From be1e2330ab84cf449fae664fd0c9788e3ae4af1f Mon Sep 17 00:00:00 2001
From: Jakob Odersky <jodersky@gmail.com>
Date: Fri, 21 Jun 2013 22:57:40 +0200
Subject: improve thread safety in serial class

---
 src/main/native/flow.c                             |  1 +
 .../com/github/jodersky/flow/SerialOperator.scala  | 26 +++++++++++++---------
 .../com/github/jodersky/flow/low/Serial.scala      | 10 ++++-----
 3 files changed, 21 insertions(+), 16 deletions(-)

diff --git a/src/main/native/flow.c b/src/main/native/flow.c
index 43dd750..c8927e9 100644
--- a/src/main/native/flow.c
+++ b/src/main/native/flow.c
@@ -163,6 +163,7 @@ int serial_close(struct serial_config* serial) {
   }
   
   free(serial);
+  return 0;
 }
 
 int serial_read(struct serial_config* serial, unsigned char* buffer, size_t size) {
diff --git a/src/main/scala/com/github/jodersky/flow/SerialOperator.scala b/src/main/scala/com/github/jodersky/flow/SerialOperator.scala
index c9f38cd..951e9f9 100644
--- a/src/main/scala/com/github/jodersky/flow/SerialOperator.scala
+++ b/src/main/scala/com/github/jodersky/flow/SerialOperator.scala
@@ -13,34 +13,38 @@ import scala.concurrent._
 
 class SerialOperator(serial: LowSerial, handler: ActorRef) extends Actor {
   import context._
-  
+
   object Reader extends Thread {
-    private var continueReading = true 
-    
+    private var continueReading = true
+
     override def run() {
       Thread.currentThread().setName("flow-reader " + serial.port)
       while (continueReading) {
-        println("beginning read")
-        val data = ByteString(serial.read())
-        println("return from read")
-        handler ! Received(data)
+        try {
+          println("beginning read")
+          val data = ByteString(serial.read())
+          println("return from read")
+          handler ! Received(data)
+        } catch {
+          case ex: PortInterruptedException => continueReading = false 
+        }
       }
     }
   }
-  
+
   Reader.start()
-  
+
   context.watch(handler)
 
   def receive = {
     case c @ Write(data) => {
       val writer = sender
-      future{serial.write(data.toArray)}.onComplete {
+      future { serial.write(data.toArray) }.onComplete {
         case Success(data) => writer ! Wrote(ByteString(data))
         case Failure(t) => writer ! CommandFailed(c, t)
       }
     }
-    
+
     case Close => {
       sender ! Closed
       context.stop(self)
diff --git a/src/main/scala/com/github/jodersky/flow/low/Serial.scala b/src/main/scala/com/github/jodersky/flow/low/Serial.scala
index 916ab84..0a098c5 100644
--- a/src/main/scala/com/github/jodersky/flow/low/Serial.scala
+++ b/src/main/scala/com/github/jodersky/flow/low/Serial.scala
@@ -21,8 +21,8 @@ class Serial private (val port: String, private val pointer: Long) {
   def close(): Unit = if (!closed.get()) {
     closed.set(true)
     requireSuccess(NativeSerial.interrupt(pointer), port)
-    if (writing.get()) wait() // if reading, wait for read to finish
-    if (reading.get()) wait()
+    if (writing.get()) synchronized{wait()} // if reading, wait for read to finish
+    if (reading.get()) synchronized{wait()}
     requireSuccess(NativeSerial.close(pointer), port)
   }
 
@@ -30,7 +30,7 @@ class Serial private (val port: String, private val pointer: Long) {
     reading.set(true)
     val buffer = new Array[Byte](100)
     val readResult = NativeSerial.read(pointer, buffer)
-    if (closed.get) notify(); //read was interrupted by close
+    if (closed.get) synchronized{notify()}; //read was interrupted by close
     reading.set(false)
     val n = requireSuccess(readResult, port)
     buffer take n
@@ -41,7 +41,7 @@ class Serial private (val port: String, private val pointer: Long) {
   def write(data: Array[Byte]): Array[Byte] = if (!closed.get) {
     writing.set(true)
     val writeResult = NativeSerial.write(pointer, data)
-    if (closed.get) notify()
+    if (closed.get) synchronized{notify()}
     writing.set(false)
     val n = requireSuccess(writeResult, port)
     data take n
@@ -54,7 +54,7 @@ class Serial private (val port: String, private val pointer: Long) {
 object Serial {
   import NativeSerial._
 
-  def requireSuccess(result: Int, port: String): Int = result match {
+  private def requireSuccess(result: Int, port: String): Int = result match {
     case E_IO => throw new IOException(port)
     case E_ACCESS_DENIED => throw new AccessDeniedException(port)
     case E_BUSY => throw new PortInUseException(port)
-- 
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