（一百三十二）AndroidOWiFi重启机制学习——重启流程

在日常生活中&＃xff0c;WiFi使用过程中出现异常用户一般都会手动关闭再打开WiFi完成一次重启&＃xff0c;那么Android机制是否有类似的呢&＃xff1f;

偶然间看到一个类叫做SelfRecovery&＃xff0c;该类有将WiFi重启的接口

2.1 SelfRecovery

/*** This class is used to recover the wifi stack from a fatal failure. The recovery mechanism* involves triggering a stack restart (essentially simulating an airplane mode toggle) using* {&＃64;link WifiController}.* The current triggers for:* 1. Last resort watchdog bite.* 2. HAL/wificond crashes during normal operation.* 3. TBD: supplicant crashes during normal operation.*/

api中简要说明了这个类是用来将WiFi从异常状态恢复的。恢复机制是通过WifiController触发一个重启&＃xff0c;基本模拟了一次飞行模式切换。

当前触发条件

• 看门狗
• 正常操作过程中的HAL/wificond crashes
• TBD:正常操作过程中的supplicant crashes&＃xff08;暂未有对应处理&＃xff09;

/*** Trigger recovery.** This method does the following:* 1. Raises a wtf.* 2. Sends {&＃64;link WifiController#CMD_RESTART_WIFI} to {&＃64;link WifiController} to initiate the* stack restart.* &＃64;param reason One of the above |REASON_*| codes.*/public void trigger(int reason) {if (!(reason &＃61;&＃61; REASON_LAST_RESORT_WATCHDOG || reason &＃61;&＃61; REASON_HAL_CRASH|| reason &＃61;&＃61; REASON_WIFICOND_CRASH)) {Log.e(TAG, "Invalid trigger reason. Ignoring...");return;}Log.e(TAG, "Triggering recovery for reason: " &＃43; REASON_STRINGS[reason]);if (reason &＃61;&＃61; REASON_WIFICOND_CRASH || reason &＃61;&＃61; REASON_HAL_CRASH) {trimPastRestartTimes();// Ensure there haven&＃39;t been too many restarts within MAX_RESTARTS_TIME_WINDOWif (mPastRestartTimes.size() >&＃61; MAX_RESTARTS_IN_TIME_WINDOW) {Log.e(TAG, "Already restarted wifi (" &＃43; MAX_RESTARTS_IN_TIME_WINDOW &＃43; ") times in"&＃43; " last (" &＃43; MAX_RESTARTS_TIME_WINDOW_MILLIS &＃43; "ms ). Ignoring...");return;}mPastRestartTimes.add(mClock.getElapsedSinceBootMillis());}mWifiController.sendMessage(WifiController.CMD_RESTART_WIFI);}/*** Process the mPastRestartTimes list, removing elements outside the max restarts time window*/private void trimPastRestartTimes() {Iterator iter &＃61; mPastRestartTimes.iterator();long now &＃61; mClock.getElapsedSinceBootMillis();while (iter.hasNext()) {Long restartTimeMillis &＃61; iter.next();if (now - restartTimeMillis > MAX_RESTARTS_TIME_WINDOW_MILLIS) {iter.remove();} else {break;}}}

1&＃xff09;首先判断是否是已知的重启原因&＃xff0c;若不是&＃xff0c;忽略

2&＃xff09;若是wificond/hal crash&＃xff0c;那么在指定时间内重启次数有限制&＃xff0c;具体为1小时内重启次数不能超过2次。

public static final long MAX_RESTARTS_IN_TIME_WINDOW &＃61; 2; // 2 restarts per hourpublic static final long MAX_RESTARTS_TIME_WINDOW_MILLIS &＃61; 60 * 60 * 1000; // 1 hour

3&＃xff09;发送CMD_RESTART_WIFI命令给WifiController触发重启

2.2 WifiController