windows: Adjust FD_SETSIZE via commandline define

When using precompiled headers, we cannot pre-define macros for the system
headers from within .c files, as headers are already processed before
the #define in the C file is reached. But we can pre-define using
-DFD_SETSIZE, as long as that's also used when building the precompiled header.

A few files #define FD_SETSIZE 1024 on windows, as the default is only 64. I
am hesitant to change FD_SETSIZE globally on windows, due to
src/backend/port/win32/socket.c using it to size on-stack arrays. Instead add
-DFD_SETSIZE=1024 when building the specific targets needing it.

We likely should move away from using select() in those places, but that's a
larger change.

Reviewed-by: Thomas Munro <thomas.munro@gmail.com>
Reviewed-by: Peter Eisentraut <peter.eisentraut@enterprisedb.com>
Reviewed-by: Justin Pryzby <pryzby@telsasoft.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/20221005190829.lda7ttalh4mzrvf4@awork3.anarazel.de
Discussion: https://postgr.es/m/CA+hUKG+50eOUbN++ocDc0Qnp9Pvmou23DSXu=ZA6fepOcftKqA@mail.gmail.com
Discussion: https://postgr.es/m/20190826054000.GE7005%40paquier.xyz

src/bin/pgbench/Makefile

@@ -18,6 +18,8 @@ LDFLAGS_INTERNAL += -L$(top_builddir)/src/fe_utils -lpgfeutils $(libpq_pgport)
 
 ifneq ($(PORTNAME), win32)
 override CFLAGS += $(PTHREAD_CFLAGS)
+else
+override CPPFLAGS += -DFD_SETSIZE=1024
 endif
 LIBS += $(PTHREAD_LIBS)
 

src/bin/pgbench/meson.build

@@ -27,6 +27,7 @@ pgbench = executable('pgbench',
   pgbench_sources,
   dependencies: [frontend_code, libpq, thread_dep],
   include_directories: include_directories('.'),
+  c_args: host_system == 'windows' ? ['-DFD_SETSIZE=1024'] : [],
   kwargs: default_bin_args,
 )
 bin_targets += pgbench

src/bin/pgbench/pgbench.c

@@ -27,8 +27,8 @@
  *
  */
 
-#ifdef WIN32
-#define FD_SETSIZE 1024			/* must set before winsock2.h is included */
+#if defined(WIN32) && FD_SETSIZE < 1024
+#error FD_SETSIZE needs to have been increased
 #endif
 
 #include "postgres_fe.h"

src/fe_utils/Makefile

@@ -34,6 +34,10 @@ OBJS = \
 	simple_list.o \
 	string_utils.o
 
+ifeq ($(PORTNAME), win32)
+override CPPFLAGS += -DFD_SETSIZE=1024
+endif
+
 all: libpgfeutils.a
 
 libpgfeutils.a: $(OBJS)

src/fe_utils/meson.build

@@ -24,6 +24,7 @@ fe_utils_sources += psqlscan
 fe_utils = static_library('libpgfeutils',
   fe_utils_sources + generated_headers,
   include_directories: [postgres_inc, libpq_inc],
+  c_args: host_system == 'windows' ? ['-DFD_SETSIZE=1024'] : [],
   dependencies: frontend_common_code,
   kwargs: default_lib_args,
 )

src/fe_utils/parallel_slot.c

@@ -12,8 +12,8 @@
  *-------------------------------------------------------------------------
  */
 
-#ifdef WIN32
-#define FD_SETSIZE 1024			/* must set before winsock2.h is included */
+#if defined(WIN32) && FD_SETSIZE < 1024
+#error FD_SETSIZE needs to have been increased
 #endif
 
 #include "postgres_fe.h"

src/tools/msvc/Mkvcbuild.pm

@@ -35,6 +35,7 @@ my $libpq;
 my @unlink_on_exit;
 
 # Set of variables for modules in contrib/ and src/test/modules/
+my $contrib_defines        = {};
 my @contrib_uselibpq       = ();
 my @contrib_uselibpgport   = ();
 my @contrib_uselibpgcommon = ();
@@ -52,6 +53,7 @@ my @contrib_excludes       = (
 	'unsafe_tests');
 
 # Set of variables for frontend modules
+my $frontend_defines = { 'pgbench' => 'FD_SETSIZE=1024' };
 my @frontend_uselibpq =
   ('pg_amcheck', 'pg_ctl', 'pg_upgrade', 'pgbench', 'psql', 'initdb');
 my @frontend_uselibpgport = (
@@ -175,6 +177,7 @@ sub mkvcbuild
 
 	$libpgfeutils = $solution->AddProject('libpgfeutils', 'lib', 'misc');
 	$libpgfeutils->AddDefine('FRONTEND');
+	$libpgfeutils->AddDefine('FD_SETSIZE=1024');
 	$libpgfeutils->AddIncludeDir('src/interfaces/libpq');
 	$libpgfeutils->AddFiles('src/fe_utils', @pgfeutilsfiles);
 
@@ -1120,10 +1123,10 @@ sub AdjustContribProj
 {
 	my $proj = shift;
 	AdjustModule(
-		$proj,                  \@contrib_uselibpq,
-		\@contrib_uselibpgport, \@contrib_uselibpgcommon,
-		$contrib_extralibs,     $contrib_extrasource,
-		$contrib_extraincludes);
+		$proj,                    $contrib_defines,
+		\@contrib_uselibpq,       \@contrib_uselibpgport,
+		\@contrib_uselibpgcommon, $contrib_extralibs,
+		$contrib_extrasource,     $contrib_extraincludes);
 	return;
 }
 
@@ -1131,16 +1134,17 @@ sub AdjustFrontendProj
 {
 	my $proj = shift;
 	AdjustModule(
-		$proj,                   \@frontend_uselibpq,
-		\@frontend_uselibpgport, \@frontend_uselibpgcommon,
-		$frontend_extralibs,     $frontend_extrasource,
-		$frontend_extraincludes);
+		$proj,                     $frontend_defines,
+		\@frontend_uselibpq,       \@frontend_uselibpgport,
+		\@frontend_uselibpgcommon, $frontend_extralibs,
+		$frontend_extrasource,     $frontend_extraincludes);
 	return;
 }
 
 sub AdjustModule
 {
 	my $proj                  = shift;
+	my $module_defines        = shift;
 	my $module_uselibpq       = shift;
 	my $module_uselibpgport   = shift;
 	my $module_uselibpgcommon = shift;
@@ -1149,6 +1153,13 @@ sub AdjustModule
 	my $module_extraincludes  = shift;
 	my $n                     = $proj->{name};
 
+	if ($module_defines->{$n})
+	{
+		foreach my $d ($module_defines->{$n})
+		{
+			$proj->AddDefine($d);
+		}
+	}
 	if (grep { /^$n$/ } @{$module_uselibpq})
 	{
 		$proj->AddIncludeDir('src\interfaces\libpq');