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;
+}
+
+}