From efa6a952b4cb9c9f139822fbf9781a610bba3813 Mon Sep 17 00:00:00 2001
From: Aleksey Kladov <aleksey.kladov@gmail.com>
Date: Fri, 31 Aug 2018 10:27:38 +0300
Subject: [PATCH] cancelation tokens

---
 crates/libanalysis/Cargo.toml |  1 +
 crates/libanalysis/src/job.rs | 49 +++++++++++++++++++++++++++++++++++
 crates/libanalysis/src/lib.rs |  4 +++
 3 files changed, 54 insertions(+)
 create mode 100644 crates/libanalysis/src/job.rs

diff --git a/crates/libanalysis/Cargo.toml b/crates/libanalysis/Cargo.toml
index 1f072533cf..9c7977e929 100644
--- a/crates/libanalysis/Cargo.toml
+++ b/crates/libanalysis/Cargo.toml
@@ -6,6 +6,7 @@ authors = ["Aleksey Kladov <aleksey.kladov@gmail.com>"]
 [dependencies]
 relative-path = "0.3.7"
 log = "0.4.2"
+crossbeam-channel = "0.2.4"
 parking_lot = "0.6.3"
 once_cell = "0.1.4"
 rayon = "1.0.2"
diff --git a/crates/libanalysis/src/job.rs b/crates/libanalysis/src/job.rs
new file mode 100644
index 0000000000..4d393b915a
--- /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,
+    }
+}
diff --git a/crates/libanalysis/src/lib.rs b/crates/libanalysis/src/lib.rs
index c25d31f4bc..20ddb69d65 100644
--- a/crates/libanalysis/src/lib.rs
+++ b/crates/libanalysis/src/lib.rs
@@ -7,10 +7,13 @@ extern crate libeditor;
 extern crate fst;
 extern crate rayon;
 extern crate relative_path;
+#[macro_use]
+extern crate crossbeam_channel;
 
 mod symbol_index;
 mod module_map;
 mod imp;
+mod job;
 
 use std::sync::Arc;
 
@@ -22,6 +25,7 @@ pub use libeditor::{
     StructureNode, LineIndex, FileSymbol,
     Runnable, RunnableKind, HighlightedRange, CompletionItem,
 };
+pub use job::{JobToken, JobHandle};
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct FileId(pub u32);