feat(identify): immediately run identify protocol on new connections

protocols/identify/CHANGELOG.md

@@ -2,7 +2,11 @@
 
 - Migrate from `prost` to `quick-protobuf`. This removes `protoc` dependency. See [PR 3312].
 
+- Reduce the initial delay before running the identify protocol to 0 and make the option deprecated.
+  See [PR 3545].
+
 [PR 3312]: https://github.com/libp2p/rust-libp2p/pull/3312
+[PR 3545]: https://github.com/libp2p/rust-libp2p/pull/3545
 
 # 0.42.0
 

protocols/identify/src/behaviour.rs

@@ -89,7 +89,13 @@ pub struct Config {
     /// The initial delay before the first identification request
     /// is sent to a remote on a newly established connection.
     ///
-    /// Defaults to 500ms.
+    /// Defaults to 0ms.
+    #[deprecated(
+        since = "0.42.1",
+        note = "The `initial_delay` is no longer necessary and will be 
+                completely removed since a remote should be able to instantly
+                answer to an identify request"
+    )]
     pub initial_delay: Duration,
     /// The interval at which identification requests are sent to
     /// the remote on established connections after the first request,
@@ -123,7 +129,7 @@ impl Config {
             protocol_version,
             agent_version: format!("rust-libp2p/{}", env!("CARGO_PKG_VERSION")),
             local_public_key,
-            initial_delay: Duration::from_millis(500),
+            initial_delay: Duration::from_millis(0),
             interval: Duration::from_secs(5 * 60),
             push_listen_addr_updates: false,
             cache_size: 100,
@@ -138,6 +144,12 @@ impl Config {
 
     /// Configures the initial delay before the first identification
     /// request is sent on a newly established connection to a peer.
+    #[deprecated(
+        since = "0.42.1",
+        note = "The `initial_delay` is no longer necessary and will be 
+                completely removed since a remote should be able to instantly
+                answer to an identify request thus also this setter will be removed"
+    )]
     pub fn with_initial_delay(mut self, d: Duration) -> Self {
         self.initial_delay = d;
         self