cancelation tokens

1 files changed, 49 insertions, 0 deletions

diff --git a/crates/libanalysis/src/job.rs b/crates/libanalysis/src/job.rs
new file mode 100644
index 000000000..4d393b915
--- /dev/null
+++ b/crates/libanalysis/src/job.rs
@@ -0,0 +1,49 @@
+use crossbeam_channel::{bounded, Receiver, Sender};
+
+pub struct JobHandle {
+    job_alive: Receiver<Never>,
+    _job_canceled: Sender<Never>,
+}
+
+pub struct JobToken {
+    _job_alive: Sender<Never>,
+    job_canceled: Receiver<Never>,
+}
+
+impl JobHandle {
+    pub fn new() -> (JobHandle, JobToken) {
+        let (sender_alive, receiver_alive) = bounded(0);
+        let (sender_canceled, receiver_canceled) = bounded(0);
+        let token = JobToken { _job_alive: sender_alive, job_canceled: receiver_canceled };
+        let handle = JobHandle { job_alive: receiver_alive, _job_canceled: sender_canceled };
+        (handle, token)
+    }
+    pub fn is_alive(&self) -> bool {
+        !is_closed(&self.job_alive)
+    }
+    pub fn cancel(self) {
+    }
+}
+
+impl JobToken {
+    pub fn is_canceled(&self) -> bool {
+        is_closed(&self.job_canceled)
+    }
+}
+
+
+// We don't actually send messages through the channels,
+// and instead just check if the channel is closed,
+// so we use uninhabited enum as a message type
+enum Never {}
+
+/// Nonblocking
+fn is_closed(chan: &Receiver<Never>) -> bool {
+    select! {
+        recv(chan, msg) => match msg {
+            None => true,
+            Some(never) => match never {}
+        }
+        default => false,
+    }
+}