aio: Add liburing dependency

Will be used in a subsequent commit, to implement io_method=io_uring. Kept
separate for easier review.

Reviewed-by: Noah Misch <noah@leadboat.com>
Discussion: https://postgr.es/m/uvrtrknj4kdytuboidbhwclo4gxhswwcpgadptsjvjqcluzmah%40brqs62irg4dt

.cirrus.tasks.yml

@@ -471,6 +471,7 @@ task:
             --enable-cassert --enable-injection-points --enable-debug \
             --enable-tap-tests --enable-nls \
             --with-segsize-blocks=6 \
+            --with-liburing \
             \
             ${LINUX_CONFIGURE_FEATURES} \
             \

configure

@@ -712,6 +712,9 @@ LIBCURL_LIBS
 LIBCURL_CFLAGS
 with_libcurl
 with_uuid
+LIBURING_LIBS
+LIBURING_CFLAGS
+with_liburing
 with_readline
 with_systemd
 with_selinux
@@ -865,6 +868,7 @@ with_selinux
 with_systemd
 with_readline
 with_libedit_preferred
+with_liburing
 with_uuid
 with_ossp_uuid
 with_libcurl
@@ -898,6 +902,8 @@ PKG_CONFIG_PATH
 PKG_CONFIG_LIBDIR
 ICU_CFLAGS
 ICU_LIBS
+LIBURING_CFLAGS
+LIBURING_LIBS
 LIBCURL_CFLAGS
 LIBCURL_LIBS
 XML2_CONFIG
@@ -1578,6 +1584,7 @@ Optional Packages:
   --without-readline      do not use GNU Readline nor BSD Libedit for editing
   --with-libedit-preferred
                           prefer BSD Libedit over GNU Readline
+  --with-liburing         build with io_uring support, for asynchronous I/O
   --with-uuid=LIB         build contrib/uuid-ossp using LIB (bsd,e2fs,ossp)
   --with-ossp-uuid        obsolete spelling of --with-uuid=ossp
   --with-libcurl          build with libcurl support
@@ -1614,6 +1621,10 @@ Some influential environment variables:
               path overriding pkg-config's built-in search path
   ICU_CFLAGS  C compiler flags for ICU, overriding pkg-config
   ICU_LIBS    linker flags for ICU, overriding pkg-config
+  LIBURING_CFLAGS
+              C compiler flags for LIBURING, overriding pkg-config
+  LIBURING_LIBS
+              linker flags for LIBURING, overriding pkg-config
   LIBCURL_CFLAGS
               C compiler flags for LIBCURL, overriding pkg-config
   LIBCURL_LIBS
@@ -8692,6 +8703,134 @@ fi
 
 
 
+#
+# liburing
+#
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether to build with liburing support" >&5
+$as_echo_n "checking whether to build with liburing support... " >&6; }
+
+
+
+# Check whether --with-liburing was given.
+if test "${with_liburing+set}" = set; then :
+  withval=$with_liburing;
+  case $withval in
+    yes)
+
+$as_echo "#define USE_LIBURING 1" >>confdefs.h
+
+      ;;
+    no)
+      :
+      ;;
+    *)
+      as_fn_error $? "no argument expected for --with-liburing option" "$LINENO" 5
+      ;;
+  esac
+
+else
+  with_liburing=no
+
+fi
+
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $with_liburing" >&5
+$as_echo "$with_liburing" >&6; }
+
+
+if test "$with_liburing" = yes; then
+
+pkg_failed=no
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for liburing" >&5
+$as_echo_n "checking for liburing... " >&6; }
+
+if test -n "$LIBURING_CFLAGS"; then
+    pkg_cv_LIBURING_CFLAGS="$LIBURING_CFLAGS"
+ elif test -n "$PKG_CONFIG"; then
+    if test -n "$PKG_CONFIG" && \
+    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"liburing\""; } >&5
+  ($PKG_CONFIG --exists --print-errors "liburing") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; then
+  pkg_cv_LIBURING_CFLAGS=`$PKG_CONFIG --cflags "liburing" 2>/dev/null`
+		      test "x$?" != "x0" && pkg_failed=yes
+else
+  pkg_failed=yes
+fi
+ else
+    pkg_failed=untried
+fi
+if test -n "$LIBURING_LIBS"; then
+    pkg_cv_LIBURING_LIBS="$LIBURING_LIBS"
+ elif test -n "$PKG_CONFIG"; then
+    if test -n "$PKG_CONFIG" && \
+    { { $as_echo "$as_me:${as_lineno-$LINENO}: \$PKG_CONFIG --exists --print-errors \"liburing\""; } >&5
+  ($PKG_CONFIG --exists --print-errors "liburing") 2>&5
+  ac_status=$?
+  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; then
+  pkg_cv_LIBURING_LIBS=`$PKG_CONFIG --libs "liburing" 2>/dev/null`
+		      test "x$?" != "x0" && pkg_failed=yes
+else
+  pkg_failed=yes
+fi
+ else
+    pkg_failed=untried
+fi
+
+
+
+if test $pkg_failed = yes; then
+        { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+
+if $PKG_CONFIG --atleast-pkgconfig-version 0.20; then
+        _pkg_short_errors_supported=yes
+else
+        _pkg_short_errors_supported=no
+fi
+        if test $_pkg_short_errors_supported = yes; then
+	        LIBURING_PKG_ERRORS=`$PKG_CONFIG --short-errors --print-errors --cflags --libs "liburing" 2>&1`
+        else
+	        LIBURING_PKG_ERRORS=`$PKG_CONFIG --print-errors --cflags --libs "liburing" 2>&1`
+        fi
+	# Put the nasty error message in config.log where it belongs
+	echo "$LIBURING_PKG_ERRORS" >&5
+
+	as_fn_error $? "Package requirements (liburing) were not met:
+
+$LIBURING_PKG_ERRORS
+
+Consider adjusting the PKG_CONFIG_PATH environment variable if you
+installed software in a non-standard prefix.
+
+Alternatively, you may set the environment variables LIBURING_CFLAGS
+and LIBURING_LIBS to avoid the need to call pkg-config.
+See the pkg-config man page for more details." "$LINENO" 5
+elif test $pkg_failed = untried; then
+        { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+	{ { $as_echo "$as_me:${as_lineno-$LINENO}: error: in \`$ac_pwd':" >&5
+$as_echo "$as_me: error: in \`$ac_pwd':" >&2;}
+as_fn_error $? "The pkg-config script could not be found or is too old.  Make sure it
+is in your PATH or set the PKG_CONFIG environment variable to the full
+path to pkg-config.
+
+Alternatively, you may set the environment variables LIBURING_CFLAGS
+and LIBURING_LIBS to avoid the need to call pkg-config.
+See the pkg-config man page for more details.
+
+To get pkg-config, see <http://pkg-config.freedesktop.org/>.
+See \`config.log' for more details" "$LINENO" 5; }
+else
+	LIBURING_CFLAGS=$pkg_cv_LIBURING_CFLAGS
+	LIBURING_LIBS=$pkg_cv_LIBURING_LIBS
+        { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+
+fi
+fi
 
 #
 # UUID library

configure.ac

@@ -975,6 +975,18 @@ AC_SUBST(with_readline)
 PGAC_ARG_BOOL(with, libedit-preferred, no,
               [prefer BSD Libedit over GNU Readline])
 
+#
+# liburing
+#
+AC_MSG_CHECKING([whether to build with liburing support])
+PGAC_ARG_BOOL(with, liburing, no, [build with io_uring support, for asynchronous I/O],
+              [AC_DEFINE([USE_LIBURING], 1, [Define to build with io_uring support. (--with-liburing)])])
+AC_MSG_RESULT([$with_liburing])
+AC_SUBST(with_liburing)
+
+if test "$with_liburing" = yes; then
+  PKG_CHECK_MODULES(LIBURING, liburing)
+fi
 
 #
 # UUID library

doc/src/sgml/installation.sgml

@@ -1156,6 +1156,24 @@ build-postgresql:
        </listitem>
       </varlistentry>
 
+      <varlistentry id="configure-option-with-liburing">
+       <term><option>--with-liburing</option></term>
+       <listitem>
+        <para>
+        Build with liburing, enabling io_uring support for asynchronous I/O.
+        </para>
+        <para>
+         To detect the required compiler and linker options, PostgreSQL will
+         query <command>pkg-config</command>.
+        </para>
+        <para>
+         To use a liburing installation that is in an unusual location, you
+         can set <command>pkg-config</command>-related environment
+         variables (see its documentation).
+        </para>
+       </listitem>
+      </varlistentry>
+
       <varlistentry id="configure-option-with-libxml">
        <term><option>--with-libxml</option></term>
        <listitem>
@@ -2611,6 +2629,22 @@ ninja install
       </listitem>
      </varlistentry>
 
+     <varlistentry id="configure-with-liburing-meson">
+      <term><option>-Dliburing={ auto | enabled | disabled }</option></term>
+      <listitem>
+       <para>
+        Build with liburing, enabling io_uring support for asynchronous I/O.
+        Defaults to auto.
+       </para>
+
+       <para>
+        To use a liburing installation that is in an unusual location, you
+        can set <command>pkg-config</command>-related environment
+        variables (see its documentation).
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry id="configure-with-libxml-meson">
       <term><option>-Dlibxml={ auto | enabled | disabled }</option></term>
       <listitem>

meson.build

@@ -944,6 +944,18 @@ endif
 
 
 
+###############################################################
+# Library: liburing
+###############################################################
+
+liburingopt = get_option('liburing')
+liburing = dependency('liburing', required: liburingopt)
+if liburing.found()
+  cdata.set('USE_LIBURING', 1)
+endif
+
+
+
 ###############################################################
 # Library: libxml
 ###############################################################
@@ -3164,6 +3176,7 @@ backend_both_deps += [
   icu_i18n,
   ldap,
   libintl,
+  liburing,
   libxml,
   lz4,
   pam,
@@ -3819,6 +3832,7 @@ if meson.version().version_compare('>=0.57')
       'icu': icu,
       'ldap': ldap,
       'libcurl': libcurl,
+      'liburing': liburing,
       'libxml': libxml,
       'libxslt': libxslt,
       'llvm': llvm,

meson_options.txt

@@ -106,6 +106,9 @@ option('libcurl', type : 'feature', value: 'auto',
 option('libedit_preferred', type: 'boolean', value: false,
   description: 'Prefer BSD Libedit over GNU Readline')
 
+option('liburing', type : 'feature', value: 'auto',
+  description: 'io_uring support, for asynchronous I/O')
+
 option('libxml', type: 'feature', value: 'auto',
   description: 'XML support')
 

src/Makefile.global.in

@@ -196,6 +196,7 @@ with_gssapi	= @with_gssapi@
 with_krb_srvnam	= @with_krb_srvnam@
 with_ldap	= @with_ldap@
 with_libcurl	= @with_libcurl@
+with_liburing	= @with_liburing@
 with_libxml	= @with_libxml@
 with_libxslt	= @with_libxslt@
 with_llvm	= @with_llvm@
@@ -222,6 +223,9 @@ krb_srvtab = @krb_srvtab@
 ICU_CFLAGS		= @ICU_CFLAGS@
 ICU_LIBS		= @ICU_LIBS@
 
+LIBURING_CFLAGS		= @LIBURING_CFLAGS@
+LIBURING_LIBS		= @LIBURING_LIBS@
+
 TCLSH			= @TCLSH@
 TCL_LIBS		= @TCL_LIBS@
 TCL_LIB_SPEC		= @TCL_LIB_SPEC@
@@ -246,7 +250,7 @@ CPP = @CPP@
 CPPFLAGS = @CPPFLAGS@
 PG_SYSROOT = @PG_SYSROOT@
 
-override CPPFLAGS := $(ICU_CFLAGS) $(CPPFLAGS)
+override CPPFLAGS := $(ICU_CFLAGS) $(LIBURING_CFLAGS) $(CPPFLAGS)
 
 ifdef PGXS
 override CPPFLAGS := -I$(includedir_server) -I$(includedir_internal) $(CPPFLAGS)

src/backend/Makefile

@@ -43,9 +43,10 @@ OBJS = \
 	$(top_builddir)/src/common/libpgcommon_srv.a \
 	$(top_builddir)/src/port/libpgport_srv.a
 
-# We put libpgport and libpgcommon into OBJS, so remove it from LIBS; also add
-# libldap and ICU
-LIBS := $(filter-out -lpgport -lpgcommon, $(LIBS)) $(LDAP_LIBS_BE) $(ICU_LIBS)
+# We put libpgport and libpgcommon into OBJS, so remove it from LIBS.
+LIBS := $(filter-out -lpgport -lpgcommon, $(LIBS))
+# The backend conditionally needs libraries that most executables don't need.
+LIBS += $(LDAP_LIBS_BE) $(ICU_LIBS) $(LIBURING_LIBS)
 
 # The backend doesn't need everything that's in LIBS, however
 LIBS := $(filter-out -lreadline -ledit -ltermcap -lncurses -lcurses, $(LIBS))

src/include/pg_config.h.in

@@ -672,6 +672,9 @@
 /* Define to 1 to build with libcurl support. (--with-libcurl) */
 #undef USE_LIBCURL
 
+/* Define to build with io_uring support. (--with-liburing) */
+#undef USE_LIBURING
+
 /* Define to 1 to build with XML support. (--with-libxml) */
 #undef USE_LIBXML
 

src/makefiles/meson.build

@@ -199,6 +199,8 @@ pgxs_empty = [
   'PTHREAD_CFLAGS', 'PTHREAD_LIBS',
 
   'ICU_LIBS',
+
+  'LIBURING_CFLAGS', 'LIBURING_LIBS',
 ]
 
 if host_system == 'windows' and cc.get_argument_syntax() != 'msvc'
@@ -230,6 +232,7 @@ pgxs_deps = {
   'icu': icu,
   'ldap': ldap,
   'libcurl': libcurl,
+  'liburing': liburing,
   'libxml': libxml,
   'libxslt': libxslt,
   'llvm': llvm,