SendableBase: remove unnecessary synchronization (#1797)

Also fixes the move constructor to update LiveWindow to follow the move.

wpilibc/src/main/native/cpp/livewindow/LiveWindow.cpp

@@ -81,9 +81,9 @@ void LiveWindow::AddChild(Sendable* parent, void* child) {
   comp.telemetryEnabled = false;
 }
 
-void LiveWindow::Remove(Sendable* sendable) {
+bool LiveWindow::Remove(Sendable* sendable) {
   std::scoped_lock lock(m_impl->mutex);
-  m_impl->components.erase(sendable);
+  return m_impl->components.erase(sendable);
 }
 
 void LiveWindow::EnableTelemetry(Sendable* sendable) {

wpilibc/src/main/native/cpp/smartdashboard/SendableBase.cpp

@@ -17,39 +17,35 @@ SendableBase::SendableBase(bool addLiveWindow) {
   if (addLiveWindow) LiveWindow::GetInstance()->Add(this);
 }
 
-SendableBase::~SendableBase() { LiveWindow::GetInstance()->Remove(this); }
-
-SendableBase::SendableBase(SendableBase&& rhs) {
-  m_name = std::move(rhs.m_name);
-  m_subsystem = std::move(rhs.m_subsystem);
+SendableBase::SendableBase(SendableBase&& other)
+    : m_name(std::move(other.m_name)),
+      m_subsystem(std::move(other.m_subsystem)) {
+  auto&& lw = LiveWindow::GetInstance();
+  if (lw->Remove(&other)) {
+    lw->Add(this);
+  }
 }
 
-SendableBase& SendableBase::operator=(SendableBase&& rhs) {
-  Sendable::operator=(std::move(rhs));
-
-  m_name = std::move(rhs.m_name);
-  m_subsystem = std::move(rhs.m_subsystem);
+SendableBase& SendableBase::operator=(SendableBase&& other) {
+  m_name = std::move(other.m_name);
+  m_subsystem = std::move(other.m_subsystem);
+  auto&& lw = LiveWindow::GetInstance();
+  if (lw->Remove(&other)) {
+    lw->Add(this);
+  }
 
   return *this;
 }
 
-std::string SendableBase::GetName() const {
-  std::scoped_lock lock(m_mutex);
-  return m_name;
-}
+SendableBase::~SendableBase() { LiveWindow::GetInstance()->Remove(this); }
 
-void SendableBase::SetName(const wpi::Twine& name) {
-  std::scoped_lock lock(m_mutex);
-  m_name = name.str();
-}
+std::string SendableBase::GetName() const { return m_name; }
 
-std::string SendableBase::GetSubsystem() const {
-  std::scoped_lock lock(m_mutex);
-  return m_subsystem;
-}
+void SendableBase::SetName(const wpi::Twine& name) { m_name = name.str(); }
+
+std::string SendableBase::GetSubsystem() const { return m_subsystem; }
 
 void SendableBase::SetSubsystem(const wpi::Twine& subsystem) {
-  std::scoped_lock lock(m_mutex);
   m_subsystem = subsystem.str();
 }
 

wpilibc/src/main/native/include/frc/livewindow/LiveWindow.h

@@ -67,8 +67,9 @@ class LiveWindow {
    * Remove the component from the LiveWindow.
    *
    * @param sendable component to remove
+   * @return true if the component was removed; false if it was not present
    */
-  void Remove(Sendable* component);
+  bool Remove(Sendable* component);
 
   /**
    * Enable telemetry for a single component.

wpilibc/src/main/native/include/frc/smartdashboard/SendableBase.h

@@ -1,5 +1,5 @@
 /*----------------------------------------------------------------------------*/
-/* Copyright (c) 2017-2018 FIRST. All Rights Reserved.                        */
+/* Copyright (c) 2017-2019 FIRST. All Rights Reserved.                        */
 /* Open Source Software - may be modified and shared by FRC teams. The code   */
 /* must be accompanied by the FIRST BSD license file in the root directory of */
 /* the project.                                                               */
@@ -10,8 +10,6 @@
 #include <memory>
 #include <string>
 
-#include <wpi/mutex.h>
-
 #include "frc/smartdashboard/Sendable.h"
 
 namespace frc {
@@ -27,8 +25,10 @@ class SendableBase : public Sendable {
 
   ~SendableBase() override;
 
-  SendableBase(SendableBase&& rhs);
-  SendableBase& operator=(SendableBase&& rhs);
+  SendableBase(const SendableBase&) = default;
+  SendableBase& operator=(const SendableBase&) = default;
+  SendableBase(SendableBase&&);
+  SendableBase& operator=(SendableBase&&);
 
   using Sendable::SetName;
 
@@ -73,7 +73,6 @@ class SendableBase : public Sendable {
   void SetName(const wpi::Twine& moduleType, int moduleNumber, int channel);
 
  private:
-  mutable wpi::mutex m_mutex;
   std::string m_name;
   std::string m_subsystem = "Ungrouped";
 };

wpilibj/src/main/java/edu/wpi/first/wpilibj/SendableBase.java

@@ -1,5 +1,5 @@
 /*----------------------------------------------------------------------------*/
-/* Copyright (c) 2017-2018 FIRST. All Rights Reserved.                        */
+/* Copyright (c) 2017-2019 FIRST. All Rights Reserved.                        */
 /* Open Source Software - may be modified and shared by FRC teams. The code   */
 /* must be accompanied by the FIRST BSD license file in the root directory of */
 /* the project.                                                               */
@@ -46,12 +46,12 @@ public abstract class SendableBase implements Sendable, AutoCloseable {
   }
 
   @Override
-  public final synchronized String getName() {
+  public final String getName() {
     return m_name;
   }
 
   @Override
-  public final synchronized void setName(String name) {
+  public final void setName(String name) {
     m_name = name;
   }
 
@@ -77,12 +77,12 @@ public abstract class SendableBase implements Sendable, AutoCloseable {
   }
 
   @Override
-  public final synchronized String getSubsystem() {
+  public final String getSubsystem() {
     return m_subsystem;
   }
 
   @Override
-  public final synchronized void setSubsystem(String subsystem) {
+  public final void setSubsystem(String subsystem) {
     m_subsystem = subsystem;
   }