Refactor (and rename) Exchange#bindings to remove memory allocations

src/lavinmq/amqp/exchange/consistent_hash.cr

@@ -42,12 +42,10 @@ module LavinMQ
         true
       end
 
-      protected def bindings(routing_key, headers) : Iterator(Destination)
+      def each_destination(routing_key : String, headers : AMQP::Table?, & : Destination ->)
         key = hash_key(routing_key, headers)
         if d = @hasher.get(key)
-          {d}.each
-        else
-          Iterator(Destination).empty
+          yield d
         end
       end
 

src/lavinmq/amqp/exchange/default.cr

@@ -11,11 +11,9 @@ module LavinMQ
         Iterator(BindingDetails).empty
       end
 
-      protected def bindings(routing_key, headers) : Iterator(Destination)
+      protected def each_destination(routing_key : String, _headers : AMQP::Table?, & : Destination ->)
         if q = @vhost.queues[routing_key]?
-          Tuple(Destination).new(q).each
-        else
-          Iterator(Destination).empty
+          yield q
         end
       end
 

src/lavinmq/amqp/exchange/direct.cr

@@ -41,8 +41,10 @@ module LavinMQ
         true
       end
 
-      protected def bindings(routing_key, headers) : Iterator(Destination)
-        @bindings[routing_key].each
+      protected def each_destination(routing_key : String, _headers : AMQP::Table?, & : Destination ->)
+        @bindings[routing_key].each do |destination|
+          yield destination
+        end
       end
     end
   end

src/lavinmq/amqp/exchange/exchange.cr

@@ -156,6 +156,7 @@ module LavinMQ
       abstract def bind(destination : Destination, routing_key : String, headers : AMQP::Table?)
       abstract def unbind(destination : Destination, routing_key : String, headers : AMQP::Table?)
       abstract def bindings_details : Iterator(BindingDetails)
+      abstract def each_destination(routing_key : String, headers : AMQP::Table?, & : Destination ->)
 
       def publish(msg : Message, immediate : Bool,
                   queues : Set(LavinMQ::Queue) = Set(LavinMQ::Queue).new,
@@ -204,7 +205,7 @@ module LavinMQ
                       queues : Set(LavinMQ::Queue) = Set(LavinMQ::Queue).new,
                       exchanges : Set(LavinMQ::Exchange) = Set(LavinMQ::Exchange).new) : Nil
         return unless exchanges.add? self
-        bindings(routing_key, headers).each do |d|
+        each_destination(routing_key, headers) do |d|
           case d
           in LavinMQ::Queue
             queues.add(d)

src/lavinmq/amqp/exchange/fanout.cr

@@ -33,8 +33,10 @@ module LavinMQ
         true
       end
 
-      protected def bindings(routing_key, headers) : Iterator(Destination)
-        @bindings.each
+      protected def each_destination(_routing_key : String, _headers : AMQP::Table?, & : Destination ->)
+        @bindings.each do |destination|
+          yield destination
+        end
       end
     end
   end

src/lavinmq/amqp/exchange/headers.cr

@@ -51,10 +51,6 @@ module LavinMQ
         true
       end
 
-      protected def bindings(routing_key, headers) : Iterator(Destination)
-        matches(headers).each
-      end
-
       private def validate!(headers) : Nil
         if h = headers
           if match = h["x-match"]?
@@ -65,19 +61,26 @@ module LavinMQ
         end
       end
 
-      private def matches(headers) : Iterator(Destination)
-        @bindings.each.select do |args, _|
+      protected def each_destination(_routing_key : String, headers : AMQP::Table?, & : Destination ->)
+        @bindings.each do |args, destinations|
           if headers.nil? || headers.empty?
-            args.empty?
+            next unless args.empty?
+            destinations.each do |destination|
+              yield destination
+            end
           else
-            case args["x-match"]?
-            when "any"
-              args.any? { |k, v| !k.starts_with?("x-") && (headers.has_key?(k) && headers[k] == v) }
-            else
-              args.all? { |k, v| k.starts_with?("x-") || (headers.has_key?(k) && headers[k] == v) }
+            is_match = case args["x-match"]?
+                       when "any"
+                         args.any? { |k, v| !k.starts_with?("x-") && (headers.has_key?(k) && headers[k] == v) }
+                       else
+                         args.all? { |k, v| k.starts_with?("x-") || (headers.has_key?(k) && headers[k] == v) }
+                       end
+            next unless is_match
+            destinations.each do |destination|
+              yield destination
             end
           end
-        end.flat_map { |_, v| v.each }
+        end
       end
     end
   end

src/lavinmq/amqp/exchange/topic.cr

@@ -42,28 +42,26 @@ module LavinMQ
         true
       end
 
-      protected def bindings(routing_key, headers) : Iterator(Destination)
-        select_matches(routing_key).each
-      end
-
       # ameba:disable Metrics/CyclomaticComplexity
-      private def select_matches(routing_key) : Iterator(Destination)
+      protected def each_destination(routing_key : String, headers : AMQP::Table?, & : Destination ->)
         binding_keys = @bindings
 
-        return Iterator(Destination).empty if binding_keys.empty?
+        return if binding_keys.empty?
 
         # optimize the case where the only binding key is '#'
         if binding_keys.size == 1
           bk, qs = binding_keys.first
           if bk.size == 1
             if bk.first == "#"
-              return qs.each
+              qs.each do |q|
+                yield q
+              end
             end
           end
         end
 
         rk_parts = routing_key.split(".")
-        binding_keys.each.select do |bks, _|
+        binding_keys.each do |bks, destinations|
           ok = false
           prev_hash = false
           size = bks.size # binding keys can max be 256 chars long anyway
@@ -120,8 +118,12 @@ module LavinMQ
             break unless ok
             i += 1
           end
-          ok
-        end.flat_map { |_, v| v.each }
+          if ok
+            destinations.each do |destination|
+              yield destination
+            end
+          end
+        end
       end
     end
   end