Move logers into seperate logger files

Constellation seems to have lots of code that could be moved into
seperate files. `FromScriptLogger` and `FromCompositorLogger` seem
to qualify for that.
Moved FromScriptLogger and FromScriptLogger to logger file.

4 files changed, 130 insertions, 114 deletions

diff --git a/components/constellation/constellation.rs b/components/constellation/constellation.rs
index 2d30004746e..88c0af2e202 100644
--- a/components/constellation/constellation.rs
+++ b/components/constellation/constellation.rs
@@ -102,7 +102,6 @@ use crate::session_history::{
 };
 use crate::timer_scheduler::TimerScheduler;
 use background_hang_monitor::HangMonitorRegister;
-use backtrace::Backtrace;
 use bluetooth_traits::BluetoothRequest;
 use canvas_traits::canvas::{CanvasId, CanvasMsg};
 use canvas_traits::webgl::WebGLThreads;
@@ -127,7 +126,6 @@ use ipc_channel::Error as IpcError;
 use keyboard_types::webdriver::Event as WebDriverInputEvent;
 use keyboard_types::KeyboardEvent;
 use layout_traits::LayoutThreadFactory;
-use log::{Level, LevelFilter, Log, Metadata, Record};
 use media::{GLPlayerThreads, WindowGLContext};
 use msg::constellation_msg::{
     BackgroundHangMonitorControlMsg, BackgroundHangMonitorRegister, HangMonitorAlert,
@@ -168,7 +166,6 @@ use script_traits::{SWManagerMsg, SWManagerSenders, UpdatePipelineIdReason, WebD
 use serde::{Deserialize, Serialize};
 use servo_config::{opts, pref};
 use servo_rand::{random, Rng, ServoRng, SliceRandom};
-use servo_remutex::ReentrantMutex;
 use servo_url::{Host, ImmutableOrigin, ServoUrl};
 use std::borrow::{Cow, ToOwned};
 use std::collections::hash_map::Entry;
@@ -613,113 +610,6 @@ enum ExitPipelineMode {
     Force,
 }
 
-/// The constellation uses logging to perform crash reporting.
-/// The constellation receives all `warn!`, `error!` and `panic!` messages,
-/// and generates a crash report when it receives a panic.
-
-/// A logger directed at the constellation from content processes
-#[derive(Clone)]
-pub struct FromScriptLogger {
-    /// A channel to the constellation
-    pub script_to_constellation_chan: Arc<ReentrantMutex<ScriptToConstellationChan>>,
-}
-
-impl FromScriptLogger {
-    /// Create a new constellation logger.
-    pub fn new(script_to_constellation_chan: ScriptToConstellationChan) -> FromScriptLogger {
-        FromScriptLogger {
-            script_to_constellation_chan: Arc::new(ReentrantMutex::new(
-                script_to_constellation_chan,
-            )),
-        }
-    }
-
-    /// The maximum log level the constellation logger is interested in.
-    pub fn filter(&self) -> LevelFilter {
-        LevelFilter::Warn
-    }
-}
-
-impl Log for FromScriptLogger {
-    fn enabled(&self, metadata: &Metadata) -> bool {
-        metadata.level() <= Level::Warn
-    }
-
-    fn log(&self, record: &Record) {
-        if let Some(entry) = log_entry(record) {
-            debug!("Sending log entry {:?}.", entry);
-            let thread_name = thread::current().name().map(ToOwned::to_owned);
-            let msg = FromScriptMsg::LogEntry(thread_name, entry);
-            let chan = self
-                .script_to_constellation_chan
-                .lock()
-                .unwrap_or_else(|err| err.into_inner());
-            let _ = chan.send(msg);
-        }
-    }
-
-    fn flush(&self) {}
-}
-
-/// A logger directed at the constellation from the compositor
-#[derive(Clone)]
-pub struct FromCompositorLogger {
-    /// A channel to the constellation
-    pub constellation_chan: Arc<ReentrantMutex<Sender<FromCompositorMsg>>>,
-}
-
-impl FromCompositorLogger {
-    /// Create a new constellation logger.
-    pub fn new(constellation_chan: Sender<FromCompositorMsg>) -> FromCompositorLogger {
-        FromCompositorLogger {
-            constellation_chan: Arc::new(ReentrantMutex::new(constellation_chan)),
-        }
-    }
-
-    /// The maximum log level the constellation logger is interested in.
-    pub fn filter(&self) -> LevelFilter {
-        LevelFilter::Warn
-    }
-}
-
-impl Log for FromCompositorLogger {
-    fn enabled(&self, metadata: &Metadata) -> bool {
-        metadata.level() <= Level::Warn
-    }
-
-    fn log(&self, record: &Record) {
-        if let Some(entry) = log_entry(record) {
-            debug!("Sending log entry {:?}.", entry);
-            let top_level_id = TopLevelBrowsingContextId::installed();
-            let thread_name = thread::current().name().map(ToOwned::to_owned);
-            let msg = FromCompositorMsg::LogEntry(top_level_id, thread_name, entry);
-            let chan = self
-                .constellation_chan
-                .lock()
-                .unwrap_or_else(|err| err.into_inner());
-            let _ = chan.send(msg);
-        }
-    }
-
-    fn flush(&self) {}
-}
-
-/// Rust uses `Record` for storing logging, but servo converts that to
-/// a `LogEntry`. We do this so that we can record panics as well as log
-/// messages, and because `Record` does not implement serde (de)serialization,
-/// so cannot be used over an IPC channel.
-fn log_entry(record: &Record) -> Option<LogEntry> {
-    match record.level() {
-        Level::Error if thread::panicking() => Some(LogEntry::Panic(
-            format!("{}", record.args()),
-            format!("{:?}", Backtrace::new()),
-        )),
-        Level::Error => Some(LogEntry::Error(format!("{}", record.args()))),
-        Level::Warn => Some(LogEntry::Warn(format!("{}", record.args()))),
-        _ => None,
-    }
-}
-
 /// The number of warnings to include in each crash report.
 const WARNINGS_BUFFER_SIZE: usize = 32;
 
diff --git a/components/constellation/lib.rs b/components/constellation/lib.rs
index 92495c50cd9..837c7235169 100644
--- a/components/constellation/lib.rs
+++ b/components/constellation/lib.rs
@@ -14,6 +14,7 @@ extern crate serde;
 mod browsingcontext;
 mod constellation;
 mod event_loop;
+mod logging;
 mod network_listener;
 mod pipeline;
 mod sandboxing;
@@ -21,8 +22,7 @@ mod serviceworker;
 mod session_history;
 mod timer_scheduler;
 
-pub use crate::constellation::{
-    Constellation, FromCompositorLogger, FromScriptLogger, InitialConstellationState,
-};
+pub use crate::constellation::{Constellation, InitialConstellationState};
+pub use crate::logging::{FromCompositorLogger, FromScriptLogger};
 pub use crate::pipeline::UnprivilegedPipelineContent;
 pub use crate::sandboxing::{content_process_sandbox_profile, UnprivilegedContent};
diff --git a/components/constellation/logging.rs b/components/constellation/logging.rs
new file mode 100644
index 00000000000..c267565658f
--- /dev/null
+++ b/components/constellation/logging.rs
@@ -0,0 +1,126 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use backtrace::Backtrace;
+use compositing::ConstellationMsg as FromCompositorMsg;
+use crossbeam_channel::Sender;
+use log::{Level, LevelFilter, Log, Metadata, Record};
+use msg::constellation_msg::TopLevelBrowsingContextId;
+use script_traits::{LogEntry, ScriptMsg as FromScriptMsg, ScriptToConstellationChan};
+use servo_remutex::ReentrantMutex;
+use std::borrow::ToOwned;
+use std::sync::Arc;
+use std::thread;
+
+/// The constellation uses logging to perform crash reporting.
+/// The constellation receives all `warn!`, `error!` and `panic!` messages,
+/// and generates a crash report when it receives a panic.
+
+/// A logger directed at the constellation from content processes
+/// #[derive(Clone)]
+pub struct FromScriptLogger {
+    /// A channel to the constellation
+    pub script_to_constellation_chan: Arc<ReentrantMutex<ScriptToConstellationChan>>,
+}
+
+/// The constellation uses logging to perform crash reporting.
+/// The constellation receives all `warn!`, `error!` and `panic!` messages,
+/// and generates a crash report when it receives a panic.
+
+/// A logger directed at the constellation from content processes
+impl FromScriptLogger {
+    /// Create a new constellation logger.
+    pub fn new(script_to_constellation_chan: ScriptToConstellationChan) -> FromScriptLogger {
+        FromScriptLogger {
+            script_to_constellation_chan: Arc::new(ReentrantMutex::new(
+                script_to_constellation_chan,
+            )),
+        }
+    }
+
+    /// The maximum log level the constellation logger is interested in.
+    pub fn filter(&self) -> LevelFilter {
+        LevelFilter::Warn
+    }
+}
+
+impl Log for FromScriptLogger {
+    fn enabled(&self, metadata: &Metadata) -> bool {
+        metadata.level() <= Level::Warn
+    }
+
+    fn log(&self, record: &Record) {
+        if let Some(entry) = log_entry(record) {
+            debug!("Sending log entry {:?}.", entry);
+            let thread_name = thread::current().name().map(ToOwned::to_owned);
+            let msg = FromScriptMsg::LogEntry(thread_name, entry);
+            let chan = self
+                .script_to_constellation_chan
+                .lock()
+                .unwrap_or_else(|err| err.into_inner());
+            let _ = chan.send(msg);
+        }
+    }
+
+    fn flush(&self) {}
+}
+
+/// A logger directed at the constellation from the compositor
+#[derive(Clone)]
+pub struct FromCompositorLogger {
+    /// A channel to the constellation
+    pub constellation_chan: Arc<ReentrantMutex<Sender<FromCompositorMsg>>>,
+}
+
+impl FromCompositorLogger {
+    /// Create a new constellation logger.
+    pub fn new(constellation_chan: Sender<FromCompositorMsg>) -> FromCompositorLogger {
+        FromCompositorLogger {
+            constellation_chan: Arc::new(ReentrantMutex::new(constellation_chan)),
+        }
+    }
+
+    /// The maximum log level the constellation logger is interested in.
+    pub fn filter(&self) -> LevelFilter {
+        LevelFilter::Warn
+    }
+}
+
+impl Log for FromCompositorLogger {
+    fn enabled(&self, metadata: &Metadata) -> bool {
+        metadata.level() <= Level::Warn
+    }
+
+    fn log(&self, record: &Record) {
+        if let Some(entry) = log_entry(record) {
+            debug!("Sending log entry {:?}.", entry);
+            let top_level_id = TopLevelBrowsingContextId::installed();
+            let thread_name = thread::current().name().map(ToOwned::to_owned);
+            let msg = FromCompositorMsg::LogEntry(top_level_id, thread_name, entry);
+            let chan = self
+                .constellation_chan
+                .lock()
+                .unwrap_or_else(|err| err.into_inner());
+            let _ = chan.send(msg);
+        }
+    }
+
+    fn flush(&self) {}
+}
+
+/// Rust uses `Record` for storing logging, but servo converts that to
+/// a `LogEntry`. We do this so that we can record panics as well as log
+/// messages, and because `Record` does not implement serde (de)serialization,
+/// so cannot be used over an IPC channel.
+fn log_entry(record: &Record) -> Option<LogEntry> {
+    match record.level() {
+        Level::Error if thread::panicking() => Some(LogEntry::Panic(
+            format!("{}", record.args()),
+            format!("{:?}", Backtrace::new()),
+        )),
+        Level::Error => Some(LogEntry::Error(format!("{}", record.args()))),
+        Level::Warn => Some(LogEntry::Warn(format!("{}", record.args()))),
+        _ => None,
+    }
+}
diff --git a/docs/HACKING_QUICKSTART.md b/docs/HACKING_QUICKSTART.md
index 3dce59cd575..ac8cf3e00fa 100644
--- a/docs/HACKING_QUICKSTART.md
+++ b/docs/HACKING_QUICKSTART.md
@@ -240,7 +240,7 @@ Using `RUST_LOG="debug"` is usually the very first thing you might want to do if
 RUST_LOG="debug" ./mach run -d -- -i -y 1 /tmp/a.html 2>&1 | ts -s "%.S: " | tee /tmp/log.txt
 ```
 
-You can filter by crate or module, for example `RUST_LOG="layout::inline=debug" ./mach run …`. Check the [env_logger](https://doc.rust-lang.org/log/env_logger/index.html) documentation for more details.
+You can filter by crate or module, for example `RUST_LOG="layout::inline=debug" ./mach run …`. Check the [env_logger](https://docs.rs/env_logger) documentation for more details.
 
 Use `RUST_BACKTRACE=1` to dump the backtrace when Servo panics.