From 950bbd6dc2792d555df08f532fed013678e342dd Mon Sep 17 00:00:00 2001
From: David Vo <auscompgeek@users.noreply.github.com>
Date: Thu, 20 Aug 2020 12:46:51 +1000
Subject: [PATCH] [wpilibj] Fix joystick button edge synchronisation (#2433)

---
 .../edu/wpi/first/wpilibj/DriverStation.java  | 104 ++++++++----------
 1 file changed, 45 insertions(+), 59 deletions(-)

diff --git a/wpilibj/src/main/java/edu/wpi/first/wpilibj/DriverStation.java b/wpilibj/src/main/java/edu/wpi/first/wpilibj/DriverStation.java
index 0f388de5f4..7ceaf1f422 100644
--- a/wpilibj/src/main/java/edu/wpi/first/wpilibj/DriverStation.java
+++ b/wpilibj/src/main/java/edu/wpi/first/wpilibj/DriverStation.java
@@ -317,21 +317,19 @@ public class DriverStation {
       reportJoystickUnpluggedError("Button indexes begin at 1 in WPILib for C++ and Java\n");
       return false;
     }
+
     m_cacheDataMutex.lock();
     try {
-      if (button > m_joystickButtons[stick].m_count) {
-        // Unlock early so error printing isn't locked.
-        m_cacheDataMutex.unlock();
-        reportJoystickUnpluggedWarning("Joystick Button " + button + " on port " + stick
-            + " not available, check if controller is plugged in");
+      if (button <= m_joystickButtons[stick].m_count) {
+        return (m_joystickButtons[stick].m_buttons & 1 << (button - 1)) != 0;
       }
-
-      return (m_joystickButtons[stick].m_buttons & 1 << (button - 1)) != 0;
     } finally {
-      if (m_cacheDataMutex.isHeldByCurrentThread()) {
-        m_cacheDataMutex.unlock();
-      }
+      m_cacheDataMutex.unlock();
     }
+
+    reportJoystickUnpluggedWarning("Joystick Button " + button + " on port " + stick
+        + " not available, check if controller is plugged in");
+    return false;
   }
 
   /**
@@ -349,27 +347,25 @@ public class DriverStation {
     if (stick < 0 || stick >= kJoystickPorts) {
       throw new IllegalArgumentException("Joystick index is out of range, should be 0-3");
     }
-    boolean error = false;
-    boolean retVal = false;
-    synchronized (m_cacheDataMutex) {
-      if (button > m_joystickButtons[stick].m_count) {
-        error = true;
-        retVal = false;
-      } else {
+
+    m_cacheDataMutex.lock();
+    try {
+      if (button <= m_joystickButtons[stick].m_count) {
         // If button was pressed, clear flag and return true
         if ((m_joystickButtonsPressed[stick] & 1 << (button - 1)) != 0) {
           m_joystickButtonsPressed[stick] &= ~(1 << (button - 1));
-          retVal = true;
+          return true;
         } else {
-          retVal = false;
+          return false;
         }
       }
+    } finally {
+      m_cacheDataMutex.unlock();
     }
-    if (error) {
-      reportJoystickUnpluggedWarning("Joystick Button " + button + " on port " + stick
-          + " not available, check if controller is plugged in");
-    }
-    return retVal;
+
+    reportJoystickUnpluggedWarning("Joystick Button " + button + " on port " + stick
+        + " not available, check if controller is plugged in");
+    return false;
   }
 
   /**
@@ -388,27 +384,25 @@ public class DriverStation {
     if (stick < 0 || stick >= kJoystickPorts) {
       throw new IllegalArgumentException("Joystick index is out of range, should be 0-3");
     }
-    boolean error = false;
-    boolean retVal = false;
-    synchronized (m_cacheDataMutex) {
-      if (button > m_joystickButtons[stick].m_count) {
-        error = true;
-        retVal = false;
-      } else {
+
+    m_cacheDataMutex.lock();
+    try {
+      if (button <= m_joystickButtons[stick].m_count) {
         // If button was released, clear flag and return true
         if ((m_joystickButtonsReleased[stick] & 1 << (button - 1)) != 0) {
           m_joystickButtonsReleased[stick] &= ~(1 << (button - 1));
-          retVal = true;
+          return true;
         } else {
-          retVal = false;
+          return false;
         }
       }
+    } finally {
+      m_cacheDataMutex.unlock();
     }
-    if (error) {
-      reportJoystickUnpluggedWarning("Joystick Button " + button + " on port " + stick
-          + " not available, check if controller is plugged in");
-    }
-    return retVal;
+
+    reportJoystickUnpluggedWarning("Joystick Button " + button + " on port " + stick
+        + " not available, check if controller is plugged in");
+    return false;
   }
 
   /**
@@ -429,20 +423,16 @@ public class DriverStation {
 
     m_cacheDataMutex.lock();
     try {
-      if (axis >= m_joystickAxes[stick].m_count) {
-        // Unlock early so error printing isn't locked.
-        m_cacheDataMutex.unlock();
-        reportJoystickUnpluggedWarning("Joystick axis " + axis + " on port " + stick
-            + " not available, check if controller is plugged in");
-        return 0.0;
+      if (axis < m_joystickAxes[stick].m_count) {
+        return m_joystickAxes[stick].m_axes[axis];
       }
-
-      return m_joystickAxes[stick].m_axes[axis];
     } finally {
-      if (m_cacheDataMutex.isHeldByCurrentThread()) {
-        m_cacheDataMutex.unlock();
-      }
+      m_cacheDataMutex.unlock();
     }
+
+    reportJoystickUnpluggedWarning("Joystick axis " + axis + " on port " + stick
+        + " not available, check if controller is plugged in");
+    return 0.0;
   }
 
   /**
@@ -460,20 +450,16 @@ public class DriverStation {
 
     m_cacheDataMutex.lock();
     try {
-      if (pov >= m_joystickPOVs[stick].m_count) {
-        // Unlock early so error printing isn't locked.
-        m_cacheDataMutex.unlock();
-        reportJoystickUnpluggedWarning("Joystick POV " + pov + " on port " + stick
-            + " not available, check if controller is plugged in");
-        return -1;
+      if (pov < m_joystickPOVs[stick].m_count) {
+        return m_joystickPOVs[stick].m_povs[pov];
       }
     } finally {
-      if (m_cacheDataMutex.isHeldByCurrentThread()) {
-        m_cacheDataMutex.unlock();
-      }
+      m_cacheDataMutex.unlock();
     }
 
-    return m_joystickPOVs[stick].m_povs[pov];
+    reportJoystickUnpluggedWarning("Joystick POV " + pov + " on port " + stick
+        + " not available, check if controller is plugged in");
+    return -1;
   }
 
   /**