Bugfix: crash during startup because of missing 'x-delayed-type' (#620)

* Clone arguments before modifying them

* Update changelog

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Fixed
+
+- A bug causing faulty definition frames for delayed exchanges, preventing LavinMQ from starting [#620](https://github.com/cloudamqp/lavinmq/pull/620)
+
 ## [1.2.7] - 2023-12-12
 
 - Version 1.2.6 may not include the bumped version of lavinmq, so instead use version 1.2.7

spec/vhost_spec.cr

@@ -26,6 +26,21 @@ describe LavinMQ::VHost do
     Server.vhosts["test"].exchanges["e"].should_not be_nil
   end
 
+  it "should be able to persist durable delayed exchanges when type = x-delayed-message" do
+    # This spec is to verify a fix where a server couldn't start again after a crash if
+    # an delayed exchange had been declared by specifiying the type as "x-delayed-message".
+    Server.vhosts.create("test")
+    v = Server.vhosts["test"].not_nil!
+    arguments = AMQ::Protocol::Table.new({"x-delayed-type": "direct"})
+    v.declare_exchange("e", "x-delayed-message", true, false, arguments: arguments)
+
+    # Start a new server with the same data dir as `Server` without stopping
+    # `Server` first, because stopping would compact definitions and therefore "rewrite"
+    # the definitions file. This is to simulate a start after a "crash".
+    # If this succeeds we assume it worked...?
+    LavinMQ::Server.new(DATA_DIR)
+  end
+
   it "should be able to persist durable queues" do
     Server.vhosts.create("test")
     v = Server.vhosts["test"].not_nil!

src/lavinmq/vhost.cr

@@ -657,6 +657,7 @@ module LavinMQ
       when "headers"
         HeadersExchange.new(vhost, name, durable, auto_delete, internal, arguments)
       when "x-delayed-message"
+        arguments = arguments.clone
         type = arguments.delete("x-delayed-type")
         raise Error::ExchangeTypeError.new("Missing required argument 'x-delayed-type'") unless type
         arguments["x-delayed-exchange"] = true