--bugs but cgo and zmq together still suck

[svn42.git] / go / door_daemon_zmq / serial_tty.go

diff --git a/go/door_daemon_zmq/serial_tty.go b/go/door_daemon_zmq/serial_tty.go
index 4ec786a..ddd41e6 100644 (file)
--- a/go/door_daemon_zmq/serial_tty.go
+++ b/go/door_daemon_zmq/serial_tty.go
@@ -9,6 +9,7 @@ import (
     "os"
     "svn.spreadspace.org/realraum/go.svn/termios"
     "log"
+    "sync"
 )
 
 // ---------- Serial TTY Code -------------
@@ -24,37 +25,60 @@ func openTTY(name string) (*os.File, error) {
     return file, nil
 }
 
-func SerialWriter(in <- chan string, serial * os.File) {
+func serialWriter(in <- chan string, serial * os.File) {
     for totty := range(in) {
         serial.WriteString(totty)
         serial.Sync()
     }
 }
 
-func SerialReader(out chan <- [][]byte, topub chan <- [][]byte, serial * os.File) {
+var last_read_serial_input [][]byte = [][]byte{{}}
+var last_read_mutex sync.Mutex
+
+func serialReader(topub chan <- [][]byte, serial * os.File) {
     linescanner := bufio.NewScanner(serial)
     linescanner.Split(bufio.ScanLines)
     for linescanner.Scan() {
         if err := linescanner.Err(); err != nil {
             panic(fmt.Sprintf("Error in read from serial: %v\n",err.Error()))
         }
+        fmt.Println("read text", linescanner.Text())
         text := bytes.Fields([]byte(linescanner.Text()))
         if len(text) == 0 {
             continue
         }
-        out <- text
+        //~ for len(serial_read) > 5 {
+            //~ //drain channel before putting new line into it
+            //~ //thus we make sure "out" only ever holds the last line
+            //~ //thus the buffer never blocks and we don't need to read from out unless we need it
+            //~ // BUT: don't drain the chan dry, or we might have a race condition resulting in a deadlock
+            //~ <- serial_read
+        //~ }
+        last_read_mutex.Lock()
+        last_read_serial_input = text
+        fmt.Println("Put Text", text)
+        last_read_mutex.Unlock()
         topub <- text
     }
 }
 
-func OpenAndHandleSerial(filename string, topub chan <- [][]byte) (chan string, chan [][]byte, error) {
+//TODO: improve this, make it work for multiple open serial devices
+func GetLastSerialLine() [][]byte {
+    var last_line_pointer [][]byte
+    last_read_mutex.Lock()
+    last_line_pointer = last_read_serial_input
+    last_read_mutex.Unlock()
+    fmt.Println("Retrieve Text", last_line_pointer)
+    return last_line_pointer
+}
+
+func OpenAndHandleSerial(filename string, topub chan <- [][]byte) (chan string, error) {
     serial, err :=openTTY(filename)
     if err != nil {
-        return nil, nil, err
+        return nil, err
     }
-    var wr chan string
-    var rd chan [][]byte
-    go SerialWriter(wr, serial)
-    go SerialReader(rd, topub, serial)
-    return wr, rd, nil
+    wr := make(chan string)
+    go serialWriter(wr, serial)
+    go serialReader(topub, serial)
+    return wr, nil
 }