Support for passing Connection::Blocked frames to downstream clients

shard.lock

@@ -10,5 +10,5 @@ shards:
 
   amqp-client:
     git: https://github.com/cloudamqp/amqp-client.cr.git
-    version: 1.2.1
+    version: 1.2.2
 

spec/amqproxy_spec.cr

@@ -201,4 +201,28 @@ describe AMQProxy::Server do
       s.stop_accepting_clients
     end
   end
+
+  it "passes connection blocked frames to clients" do
+    s = AMQProxy::Server.new("127.0.0.1", 5672, false)
+    done = Channel(Nil).new
+    begin
+      spawn { s.listen("127.0.0.1", 5673) }
+      Fiber.yield
+      AMQP::Client.start("amqp://localhost:5673") do |conn|
+        conn.on_blocked do
+          done.send nil
+          system("#{MAYBE_SUDO}rabbitmqctl set_vm_memory_high_watermark 0.8 > /dev/null").should be_true
+        end
+        conn.on_unblocked do
+          done.send nil
+        end
+        ch = conn.channel
+        system("#{MAYBE_SUDO}rabbitmqctl set_vm_memory_high_watermark 0.001 > /dev/null").should be_true
+        ch.basic_publish "foobar", "amq.fanout"
+        2.times { done.receive }
+      end
+    ensure
+      s.stop_accepting_clients
+    end
+  end
 end

src/amqproxy/client.cr

@@ -223,7 +223,7 @@ module AMQProxy
       capabilities: {
         consumer_priorities:          true,
         exchange_exchange_bindings:   true,
-        "connection.blocked":         false,
+        "connection.blocked":         true,
         authentication_failure_close: true,
         per_consumer_qos:             true,
         "basic.nack":                 true,

src/amqproxy/upstream.cr

@@ -74,7 +74,7 @@ module AMQProxy
     end
 
     # Frames from upstream (to client)
-    private def read_loop(socket, remote_address : String)
+    private def read_loop(socket, remote_address : String) # ameba:disable Metrics/CyclomaticComplexity
       Log.context.set(remote_address: remote_address)
       loop do
         case frame = AMQ::Protocol::Frame.from_io(socket, IO::ByteFormat::NetworkEndian)
@@ -87,6 +87,9 @@ module AMQProxy
           end
           return
         when AMQ::Protocol::Frame::Connection::CloseOk then return
+        when AMQ::Protocol::Frame::Connection::Blocked,
+             AMQ::Protocol::Frame::Connection::Unblocked
+          send_to_all_clients(frame)
         when AMQ::Protocol::Frame::Channel::OpenOk  # we assume it always succeeds
         when AMQ::Protocol::Frame::Channel::CloseOk # when channel pool requested channel close
         else
@@ -125,6 +128,21 @@ module AMQProxy
       end
     end
 
+    private def send_to_all_clients(frame : AMQ::Protocol::Frame::Connection)
+      Log.debug { "Sending broadcast frame to all client connections" }
+      clients = Set(Client).new
+      @channels_lock.synchronize do
+        @channels.each_value do |downstream_channel|
+          if dc = downstream_channel
+            clients << dc.client
+          end
+        end
+      end
+      clients.each do |client|
+        client.write frame
+      end
+    end
+
     # Forward frames from client to upstream
     def write(frame : AMQ::Protocol::Frame) : Nil
       case frame
@@ -232,7 +250,7 @@ module AMQProxy
       capabilities:    {
         consumer_priorities:          true,
         exchange_exchange_bindings:   true,
-        "connection.blocked":         false,
+        "connection.blocked":         true,
         authentication_failure_close: true,
         per_consumer_qos:             true,
         "basic.nack":                 true,