Expose Netty's CONNECT_TIMEOUT_MILLIS client channel option

Netty has a default connect timeout for client channels (currently 30s) which was only accessible by
means of `bootstrap-transform`. Since it's a rather important option to get predictable connection
behavior, expose it as `connect-timeout` in all relevant APIs.

Author: DerGuteMoritz

src/aleph/http.clj

@@ -157,6 +157,7 @@
    | `insecure?`               | if `true`, ignores the certificate for any `https://` domains
    | `response-buffer-size`    | the amount of the response, in bytes, that is buffered before the request returns, defaults to `65536`.  This does *not* represent the maximum size response that the client can handle (which is unbounded), and is only a means of maximizing performance.
    | `keep-alive?`             | if `true`, attempts to reuse connections for multiple requests, defaults to `true`.
+   | `connect-timeout`         | timeout for a connection to be established, in milliseconds. Default determined by Netty, see `aleph.netty/default-connect-timeout`.
    | `idle-timeout`            | when set, forces keep-alive connections to be closed after an idle time, in milliseconds.
    | `transport`               | the transport to use, one of `:nio`, `:epoll`, `:kqueue` or `:io-uring` (defaults to `:nio`).
    | `raw-stream?`             | if `true`, bodies of responses will not be buffered at all, and represented as Manifold streams of `io.netty.buffer.ByteBuf` objects rather than as an `InputStream`.  This will minimize copying, but means that care must be taken with Netty's buffer reference counting.  Only recommended for advanced users.
@@ -275,6 +276,7 @@
    | `pipeline-transform`  | an optional function that takes an `io.netty.channel.ChannelPipeline` object, which represents a connection, and modifies it.
    | `max-frame-payload`   | maximum allowable frame payload length, in bytes, defaults to `65536`.
    | `max-frame-size`      | maximum aggregate message size, in bytes, defaults to `1048576`.
+   | `connect-timeout`     | timeout for a connection to be established, in milliseconds. Default determined by Netty, see `aleph.netty/default-connect-timeout`.
    | `bootstrap-transform` | an optional function that takes an `io.netty.bootstrap.Bootstrap` object and modifies it.
    | `transport`               | the transport to use, one of `:nio`, `:epoll`, `:kqueue` or `:io-uring` (defaults to `:nio`).
    | `heartbeats`          | optional configuration to send Ping frames to the server periodically (if the connection is idle), configuration keys are `:send-after-idle` (in milliseconds), `:payload` (optional, empty frame by default) and `:timeout` (optional, to close the connection if Pong is not received after specified timeout)."
@@ -342,7 +344,7 @@
 
      Param key            | Description
      -------------------- | -----------------------------------------------------------------------------------------------------------------------------------------------------------------
-     `connection-timeout` | timeout in milliseconds for the connection to become established
+     `connection-timeout` | timeout in milliseconds for the connection to become established, defaults to 60s. Note that this timeout will be ineffective if the pool's `connect-timeout` is lower.
      `follow-redirects?`  | whether to follow redirects, defaults to `true`; see `aleph.http.client-middleware/handle-redirects`
      `middleware`         | custom client middleware for the request
      `pool-timeout`       | timeout in milliseconds for the pool to generate a connection
@@ -496,7 +498,7 @@
    | `follow-redirects?`  | whether to follow redirects, defaults to `true`; see `aleph.http.client-middleware/handle-redirects`
    | `pool`               | a custom connection pool
    | `pool-timeout`       | timeout in milliseconds for the pool to generate a connection
-   | `connection-timeout` | timeout in milliseconds for the connection to become established
+   | `connection-timeout` | timeout in milliseconds for the connection to become established, defaults to 60s. Note that this timeout will be ineffective if the pool's `connect-timeout` is lower.
    | `request-timeout`    | timeout in milliseconds for the arrival of a response over the established connection
    | `read-timeout`       | timeout in milliseconds for the response to be completed
    | `response-executor`  | optional `java.util.concurrent.Executor` that will handle the requests (defaults to a `flow/utilization-executor` of 256 `max-threads` and a `queue-length` of 0)")

src/aleph/http/client.clj

@@ -770,13 +770,15 @@
            log-activity
            http-versions
            force-h2c?
-           on-closed]
+           on-closed
+           connect-timeout]
     :or   {raw-stream?          false
            bootstrap-transform  identity
            pipeline-transform   identity
            keep-alive?          true
            ssl-endpoint-id-alg  netty/default-ssl-endpoint-id-alg
            response-buffer-size 65536
+           connect-timeout      netty/default-connect-timeout
            epoll?               false
            name-resolver        :default
            log-activity         :debug
@@ -818,7 +820,8 @@
                :remote-address      remote-address
                :local-address       local-address
                :transport           (netty/determine-transport transport epoll?)
-               :name-resolver       name-resolver})]
+               :name-resolver       name-resolver
+               :connect-timeout     connect-timeout})]
 
     (attach-on-close-handler ch-d on-closed)
 

src/aleph/http/websocket/client.clj

@@ -244,7 +244,8 @@
            max-frame-payload
            max-frame-size
            compression?
-           heartbeats]
+           heartbeats
+           connect-timeout]
     :or   {bootstrap-transform identity
            pipeline-transform  identity
            raw-stream?         false
@@ -254,7 +255,8 @@
            extensions?         false
            max-frame-payload   65536
            max-frame-size      1048576
-           compression?        false}
+           compression?        false
+           connect-timeout     netty/default-connect-timeout}
     :as   options}]
 
   (when (and (true? (:compression? options))
@@ -312,5 +314,6 @@
                  :bootstrap-transform bootstrap-transform
                  :remote-address      remote-address
                  :local-address       local-address
-                 :transport           (netty/determine-transport transport epoll?)})
+                 :transport           (netty/determine-transport transport epoll?)
+                 :connect-timeout     connect-timeout})
               (fn [_] s))))

src/aleph/netty.clj

@@ -38,6 +38,8 @@
       EpollEventLoopGroup
       EpollServerSocketChannel
       EpollSocketChannel)
+    (io.netty.channel.embedded
+      EmbeddedChannel)
     (io.netty.channel.group
       ChannelGroup
       DefaultChannelGroup)
@@ -1516,6 +1518,14 @@
                     (ssl-handler ch ssl-ctx))))
      (pipeline-builder p))))
 
+(def ^:const
+  default-connect-timeout
+  "Netty's default connect timeout."
+  ;; This hack is necessary due to io.netty.channel.DefaultChannelConfig/DEFAULT_CONNECT_TIMEOUT
+  ;; being private.
+  (with-open [c (EmbeddedChannel.)]
+    (.getConnectTimeoutMillis (.config c))))
+
 (defn ^:no-doc create-client-chan
   "Returns a deferred containing a new Channel.
 
@@ -1527,7 +1537,9 @@
            ^SocketAddress remote-address
            ^SocketAddress local-address
            transport
-           name-resolver]
+           name-resolver
+           connect-timeout]
+    :or {connect-timeout default-connect-timeout}
     :as opts}]
   (ensure-transport-available! transport)
 
@@ -1546,6 +1558,7 @@
                           (instance? AddressResolverGroup name-resolver) name-resolver))
             bootstrap (doto (Bootstrap.)
                             (.option ChannelOption/SO_REUSEADDR true)
+                            (.option ChannelOption/CONNECT_TIMEOUT_MILLIS (int connect-timeout))
                             #_(.option ChannelOption/MAX_MESSAGES_PER_READ Integer/MAX_VALUE) ; option deprecated, removed in v5
                             (.group client-event-loop-group)
                             (.channel chan-class)

src/aleph/tcp.clj

@@ -165,12 +165,26 @@
    | `ssl-endpoint-id-alg` | the name of the algorithm to use for SSL endpoint identification (see https://docs.oracle.com/en/java/javase/17/docs/specs/security/standard-names.html#endpoint-identification-algorithms), defaults to \"HTTPS\" which is a reasonable default for non-HTTPS uses, too. Only used by SSL connections. Pass `nil` to disable endpoint identification.
    | `ssl?`                | if true, the client attempts to establish a secure connection with the server.
    | `insecure?`           | if true, the client will ignore the server's certificate.
+   | `connect-timeout`     | timeout for a connection to be established, in milliseconds. Default determined by Netty, see `aleph.netty/default-connect-timeout`.
    | `bootstrap-transform` | a function that takes an `io.netty.bootstrap.Bootstrap` object, which represents the client, and modifies it.
    | `pipeline-transform`  | a function that takes an `io.netty.channel.ChannelPipeline` object, which represents a connection, and modifies it.
    | `raw-stream?`         | if true, messages from the stream will be `io.netty.buffer.ByteBuf` objects rather than byte-arrays.  This will minimize copying, but means that care must be taken with Netty's buffer reference counting.  Only recommended for advanced users.
    | `transport`           | the transport to use, one of `:nio`, `:epoll`, `:kqueue` or `:io-uring` (defaults to `:nio`)."
-  [{:keys [host port remote-address local-address ssl-context ssl-endpoint-id-alg ssl? insecure? pipeline-transform bootstrap-transform epoll? transport]
+  [{:keys [host
+           port
+           remote-address
+           local-address
+           ssl-context
+           ssl-endpoint-id-alg
+           ssl?
+           insecure?
+           connect-timeout
+           pipeline-transform
+           bootstrap-transform
+           epoll?
+           transport]
     :or {ssl-endpoint-id-alg netty/default-ssl-endpoint-id-alg
+         connect-timeout netty/default-connect-timeout
          bootstrap-transform identity
          epoll? false}
     :as options}]
@@ -196,6 +210,7 @@
            :bootstrap-transform bootstrap-transform
            :remote-address      remote-address
            :local-address       local-address
-           :transport           (netty/determine-transport transport epoll?)})
+           :transport           (netty/determine-transport transport epoll?)
+           :connect-timeout     connect-timeout})
         (d/catch' #(d/error! s %)))
     s))

test/aleph/http_test.clj

@@ -31,7 +31,8 @@
       ChannelHandlerContext
       ChannelOutboundHandlerAdapter
       ChannelPipeline
-      ChannelPromise)
+      ChannelPromise
+      ConnectTimeoutException)
     (io.netty.handler.codec TooLongFrameException)
     (io.netty.handler.codec.compression
       CompressionOptions
@@ -633,6 +634,17 @@
                  @(http/get "http://192.0.2.0"              ;; "TEST-NET" in RFC 5737
                             (merge (default-request-options) {:pool *pool* :connection-timeout 2}))))))
 
+
+(deftest test-pool-connect-timeout
+  (binding [*connection-options* {:connect-timeout 2}]
+    (with-handler basic-handler
+      (is (thrown? ConnectTimeoutException
+                   (deref (http/get "http://192.0.2.0" ;; "TEST-NET" in RFC 5737
+                                    (merge (default-request-options) {:pool *pool*
+                                                                      :connection-timeout 500}))
+                          1e3
+                          :timeout))))))
+
 (deftest test-request-timeout
   (with-handler basic-handler
     (is (thrown? TimeoutException