732,10 +750,14 @@ EOF
 		}
 	    }
 	    push @wrap, <<EOF;
-#   endif
+#  endif /* if defined(PERL_REENTR_API) && (PERL_REENTR_API == 1) */
 EOF
 	}
 
+	    push @wrap, <<EOF;
+#   endif /* HAS_\U$func */
+EOF
+
 	push @wrap, $endif, "\n";
     }
 }