Add --with-threads configure option to control threaded libpq.

Author: bmomjian

configure

@@ -855,6 +855,7 @@ Optional Packages:
   --with-libraries=DIRS   look for additional libraries in DIRS
   --with-libs=DIRS        alternative spelling of --with-libraries
   --with-pgport=PORTNUM   change default port number 5432
+  --with-threads          allow libpq to be thread-safe
   --with-tcl              build Tcl and Tk interfaces
   --without-tk            do not build Tk interfaces if Tcl is enabled
   --with-tclconfig=DIR    tclConfig.sh and tkConfig.sh are in DIR
@@ -2809,6 +2810,41 @@ echo "$as_me: WARNING: *** Library directory $dir does not exist." >&2;}
 done
 IFS=$ac_save_IFS
 
+#
+# Enable libpq to be thread-safe
+#
+echo "$as_me:$LINENO: checking allow threaded libpq" >&5
+echo $ECHO_N "checking allow threaded libpq... $ECHO_C" >&6
+
+
+
+# Check whether --with-threads or --without-threads was given.
+if test "${with_threads+set}" = set; then
+  withval="$with_threads"
+
+  case $withval in
+    yes)
+      :
+      ;;
+    no)
+      :
+      ;;
+    *)
+      { { echo "$as_me:$LINENO: error: no argument expected for --with-threads option" >&5
+echo "$as_me: error: no argument expected for --with-threads option" >&2;}
+   { (exit 1); exit 1; }; }
+      ;;
+  esac
+
+else
+  with_threads=no
+
+fi;
+
+echo "$as_me:$LINENO: result: $with_threads" >&5
+echo "${ECHO_T}$with_threads" >&6
+
+
 #
 # Tcl/Tk
 #
@@ -3550,7 +3586,7 @@ rm -f conftest*
 #
 # Pthreads
 #
-
+if test "$with_threads" = yes; then
 echo "$as_me:$LINENO: checking for ANSI C header files" >&5
 echo $ECHO_N "checking for ANSI C header files... $ECHO_C" >&6
 if test "${ac_cv_header_stdc+set}" = set; then
@@ -3850,25 +3886,38 @@ echo "${ECHO_T}$ac_cv_header_pthread_h" >&6
 
 fi
 if test $ac_cv_header_pthread_h = yes; then
-
-cat >>confdefs.h <<\_ACEOF
-#define HAVE_THREADS 1
-_ACEOF
-
+  :
+else
+  { { echo "$as_me:$LINENO: error: pthread.h not found, required for --with-threads" >&5
+echo "$as_me: error: pthread.h not found, required for --with-threads" >&2;}
+   { (exit 1); exit 1; }; }
 fi
 
 
-if test ! -z "$HAVE_THREADS"
-then
-	case $host_os in
-		# BSD/OS and NetBSD require no special libraries or flags
-		netbsd*|bsdi*) ;;
+case $host_os in
+		netbsd*|bsdi*)
+			# these require no special flags or libraries
+			;;
 		freebsd2*|freebsd3*|freebsd4*) THREAD_CFLAGS="-pthread" ;;
 		freebsd*) THREAD_LIBS="-lc_r" ;;
 		linux*) THREAD_LIBS="-lpthread"
 			THREAD_CFLAGS="-D_REENTRANT" ;;
-	# other operating systems might fail because they have pthread.h but need
-	# special libs we don't know about yet.
+		*)
+			# other operating systems might fail because they have pthread.h but need
+			# special libs we don't know about yet.
+			{ { echo "$as_me:$LINENO: error:
+Cannot enable threads on your platform.
+Please report your platform threading info to the PostgreSQL mailing lists
+so it can be added to the next release.  Report any compile or link flags,
+or libraries required for threading support.
+" >&5
+echo "$as_me: error:
+Cannot enable threads on your platform.
+Please report your platform threading info to the PostgreSQL mailing lists
+so it can be added to the next release.  Report any compile or link flags,
+or libraries required for threading support.
+" >&2;}
+   { (exit 1); exit 1; }; }
 	esac
 fi
 
@@ -17540,6 +17589,7 @@ s,@CPP@,$CPP,;t t
 s,@GCC@,$GCC,;t t
 s,@autodepend@,$autodepend,;t t
 s,@INCLUDES@,$INCLUDES,;t t
+s,@with_threads@,$with_threads,;t t
 s,@with_tcl@,$with_tcl,;t t
 s,@with_tk@,$with_tk,;t t
 s,@with_perl@,$with_perl,;t t

configure.in

@@ -1,5 +1,5 @@
 dnl Process this file with autoconf to produce a configure script.
-dnl $Header: /cvsroot/pgsql/configure.in,v 1.260 2003/06/12 16:05:09 tgl Exp $
+dnl $Header: /cvsroot/pgsql/configure.in,v 1.261 2003/06/13 23:10:07 momjian Exp $
 dnl
 dnl Developers, please strive to achieve this order:
 dnl
@@ -319,6 +319,14 @@ for dir in $LIBRARY_DIRS $SRCH_LIB; do
 done
 IFS=$ac_save_IFS
 
+#
+# Enable libpq to be thread-safe
+#
+AC_MSG_CHECKING([allow threaded libpq])
+PGAC_ARG_BOOL(with, threads, no, [  --with-threads          allow libpq to be thread-safe])
+AC_MSG_RESULT([$with_threads])
+AC_SUBST(with_threads)
+
 #
 # Tcl/Tk
 #
@@ -544,20 +552,25 @@ AC_SUBST(ELF_SYS)
 #
 # Pthreads
 #
-
-AC_CHECK_HEADER(pthread.h,
-	[AC_DEFINE(HAVE_THREADS, 1, [Define to 1 if you have the threads interface.])])
-if test ! -z "$HAVE_THREADS"
-then	
-	case $host_os in
-		# BSD/OS and NetBSD require no special libraries or flags
-		netbsd*|bsdi*) ;;
+if test "$with_threads" = yes; then
+AC_CHECK_HEADER(pthread.h, [], [AC_MSG_ERROR([pthread.h not found, required for --with-threads])])
+case $host_os in
+		netbsd*|bsdi*) 
+			# these require no special flags or libraries
+			;;
 		freebsd2*|freebsd3*|freebsd4*) THREAD_CFLAGS="-pthread" ;;
 		freebsd*) THREAD_LIBS="-lc_r" ;;
 		linux*) THREAD_LIBS="-lpthread"
 			THREAD_CFLAGS="-D_REENTRANT" ;;
-	# other operating systems might fail because they have pthread.h but need
-	# special libs we don't know about yet.
+		*)
+			# other operating systems might fail because they have pthread.h but need
+			# special libs we don't know about yet.
+			AC_MSG_ERROR([
+Cannot enable threads on your platform.
+Please report your platform threading info to the PostgreSQL mailing lists
+so it can be added to the next release.  Report any compile or link flags,
+or libraries required for threading support.
+])
 	esac
 fi
 AC_SUBST(THREAD_LIBS)

doc/src/sgml/installation.sgml

@@ -1,4 +1,4 @@
-<!-- $Header: /cvsroot/pgsql/doc/src/sgml/installation.sgml,v 1.133 2003/06/11 06:56:06 momjian Exp $ -->
+<!-- $Header: /cvsroot/pgsql/doc/src/sgml/installation.sgml,v 1.134 2003/06/13 23:10:07 momjian Exp $ -->
 
 <chapter id="installation">
  <title><![%standalone-include[<productname>PostgreSQL</>]]>
@@ -914,6 +914,15 @@ JAVACMD=$JAVA_HOME/bin/java
        </listitem>
       </varlistentry>
 
+      <varlistentry>
+       <term><option>--with-threads</option></term>
+       <listitem>
+        <para>
+	 Allow separate libpq threads to safely control their private connection handles.
+        </para>
+       </listitem>
+      </varlistentry>
+
       <varlistentry>
        <term><option>--without-zlib</option></term>
        <listitem>

doc/src/sgml/libpq.sgml

@@ -1,5 +1,5 @@
 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/libpq.sgml,v 1.123 2003/05/14 03:25:58 tgl Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/libpq.sgml,v 1.124 2003/06/13 23:10:07 momjian Exp $
 -->
 
  <chapter id="libpq">
@@ -509,11 +509,6 @@ typedef struct
     is leaked for each call to <function>PQconndefaults</function>.
    </para>
 
-   <para>
-    In <productname>PostgreSQL</productname> versions before 7.0, <function>PQconndefaults</function> returned a pointer
-    to a static array, rather than a dynamically allocated array.  That
-    was not thread-safe, so the behavior has been changed.
-   </para>
   </listitem>
  </varlistentry>
 
@@ -2549,17 +2544,23 @@ If the permissions are less strict than this, the file will be ignored.
 </indexterm>
 
 <para>
-<application>libpq</application> is thread-safe as of
-<productname>PostgreSQL</productname> 7.0, so long as no two threads
-attempt to manipulate the same <structname>PGconn</> object at the same
-time. In particular, you cannot issue concurrent commands from different
-threads through the same connection object. (If you need to run
-concurrent commands, start up multiple connections.)
+<application>libpq</application> is thread-safe if the library is
+compiled using the <literal>--with-threads</>
+<filename>configure</filename> command-line option.  (You might need to
+use other threading command-line options to compile your client code.)
+</para>
+
+<para>
+One restriction is that no two threads attempt to manipulate the same
+<structname>PGconn</> object at the same time. In particular, you cannot
+issue concurrent commands from different threads through the same
+connection object. (If you need to run concurrent commands, start up
+multiple connections.)
 </para>
 
 <para>
-<structname>PGresult</> objects are read-only after creation, and so can be passed around
-freely between threads.
+<structname>PGresult</> objects are read-only after creation, and so can be 
+passed around freely between threads.
 </para>
 
 <para>

src/include/pg_config.h.in

@@ -468,9 +468,6 @@
 /* Define to 1 if you have the <termios.h> header file. */
 #undef HAVE_TERMIOS_H
 
-/* Define to 1 if you have the threads interface. */
-#undef HAVE_THREADS
-
 /* Define to 1 if your `struct tm' has `tm_zone'. Deprecated, use
    `HAVE_STRUCT_TM_TM_ZONE' instead. */
 #undef HAVE_TM_ZONE