1 files changed, 128 insertions, 0 deletions
diff --git a/src/task/promise.rs b/src/task/promise.rs
new file mode 100644
index 0000000..02e9419
--- /dev/null
+++ b/src/task/promise.rs
@@ -0,0 +1,128 @@
+// Copyright 2019 TiKV Project Authors. Licensed under Apache-2.0.
+
+use std::fmt::{self, Debug, Formatter};
+use std::sync::Arc;
+
+use super::Inner;
+use crate::call::{BatchContext, MessageReader, RpcStatusCode};
+use crate::error::Error;
+
+/// Batch job type.
+#[derive(PartialEq, Debug)]
+pub enum BatchType {
+    /// Finish without reading any message.
+    Finish,
+    /// Extract one message when finish.
+    Read,
+    /// Check the rpc code and then extract one message.
+    CheckRead,
+}
+
+/// A promise used to resolve batch jobs.
+pub struct Batch {
+    ty: BatchType,
+    ctx: BatchContext,
+    inner: Arc<Inner<Option<MessageReader>>>,
+}
+
+impl Batch {
+    pub fn new(ty: BatchType, inner: Arc<Inner<Option<MessageReader>>>) -> Batch {
+        Batch {
+            ty,
+            ctx: BatchContext::new(),
+            inner,
+        }
+    }
+
+    pub fn context(&self) -> &BatchContext {
+        &self.ctx
+    }
+
+    fn read_one_msg(&mut self, success: bool) {
+        let task = {
+            let mut guard = self.inner.lock();
+            if success {
+                guard.set_result(Ok(self.ctx.recv_message()))
+            } else {
+                // rely on C core to handle the failed read (e.g. deliver approriate
+                // statusCode on the clientside).
+                guard.set_result(Ok(None))
+            }
+        };
+        task.map(|t| t.wake());
+    }
+
+    fn finish_response(&mut self, succeed: bool) {
+        let task = {
+            let mut guard = self.inner.lock();
+            if succeed {
+                let status = self.ctx.rpc_status();
+                if status.status == RpcStatusCode::OK {
+                    guard.set_result(Ok(None))
+                } else {
+                    guard.set_result(Err(Error::RpcFailure(status)))
+                }
+            } else {
+                guard.set_result(Err(Error::RemoteStopped))
+            }
+        };
+        task.map(|t| t.wake());
+    }
+
+    fn handle_unary_response(&mut self) {
+        let task = {
+            let mut guard = self.inner.lock();
+            let status = self.ctx.rpc_status();
+            if status.status == RpcStatusCode::OK {
+                guard.set_result(Ok(self.ctx.recv_message()))
+            } else {
+                guard.set_result(Err(Error::RpcFailure(status)))
+            }
+        };
+        task.map(|t| t.wake());
+    }
+
+    pub fn resolve(mut self, success: bool) {
+        match self.ty {
+            BatchType::CheckRead => {
+                assert!(success);
+                self.handle_unary_response();
+            }
+            BatchType::Finish => {
+                self.finish_response(success);
+            }
+            BatchType::Read => {
+                self.read_one_msg(success);
+            }
+        }
+    }
+}
+
+impl Debug for Batch {
+    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
+        write!(f, "Batch [{:?}]", self.ty)
+    }
+}
+
+/// A promise used to resolve async shutdown result.
+pub struct Shutdown {
+    inner: Arc<Inner<()>>,
+}
+
+impl Shutdown {
+    pub fn new(inner: Arc<Inner<()>>) -> Shutdown {
+        Shutdown { inner }
+    }
+
+    pub fn resolve(self, success: bool) {
+        let task = {
+            let mut guard = self.inner.lock();
+            if success {
+                guard.set_result(Ok(()))
+            } else {
+                guard.set_result(Err(Error::ShutdownFailed))
+            }
+        };
+        task.map(|t| t.wake());
+    }
+}