quic: apply multiple quic performance and packet handling improvements

.gitignore

@@ -31,6 +31,7 @@
 /tags
 /tags.*
 /doc/api.xml
+/docs/
 /node
 /node_g
 /gon-config.json

doc/api/quic.md

@@ -2094,6 +2094,20 @@ added: v23.8.0
 
 * Type: {bigint}
 
+### `streamStats.bytesAccumulated`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* Type: {bigint}
+
+The current number of bytes sitting in the stream's receive accumulation
+buffer, awaiting delivery to the application. A value near zero indicates
+the reader is keeping up with incoming data. A value near the stream's
+flow control window indicates the application is not consuming data fast
+enough.
+
 ### `streamStats.bytesReceived`
 
 <!-- YAML
@@ -2142,6 +2156,20 @@ added: v23.8.0
 
 * Type: {bigint}
 
+### `streamStats.maxBytesAccumulated`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* Type: {bigint}
+
+The peak number of bytes that were accumulated in the stream's receive
+buffer at any point during the stream's lifetime. This value only
+increases monotonically. It is useful for diagnosing whether a stream
+experienced backpressure episodes and whether the accumulation buffer
+sizing is appropriate for the workload.
+
 ### `streamStats.maxOffset`
 
 <!-- YAML
@@ -2258,6 +2286,23 @@ added: v23.8.0
 
 When `true`, indicates that the endpoint should bind only to IPv6 addresses.
 
+#### `endpointOptions.reusePort`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* Type: {boolean}
+* Default: `false`
+
+When `true`, allows multiple endpoints (across separate processes) to bind to
+the same address and port. The kernel will load-balance incoming UDP datagrams
+across all sockets bound with this option. This enables horizontal scaling of
+QUIC servers by running multiple Node.js processes on the same port.
+
+Supported on Linux 3.9+ and DragonFlyBSD 3.6+. On unsupported platforms, the
+bind will fail with an error.
+
 #### `endpointOptions.maxConnectionsPerHost`
 
 <!-- YAML
@@ -2698,6 +2743,23 @@ added: v23.8.0
 Specifies the maximum number of milliseconds a TLS handshake is permitted to take
 to complete before timing out.
 
+#### `sessionOptions.initialRtt`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+* Type: {bigint|number}
+* **Default:** `0` (use ngtcp2 default of 333ms)
+
+Specifies the initial round-trip time estimate in milliseconds. This value is
+used for probe timeout (PTO) computation, initial pacing, and early loss
+detection before the first actual RTT sample is collected from the connection.
+The default of 333ms is appropriate for the general internet. For low-latency
+environments such as loopback or same-rack deployments, setting a value closer
+to the actual RTT (e.g., `1`) avoids unnecessarily conservative initial
+behavior.
+
 #### `sessionOptions.keepAlive`
 
 <!-- YAML

lib/internal/fs/promises.js

@@ -178,6 +178,12 @@ function handleErrorFromBinding(error) {
 }
 
 class FileHandle extends EventEmitter {
+  #brandCheck = undefined;
+
+  static isFileHandle(value) {
+    return (value != null && typeof value === 'object' && #brandCheck in value);
+  }
+
   /**
    * @param {InternalFSBinding.FileHandle | undefined} filehandle
    */