Fix bogus port disconnection during serial event

Fixes https://github.com/arduino/Arduino/issues/9785 and probably many others

This commit strongly simplyfies the serial list code

Pluggable discovery introduced a bug since BoardPort.toString() started reporting only the name of the port, not the complete name_vid_pid needed to match liblistserial output.
Adding .toCompleteString() almost solves the bogus disconnection part alone, but resolveDeviceByVendorIdProductId() uses "0x" prefixes VID/PID, breaking it again.

In addition, all the logic used to match a board with its bootloader (to obtain a serial number on 32u4 boards) has been completely removed since it is currently useless (and unused).

arduino-core/src/cc/arduino/packages/BoardPort.java

@@ -122,6 +122,10 @@ public class BoardPort {
     return this.address;
   }
 
+  public String toCompleteString() {
+    return this.address + "_" + this.getPrefs().get("vid") + "_" + this.getPrefs().get("pid");
+  }
+
   // Search for the board which matches identificationPrefs.
   // If found, boardName is set to the name from boards.txt
   // and the board is returned.  If not found, null is returned.

arduino-core/src/cc/arduino/packages/discoverers/serial/SerialDiscovery.java

@@ -46,7 +46,6 @@ public class SerialDiscovery implements Discovery, Runnable {
   private final List<String> oldPorts = new ArrayList<>();
   public boolean uploadInProgress = false;
   public boolean pausePolling = false;
-  private BoardPort oldUploadBoardPort = null;
   private final BoardCloudResolver boardCloudResolver = new BoardCloudResolver();
 
 
@@ -56,7 +55,7 @@ public class SerialDiscovery implements Discovery, Runnable {
   }
 
   @Override
-  public List<BoardPort> listDiscoveredBoards(boolean complete) {
+  public synchronized List<BoardPort> listDiscoveredBoards(boolean complete) {
       if (complete) {
         return new ArrayList<>(serialBoardPorts);
       }
@@ -69,7 +68,7 @@ public class SerialDiscovery implements Discovery, Runnable {
       return onlineBoardPorts;
   }
 
-  public void setSerialBoardPorts(List<BoardPort> newSerialBoardPorts) {
+  public synchronized void setSerialBoardPorts(List<BoardPort> newSerialBoardPorts) {
       serialBoardPorts.clear();
       serialBoardPorts.addAll(newSerialBoardPorts);
   }
@@ -116,27 +115,17 @@ public class SerialDiscovery implements Discovery, Runnable {
       return;
     }
 
-    // if (updating) {}
-    // a port will disappear, another will appear
-    // use this information to "merge" the boards
-    // updating must be signaled by SerialUpload class
-
     oldPorts.clear();
     oldPorts.addAll(ports);
 
+    // set unreachable ports offline
     for (BoardPort board : boardPorts) {
-      if (ports.contains(board.toString())) {
-        if (board.isOnline()) {
-          ports.remove(ports.indexOf(board.toString()));
-        }
-      } else {
-        if (uploadInProgress && board.isOnline()) {
-          oldUploadBoardPort = board;
-        }
+      if (!ports.contains(board.toCompleteString())) {
         board.setOnlineStatus(false);
       }
     }
 
+    // add information for newly added ports
     for (String newPort : ports) {
 
       String[] parts = newPort.split("_");
@@ -161,35 +150,35 @@ public class SerialDiscovery implements Discovery, Runnable {
 
       BoardPort boardPort = null;
       int i = 0;
-      // create new board or update existing
+
+      // create new board if in ports but not in boardPorts
       for (BoardPort board : boardPorts) {
-        if (board.toString().equals(newPort)) {
+        if (board.toCompleteString().equalsIgnoreCase(newPort)) {
           boardPort = boardPorts.get(i);
+          boardPorts.get(i).setOnlineStatus(true);
           break;
         }
         i++;
       }
-      if (boardPort == null) {
-        boardPort = new BoardPort();
-        boardPorts.add(boardPort);
+
+      if (boardPort != null) {
+        continue;
       }
+        
+      boardPort = new BoardPort();
+      boardPorts.add(boardPort);
       boardPort.setAddress(port);
       boardPort.setProtocol("serial");
       boardPort.setOnlineStatus(true);
 
-      String label = port;
+      boardPort.setLabel(port);
 
       if (boardData != null) {
         boardPort.getPrefs().put("vid", boardData.get("vid").toString());
         boardPort.getPrefs().put("pid", boardData.get("pid").toString());
 
         String iserial = boardData.get("iserial").toString();
-        if (iserial.length() >= 10) {
-          boardPort.getPrefs().put("iserial", iserial);
-        }
-        if (uploadInProgress && oldUploadBoardPort!=null) {
-          oldUploadBoardPort.getPrefs().put("iserial", iserial);
-        }
+        boardPort.getPrefs().put("iserial", iserial);
 
         TargetBoard board = (TargetBoard) boardData.get("board");
         if (board != null) {
@@ -208,8 +197,6 @@ public class SerialDiscovery implements Discovery, Runnable {
           boardPort.getPrefs().put("iserial", "");
         }
       }
-
-      boardPort.setLabel(label);
     }
     setSerialBoardPorts(boardPorts);
   }

arduino-core/src/processing/app/Platform.java

@@ -202,8 +202,9 @@ public class Platform {
                 }
                 Map<String, Object> boardData = new HashMap<>();
                 boardData.put("board", board);
-                boardData.put("vid", vids.get(i));
-                boardData.put("pid", pids.get(i));
+                // remove 0x from VID / PID to keep them as reported by liblistserial
+                boardData.put("vid", vids.get(i).replaceAll("0x", ""));
+                boardData.put("pid", pids.get(i).replaceAll("0x", ""));
                 String extrafields = vid_pid_iSerial.substring(vidPid.length() + 1);
                 String[] parts = extrafields.split("_");
                 boardData.put("iserial", parts[0]);