Added Null monitor for testing

Author: cmaglie

arduino/monitors/null.go

@@ -0,0 +1,70 @@
+// This file is part of arduino-cli.
+//
+// Copyright 2021 ARDUINO SA (http://www.arduino.cc/)
+//
+// This software is released under the GNU General Public License version 3,
+// which covers the main part of arduino-cli.
+// The terms of this license can be found at:
+// https://www.gnu.org/licenses/gpl-3.0.en.html
+//
+// You can be released from the requirements of the above licenses by purchasing
+// a commercial license. Buying such a license is mandatory if you want to
+// modify or otherwise use the software for commercial activities involving the
+// Arduino software without disclosing the source code of your own applications.
+// To purchase a commercial license, send an email to [email protected].
+
+package monitors
+
+import (
+	"log"
+	"time"
+)
+
+// NullMonitor outputs zeros at a constant rate and discards anything sent
+type NullMonitor struct {
+	started time.Time
+	sent    int
+	bps     float64
+}
+
+// OpenNullMonitor creates a monitor that outputs the same character at a fixed
+// rate.
+func OpenNullMonitor(bytesPerSecondRate float64) *NullMonitor {
+	log.Printf("Started streaming at %f\n", bytesPerSecondRate)
+	return &NullMonitor{
+		started: time.Now(),
+		bps:     bytesPerSecondRate,
+	}
+}
+
+// Close the connection
+func (mon *NullMonitor) Close() error {
+	return nil
+}
+
+// Read bytes from the port
+func (mon *NullMonitor) Read(bytes []byte) (int, error) {
+	for {
+		elapsed := time.Now().Sub(mon.started).Seconds()
+		n := int(elapsed*mon.bps) - mon.sent
+		if n == 0 {
+			// Delay until the next char...
+			time.Sleep(time.Millisecond)
+			continue
+		}
+		if len(bytes) < n {
+			n = len(bytes)
+		}
+		mon.sent += n
+		for i := 0; i < n; i++ {
+			bytes[i] = 0
+		}
+		return n, nil
+	}
+}
+
+// Write bytes to the port
+func (mon *NullMonitor) Write(bytes []byte) (int, error) {
+	// Discard all chars
+	return len(bytes), nil
+}

commands/daemon/monitor.go

@@ -16,6 +16,7 @@
 package daemon
 
 import (
+	"errors"
 	"fmt"
 	"io"
 
@@ -61,6 +62,16 @@ func (s *MonitorService) StreamingOpen(stream rpc.Monitor_StreamingOpenServer) e
 		if mon, err = monitors.OpenSerialMonitor(config.GetTarget(), int(baudRate)); err != nil {
 			return err
 		}
+
+	case rpc.MonitorConfig_NULL:
+		if addCfg, ok := config.GetAdditionalConfig().AsMap()["OutputRate"]; !ok {
+			mon = monitors.OpenNullMonitor(100.0) // 100 bytes per second as default
+		} else if outputRate, ok := addCfg.(float64); !ok {
+			return errors.New("OutputRate in Null monitor must be a float64")
+		} else {
+			// get the Monitor instance
+			mon = monitors.OpenNullMonitor(outputRate)
+		}
 	}
 
 	// we'll use these channels to communicate with the goroutines

rpc/monitor/monitor.pb.go

@@ -50,7 +50,10 @@ message StreamingOpenReq {
 // Tells the monitor which target to open and provides additional parameters
 // that might be needed to configure the target or the monitor itself.
 message MonitorConfig {
-  enum TargetType { SERIAL = 0; }
+  enum TargetType {
+    SERIAL = 0;
+    NULL = 99;
+  }
 
   // The target name.
   string target = 1;