Merge pull request #11 from pingcap/siddontang/update-error

update error

src/raft/errors.rs

@@ -1,20 +1,56 @@
 use std::{result, io, fmt};
+use std::error;
 
+use protobuf::ProtobufError;
 
-#[derive(Debug, Clone)]
+#[derive(Debug)]
 pub enum Error {
     Io(io::Error),
     NotFound,
+    Protobuf(ProtobufError),
+    Other(String),
 }
 
 impl fmt::Display for Error {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match *self {
             Error::NotFound => write!(f, "not found"),
             Error::Io(ref error) => fmt::Display::fmt(error, f),
+            _ => fmt::Display::fmt(self, f),
         }
     }
 }
 
+impl error::Error for Error {
+    fn description(&self) -> &str {
+        match self {
+            // not sure that cause should be included in message
+            &Error::Io(ref e) => e.description(),
+            &Error::NotFound => "not found",
+            &Error::Protobuf(ref e) => e.description(),
+            &Error::Other(ref e) => &e,
+        }
+    }
+
+    fn cause(&self) -> Option<&error::Error> {
+        match self {
+            &Error::Io(ref e) => Some(e),
+            &Error::Protobuf(ref e) => Some(e),
+            _ => None,
+        }
+    }
+}
+
+impl From<io::Error> for Error {
+    fn from(err: io::Error) -> Error {
+        Error::Io(err)
+    }
+}
+
+impl From<ProtobufError> for Error {
+    fn from(err: ProtobufError) -> Error {
+        Error::Protobuf(err)
+    }
+}
 
 pub type Result<T> = result::Result<T, Error>;

src/raft/raft_log.rs

@@ -2,6 +2,6 @@ use raft::storage::Storage;
 
 
 /// Raft log implementation
-pub struct RaftLog {
-    store: Storage,
+pub struct RaftLog<T: Storage> {
+    store: T,
 }