Add Connection#send_pipeline_sync, async_pipeline_sync and release GV…

…L at PQ(sendP|P)ipelineSync

Also make pipeline_sync an alias for sync_pipeline_sync vs. async_pipeline_sync.

Now send_pipeline_sync and flush is used to notify IO waiting to the scheduler.

ext/gvl_wrappers.c

@@ -11,6 +11,7 @@ PGresult *PQclosePrepared(PGconn *conn, const char *stmtName){return NULL;}
 PGresult *PQclosePortal(PGconn *conn, const char *portalName){return NULL;}
 int PQsendClosePrepared(PGconn *conn, const char *stmtName){return 0;}
 int PQsendClosePortal(PGconn *conn, const char *portalName){return 0;}
+int PQsendPipelineSync(PGconn *conn){return 0;}
 #endif
 
 #ifdef ENABLE_GVL_UNLOCK

ext/gvl_wrappers.h

@@ -208,6 +208,10 @@
 #define FOR_EACH_PARAM_OF_PQsendClosePortal(param) \
 	param(PGconn *, conn)
 
+#define FOR_EACH_PARAM_OF_PQpipelineSync(param)
+
+#define FOR_EACH_PARAM_OF_PQsendPipelineSync(param)
+
 #define FOR_EACH_PARAM_OF_PQsetClientEncoding(param) \
 	param(PGconn *, conn)
 
@@ -252,6 +256,8 @@
 	function(PQsendDescribePortal, GVL_TYPE_NONVOID, int, const char *, portal) \
 	function(PQsendClosePrepared, GVL_TYPE_NONVOID, int, const char *, stmt) \
 	function(PQsendClosePortal, GVL_TYPE_NONVOID, int, const char *, portal) \
+	function(PQpipelineSync, GVL_TYPE_NONVOID, int, PGconn *, conn) \
+	function(PQsendPipelineSync, GVL_TYPE_NONVOID, int, PGconn *, conn) \
 	function(PQsetClientEncoding, GVL_TYPE_NONVOID, int, const char *, encoding) \
 	function(PQisBusy, GVL_TYPE_NONVOID, int, PGconn *, conn) \
 	function(PQencryptPasswordConn, GVL_TYPE_NONVOID, char *, const char *, algorithm) \

ext/pg_connection.c

@@ -3751,6 +3751,8 @@ pgconn_pipeline_status(VALUE self)
  * Raises PG::Error and has no effect if the connection is not currently idle, i.e., it has a result ready, or it is waiting for more input from the server, etc.
  * This function does not actually send anything to the server, it just changes the libpq connection state.
  *
+ * See the {PostgreSQL documentation}[https://www.postgresql.org/docs/17/libpq-pipeline-mode.html#LIBPQ-PIPELINE-MODE].
+ *
  * Available since PostgreSQL-14
  */
 static VALUE
@@ -3789,29 +3791,55 @@ pgconn_exit_pipeline_mode(VALUE self)
 
 /*
  * call-seq:
- *    conn.pipeline_sync -> nil
+ *    conn.sync_pipeline_sync -> nil
  *
- * Marks a synchronization point in a pipeline by sending a sync message and flushing the send buffer.
- * This serves as the delimiter of an implicit transaction and an error recovery point; see Section 34.5.1.3 of the PostgreSQL documentation.
+ * This function has the same behavior as #async_pipeline_sync, but is implemented using the synchronous command processing API of libpq.
+ * See #async_exec for the differences between the two API variants.
+ * It's not recommended to use explicit sync or async variants but #pipeline_sync instead, unless you have a good reason to do so.
  *
+ * Available since PostgreSQL-14
+ */
+static VALUE
+pgconn_sync_pipeline_sync(VALUE self)
+{
+	PGconn *conn = pg_get_pgconn(self);
+	int res = gvl_PQpipelineSync(conn);
+	if( res != 1 )
+		pg_raise_conn_error( rb_ePGerror, self, "%s", PQerrorMessage(conn));
+
+	return Qnil;
+}
+
+
+#ifdef HAVE_PQSETCHUNKEDROWSMODE
+/*
+ * call-seq:
+ *    conn.send_pipeline_sync -> nil
+ *
+ * Marks a synchronization point in a pipeline by sending a sync message without flushing the send buffer.
+ *
+ * This serves as the delimiter of an implicit transaction and an error recovery point.
  * Raises PG::Error if the connection is not in pipeline mode or sending a sync message failed.
+ * Note that the message is not itself flushed to the server automatically; use flush if necessary.
  *
- * Available since PostgreSQL-14
+ * Available since PostgreSQL-17
  */
 static VALUE
-pgconn_pipeline_sync(VALUE self)
+pgconn_send_pipeline_sync(VALUE self)
 {
 	PGconn *conn = pg_get_pgconn(self);
-	int res = PQpipelineSync(conn);
+	int res = gvl_PQsendPipelineSync(conn);
 	if( res != 1 )
 		pg_raise_conn_error( rb_ePGerror, self, "%s", PQerrorMessage(conn));
 
 	return Qnil;
 }
+#endif
+
 
 /*
  * call-seq:
- *    conn.pipeline_sync -> nil
+ *    conn.send_flush_request -> nil
  *
  * Sends a request for the server to flush its output buffer.
  *
@@ -4769,8 +4797,11 @@ init_pg_connection(void)
 	rb_define_method(rb_cPGconn, "pipeline_status", pgconn_pipeline_status, 0);
 	rb_define_method(rb_cPGconn, "enter_pipeline_mode", pgconn_enter_pipeline_mode, 0);
 	rb_define_method(rb_cPGconn, "exit_pipeline_mode", pgconn_exit_pipeline_mode, 0);
-	rb_define_method(rb_cPGconn, "pipeline_sync", pgconn_pipeline_sync, 0);
+	rb_define_method(rb_cPGconn, "sync_pipeline_sync", pgconn_sync_pipeline_sync, 0);
 	rb_define_method(rb_cPGconn, "send_flush_request", pgconn_send_flush_request, 0);
+#ifdef HAVE_PQSETCHUNKEDROWSMODE
+	rb_define_method(rb_cPGconn, "send_pipeline_sync", pgconn_send_pipeline_sync, 0);
+#endif
 #endif
 
 	/******     PG::Connection INSTANCE METHODS: Large Object Support     ******/

lib/pg/connection.rb

@@ -536,6 +536,25 @@ def put_copy_end(*args)
 	end
 	alias async_put_copy_end put_copy_end
 
+	if method_defined? :send_pipeline_sync
+		# call-seq:
+		#    conn.pipeline_sync
+		#
+		# Marks a synchronization point in a pipeline by sending a sync message and flushing the send buffer.
+		# This serves as the delimiter of an implicit transaction and an error recovery point.
+		#
+		# See enter_pipeline_mode
+		#
+		# Raises PG::Error if the connection is not in pipeline mode or sending a sync message failed.
+		#
+		# Available since PostgreSQL-14
+		def pipeline_sync(*args)
+			send_pipeline_sync(*args)
+			flush
+		end
+		alias async_pipeline_sync pipeline_sync
+	end
+
 	if method_defined? :sync_encrypt_password
 		# call-seq:
 		#    conn.encrypt_password( password, username, algorithm=nil ) -> String
@@ -894,14 +913,29 @@ def ping(*args)
 		private_constant :REDIRECT_CLASS_METHODS
 
 		# These methods are affected by PQsetnonblocking
-		REDIRECT_SEND_METHODS = PG.make_shareable({
+		REDIRECT_SEND_METHODS = {
 			:isnonblocking => [:async_isnonblocking, :sync_isnonblocking],
 			:nonblocking? => [:async_isnonblocking, :sync_isnonblocking],
 			:put_copy_data => [:async_put_copy_data, :sync_put_copy_data],
 			:put_copy_end => [:async_put_copy_end, :sync_put_copy_end],
 			:flush => [:async_flush, :sync_flush],
-		})
+		}
 		private_constant :REDIRECT_SEND_METHODS
+		if PG::Connection.instance_methods.include? :sync_pipeline_sync
+			if PG::Connection.instance_methods.include? :send_pipeline_sync
+				# PostgreSQL-17+
+				REDIRECT_SEND_METHODS.merge!({
+					:pipeline_sync => [:async_pipeline_sync, :sync_pipeline_sync],
+				})
+			else
+				# PostgreSQL-14+
+				REDIRECT_SEND_METHODS.merge!({
+					:pipeline_sync => [:sync_pipeline_sync, :sync_pipeline_sync],
+				})
+			end
+		end
+		PG.make_shareable(REDIRECT_SEND_METHODS)
+
 		REDIRECT_METHODS = {
 			:exec => [:async_exec, :sync_exec],
 			:query => [:async_exec, :sync_exec],

spec/pg/connection_spec.rb

@@ -2173,6 +2173,11 @@ def wait_check_socket(conn)
 					@conn.pipeline_sync
 				}.to raise_error(PG::Error){|err| expect(err).to have_attributes(connection: @conn) }
 			end
+
+			it "has send_pipeline_sync method", :postgresql_17 do
+				expect( @conn.respond_to?(:send_pipeline_sync) ).to be_truthy
+				expect( @conn.respond_to?(:async_pipeline_sync) ).to be_truthy
+			end
 		end
 
 		describe "send_flush_request" do

spec/pg/scheduler_spec.rb

@@ -263,4 +263,20 @@
 			expect( ping ).to eq( PG::PQPING_OK )
 		end
 	end
+
+	it "can send a pipeline_sync message" do
+		run_with_scheduler(99) do |conn|
+			conn.enter_pipeline_mode
+			1000.times do |idx|
+				# This doesn't fail on sync_pipeline_sync, since PQpipelineSync() tries to flush, but doesn't wait for writablility.
+				conn.pipeline_sync
+			end
+			1000.times do
+				expect( conn.get_result.result_status ).to eq( PG::PGRES_PIPELINE_SYNC )
+			end
+			expect( conn.get_result ).to be_nil
+			expect( conn.get_result ).to be_nil
+			conn.exit_pipeline_mode
+		end
+	end
 end