rtc关机闹钟6 AlarmManagerService研究

这个是

private void setLocked(int type, long when) {

if (mNativeData != 0) {
            // The kernel never triggers alarms with negative wakeup times
            // so we ensure they are positive.
            long alarmSeconds, alarmNanoseconds;
            if (when < 0) {
                alarmSeconds = 0;
                alarmNanoseconds = 0;
            } else {
                alarmSeconds = when / 1000;
                alarmNanoseconds = (when % 1000) * 1000 * 1000;
            }
            
            set(mNativeData, type, alarmSeconds, alarmNanoseconds);
        } else {
            Message msg = Message.obtain();
            msg.what = ALARM_EVENT;
            
            mHandler.removeMessages(ALARM_EVENT);
            mHandler.sendMessageAtTime(msg, when);
        }

}

setLocked()内部会调用native函数set()：

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1. private native void set(int fd, int type, long seconds, long nanoseconds);

重新设置“实体闹钟”的激发时间。这个函数内部会调用ioctl()和底层打交道。具体代码可参考frameworks/base/services/jni/com_android_server_AlarmManagerService.cpp文件：

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1. static void android_server_AlarmManagerService_set(JNIEnv* env, jobject obj, jint fd,
2. jint type, jlong seconds, jlong nanoseconds)
3. {
4. struct timespec ts;
5. ts.tv_sec = seconds;
6. ts.tv_nsec = nanoseconds;
7. int result = ioctl(fd, ANDROID_ALARM_SET(type), &ts);
8. if (result < )
9. {
10. ALOGE("Unable to set alarm to %lld.%09lld: %s\n", seconds, nanoseconds, strerror(errno));
11. }
12. }