Mention that disabling heartbeats will now disabled TCP socket read t…

…imeouts

References #519.

lib/bunny/session.rb

@@ -101,7 +101,7 @@ class Session
     # @option connection_string_or_opts [String] :username ("guest") Username
     # @option connection_string_or_opts [String] :password ("guest") Password
     # @option connection_string_or_opts [String] :vhost ("/") Virtual host to use
-    # @option connection_string_or_opts [Integer, Symbol] :heartbeat (:server) Heartbeat interval. :server means use the default suggested by RabbitMQ. 0 means no heartbeat (not recommended).
+    # @option connection_string_or_opts [Integer, Symbol] :heartbeat (:server) Heartbeat interval. :server means use the default suggested by RabbitMQ. 0 means heartbeats and socket read timeouts will be disabled (not recommended).
     # @option connection_string_or_opts [Integer] :network_recovery_interval (4) Recovery interval periodic network recovery will use. This includes initial pause after network failure.
     # @option connection_string_or_opts [Boolean] :tls (false) Should TLS/SSL be used?
     # @option connection_string_or_opts [String] :tls_cert (nil) Path to client TLS/SSL certificate file (.pem)
@@ -111,7 +111,7 @@ class Session
     # @option connection_string_or_opts [Symbol] :tls_version (negotiated) What TLS version should be used (:TLSv1, :TLSv1_1, or :TLSv1_2)
     # @option connection_string_or_opts [Integer] :continuation_timeout (15000) Timeout for client operations that expect a response (e.g. {Bunny::Queue#get}), in milliseconds.
     # @option connection_string_or_opts [Integer] :connection_timeout (30) Timeout in seconds for connecting to the server.
-    # @option connection_string_or_opts [Integer] :read_timeout (30) TCP socket read timeout in seconds.
+    # @option connection_string_or_opts [Integer] :read_timeout (30) TCP socket read timeout in seconds. If heartbeats are disabled this will be ignored.
     # @option connection_string_or_opts [Integer] :write_timeout (30) TCP socket write timeout in seconds.
     # @option connection_string_or_opts [Proc] :hosts_shuffle_strategy A Proc that reorders a list of host strings, defaults to Array#shuffle
     # @option connection_string_or_opts [Logger] :logger The logger.  If missing, one is created using :log_file and :log_level.
@@ -1180,6 +1180,8 @@ def open_connection
       # We set the read_write_timeout to twice the heartbeat value,
       # and then some padding for edge cases.
       # This allows us to miss a single heartbeat before we time out the socket.
+      # If heartbeats are disabled, assume that TCP keepalives or a similar mechanism will be used
+      # and disable socket read timeouts. See ruby-amqp/bunny#551.
       @transport.read_timeout = @heartbeat * 2.2
       @logger.debug { "Will use socket read timeout of #{@transport.read_timeout}" }