Move the specs from the previous commit back back

... so that it's executed with sync and async methods.
This is possible by moving execution of TcpGateSwitcher from concurrent threads to a separate process.

Author: larskanis

Gemfile

@@ -20,4 +20,5 @@ group :test do
   # With bigdecimal commented out here, corresponding tests are omitted on ruby-3.4+ but are executed on ruby < 3.4.
   # That way we can check both situations in CI.
   # gem "bigdecimal", "~> 3.0"
+  gem "drb"
 end

spec/helpers.rb

@@ -7,9 +7,10 @@
 require 'openssl'
 require 'fileutils'
 require 'objspace'
-require_relative 'helpers/scheduler.rb'
-require_relative 'helpers/tcp_gate_scheduler.rb'
-require_relative 'helpers/tcp_gate_switcher.rb'
+require_relative 'helpers/scheduler'
+require_relative 'helpers/tcp_gate_scheduler'
+require_relative 'helpers/tcp_gate_switcher'
+require_relative 'helpers/tcp_gate_switcher_process'
 
 TEST_DIRECTORY = Pathname.new(ENV['RUBY_PG_TEST_DIR'] || Dir.pwd)
 DATA_OBJ_MEMSIZE = ObjectSpace.memsize_of(Object.new)
@@ -616,7 +617,7 @@ def run_with_scheduler(timeout=10)
 
 	def gate_setup
 		# Run examples with gate
-		gate = Helpers::TcpGateSwitcher.new(external_host: 'localhost', external_port: ENV['PGPORT'].to_i, debug: ENV['PG_DEBUG']=='1')
+		gate = Helpers::TcpGateSwitcherProcess.new(external_host: 'localhost', external_port: ENV['PGPORT'].to_i, debug: ENV['PG_DEBUG']=='1')
 		@conninfo_gate = @conninfo.gsub(/(^| )port=\d+/, " port=#{gate.internal_port}")
 
 		# Run examples without gate

spec/helpers/tcp_gate_switcher.rb

@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require "socket"
+
 # This is a transparent TCP proxy for testing blocking behaviour in a time insensitive way.
 #
 # It works as a gate between the client and the server, which is enabled or disabled by the spec.

spec/helpers/tcp_gate_switcher_process.rb

@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+require 'drb/drb'
+
+# This is a wrapper of TcpGateSwitcher running in a separate process to avoid the need of threads.
+# It can therefore be used in conjunction with blocking GVL locking functions.
+
+module Helpers
+class TcpGateSwitcherProcess
+	def initialize(*args, **kwargs)
+		file = File.expand_path("tcp_gate_switcher", __dir__)
+		rbtext = <<~RBTEXT
+			require #{file.inspect}
+			require "drb/drb"
+
+			switcher = Helpers::TcpGateSwitcher.allocate
+			def switcher.finish
+				super
+				DRb.stop_service
+			end
+			def switcher.init(*args, **kwargs)
+				initialize(*args, **kwargs)
+			end
+			DRb.start_service('druby://localhost:0', switcher)
+			puts DRb.uri
+			# Redirect STDOUT to STDERR, so that p prints to STDERR
+			STDOUT.reopen(STDERR)
+
+			# Wait for the drb server thread to finish before exiting.
+			DRb.thread.join
+		RBTEXT
+
+		io = IO.popen("ruby", "w+")
+		io.write rbtext
+		io.close_write
+		server_uri = io.gets.strip
+		@server = DRbObject.new_with_uri(server_uri)
+		# Call initialize through DRb, so that Exceptions are passed to caller
+		@server.init *args, **kwargs
+	end
+
+	%i[finish internal_port start stop].each do |meth|
+		define_method(meth) do
+			@server.send(meth)
+		end
+	end
+end
+end

spec/pg/connection_async_spec.rb

@@ -135,31 +135,6 @@ def interrupt_thread(exc=nil)
 		end
 	end
 
-	it "connects without port and then retrieves the default port" do
-		gate = Helpers::TcpGateSwitcher.new(
-			external_host: 'localhost',
-			external_port: ENV['PGPORT'].to_i,
-			internal_host: "127.0.0.1",
-			internal_port: PG::DEF_PGPORT,
-			debug: ENV['PG_DEBUG']=='1')
-
-		PG.connect(host: "localhost",
-		           port: "",
-		           dbname: "test") do |conn|
-			expect( conn.port ).to eq( PG::DEF_PGPORT )
-		end
-
-		PG.connect(hostaddr: "127.0.0.1",
-		           port: nil,
-		           dbname: "test") do |conn|
-			expect( conn.port ).to eq( PG::DEF_PGPORT )
-		end
-
-		gate.finish
-	rescue Errno::EADDRINUSE, Errno::EACCES => err
-		skip err.to_s
-	end
-
 	it "doesn't duplicate hosts in conn.reset", :without_transaction, :ipv6, :postgresql_12 do
 		set_etc_hosts "::1", "rubypg_test2 rubypg_test_ipv6"
 		set_etc_hosts "127.0.0.1", "rubypg_test2 rubypg_test_ipv4"
@@ -181,64 +156,4 @@ def interrupt_thread(exc=nil)
 		expect( conn.hostaddr ).to eq( "::1" )
 		expect( conn.port ).to eq( @port )
 	end
-
-	context "in nonblocking mode" do
-		after :each do
-			@conn.setnonblocking(false)
-		end
-
-		it "rejects to send lots of COPY data" do
-			unless RUBY_PLATFORM =~ /i386-mingw|x86_64-darwin|x86_64-linux$/
-					skip "this spec depends on out-of-memory condition in put_copy_data, which is not reliable on all platforms"
-			end
-
-			run_with_gate(200) do |conn, gate|
-				conn.setnonblocking(true)
-
-				res = nil
-				conn.exec <<-EOSQL
-					CREATE TEMP TABLE copytable (col1 TEXT);
-				EOSQL
-
-				conn.exec( "COPY copytable FROM STDOUT CSV" )
-
-				gate.stop
-
-				data = "x" * 1000 * 1000
-				data << "\n"
-				20000.times do |idx|
-					res = conn.put_copy_data(data)
-					break if res == false
-				end
-				expect( res ).to be_falsey
-
-				gate.start
-				conn.cancel
-				conn.discard_results
-			end
-		end
-
-		it "needs to flush data after send_query" do
-			run_with_gate(200) do |conn, gate|
-				conn.setnonblocking(true)
-
-				gate.stop
-				data = "x" * 1000 * 1000 * 30
-				res = conn.send_query_params("SELECT LENGTH($1)", [data])
-				expect( res ).to be_nil
-
-				res = conn.flush
-				expect( res ).to be_falsey
-
-				gate.start
-				until conn.flush
-					IO.select(nil, [conn.socket_io], [conn.socket_io], 10)
-				end
-				expect( conn.flush ).to be_truthy
-
-				res = conn.get_last_result
-				expect( res.values ).to eq( [[data.length.to_s]] )
-			end
-		end
-	end
 end

spec/pg/connection_spec.rb

@@ -796,6 +796,60 @@
 			expect( res.values ).to eq([[data.length.to_s]])
 		end
 
+		it "rejects to send lots of COPY data" do
+			unless RUBY_PLATFORM =~ /i386-mingw|x86_64-darwin|x86_64-linux$/
+				skip "this spec depends on out-of-memory condition in put_copy_data, which is not reliable on all platforms"
+			end
+
+			run_with_gate(200) do |conn, gate|
+				conn.setnonblocking(true)
+
+				res = nil
+				conn.exec <<-EOSQL
+					CREATE TEMP TABLE copytable (col1 TEXT);
+				EOSQL
+
+				conn.exec( "COPY copytable FROM STDOUT CSV" )
+
+				gate.stop
+
+				data = "x" * 1000 * 1000
+				data << "\n"
+				20000.times do |idx|
+					res = conn.put_copy_data(data)
+					break if res == false
+				end
+				expect( res ).to be_falsey
+
+				gate.start
+				conn.cancel
+				conn.discard_results
+			end
+		end
+
+		it "needs to flush data after send_query" do
+			run_with_gate(200) do |conn, gate|
+				conn.setnonblocking(true)
+
+				gate.stop
+				data = "x" * 1000 * 1000 * 30
+				res = conn.send_query_params("SELECT LENGTH($1)", [data])
+				expect( res ).to be_nil
+
+				res = conn.flush
+				expect( res ).to be_falsey
+
+				gate.start
+				until conn.flush
+					IO.select(nil, [conn.socket_io], [conn.socket_io], 10)
+				end
+				expect( conn.flush ).to be_truthy
+
+				res = conn.get_last_result
+				expect( res.values ).to eq( [[data.length.to_s]] )
+			end
+		end
+
 		it "returns immediately from get_copy_data(nonblock=true)" do
 			expect do
 				@conn.copy_data( "COPY (SELECT generate_series(0,999), NULL UNION ALL SELECT 1000, pg_sleep(10)) TO STDOUT" ) do |res|
@@ -844,6 +898,31 @@
 		expect( @conn.options ).to eq( "" )
 	end
 
+	it "connects without port and then retrieves the default port" do
+		gate = Helpers::TcpGateSwitcherProcess.new(
+				external_host: 'localhost',
+				external_port: ENV['PGPORT'].to_i,
+				internal_host: "127.0.0.1",
+				internal_port: PG::DEF_PGPORT,
+				debug: ENV['PG_DEBUG']=='1')
+
+		PG.connect(host: "localhost",
+				port: "",
+				dbname: "test") do |conn|
+			expect( conn.port ).to eq( PG::DEF_PGPORT )
+		end
+
+		PG.connect(hostaddr: "127.0.0.1",
+				port: nil,
+				dbname: "test") do |conn|
+			expect( conn.port ).to eq( PG::DEF_PGPORT )
+		end
+
+		gate.finish
+	rescue Errno::EADDRINUSE, Errno::EACCES => err
+		skip err.to_s
+	end
+
 	it "can retrieve hostaddr for the established connection", :postgresql_12 do
 		expect( @conn.hostaddr ).to match( /^127\.0\.0\.1$|^::1$/ )
 	end