Adds new Threads API for priority setting while using std::thread (#379)

Also adds Java API for doing the same to Java threads (standard Java Thread.setPriority only works
when Java is run as root, even if the process has the right privileges).

wpilibj/src/athena/cpp/lib/ThreadsJNI.cpp

@@ -0,0 +1,73 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) FIRST 2016. 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 <assert.h>
+#include <jni.h>
+#include "HAL/cpp/Log.h"
+
+#include "edu_wpi_first_wpilibj_hal_ThreadsJNI.h"
+
+#include "HAL/Threads.h"
+#include "HALUtil.h"
+
+using namespace frc;
+
+// set the logging level
+TLogLevel threadsJNILogLevel = logWARNING;
+
+#define THREADSJNI_LOG(level)     \
+  if (level > threadsJNILogLevel) \
+    ;                            \
+  else                           \
+  Log().Get(level)
+
+extern "C" {
+/*
+ * Class:     edu_wpi_first_wpilibj_hal_ThreadsJNI
+ * Method:    GetCurrentThreadPriority
+ * Signature: ()I
+ */
+JNIEXPORT jint JNICALL Java_edu_wpi_first_wpilibj_hal_ThreadsJNI_getCurrentThreadPriority
+  (JNIEnv *env, jclass) {
+  THREADSJNI_LOG(logDEBUG) << "Callling GetCurrentThreadPriority";
+  int32_t status = 0;
+  HAL_Bool isRT = false;
+  auto ret = HAL_GetCurrentThreadPriority(&isRT, &status);
+  CheckStatus(env, status);
+  return (jint)ret;
+}
+
+/*
+ * Class:     edu_wpi_first_wpilibj_hal_ThreadsJNI
+ * Method:    GetCurrentThreadIsRealTime
+ * Signature: ()Z
+ */
+JNIEXPORT jboolean JNICALL Java_edu_wpi_first_wpilibj_hal_ThreadsJNI_getCurrentThreadIsRealTime
+  (JNIEnv *env, jclass) {
+  THREADSJNI_LOG(logDEBUG) << "Callling GetCurrentThreadIsRealTime";
+  int32_t status = 0;
+  HAL_Bool isRT = false;
+  HAL_GetCurrentThreadPriority(&isRT, &status);
+  CheckStatus(env, status);
+  return (jboolean)isRT;
+}
+
+/*
+ * Class:     edu_wpi_first_wpilibj_hal_ThreadsJNI
+ * Method:    SetCurrentThreadPriority
+ * Signature: (ZI)Z
+ */
+JNIEXPORT jboolean JNICALL Java_edu_wpi_first_wpilibj_hal_ThreadsJNI_setCurrentThreadPriority
+  (JNIEnv *env, jclass, jboolean realTime, jint priority) {
+  THREADSJNI_LOG(logDEBUG) << "Callling SetCurrentThreadPriority";
+  int32_t status = 0;
+  auto ret = HAL_SetCurrentThreadPriority((HAL_Bool)realTime, (int32_t)priority, &status);
+  CheckStatus(env, status);
+  return (jboolean)ret;
+}
+
+}

wpilibj/src/athena/java/edu/wpi/first/wpilibj/Threads.java

@@ -0,0 +1,43 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) FIRST 2008-2016. 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.                                                               */
+/*----------------------------------------------------------------------------*/
+
+package edu.wpi.first.wpilibj;
+
+import edu.wpi.first.wpilibj.hal.ThreadsJNI;
+
+public class Threads {
+
+  /**
+  * Get the thread priority for the current thread.
+  * @return The current thread priority. Scaled 1-99.
+  */
+  public static int getCurrentThreadPriority() {
+    return ThreadsJNI.getCurrentThreadPriority();
+  }
+
+  /**
+  * Get if the current thread is realtime.
+  * @return If the current thread is realtime
+  */
+  public static boolean getCurrentThreadIsRealTime() {
+    return ThreadsJNI.getCurrentThreadIsRealTime();
+  }
+
+  /**
+  * Sets the thread priority for the current thread.
+  *
+  * @param realTime Set to true to set a realtime priority, false for standard
+  *     priority
+  * @param priority Priority to set the thread to. Scaled 1-99, with 1 being
+  *     highest. On RoboRIO, priority is ignored for non realtime setting
+  *
+  * @return The success state of setting the priority
+  */
+  public static boolean setCurrentThreadPriority(boolean realTime, int priority) {
+    return ThreadsJNI.setCurrentThreadPriority(realTime, priority);
+  }
+}

wpilibj/src/athena/java/edu/wpi/first/wpilibj/hal/ThreadsJNI.java

@@ -0,0 +1,16 @@
+/*----------------------------------------------------------------------------*/
+/* Copyright (c) FIRST 2016. 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.                                                               */
+/*----------------------------------------------------------------------------*/
+
+package edu.wpi.first.wpilibj.hal;
+
+public class ThreadsJNI extends JNIWrapper {
+  public static native int getCurrentThreadPriority();
+
+  public static native boolean getCurrentThreadIsRealTime();
+
+  public static native boolean setCurrentThreadPriority(boolean realTime, int priority);
+}