2 files changed, 137 insertions, 0 deletions

diff --git a/crates/ra_progress/Cargo.toml b/crates/ra_progress/Cargo.toml
new file mode 100644
index 000000000..c7f7c6dd3
--- /dev/null
+++ b/crates/ra_progress/Cargo.toml
@@ -0,0 +1,8 @@
+[package]
+name = "ra_progress"
+version = "0.1.0"
+authors = ["rust-analyzer developers"]
+edition = "2018"
+
+[dependencies]
+crossbeam-channel = { version = "0.4" }
diff --git a/crates/ra_progress/src/lib.rs b/crates/ra_progress/src/lib.rs
new file mode 100644
index 000000000..0ff1f846c
--- /dev/null
+++ b/crates/ra_progress/src/lib.rs
@@ -0,0 +1,129 @@
+//! General-purpose instrumentation for progress reporting.
+//!
+//! Note:
+//! Most of the methods accept `&mut self` just to be more restrictive (for forward compat)
+//! even tho for some of them we can weaken this requirement to shared reference (`&self`).
+
+use crossbeam_channel::Receiver;
+use std::fmt;
+
+#[derive(Debug)]
+pub enum ProgressStatus<B, P> {
+    Begin(B),
+    Progress(P),
+    End,
+}
+
+pub struct Progress<B, P>(Option<crossbeam_channel::Sender<ProgressStatus<B, P>>>);
+impl<B, P> Progress<B, P> {
+    pub fn report(&mut self, payload: P) {
+        self.report_with(|| payload);
+    }
+
+    pub fn report_with(&mut self, payload: impl FnOnce() -> P) {
+        self.send_status(|| ProgressStatus::Progress(payload()));
+    }
+
+    fn send_status(&self, status: impl FnOnce() -> ProgressStatus<B, P>) {
+        if let Some(sender) = &self.0 {
+            sender.try_send(status()).expect("progress report must not block");
+        }
+    }
+}
+
+impl<B, P> Drop for Progress<B, P> {
+    fn drop(&mut self) {
+        self.send_status(|| ProgressStatus::End);
+    }
+}
+
+pub struct ProgressSource<B, P>(Option<crossbeam_channel::Sender<ProgressStatus<B, P>>>);
+impl<B, P> ProgressSource<B, P> {
+    pub fn real_if(real: bool) -> (Receiver<ProgressStatus<B, P>>, Self) {
+        if real {
+            let (sender, receiver) = crossbeam_channel::unbounded();
+            (receiver, Self(Some(sender)))
+        } else {
+            (crossbeam_channel::never(), Self(None))
+        }
+    }
+
+    pub fn begin(&mut self, payload: B) -> Progress<B, P> {
+        self.begin_with(|| payload)
+    }
+
+    pub fn begin_with(&mut self, payload: impl FnOnce() -> B) -> Progress<B, P> {
+        let progress = Progress(self.0.clone());
+        progress.send_status(|| ProgressStatus::Begin(payload()));
+        progress
+    }
+}
+
+impl<B, P> Clone for ProgressSource<B, P> {
+    fn clone(&self) -> Self {
+        Self(self.0.clone())
+    }
+}
+
+impl<B, P> fmt::Debug for ProgressSource<B, P> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_tuple("ProgressSource").field(&self.0).finish()
+    }
+}
+
+pub type U32ProgressStatus = ProgressStatus<U32ProgressReport, U32ProgressReport>;
+
+#[derive(Debug)]
+pub struct U32ProgressReport {
+    pub processed: u32,
+    pub total: u32,
+}
+impl U32ProgressReport {
+    pub fn percentage(&self) -> f64 {
+        f64::from(100 * self.processed) / f64::from(self.total)
+    }
+    pub fn to_message(&self, prefix: &str, unit: &str) -> String {
+        format!("{} ({}/{} {})", prefix, self.processed, self.total, unit)
+    }
+}
+
+pub struct U32Progress {
+    inner: Progress<U32ProgressReport, U32ProgressReport>,
+    processed: u32,
+    total: u32,
+}
+
+#[derive(Debug, Eq, PartialEq)]
+pub struct IsDone(pub bool);
+
+impl U32Progress {
+    pub fn report(&mut self, new_processed: u32) -> IsDone {
+        if self.processed < new_processed {
+            self.processed = new_processed;
+            self.inner.report(U32ProgressReport { processed: new_processed, total: self.total });
+        }
+        IsDone(self.processed >= self.total)
+    }
+}
+
+#[derive(Clone)]
+pub struct U32ProgressSource {
+    inner: ProgressSource<U32ProgressReport, U32ProgressReport>,
+}
+
+impl U32ProgressSource {
+    pub fn real_if(
+        real: bool,
+    ) -> (Receiver<ProgressStatus<U32ProgressReport, U32ProgressReport>>, Self) {
+        let (recv, inner) = ProgressSource::real_if(real);
+        (recv, Self { inner })
+    }
+
+    pub fn begin(&mut self, initial: u32, total: u32) -> U32Progress {
+        U32Progress {
+            inner: self.inner.begin(U32ProgressReport { processed: initial, total }),
+            processed: initial,
+            total,
+        }
+    }
+}