Remove --disable-thread-safety and related code.

All supported computers have either POSIX or Windows threads, and we no
longer have any automated testing of --disable-thread-safety.  We define
a vestigial ENABLE_THREAD_SAFETY macro to 1 in ecpg_config.h in case it
is useful, but we no longer test it anywhere in PostgreSQL code, and
associated dead code paths are removed.

The Meson and perl-based Windows build scripts never had an equivalent
build option.

Reviewed-by: Andres Freund <andres@anarazel.de>
Reviewed-by: Peter Eisentraut <peter@eisentraut.org>
Reviewed-by: Heikki Linnakangas <hlinnaka@iki.fi>
Discussion: https://postgr.es/m/CA%2BhUKGLtmexrpMtxBRLCVePqV_dtWG-ZsEbyPrYc%2BNBB2TkNsw%40mail.gmail.com

Author: macdice

configure

@@ -722,7 +722,6 @@ with_tcl
 ICU_LIBS
 ICU_CFLAGS
 with_icu
-enable_thread_safety
 INCLUDES
 autodepend
 PKG_CONFIG_LIBDIR
@@ -848,7 +847,6 @@ with_CC
 with_llvm
 enable_depend
 enable_cassert
-enable_thread_safety
 with_icu
 with_tcl
 with_tclconfig
@@ -1536,7 +1534,6 @@ Optional Features:
   --enable-tap-tests      enable TAP tests (requires Perl and IPC::Run)
   --enable-depend         turn on automatic dependency tracking
   --enable-cassert        enable assertion checks (for debugging)
-  --disable-thread-safety disable thread-safety in client libraries
   --disable-largefile     omit support for large files
 
 Optional Packages:
@@ -8338,43 +8335,6 @@ $as_echo "$as_me: WARNING: *** Library directory $dir does not exist." >&2;}
 done
 IFS=$ac_save_IFS
 
-#
-# Enable thread-safe client libraries
-#
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking allow thread-safe client libraries" >&5
-$as_echo_n "checking allow thread-safe client libraries... " >&6; }
-
-
-# Check whether --enable-thread-safety was given.
-if test "${enable_thread_safety+set}" = set; then :
-  enableval=$enable_thread_safety;
-  case $enableval in
-    yes)
-      :
-      ;;
-    no)
-      :
-      ;;
-    *)
-      as_fn_error $? "no argument expected for --enable-thread-safety option" "$LINENO" 5
-      ;;
-  esac
-
-else
-  enable_thread_safety=yes
-
-fi
-
-
-if test "$enable_thread_safety" = yes; then
-
-$as_echo "#define ENABLE_THREAD_SAFETY 1" >>confdefs.h
-
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $enable_thread_safety" >&5
-$as_echo "$enable_thread_safety" >&6; }
-
-
 #
 # ICU
 #
@@ -11064,7 +11024,7 @@ fi
 done
 
 
-if test "$enable_thread_safety" = yes -a "$PORTNAME" != "win32"; then :
+if test "$PORTNAME" != "win32"; then :
    # then
 
 
@@ -11723,7 +11683,7 @@ if test "x$ac_cv_header_pthread_h" = xyes; then :
 
 else
   as_fn_error $? "
-pthread.h not found;  use --disable-thread-safety to disable thread safety" "$LINENO" 5
+pthread.h not found" "$LINENO" 5
 fi
 
 
@@ -12407,8 +12367,7 @@ if test "$ac_res" != no; then :
 fi
 
 
-if test "$enable_thread_safety" = yes; then
-  { $as_echo "$as_me:${as_lineno-$LINENO}: checking for library containing pthread_barrier_wait" >&5
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for library containing pthread_barrier_wait" >&5
 $as_echo_n "checking for library containing pthread_barrier_wait... " >&6; }
 if ${ac_cv_search_pthread_barrier_wait+:} false; then :
   $as_echo_n "(cached) " >&6
@@ -12464,7 +12423,6 @@ if test "$ac_res" != no; then :
 
 fi
 
-fi
 
 if test "$with_readline" = yes; then
 
@@ -13349,7 +13307,7 @@ else
   thread_safe_libldap=no
 fi
 
-    if test "$enable_thread_safety" = yes -a "$thread_safe_libldap" = no; then
+    if test "$thread_safe_libldap" = no; then
       # Use ldap_r for FE if available, else assume ldap is thread-safe.
       # On some platforms ldap_r fails to link without PTHREAD_LIBS.
       LIBS="$_LIBS"
@@ -16377,8 +16335,7 @@ fi
 
 
 
-if test "$enable_thread_safety" = yes; then
-  ac_fn_c_check_func "$LINENO" "pthread_barrier_wait" "ac_cv_func_pthread_barrier_wait"
+ac_fn_c_check_func "$LINENO" "pthread_barrier_wait" "ac_cv_func_pthread_barrier_wait"
 if test "x$ac_cv_func_pthread_barrier_wait" = xyes; then :
   $as_echo "#define HAVE_PTHREAD_BARRIER_WAIT 1" >>confdefs.h
 
@@ -16392,7 +16349,6 @@ esac
 fi
 
 
-fi
 
 if test "$PORTNAME" = "win32" -o "$PORTNAME" = "cygwin"; then
 	# Cygwin and (apparently, based on test results) Mingw both

configure.ac

@@ -837,18 +837,6 @@ for dir in $LIBRARY_DIRS $SRCH_LIB; do
 done
 IFS=$ac_save_IFS
 
-#
-# Enable thread-safe client libraries
-#
-AC_MSG_CHECKING([allow thread-safe client libraries])
-PGAC_ARG_BOOL(enable, thread-safety, yes, [disable thread-safety in client libraries])
-if test "$enable_thread_safety" = yes; then
-  AC_DEFINE([ENABLE_THREAD_SAFETY], 1,
-          [Define to 1 to build client libraries as thread-safe code. (--enable-thread-safety)])
-fi
-AC_MSG_RESULT([$enable_thread_safety])
-AC_SUBST(enable_thread_safety)
-
 #
 # ICU
 #
@@ -1243,7 +1231,7 @@ dnl note: We have to use AS_IF here rather than plain if. The AC_CHECK_HEADER
 dnl invocation below is the first one in the script, and autoconf generates
 dnl additional code for that, which must not be inside the if-block. AS_IF
 dnl knows how to do that.
-AS_IF([test "$enable_thread_safety" = yes -a "$PORTNAME" != "win32"],
+AS_IF([test "$PORTNAME" != "win32"],
 [ # then
 AX_PTHREAD	# set thread flags
 
@@ -1258,7 +1246,7 @@ CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
 LIBS="$LIBS $PTHREAD_LIBS"
 
 AC_CHECK_HEADER(pthread.h, [], [AC_MSG_ERROR([
-pthread.h not found;  use --disable-thread-safety to disable thread safety])])
+pthread.h not found])])
 
 AC_CHECK_FUNCS([strerror_r])
 
@@ -1305,9 +1293,7 @@ AC_SEARCH_LIBS(shmget, cygipc)
 # *BSD:
 AC_SEARCH_LIBS(backtrace_symbols, execinfo)
 
-if test "$enable_thread_safety" = yes; then
-  AC_SEARCH_LIBS(pthread_barrier_wait, pthread)
-fi
+AC_SEARCH_LIBS(pthread_barrier_wait, pthread)
 
 if test "$with_readline" = yes; then
   PGAC_CHECK_READLINE
@@ -1434,7 +1420,7 @@ if test "$with_ldap" = yes ; then
     AC_CHECK_FUNC([ldap_verify_credentials],
 		  [thread_safe_libldap=yes],
 		  [thread_safe_libldap=no])
-    if test "$enable_thread_safety" = yes -a "$thread_safe_libldap" = no; then
+    if test "$thread_safe_libldap" = no; then
       # Use ldap_r for FE if available, else assume ldap is thread-safe.
       # On some platforms ldap_r fails to link without PTHREAD_LIBS.
       LIBS="$_LIBS"
@@ -1858,9 +1844,7 @@ AC_REPLACE_FUNCS(m4_normalize([
 	strnlen
 ]))
 
-if test "$enable_thread_safety" = yes; then
-  AC_REPLACE_FUNCS(pthread_barrier_wait)
-fi
+AC_REPLACE_FUNCS(pthread_barrier_wait)
 
 if test "$PORTNAME" = "win32" -o "$PORTNAME" = "cygwin"; then
 	# Cygwin and (apparently, based on test results) Mingw both

doc/src/sgml/installation.sgml

@@ -1306,19 +1306,6 @@ build-postgresql:
        </listitem>
       </varlistentry>
 
-      <varlistentry id="configure-option-disable-thread-safety">
-       <term><option>--disable-thread-safety</option></term>
-       <listitem>
-        <para>
-         Disable the thread-safety of client libraries.  This prevents
-         concurrent threads in <application>libpq</application> and
-         <application>ECPG</application> programs from safely controlling
-         their private connection handles.  Use this only on platforms
-         with deficient threading support.
-        </para>
-       </listitem>
-      </varlistentry>
-
      </variablelist>
 
    </sect3>

meson.build

@@ -2508,17 +2508,6 @@ cdata.set_quoted('PG_VERSION_STR',
 )
 
 
-
-###############################################################
-# Threading
-###############################################################
-
-# XXX: About to rely on thread safety in the autoconf build, so not worth
-# implementing a fallback.
-cdata.set('ENABLE_THREAD_SAFETY', 1)
-
-
-
 ###############################################################
 # NLS / Gettext
 ###############################################################

src/Makefile.global.in

@@ -202,7 +202,6 @@ enable_debug	= @enable_debug@
 enable_dtrace	= @enable_dtrace@
 enable_coverage	= @enable_coverage@
 enable_tap_tests	= @enable_tap_tests@
-enable_thread_safety	= @enable_thread_safety@
 
 python_includespec	= @python_includespec@
 python_libdir		= @python_libdir@

src/bin/pgbench/pgbench.c

@@ -137,7 +137,7 @@ typedef struct socket_set
 	EnterSynchronizationBarrier((barrier), \
 								SYNCHRONIZATION_BARRIER_FLAGS_BLOCK_ONLY)
 #define THREAD_BARRIER_DESTROY(barrier)
-#elif defined(ENABLE_THREAD_SAFETY)
+#else
 /* Use POSIX threads */
 #include "port/pg_pthread.h"
 #define THREAD_T pthread_t
@@ -153,16 +153,6 @@ typedef struct socket_set
 	pthread_barrier_init((barrier), NULL, (n))
 #define THREAD_BARRIER_WAIT(barrier) pthread_barrier_wait((barrier))
 #define THREAD_BARRIER_DESTROY(barrier) pthread_barrier_destroy((barrier))
-#else
-/* No threads implementation, use none (-j 1) */
-#define THREAD_T void *
-#define THREAD_FUNC_RETURN_TYPE void *
-#define THREAD_FUNC_RETURN return NULL
-#define THREAD_FUNC_CC
-#define THREAD_BARRIER_T int
-#define THREAD_BARRIER_INIT(barrier, n) (*(barrier) = 0)
-#define THREAD_BARRIER_WAIT(barrier)
-#define THREAD_BARRIER_DESTROY(barrier)
 #endif
 
 
@@ -6749,10 +6739,6 @@ main(int argc, char **argv)
 				{
 					exit(1);
 				}
-#ifndef ENABLE_THREAD_SAFETY
-				if (nthreads != 1)
-					pg_fatal("threads are not supported on this platform; use -j1");
-#endif							/* !ENABLE_THREAD_SAFETY */
 				break;
 			case 'l':
 				benchmarking_option_set = true;
@@ -7236,7 +7222,6 @@ main(int argc, char **argv)
 	if (errno != 0)
 		pg_fatal("could not initialize barrier: %m");
 
-#ifdef ENABLE_THREAD_SAFETY
 	/* start all threads but thread 0 which is executed directly later */
 	for (i = 1; i < nthreads; i++)
 	{
@@ -7248,9 +7233,6 @@ main(int argc, char **argv)
 		if (errno != 0)
 			pg_fatal("could not create thread: %m");
 	}
-#else
-	Assert(nthreads == 1);
-#endif							/* ENABLE_THREAD_SAFETY */
 
 	/* compute when to stop */
 	threads[0].create_time = pg_time_now();
@@ -7268,10 +7250,8 @@ main(int argc, char **argv)
 	{
 		TState	   *thread = &threads[i];
 
-#ifdef ENABLE_THREAD_SAFETY
 		if (i > 0)
 			THREAD_JOIN(thread->thread);
-#endif							/* ENABLE_THREAD_SAFETY */
 
 		for (int j = 0; j < thread->nstate; j++)
 			if (thread->state[j].state != CSTATE_FINISHED)

src/include/pg_config.h.in

@@ -51,10 +51,6 @@
 /* Define to 1 if you want National Language Support. (--enable-nls) */
 #undef ENABLE_NLS
 
-/* Define to 1 to build client libraries as thread-safe code.
-   (--enable-thread-safety) */
-#undef ENABLE_THREAD_SAFETY
-
 /* Define to 1 if you have the `append_history' function. */
 #undef HAVE_APPEND_HISTORY