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// Copyright 2017-2020 Parity Technologies (UK) Ltd. // This file is part of Substrate. // Substrate 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. // Substrate 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 Substrate. If not, see <http://www.gnu.org/licenses/>. //! Telemetry utilities. //! //! Calling `init_telemetry` registers a global `slog` logger using `slog_scope::set_global_logger`. //! After that, calling `slog_scope::with_logger` will return a logger that sends information to //! the telemetry endpoints. The `telemetry!` macro is a short-cut for calling //! `slog_scope::with_logger` followed with `slog_log!`. //! //! Note that you are supposed to only ever use `telemetry!` and not `slog_scope::with_logger` at //! the moment. Substate may eventually be reworked to get proper `slog` support, including sending //! information to the telemetry. //! //! The [`Telemetry`] struct implements `Stream` and must be polled regularly (or sent to a //! background thread/task) in order for the telemetry to properly function. Dropping the object //! will also deregister the global logger and replace it with a logger that discards messages. //! The `Stream` generates [`TelemetryEvent`]s. //! //! > **Note**: Cloning the [`Telemetry`] and polling from multiple clones has an unspecified behaviour. //! //! # Example //! //! ```no_run //! use futures::prelude::*; //! //! let telemetry = sc_telemetry::init_telemetry(sc_telemetry::TelemetryConfig { //! endpoints: sc_telemetry::TelemetryEndpoints::new(vec![ //! // The `0` is the maximum verbosity level of messages to send to this endpoint. //! ("wss://example.com".into(), 0) //! ]), //! // Can be used to pass an external implementation of WebSockets. //! wasm_external_transport: None, //! }); //! //! // The `telemetry` object implements `Stream` and must be processed. //! std::thread::spawn(move || { //! futures::executor::block_on(telemetry.for_each(|_| future::ready(()))); //! }); //! //! // Sends a message on the telemetry. //! sc_telemetry::telemetry!(sc_telemetry::SUBSTRATE_INFO; "test"; //! "foo" => "bar", //! ) //! ``` //! use futures::{prelude::*, channel::mpsc}; use libp2p::{Multiaddr, wasm_ext}; use log::{error, warn}; use parking_lot::Mutex; use serde::{Serialize, Deserialize}; use std::{pin::Pin, sync::Arc, task::{Context, Poll}, time::Duration}; use wasm_timer::Instant; pub use libp2p::wasm_ext::ExtTransport; pub use slog_scope::with_logger; pub use slog; mod async_record; mod worker; /// Configuration for telemetry. pub struct TelemetryConfig { /// Collection of telemetry WebSocket servers with a corresponding verbosity level. pub endpoints: TelemetryEndpoints, /// Optional external implementation of a libp2p transport. Used in WASM contexts where we need /// some binding between the networking provided by the operating system or environment and /// libp2p. /// /// This parameter exists whatever the target platform is, but it is expected to be set to /// `Some` only when compiling for WASM. /// /// > **Important**: Each individual call to `write` corresponds to one message. There is no /// > internal buffering going on. In the context of WebSockets, each `write` /// > must be one individual WebSockets frame. pub wasm_external_transport: Option<wasm_ext::ExtTransport>, } /// List of telemetry servers we want to talk to. Contains the URL of the server, and the /// maximum verbosity level. /// /// The URL string can be either a URL or a multiaddress. #[derive(Debug, Clone, Serialize, Deserialize, PartialEq)] pub struct TelemetryEndpoints(Vec<(String, u8)>); impl TelemetryEndpoints { pub fn new(endpoints: Vec<(String, u8)>) -> Self { TelemetryEndpoints(endpoints) } } /// Log levels. pub const SUBSTRATE_DEBUG: &str = "9"; pub const SUBSTRATE_INFO: &str = "0"; pub const CONSENSUS_TRACE: &str = "9"; pub const CONSENSUS_DEBUG: &str = "5"; pub const CONSENSUS_WARN: &str = "4"; pub const CONSENSUS_INFO: &str = "1"; /// Telemetry object. Implements `Future` and must be polled regularly. /// Contains an `Arc` and can be cloned and pass around. Only one clone needs to be polled /// regularly and should be polled regularly. /// Dropping all the clones unregisters the telemetry. #[derive(Clone)] pub struct Telemetry { inner: Arc<Mutex<TelemetryInner>>, /// Slog guard so that we don't get deregistered. _guard: Arc<slog_scope::GlobalLoggerGuard>, } /// Behind the `Mutex` in `Telemetry`. /// /// Note that ideally we wouldn't have to make the `Telemetry` cloneable, as that would remove the /// need for a `Mutex`. However there is currently a weird hack in place in `sc-service` /// where we extract the telemetry registration so that it continues running during the shutdown /// process. struct TelemetryInner { /// Worker for the telemetry. `None` if it failed to initialize. worker: Option<worker::TelemetryWorker>, /// Receives log entries for them to be dispatched to the worker. receiver: mpsc::Receiver<async_record::AsyncRecord>, } /// Implements `slog::Drain`. struct TelemetryDrain { /// Sends log entries. sender: std::panic::AssertUnwindSafe<mpsc::Sender<async_record::AsyncRecord>>, } /// Initializes the telemetry. See the crate root documentation for more information. /// /// Please be careful to not call this function twice in the same program. The `slog` crate /// doesn't provide any way of knowing whether a global logger has already been registered. pub fn init_telemetry(config: TelemetryConfig) -> Telemetry { // Build the list of telemetry endpoints. let mut endpoints = Vec::new(); for &(ref url, verbosity) in &config.endpoints.0 { match url_to_multiaddr(url) { Ok(addr) => endpoints.push((addr, verbosity)), Err(err) => warn!(target: "telemetry", "Invalid telemetry URL {}: {}", url, err), } } let (sender, receiver) = mpsc::channel(16); let guard = { let logger = TelemetryDrain { sender: std::panic::AssertUnwindSafe(sender) }; let root = slog::Logger::root(slog::Drain::fuse(logger), slog::o!()); slog_scope::set_global_logger(root) }; let worker = match worker::TelemetryWorker::new(endpoints, config.wasm_external_transport) { Ok(w) => Some(w), Err(err) => { error!(target: "telemetry", "Failed to initialize telemetry worker: {:?}", err); None } }; Telemetry { inner: Arc::new(Mutex::new(TelemetryInner { worker, receiver, })), _guard: Arc::new(guard), } } /// Event generated when polling the worker. #[derive(Debug)] pub enum TelemetryEvent { /// We have established a connection to one of the telemetry endpoint, either for the first /// time or after having been disconnected earlier. Connected, } impl Stream for Telemetry { type Item = TelemetryEvent; fn poll_next(self: Pin<&mut Self>, cx: &mut Context) -> Poll<Option<Self::Item>> { let before = Instant::now(); // Because the `Telemetry` is cloneable, we need to put the actual fields behind a `Mutex`. // However, the user is only ever supposed to poll from one instance of `Telemetry`, while // the other instances are used only for RAII purposes. // We assume that the user is following this advice and therefore that the `Mutex` is only // ever locked once at a time. let mut inner = match self.inner.try_lock() { Some(l) => l, None => { warn!( target: "telemetry", "The telemetry seems to be polled multiple times simultaneously" ); // Returning `Pending` here means that we may never get polled again, but this is // ok because we're in a situation where something else is actually currently doing // the polling. return Poll::Pending; } }; let mut has_connected = false; // The polling pattern is: poll the worker so that it processes its queue, then add one // message from the receiver (if possible), then poll the worker again, and so on. loop { if let Some(worker) = inner.worker.as_mut() { while let Poll::Ready(event) = worker.poll(cx) { // Right now we only have one possible event. This line is here in order to not // forget to handle any possible new event type. let worker::TelemetryWorkerEvent::Connected = event; has_connected = true; } } if let Poll::Ready(Some(log_entry)) = Stream::poll_next(Pin::new(&mut inner.receiver), cx) { if let Some(worker) = inner.worker.as_mut() { log_entry.as_record_values(|rec, val| { let _ = worker.log(rec, val); }); } } else { break; } } if before.elapsed() > Duration::from_millis(200) { warn!(target: "telemetry", "Polling the telemetry took more than 200ms"); } if has_connected { Poll::Ready(Some(TelemetryEvent::Connected)) } else { Poll::Pending } } } impl slog::Drain for TelemetryDrain { type Ok = (); type Err = (); fn log(&self, record: &slog::Record, values: &slog::OwnedKVList) -> Result<Self::Ok, Self::Err> { let before = Instant::now(); let serialized = async_record::AsyncRecord::from(record, values); // Note: interestingly, `try_send` requires a `&mut` because it modifies some internal value, while `clone()` // is lock-free. if let Err(err) = self.sender.clone().try_send(serialized) { warn!(target: "telemetry", "Ignored telemetry message because of error on channel: {:?}", err); } if before.elapsed() > Duration::from_millis(50) { warn!(target: "telemetry", "Writing a telemetry log took more than 50ms"); } Ok(()) } } /// Parses a WebSocket URL into a libp2p `Multiaddr`. fn url_to_multiaddr(url: &str) -> Result<Multiaddr, libp2p::multiaddr::Error> { // First, assume that we have a `Multiaddr`. let parse_error = match url.parse() { Ok(ma) => return Ok(ma), Err(err) => err, }; // If not, try the `ws://path/url` format. if let Ok(ma) = libp2p::multiaddr::from_url(url) { return Ok(ma) } // If we have no clue about the format of that string, assume that we were expecting a // `Multiaddr`. Err(parse_error) } /// Translates to `slog_scope::info`, but contains an additional verbosity /// parameter which the log record is tagged with. Additionally the verbosity /// parameter is added to the record as a key-value pair. #[macro_export] macro_rules! telemetry { ( $a:expr; $b:expr; $( $t:tt )* ) => { $crate::with_logger(|l| { $crate::slog::slog_info!(l, #$a, $b; $($t)* ) }) } }