refactor: reduce noise in fmt::Debug outputs (#855)

Author: seanmonstar

src/proto/streams/mod.rs

@@ -73,3 +73,56 @@ pub struct Config {
     /// When this gets exceeded, we issue GOAWAYs.
     pub local_max_error_reset_streams: Option<usize>,
 }
+
+trait DebugStructExt<'a, 'b> {
+    // h2_ prefixes to protect against possible future name collisions
+    fn h2_field_if(&mut self, name: &str, val: &bool) -> &mut std::fmt::DebugStruct<'a, 'b>;
+
+    fn h2_field_if_then<T: std::fmt::Debug>(
+        &mut self,
+        name: &str,
+        cond: bool,
+        val: &T,
+    ) -> &mut std::fmt::DebugStruct<'a, 'b>;
+
+    fn h2_field_some<T: std::fmt::Debug>(
+        &mut self,
+        name: &str,
+        val: &Option<T>,
+    ) -> &mut std::fmt::DebugStruct<'a, 'b>;
+}
+
+impl<'a, 'b> DebugStructExt<'a, 'b> for std::fmt::DebugStruct<'a, 'b> {
+    fn h2_field_if(&mut self, name: &str, val: &bool) -> &mut std::fmt::DebugStruct<'a, 'b> {
+        if *val {
+            self.field(name, val)
+        } else {
+            self
+        }
+    }
+
+    fn h2_field_if_then<T: std::fmt::Debug>(
+        &mut self,
+        name: &str,
+        cond: bool,
+        val: &T,
+    ) -> &mut std::fmt::DebugStruct<'a, 'b> {
+        if cond {
+            self.field(name, val)
+        } else {
+            self
+        }
+    }
+
+    fn h2_field_some<T: std::fmt::Debug>(
+        &mut self,
+        name: &str,
+        val: &Option<T>,
+    ) -> &mut std::fmt::DebugStruct<'a, 'b> {
+        if val.is_some() {
+            self.field(name, val)
+        } else {
+            self
+        }
+    }
+}

src/proto/streams/state.rs

@@ -1,3 +1,4 @@
+use std::fmt;
 use std::io;
 
 use crate::codec::UserError;
@@ -47,7 +48,7 @@ use self::Peer::*;
 ///        ES: END_STREAM flag
 ///        R:  RST_STREAM frame
 /// ```
-#[derive(Debug, Clone)]
+#[derive(Clone)]
 pub struct State {
     inner: Inner,
 }
@@ -465,3 +466,10 @@ impl Default for State {
         State { inner: Inner::Idle }
     }
 }
+
+// remove some noise for debug output
+impl fmt::Debug for State {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        self.inner.fmt(f)
+    }
+}

src/proto/streams/store.rs

@@ -34,7 +34,6 @@ pub(crate) struct Key {
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 struct SlabIndex(u32);
 
-#[derive(Debug)]
 pub(super) struct Queue<N> {
     indices: Option<store::Indices>,
     _p: PhantomData<N>,
@@ -378,6 +377,15 @@ where
     }
 }
 
+impl<N> fmt::Debug for Queue<N> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("Queue")
+            .field("indices", &self.indices)
+            // skip phantom data
+            .finish()
+    }
+}
+
 // ===== impl Ptr =====
 
 impl<'a> Ptr<'a> {

src/proto/streams/stream.rs

@@ -398,35 +398,47 @@ impl fmt::Debug for Stream {
             .field("state", &self.state)
             .field("is_counted", &self.is_counted)
             .field("ref_count", &self.ref_count)
-            .field("next_pending_send", &self.next_pending_send)
-            .field("is_pending_send", &self.is_pending_send)
+            .h2_field_some("next_pending_send", &self.next_pending_send)
+            .h2_field_if("is_pending_send", &self.is_pending_send)
             .field("send_flow", &self.send_flow)
             .field("requested_send_capacity", &self.requested_send_capacity)
             .field("buffered_send_data", &self.buffered_send_data)
-            .field("send_task", &self.send_task.as_ref().map(|_| ()))
-            .field("pending_send", &self.pending_send)
-            .field(
+            .h2_field_some("send_task", &self.send_task.as_ref().map(|_| ()))
+            .h2_field_if_then(
+                "pending_send",
+                !self.pending_send.is_empty(),
+                &self.pending_send,
+            )
+            .h2_field_some(
                 "next_pending_send_capacity",
                 &self.next_pending_send_capacity,
             )
-            .field("is_pending_send_capacity", &self.is_pending_send_capacity)
-            .field("send_capacity_inc", &self.send_capacity_inc)
-            .field("next_open", &self.next_open)
-            .field("is_pending_open", &self.is_pending_open)
-            .field("is_pending_push", &self.is_pending_push)
-            .field("next_pending_accept", &self.next_pending_accept)
-            .field("is_pending_accept", &self.is_pending_accept)
+            .h2_field_if("is_pending_send_capacity", &self.is_pending_send_capacity)
+            .h2_field_if("send_capacity_inc", &self.send_capacity_inc)
+            .h2_field_some("next_open", &self.next_open)
+            .h2_field_if("is_pending_open", &self.is_pending_open)
+            .h2_field_if("is_pending_push", &self.is_pending_push)
+            .h2_field_some("next_pending_accept", &self.next_pending_accept)
+            .h2_field_if("is_pending_accept", &self.is_pending_accept)
             .field("recv_flow", &self.recv_flow)
             .field("in_flight_recv_data", &self.in_flight_recv_data)
-            .field("next_window_update", &self.next_window_update)
-            .field("is_pending_window_update", &self.is_pending_window_update)
-            .field("reset_at", &self.reset_at)
-            .field("next_reset_expire", &self.next_reset_expire)
-            .field("pending_recv", &self.pending_recv)
-            .field("is_recv", &self.is_recv)
-            .field("recv_task", &self.recv_task.as_ref().map(|_| ()))
-            .field("push_task", &self.push_task.as_ref().map(|_| ()))
-            .field("pending_push_promises", &self.pending_push_promises)
+            .h2_field_some("next_window_update", &self.next_window_update)
+            .h2_field_if("is_pending_window_update", &self.is_pending_window_update)
+            .h2_field_some("reset_at", &self.reset_at)
+            .h2_field_some("next_reset_expire", &self.next_reset_expire)
+            .h2_field_if_then(
+                "pending_recv",
+                !self.pending_recv.is_empty(),
+                &self.pending_recv,
+            )
+            .h2_field_if("is_recv", &self.is_recv)
+            .h2_field_some("recv_task", &self.recv_task.as_ref().map(|_| ()))
+            .h2_field_some("push_task", &self.push_task.as_ref().map(|_| ()))
+            .h2_field_if_then(
+                "pending_push_promises",
+                !self.pending_push_promises.is_empty(),
+                &self.pending_push_promises,
+            )
             .field("content_length", &self.content_length)
             .finish()
     }