sp-utils => sc-utils (#9677)

* sp-utils => sc-utils

* cargo fmt

* These files are now in the client so should be licensed as GPL3

* Apply suggestions from code review

Co-authored-by: Bastian Köcher <bkchr@users.noreply.github.com>

substrate/client/utils/src/mpsc.rs

@@ -0,0 +1,232 @@
+// This file is part of Substrate.
+
+// Copyright (C) 2020-2021 Parity Technologies (UK) Ltd.
+// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0
+
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+//! Features to meter unbounded channels
+
+#[cfg(not(feature = "metered"))]
+mod inner {
+	// just aliased, non performance implications
+	use futures::channel::mpsc::{self, UnboundedReceiver, UnboundedSender};
+	pub type TracingUnboundedSender<T> = UnboundedSender<T>;
+	pub type TracingUnboundedReceiver<T> = UnboundedReceiver<T>;
+
+	/// Alias `mpsc::unbounded`
+	pub fn tracing_unbounded<T>(
+		_key: &'static str,
+	) -> (TracingUnboundedSender<T>, TracingUnboundedReceiver<T>) {
+		mpsc::unbounded()
+	}
+}
+
+#[cfg(feature = "metered")]
+mod inner {
+	// tracing implementation
+	use crate::metrics::UNBOUNDED_CHANNELS_COUNTER;
+	use futures::{
+		channel::mpsc::{
+			self, SendError, TryRecvError, TrySendError, UnboundedReceiver, UnboundedSender,
+		},
+		sink::Sink,
+		stream::{FusedStream, Stream},
+		task::{Context, Poll},
+	};
+	use std::pin::Pin;
+
+	/// Wrapper Type around `UnboundedSender` that increases the global
+	/// measure when a message is added
+	#[derive(Debug)]
+	pub struct TracingUnboundedSender<T>(&'static str, UnboundedSender<T>);
+
+	// Strangely, deriving `Clone` requires that `T` is also `Clone`.
+	impl<T> Clone for TracingUnboundedSender<T> {
+		fn clone(&self) -> Self {
+			Self(self.0, self.1.clone())
+		}
+	}
+
+	/// Wrapper Type around `UnboundedReceiver` that decreases the global
+	/// measure when a message is polled
+	#[derive(Debug)]
+	pub struct TracingUnboundedReceiver<T>(&'static str, UnboundedReceiver<T>);
+
+	/// Wrapper around `mpsc::unbounded` that tracks the in- and outflow via
+	/// `UNBOUNDED_CHANNELS_COUNTER`
+	pub fn tracing_unbounded<T>(
+		key: &'static str,
+	) -> (TracingUnboundedSender<T>, TracingUnboundedReceiver<T>) {
+		let (s, r) = mpsc::unbounded();
+		(TracingUnboundedSender(key, s), TracingUnboundedReceiver(key, r))
+	}
+
+	impl<T> TracingUnboundedSender<T> {
+		/// Proxy function to mpsc::UnboundedSender
+		pub fn poll_ready(&self, ctx: &mut Context) -> Poll<Result<(), SendError>> {
+			self.1.poll_ready(ctx)
+		}
+
+		/// Proxy function to mpsc::UnboundedSender
+		pub fn is_closed(&self) -> bool {
+			self.1.is_closed()
+		}
+
+		/// Proxy function to mpsc::UnboundedSender
+		pub fn close_channel(&self) {
+			self.1.close_channel()
+		}
+
+		/// Proxy function to mpsc::UnboundedSender
+		pub fn disconnect(&mut self) {
+			self.1.disconnect()
+		}
+
+		/// Proxy function to mpsc::UnboundedSender
+		pub fn start_send(&mut self, msg: T) -> Result<(), SendError> {
+			self.1.start_send(msg)
+		}
+
+		/// Proxy function to mpsc::UnboundedSender
+		pub fn unbounded_send(&self, msg: T) -> Result<(), TrySendError<T>> {
+			self.1.unbounded_send(msg).map(|s| {
+				UNBOUNDED_CHANNELS_COUNTER.with_label_values(&[self.0, "send"]).inc();
+				s
+			})
+		}
+
+		/// Proxy function to mpsc::UnboundedSender
+		pub fn same_receiver(&self, other: &UnboundedSender<T>) -> bool {
+			self.1.same_receiver(other)
+		}
+	}
+
+	impl<T> TracingUnboundedReceiver<T> {
+		fn consume(&mut self) {
+			// consume all items, make sure to reflect the updated count
+			let mut count = 0;
+			loop {
+				if self.1.is_terminated() {
+					break
+				}
+
+				match self.try_next() {
+					Ok(Some(..)) => count += 1,
+					_ => break,
+				}
+			}
+			// and discount the messages
+			if count > 0 {
+				UNBOUNDED_CHANNELS_COUNTER.with_label_values(&[self.0, "dropped"]).inc_by(count);
+			}
+		}
+
+		/// Proxy function to mpsc::UnboundedReceiver
+		/// that consumes all messages first and updates the counter
+		pub fn close(&mut self) {
+			self.consume();
+			self.1.close()
+		}
+
+		/// Proxy function to mpsc::UnboundedReceiver
+		/// that discounts the messages taken out
+		pub fn try_next(&mut self) -> Result<Option<T>, TryRecvError> {
+			self.1.try_next().map(|s| {
+				if s.is_some() {
+					UNBOUNDED_CHANNELS_COUNTER.with_label_values(&[self.0, "received"]).inc();
+				}
+				s
+			})
+		}
+	}
+
+	impl<T> Drop for TracingUnboundedReceiver<T> {
+		fn drop(&mut self) {
+			self.consume();
+		}
+	}
+
+	impl<T> Unpin for TracingUnboundedReceiver<T> {}
+
+	impl<T> Stream for TracingUnboundedReceiver<T> {
+		type Item = T;
+
+		fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<T>> {
+			let s = self.get_mut();
+			match Pin::new(&mut s.1).poll_next(cx) {
+				Poll::Ready(msg) => {
+					if msg.is_some() {
+						UNBOUNDED_CHANNELS_COUNTER.with_label_values(&[s.0, "received"]).inc();
+					}
+					Poll::Ready(msg)
+				},
+				Poll::Pending => Poll::Pending,
+			}
+		}
+	}
+
+	impl<T> FusedStream for TracingUnboundedReceiver<T> {
+		fn is_terminated(&self) -> bool {
+			self.1.is_terminated()
+		}
+	}
+
+	impl<T> Sink<T> for TracingUnboundedSender<T> {
+		type Error = SendError;
+
+		fn poll_ready(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+			TracingUnboundedSender::poll_ready(&*self, cx)
+		}
+
+		fn start_send(mut self: Pin<&mut Self>, msg: T) -> Result<(), Self::Error> {
+			TracingUnboundedSender::start_send(&mut *self, msg)
+		}
+
+		fn poll_flush(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+			Poll::Ready(Ok(()))
+		}
+
+		fn poll_close(
+			mut self: Pin<&mut Self>,
+			_: &mut Context<'_>,
+		) -> Poll<Result<(), Self::Error>> {
+			self.disconnect();
+			Poll::Ready(Ok(()))
+		}
+	}
+
+	impl<T> Sink<T> for &TracingUnboundedSender<T> {
+		type Error = SendError;
+
+		fn poll_ready(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+			TracingUnboundedSender::poll_ready(*self, cx)
+		}
+
+		fn start_send(self: Pin<&mut Self>, msg: T) -> Result<(), Self::Error> {
+			self.unbounded_send(msg).map_err(TrySendError::into_send_error)
+		}
+
+		fn poll_flush(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+			Poll::Ready(Ok(()))
+		}
+
+		fn poll_close(self: Pin<&mut Self>, _: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+			self.close_channel();
+			Poll::Ready(Ok(()))
+		}
+	}
+}
+
+pub use inner::{tracing_unbounded, TracingUnboundedReceiver, TracingUnboundedSender};