Squashed 'third_party/allwpilib_2019/' content from commit bd05dfa1c

Change-Id: I2b1c2250cdb9b055133780c33593292098c375b7
git-subtree-dir: third_party/allwpilib_2019
git-subtree-split: bd05dfa1c7cca74c4fac451e7b9d6a37e7b53447
diff --git a/wpilibc/src/main/native/cpp/Watchdog.cpp b/wpilibc/src/main/native/cpp/Watchdog.cpp
new file mode 100644
index 0000000..b67f94d
--- /dev/null
+++ b/wpilibc/src/main/native/cpp/Watchdog.cpp
@@ -0,0 +1,184 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) 2018 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.                                                               */
+/*----------------------------------------------------------------------------*/
+
+#include "frc/Watchdog.h"
+
+#include <wpi/Format.h>
+#include <wpi/PriorityQueue.h>
+#include <wpi/raw_ostream.h>
+
+using namespace frc;
+
+constexpr std::chrono::milliseconds Watchdog::kMinPrintPeriod;
+
+class Watchdog::Thread : public wpi::SafeThread {
+ public:
+  template <typename T>
+  struct DerefGreater : public std::binary_function<T, T, bool> {
+    constexpr bool operator()(const T& lhs, const T& rhs) const {
+      return *lhs > *rhs;
+    }
+  };
+
+  wpi::PriorityQueue<Watchdog*, std::vector<Watchdog*>, DerefGreater<Watchdog*>>
+      m_watchdogs;
+
+ private:
+  void Main() override;
+};
+
+void Watchdog::Thread::Main() {
+  std::unique_lock<wpi::mutex> lock(m_mutex);
+
+  while (m_active) {
+    if (m_watchdogs.size() > 0) {
+      if (m_cond.wait_until(lock, m_watchdogs.top()->m_expirationTime) ==
+          std::cv_status::timeout) {
+        if (m_watchdogs.size() == 0 ||
+            m_watchdogs.top()->m_expirationTime > hal::fpga_clock::now()) {
+          continue;
+        }
+
+        // If the condition variable timed out, that means a Watchdog timeout
+        // has occurred, so call its timeout function.
+        auto watchdog = m_watchdogs.top();
+        m_watchdogs.pop();
+
+        auto now = hal::fpga_clock::now();
+        if (now - watchdog->m_lastTimeoutPrintTime > kMinPrintPeriod) {
+          watchdog->m_lastTimeoutPrintTime = now;
+          if (!watchdog->m_suppressTimeoutMessage) {
+            wpi::outs() << "Watchdog not fed within "
+                        << wpi::format("%.6f",
+                                       watchdog->m_timeout.count() / 1.0e6)
+                        << "s\n";
+          }
+        }
+
+        // Set expiration flag before calling the callback so any manipulation
+        // of the flag in the callback (e.g., calling Disable()) isn't
+        // clobbered.
+        watchdog->m_isExpired = true;
+
+        lock.unlock();
+        watchdog->m_callback();
+        lock.lock();
+      }
+      // Otherwise, a Watchdog removed itself from the queue (it notifies the
+      // scheduler of this) or a spurious wakeup occurred, so just rewait with
+      // the soonest watchdog timeout.
+    } else {
+      m_cond.wait(lock, [&] { return m_watchdogs.size() > 0 || !m_active; });
+    }
+  }
+}
+
+Watchdog::Watchdog(double timeout, std::function<void()> callback)
+    : m_timeout(static_cast<int64_t>(timeout * 1.0e6)),
+      m_callback(callback),
+      m_owner(&GetThreadOwner()) {}
+
+Watchdog::~Watchdog() { Disable(); }
+
+double Watchdog::GetTime() const {
+  return (hal::fpga_clock::now() - m_startTime).count() / 1.0e6;
+}
+
+void Watchdog::SetTimeout(double timeout) {
+  m_startTime = hal::fpga_clock::now();
+  m_epochs.clear();
+
+  // Locks mutex
+  auto thr = m_owner->GetThread();
+  if (!thr) return;
+
+  m_timeout = std::chrono::microseconds(static_cast<int64_t>(timeout * 1.0e6));
+  m_isExpired = false;
+
+  thr->m_watchdogs.remove(this);
+  m_expirationTime = m_startTime + m_timeout;
+  thr->m_watchdogs.emplace(this);
+  thr->m_cond.notify_all();
+}
+
+double Watchdog::GetTimeout() const {
+  // Locks mutex
+  auto thr = m_owner->GetThread();
+
+  return m_timeout.count() / 1.0e6;
+}
+
+bool Watchdog::IsExpired() const {
+  // Locks mutex
+  auto thr = m_owner->GetThread();
+
+  return m_isExpired;
+}
+
+void Watchdog::AddEpoch(wpi::StringRef epochName) {
+  auto currentTime = hal::fpga_clock::now();
+  m_epochs[epochName] = currentTime - m_startTime;
+  m_startTime = currentTime;
+}
+
+void Watchdog::PrintEpochs() {
+  auto now = hal::fpga_clock::now();
+  if (now - m_lastEpochsPrintTime > kMinPrintPeriod) {
+    m_lastEpochsPrintTime = now;
+    for (const auto& epoch : m_epochs) {
+      wpi::outs() << '\t' << epoch.getKey() << ": "
+                  << wpi::format("%.6f", epoch.getValue().count() / 1.0e6)
+                  << "s\n";
+    }
+  }
+}
+
+void Watchdog::Reset() { Enable(); }
+
+void Watchdog::Enable() {
+  m_startTime = hal::fpga_clock::now();
+  m_epochs.clear();
+
+  // Locks mutex
+  auto thr = m_owner->GetThread();
+  if (!thr) return;
+
+  m_isExpired = false;
+
+  thr->m_watchdogs.remove(this);
+  m_expirationTime = m_startTime + m_timeout;
+  thr->m_watchdogs.emplace(this);
+  thr->m_cond.notify_all();
+}
+
+void Watchdog::Disable() {
+  // Locks mutex
+  auto thr = m_owner->GetThread();
+  if (!thr) return;
+
+  m_isExpired = false;
+
+  thr->m_watchdogs.remove(this);
+  thr->m_cond.notify_all();
+}
+
+void Watchdog::SuppressTimeoutMessage(bool suppress) {
+  m_suppressTimeoutMessage = suppress;
+}
+
+bool Watchdog::operator>(const Watchdog& rhs) {
+  return m_expirationTime > rhs.m_expirationTime;
+}
+
+wpi::SafeThreadOwner<Watchdog::Thread>& Watchdog::GetThreadOwner() {
+  static wpi::SafeThreadOwner<Thread> inst = [] {
+    wpi::SafeThreadOwner<Watchdog::Thread> inst;
+    inst.Start();
+    return inst;
+  }();
+  return inst;
+}