cutils: add thread_defs header

/*

 * Copyright (C) 2013 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

#ifndef ANDROID_THREAD_DEFS_H

#define ANDROID_THREAD_DEFS_H

#include <sys/cdefs.h>

#include "graphics.h"

__BEGIN_DECLS

enum {

    /*

     * ***********************************************

     * ** Keep in sync with android.os.Process.java **

     * ***********************************************

     * 

     * This maps directly to the "nice" priorities we use in Android.

     * A thread priority should be chosen inverse-proportionally to

     * the amount of work the thread is expected to do. The more work

     * a thread will do, the less favorable priority it should get so that 

     * it doesn't starve the system. Threads not behaving properly might

     * be "punished" by the kernel.

     * Use the levels below when appropriate. Intermediate values are

     * acceptable, preferably use the {MORE|LESS}_FAVORABLE constants below.

     */

    ANDROID_PRIORITY_LOWEST         =  19,

    /* use for background tasks */

    ANDROID_PRIORITY_BACKGROUND     =  10,

    /* most threads run at normal priority */

    ANDROID_PRIORITY_NORMAL         =   0,

    /* threads currently running a UI that the user is interacting with */

    ANDROID_PRIORITY_FOREGROUND     =  -2,

    /* the main UI thread has a slightly more favorable priority */

    ANDROID_PRIORITY_DISPLAY        =  -4,

    /* ui service treads might want to run at a urgent display (uncommon) */

    ANDROID_PRIORITY_URGENT_DISPLAY =  HAL_PRIORITY_URGENT_DISPLAY,

    /* all normal audio threads */

    ANDROID_PRIORITY_AUDIO          = -16,

    /* service audio threads (uncommon) */

    ANDROID_PRIORITY_URGENT_AUDIO   = -19,

    /* should never be used in practice. regular process might not 

     * be allowed to use this level */

    ANDROID_PRIORITY_HIGHEST        = -20,

    ANDROID_PRIORITY_DEFAULT        = ANDROID_PRIORITY_NORMAL,

    ANDROID_PRIORITY_MORE_FAVORABLE = -1,

    ANDROID_PRIORITY_LESS_FAVORABLE = +1,

};

__END_DECLS

#endif /* ANDROID_THREAD_DEFS_H */