1 files changed, 161 insertions, 0 deletions
diff --git a/services/sync/golden_gate/src/log.rs b/services/sync/golden_gate/src/log.rs
new file mode 100644
index 0000000000..de7fd0dfc3
--- /dev/null
+++ b/services/sync/golden_gate/src/log.rs
@@ -0,0 +1,161 @@
+/* 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 http://mozilla.org/MPL/2.0/. */
+
+use std::fmt::{self, Write};
+
+use log::{Level, LevelFilter, Log, Metadata, Record};
+use moz_task::{Task, TaskRunnable, ThreadPtrHandle, ThreadPtrHolder};
+use nserror::nsresult;
+use nsstring::nsString;
+use xpcom::{interfaces::mozIServicesLogSink, RefPtr};
+
+pub struct LogSink {
+    pub max_level: LevelFilter,
+    logger: Option<ThreadPtrHandle<mozIServicesLogSink>>,
+}
+
+impl Default for LogSink {
+    fn default() -> Self {
+        LogSink {
+            max_level: LevelFilter::Off,
+            logger: None,
+        }
+    }
+}
+
+impl LogSink {
+    /// Creates a log sink that adapts the Rust `log` crate to the Sync
+    /// `Log.sys.mjs` logger.
+    ///
+    /// This is copied from `bookmark_sync::Logger`. It would be nice to share
+    /// these, but, for now, we've just duplicated it to make prototyping
+    /// easier.
+    #[inline]
+    pub fn new(max_level: LevelFilter, logger: ThreadPtrHandle<mozIServicesLogSink>) -> LogSink {
+        LogSink {
+            max_level,
+            logger: Some(logger),
+        }
+    }
+
+    /// Creates a log sink using the given Services `logger` as the
+    /// underlying implementation. The `logger` will always be called
+    /// asynchronously on its owning thread; it doesn't need to be
+    /// thread-safe.
+    pub fn with_logger(logger: Option<&mozIServicesLogSink>) -> Result<LogSink, nsresult> {
+        Ok(if let Some(logger) = logger {
+            // Fetch the maximum log level while we're on the main thread, so
+            // that `LogSink::enabled()` can check it while on the background
+            // thread. Otherwise, we'd need to dispatch a `LogTask` for every
+            // log message, only to discard most of them when the task calls
+            // into the logger on the main thread.
+            let mut raw_max_level = 0i16;
+            let rv = unsafe { logger.GetMaxLevel(&mut raw_max_level) };
+            let max_level = if rv.succeeded() {
+                match raw_max_level {
+                    mozIServicesLogSink::LEVEL_ERROR => LevelFilter::Error,
+                    mozIServicesLogSink::LEVEL_WARN => LevelFilter::Warn,
+                    mozIServicesLogSink::LEVEL_DEBUG => LevelFilter::Debug,
+                    mozIServicesLogSink::LEVEL_TRACE => LevelFilter::Trace,
+                    mozIServicesLogSink::LEVEL_INFO => LevelFilter::Info,
+                    _ => LevelFilter::Off,
+                }
+            } else {
+                LevelFilter::Off
+            };
+            LogSink::new(
+                max_level,
+                ThreadPtrHolder::new(cstr!("mozIServicesLogSink"), RefPtr::new(logger))?,
+            )
+        } else {
+            LogSink::default()
+        })
+    }
+
+    /// Returns a reference to the underlying `mozIServicesLogSink`.
+    pub fn logger(&self) -> Option<&mozIServicesLogSink> {
+        self.logger.as_ref().and_then(|l| l.get())
+    }
+
+    /// Logs a message to the Sync logger, if one is set. This would be better
+    /// implemented as a macro, as Dogear does, so that we can pass variadic
+    /// arguments without manually invoking `fmt_args!()` every time we want
+    /// to log a message.
+    ///
+    /// The `log` crate's macros aren't suitable here, because those log to the
+    /// global logger. However, we don't want to set the global logger in our
+    /// crate, because that will log _everything_ that uses the Rust `log` crate
+    /// to the Sync logs, including WebRender and audio logging.
+    pub fn debug(&self, args: fmt::Arguments) {
+        let meta = Metadata::builder()
+            .level(Level::Debug)
+            .target(module_path!())
+            .build();
+        if self.enabled(&meta) {
+            self.log(&Record::builder().args(args).metadata(meta).build());
+        }
+    }
+}
+
+impl Log for LogSink {
+    #[inline]
+    fn enabled(&self, meta: &Metadata) -> bool {
+        self.logger.is_some() && meta.level() <= self.max_level
+    }
+
+    fn log(&self, record: &Record) {
+        if !self.enabled(record.metadata()) {
+            return;
+        }
+        if let Some(logger) = &self.logger {
+            let mut message = nsString::new();
+            if write!(message, "{}", record.args()).is_ok() {
+                let task = LogTask {
+                    logger: logger.clone(),
+                    level: record.metadata().level(),
+                    message,
+                };
+                let _ = TaskRunnable::new("extension_storage_sync::Logger::log", Box::new(task))
+                    .and_then(|r| TaskRunnable::dispatch(r, logger.owning_thread()));
+            }
+        }
+    }
+
+    fn flush(&self) {}
+}
+
+/// Logs a message to the mirror logger. This task is created on the background
+/// thread queue, and dispatched to the main thread.
+struct LogTask {
+    logger: ThreadPtrHandle<mozIServicesLogSink>,
+    level: Level,
+    message: nsString,
+}
+
+impl Task for LogTask {
+    fn run(&self) {
+        let logger = self.logger.get().unwrap();
+        match self.level {
+            Level::Error => unsafe {
+                logger.Error(&*self.message);
+            },
+            Level::Warn => unsafe {
+                logger.Warn(&*self.message);
+            },
+            Level::Debug => unsafe {
+                logger.Debug(&*self.message);
+            },
+            Level::Trace => unsafe {
+                logger.Trace(&*self.message);
+            },
+            Level::Info => unsafe {
+                logger.Info(&*self.message);
+            },
+        }
+    }
+
+    fn done(&self) -> Result<(), nsresult> {
+        Ok(())
+    }
+}