Adding a new getThreadScheduler() method.

bug:  30226969
Change-Id: Icbd57e99740ebf6ba744a103e6fa69a3160c9422

api/test-current.txt

@@ -29225,6 +29225,7 @@ package android.os {
     method public static final long getStartElapsedRealtime();
     method public static final long getStartUptimeMillis();
     method public static final int getThreadPriority(int) throws java.lang.IllegalArgumentException;
+    method public static final int getThreadScheduler(int) throws java.lang.IllegalArgumentException;
     method public static final int getUidForName(java.lang.String);
     method public static final boolean is64Bit();
     method public static boolean isApplicationUid(int);

core/java/android/os/Process.java

@@ -16,6 +16,7 @@
 
 package android.os;
 
+import android.annotation.TestApi;
 import android.net.LocalSocket;
 import android.net.LocalSocketAddress;
 import android.system.Os;
@@ -1067,6 +1068,24 @@ public class Process {
     public static final native int getThreadPriority(int tid)
             throws IllegalArgumentException;
     
+    /**
+     * Return the current scheduling policy of a thread, based on Linux.
+     *
+     * @param tid The identifier of the thread/process to get the scheduling policy.
+     *
+     * @throws IllegalArgumentException Throws IllegalArgumentException if
+     * <var>tid</var> does not exist, or if <var>priority</var> is out of range for the policy.
+     * @throws SecurityException Throws SecurityException if your process does
+     * not have permission to modify the given thread, or to use the given
+     * scheduling policy or priority.
+     *
+     * {@hide}
+     */
+    
+    @TestApi
+    public static final native int getThreadScheduler(int tid)
+            throws IllegalArgumentException;
+
     /**
      * Set the scheduling policy and priority of a thread, based on Linux.
      *
@@ -1082,6 +1101,7 @@ public class Process {
      *
      * {@hide}
      */
+
     public static final native void setThreadScheduler(int tid, int policy, int priority)
             throws IllegalArgumentException;
 

core/jni/android_util_Process.cpp

@@ -440,6 +440,23 @@ static void android_os_Process_setCanSelfBackground(JNIEnv* env, jobject clazz,
 #endif
 }
 
+jint android_os_Process_getThreadScheduler(JNIEnv* env, jclass clazz,
+                                              jint tid)
+{
+    int policy = 0;
+// linux has sched_getscheduler(), others don't.
+#if defined(__linux__)
+    errno = 0;
+    policy = sched_getscheduler(tid);
+    if (errno != 0) {
+        signalExceptionForPriorityError(env, errno);
+    }
+#else
+    signalExceptionForPriorityError(env, ENOSYS);
+#endif
+    return policy;
+}
+
 void android_os_Process_setThreadScheduler(JNIEnv* env, jclass clazz,
                                               jint tid, jint policy, jint pri)
 {
@@ -1191,6 +1208,7 @@ static const JNINativeMethod methods[] = {
     {"setCanSelfBackground", "(Z)V", (void*)android_os_Process_setCanSelfBackground},
     {"setThreadPriority",   "(I)V", (void*)android_os_Process_setCallingThreadPriority},
     {"getThreadPriority",   "(I)I", (void*)android_os_Process_getThreadPriority},
+    {"getThreadScheduler",   "(I)I", (void*)android_os_Process_getThreadScheduler},
     {"setThreadGroup",      "(II)V", (void*)android_os_Process_setThreadGroup},
     {"setProcessGroup",     "(II)V", (void*)android_os_Process_setProcessGroup},
     {"getProcessGroup",     "(I)I", (void*)android_os_Process_getProcessGroup},