stream: redo socket management logic

* Make process only open and set_remote only close sockets
* Streamline queue flushing in all cases where we just opened the socket
* Streamline dequeuing using Option/Result API, removing a
  queue.ready() check

src/net/data_stream.rs

@@ -271,28 +271,28 @@ impl DataStream {
     }
 
     fn close(&mut self) {
+        if let Some(socket) = self.socket.take() {
             log::info!("Closing stream");
             // Note(unwrap): We guarantee that the socket is available above.
-        let socket = self.socket.take().unwrap();
             self.stack.close(socket).unwrap();
         }
-
-    fn open(&mut self, remote: SocketAddr) -> Result<(), ()> {
-        if self.socket.is_some() {
-            self.close();
     }
 
-        // If the remote address is unspecified, don't open a new socket.
-        if remote.ip().is_unspecified() {
+    // Open new socket.
+    fn open(&mut self) -> Result<(), ()> {
+        // If there is already a socket of if remote address is unspecified,
+        // do not open a new socket.
+        if self.socket.is_some() || self.remote.ip().is_unspecified() {
             return Err(());
         }
 
-        let mut socket = self.stack.socket().map_err(|_| ())?;
-
         log::info!("Opening stream");
+
+        let mut socket = self.stack.socket().or(Err(()))?;
+
         // Note(unwrap): We only connect with a new socket, so it is guaranteed to not already be
         // bound.
-        self.stack.connect(&mut socket, remote).unwrap();
+        self.stack.connect(&mut socket, self.remote).unwrap();
 
         self.socket.replace(socket);
 
@@ -304,48 +304,43 @@ impl DataStream {
     /// # Args
     /// * `remote` - The destination to send stream data to.
     pub fn set_remote(&mut self, remote: SocketAddr) {
-        // If the remote is identical to what we already have, do nothing.
-        if remote == self.remote {
-            return;
+        // Close socket to be reopened if the remote has changed.
+        if remote != self.remote {
+            self.close();
         }
-
-        // Open the new remote connection.
-        self.open(remote).ok();
         self.remote = remote;
     }
 
     /// Process any data for transmission.
     pub fn process(&mut self) {
+        match self.socket.as_mut() {
+            None => {
                 // If there's no socket available, try to connect to our remote.
-        if self.socket.is_none() {
-            // If we can't open the socket (e.g. we do not have an IP address yet), clear data from
-            // the queue.
-            if self.open(self.remote).is_err() {
-                while self.queue.ready() {
-                    self.queue.dequeue();
-                }
-                return;
+                if self.open().is_ok() {
+                    // If we just successfully opened the socket, flush old data from queue.
+                    while self.queue.dequeue().is_some() {}
                 }
             }
-
+            Some(handle) => {
                 if self.queue.ready() {
                     // Dequeue data from the queue into a larger block structure.
-            let mut packet = DataPacket::new(&mut self.buffer, SUBSAMPLE_RATE);
-            while self.queue.ready() {
-                // Note(unwrap): We check above that the queue is ready before calling this.
-                if packet.add_batch(self.queue.peek().unwrap()).is_err() {
-                    // If we cannot add another batch, break out of the loop and send the packet.
-                    break;
-                }
-
-                // Remove the batch that we just added.
+                    let mut packet =
+                        DataPacket::new(&mut self.buffer, SUBSAMPLE_RATE);
+                    while self
+                        .queue
+                        .peek()
+                        .and_then(|batch| packet.add_batch(batch).ok())
+                        .is_some()
+                    {
+                        // Dequeue the batch that we just added to the packet.
                         self.queue.dequeue();
                     }
 
-            // Transmit the data block.
-            let mut handle = self.socket.as_mut().unwrap();
+                    // Transmit the data packet.
                     let size = packet.finish();
-            self.stack.send(&mut handle, &self.buffer[..size]).ok();
+                    self.stack.send(handle, &self.buffer[..size]).ok();
+                }
+            }
         }
     }
 }