android wakelock申請與釋放
wakelock可以被核心空間 申請和釋放。如果申請的是非超時鎖wake_lock,需要相應的呼叫wake_unlock來釋放,而超時鎖則不需要手工釋放(當然你也可以手工釋放),超時後kernel系統會自動釋放鎖,在核心空間可以直接呼叫wake_lock, wake_lock_timeout 申請鎖 Android kernel為使用者空間提供了申請和釋放wakelock的介面,實現在kernel/power/userwakelock.c中。
例項:
1:首先申明一個wake_lock
static struct wake_lock alarm_rtc_wake_lock;
2:在init函式中對wake_lock初始化
wake_lock_init(&alarm_rtc_wake_lock, WAKE_LOCK_SUSPEND, "alarm_rtc");//WAKE_LOCK_SUSPEND 為suspend lock還有一種idle lock
WAKE_LOCK_SUSPEND, /* Prevent suspend */
WAKE_LOCK_IDLE, /* Prevent low power idle*/
3:使用wake_lock()或者wake_lock_timeout()
wake_lock_timeout(&alarm_rtc_wake_lock, 1 * HZ);
wake_lock(&alarm_rtc_wake_lock);
4:使用wake_unlock()
wake_unlock(&alarm_rtc_wake_lock);
4:在exit中呼叫wake_lock_destroy()
wake_lock_destroy(&alarm_rtc_wake_lock);
wake_lock_init(&alarm_rtc_wake_lock, WAKE_LOCK_SUSPEND, "alarm_rtc");
if (is_wakeup && !suspended && head_removed)
wake_unlock(&alarm_rtc_wake_lock);
if (is_wakeup && suspended) {
pr_alarm(FLOW, "changed alarm while suspened\n");
wake_lock_timeout(&alarm_rtc_wake_lock, 1 * HZ);
return;
}
wake_lock(&alarm_rtc_wake_lock);
wake_unlock(&alarm_rtc_wake_lock);
wake_lock_timeout(&alarm_rtc_wake_lock, 1 * HZ);
suspended = false;
wake_lock_timeout(&alarm_rtc_wake_lock, 2 * HZ);
wake_lock_destroy(&alarm_rtc_wake_lock);