healthd主要是读取电池节点的信息，传给BatteryService。或者在关机充电等使用。注意healthd中使用的是kernel的log，存在路径：system\core\healthd
main函数
int main(int argc, char **argv) {
int ch;
int ret;
klog_set_level(KLOG_LEVEL);
healthd_mode_ops = &android_ops;
if (!strcmp(basename(argv[0]), "charger")) {
healthd_mode_ops = &charger_ops;
} else {
while ((ch = getopt(argc, argv, "cr")) != -1) {
switch (ch) {
case 'c':
healthd_mode_ops = &charger_ops;
break;
case 'r':
healthd_mode_ops = &recovery_ops;
break;
case '?':
default:
KLOG_ERROR(LOG_TAG, "Unrecognized healthd option: %c\n",
optopt);
exit(1);
}
}
}
ret = healthd_init();//healthd初始化
if (ret) {
KLOG_ERROR("Initialization failed, exiting\n");
exit(2);
}
healthd_mainloop();//healthd主函数
KLOG_ERROR("Main loop terminated, exiting\n");
return 3;
}
如果是正常开机，不走关机充电等，healthd_mode_ops = &android_ops;而这里面具体的函数在后面进行详细的介绍。
static struct healthd_mode_ops android_ops = {
.init = healthd_mode_android_init,
.preparetowait = healthd_mode_android_preparetowait,
.heartbeat = healthd_mode_nop_heartbeat,
.battery_update = healthd_mode_android_battery_update,
};
healthd_init
heathd使用了epoll进行IO复用
static int healthd_init() {
epollfd = epoll_create(MAX_EPOLL_EVENTS);
if (epollfd == -1) {
KLOG_ERROR(LOG_TAG,
"epoll_create failed; errno=%d\n",
errno);
return -1;
}
healthd_board_init(&healthd_config);
healthd_mode_ops->init(&healthd_config);
wakealarm_init();
uevent_init();
gBatteryMonitor = new BatteryMonitor();
gBatteryMonitor->init(&healthd_config);
return 0;
}
这里的healthd_mode_ops->init的函数是android_ops 的healthd_mode_android_init函数，这里主要是将binder通信的fd也加入epoll，而不像普通binder进程最后使用IPCThreadState::self()->joinThreadPool。这样所有的fd全在epoll管理，只用了一个线程
void healthd_mode_android_init(struct healthd_config* /*config*/) {
ProcessState::self()->setThreadPoolMaxThreadCount(0);
IPCThreadState::self()->disableBackgroundScheduling(true);
IPCThreadState::self()->setupPolling(&gBinderFd);
if (gBinderFd >= 0) {
if (healthd_register_event(gBinderFd, binder_event))
KLOG_ERROR(LOG_TAG,
"Register for binder events failed\n");
}
gBatteryPropertiesRegistrar = new BatteryPropertiesRegistrar();
gBatteryPropertiesRegistrar->publish();
}
gBatteryPropertiesRegistrar->publish将"batteryproperties"这个Service加入到ServiceManager中
void BatteryPropertiesRegistrar::publish() {
defaultServiceManager()->addService(String16("batteryproperties"), this);
}
wakealarm_init
static void wakealarm_init(void) {
wakealarm_fd = timerfd_create(CLOCK_BOOTTIME_ALARM, TFD_NONBLOCK);
if (wakealarm_fd == -1) {
KLOG_ERROR(LOG_TAG, "wakealarm_init: timerfd_create failed\n");
return;
}
if (healthd_register_event(wakealarm_fd, wakealarm_event))
KLOG_ERROR(LOG_TAG,
"Registration of wakealarm event failed\n");
wakealarm_set_interval(healthd_config.periodic_chores_interval_fast);
}
wakealarm_init设置alarm唤醒的interval，再来看下时间处理函数
static void wakealarm_event(uint32_t /*epevents*/) {
unsigned long long wakeups;
if (read(wakealarm_fd, &wakeups, sizeof(wakeups)) == -1) {
KLOG_ERROR(LOG_TAG, "wakealarm_event: read wakealarm fd failed\n");
return;
}
periodic_chores();
}
static void periodic_chores() {
healthd_battery_update();
}
void healthd_battery_update(void) {
// Fast wake interval when on charger (watch for overheat);
// slow wake interval when on battery (watch for drained battery).
int new_wake_interval = gBatteryMonitor->update() ?//调用主要的update函数，根据返回值，如果当前在充电返回true
healthd_config.periodic_chores_interval_fast :
healthd_config.periodic_chores_interval_slow;
if (new_wake_interval != wakealarm_wake_interval)
wakealarm_set_interval(new_wake_interval);
// During awake periods poll at fast rate. If wake alarm is set at fast
// rate then just use the alarm; if wake alarm is set at slow rate then
// poll at fast rate while awake and let alarm wake up at slow rate when
// asleep.
if (healthd_config.periodic_chores_interval_fast == -1)
awake_poll_interval = -1;
else
awake_poll_interval =
new_wake_interval == healthd_config.periodic_chores_interval_fast ?
-1 : healthd_config.periodic_chores_interval_fast * 1000;
}
uevent_init
static void uevent_init(void) {
uevent_fd = uevent_open_socket(64*1024, true);
if (uevent_fd < 0) {
KLOG_ERROR(LOG_TAG, "uevent_init: uevent_open_socket failed\n");
return;
}
fcntl(uevent_fd, F_SETFL, O_NONBLOCK);
if (healthd_register_event(uevent_fd, uevent_event))
KLOG_ERROR(LOG_TAG,
"register for uevent events failed\n");
}
看看uevent_event的处理函数,获取uevent后主要判断是否是电源系统的，如果是调用healthd_battery_update函数
#define UEVENT_MSG_LEN 2048
static void uevent_event(uint32_t /*epevents*/) {
char msg[UEVENT_MSG_LEN+2];
char *cp;
int n;
n = uevent_kernel_multicast_recv(uevent_fd, msg, UEVENT_MSG_LEN);
if (n <= 0)
return;
if (n >= UEVENT_MSG_LEN) /* overflow -- discard */
return;
msg[n] = '\0';
msg[n+1] = '\0';
cp = msg;
while (*cp) {
if (!strcmp(cp, "SUBSYSTEM=" POWER_SUPPLY_SUBSYSTEM)) {//是这个子系统的调用healthd_battery_update函数
healthd_battery_update();
break;
}
/* advance to after the next \0 */
while (*cp++)
;
}
}
下面分析下healthd_mainloop这个主函数，主函数主要是epoll函数监听3个fd，有事件就处理。
static void healthd_mainloop(void) {
while (1) {
struct epoll_event events[eventct];
int nevents;
int timeout = awake_poll_interval;
int mode_timeout;
mode_timeout = healthd_mode_ops->preparetowait();
if (timeout < 0 || (mode_timeout > 0 && mode_timeout < timeout))
timeout = mode_timeout;
nevents = epoll_wait(epollfd, events, eventct, timeout);//epoll_wait等待各个fd的事件，timeout为超时时间
if (nevents == -1) {
if (errno == EINTR)
continue;
KLOG_ERROR(LOG_TAG, "healthd_mainloop: epoll_wait failed\n");
break;
}
for (int n = 0; n < nevents; ++n) {
if (events[n].data.ptr)//遍历各个fd的事件上来，每个处理函数处理
(*(void (*)(int))events[n].data.ptr)(events[n].events);
}
if (!nevents)//没有event的时候也需要update
periodic_chores();
healthd_mode_ops->heartbeat();
}
return;
}
BatteryMonitor::init
gBatteryMonitor->init(&healthd_config),init函数主要将healthd_config 对象传入，并且将里面的成员的一些地址信息去初始化保存起来。主要是保存一些地址信息，以及充电方式
void BatteryMonitor::init(struct healthd_config *hc) {
String8 path;
char pval[PROPERTY_VALUE_MAX];
mHealthdConfig = hc;//将外面传进来的heathdconfig的指针赋给成员变量
DIR* dir = opendir(POWER_SUPPLY_SYSFS_PATH);//打开地址 /sys/class/power_supply
if (dir == NULL) {
KLOG_ERROR(LOG_TAG, "Could not open %s\n", POWER_SUPPLY_SYSFS_PATH);
} else {
struct dirent* entry;
while ((entry = readdir(dir))) {
const char* name = entry->d_name;
if (!strcmp(name, ".") || !strcmp(name, ".."))
continue;
char buf[20];
// Look for "type" file in each subdirectory
path.clear();
path.appendFormat("%s/%s/type", POWER_SUPPLY_SYSFS_PATH, name);
switch(readPowerSupplyType(path)) {//读取各个目录下type的值，比如/sys/class/power_supply/battery 下type的值为Battery，在readPowerSupplyType读取并且转化为ANDROID_POWER_SUPPLY_TYPE_BATTERY
case ANDROID_POWER_SUPPLY_TYPE_AC:
if (mHealthdConfig->acChargeHeathPath.isEmpty()) {
path.clear();
path.appendFormat("%s/%s/health", POWER_SUPPLY_SYSFS_PATH,
name);
if (access(path, R_OK) == 0)
mHealthdConfig->acChargeHeathPath = path;//配置路径
}
path.clear();
path.appendFormat("%s/%s/online", POWER_SUPPLY_SYSFS_PATH, name);
if (access(path.string(), R_OK) == 0)
mChargerNames.add(String8(name));//chargername 就是当前目录名字：ac
break;
case ANDROID_POWER_SUPPLY_TYPE_USB://usb 类似ac
if (mHealthdConfig->usbChargeHeathPath.isEmpty()) {
path.clear();
path.appendFormat("%s/%s/health", POWER_SUPPLY_SYSFS_PATH,
name);
if (access(path, R_OK) == 0)
mHealthdConfig->usbChargeHeathPath = path;
}
path.clear();
path.appendFormat("%s/%s/online", POWER_SUPPLY_SYSFS_PATH, name);
if (access(path.string(), R_OK) == 0)
mChargerNames.add(String8(name));
break;
case ANDROID_POWER_SUPPLY_TYPE_WIRELESS://类似
path.clear();
path.appendFormat("%s/%s/online", POWER_SUPPLY_SYSFS_PATH, name);
if (access(path.string(), R_OK) == 0)
mChargerNames.add(String8(name));
break;
case ANDROID_POWER_SUPPLY_TYPE_BATTERY://battery
mBatteryDevicePresent = true;
if (mHealthdConfig->batteryStatusPath.isEmpty()) {
path.clear();
path.appendFormat("%s/%s/status", POWER_SUPPLY_SYSFS_PATH,
name);
if (access(path, R_OK) == 0)
mHealthdConfig->batteryStatusPath = path;
}
if (mHealthdConfig->batteryHealthPath.isEmpty()) {
path.clear();
path.appendFormat("%s/%s/health", POWER_SUPPLY_SYSFS_PATH,
name);
if (access(path, R_OK) == 0)
mHealthdConfig->batteryHealthPath = path;
}
if (mHealthdConfig->batteryPresentPath.isEmpty()) {
path.clear();
path.appendFormat("%s/%s/present", POWER_SUPPLY_SYSFS_PATH,
name);
if (access(path, R_OK) == 0)
mHealthdConfig->batteryPresentPath = path;
}
if (mHealthdConfig->batteryCapacityPath.isEmpty()) {
path.clear();
path.appendFormat("%s/%s/capacity", POWER_SUPPLY_SYSFS_PATH,
name);
if (access(path, R_OK) == 0)
mHealthdConfig->batteryCapacityPath = path;
}
if (mHealthdConfig->batteryVoltagePath.isEmpty()) {
path.clear();
path.appendFormat("%s/%s/voltage_now",
POWER_SUPPLY_SYSFS_PATH, name);
if (access(path, R_OK) == 0) {
mHealthdConfig->batteryVoltagePath = path;
} else {
path.clear();
path.appendFormat("%s/%s/batt_vol",
POWER_SUPPLY_SYSFS_PATH, name);
if (access(path, R_OK) == 0)
mHealthdConfig->batteryVoltagePath = path;
}
}
if (mHealthdConfig->batteryCurrentNowPath.isEmpty()) {
path.clear();
path.appendFormat("%s/%s/current_now",
POWER_SUPPLY_SYSFS_PATH, name);
if (access(path, R_OK) == 0)
mHealthdConfig->batteryCurrentNowPath = path;
}
if (mHealthdConfig->batteryCurrentAvgPath.isEmpty()) {
path.clear();
path.appendFormat("%s/%s/current_avg",
POWER_SUPPLY_SYSFS_PATH, name);
if (access(path, R_OK) == 0)
mHealthdConfig->batteryCurrentAvgPath = path;
}
if (mHealthdConfig->batteryChargeCounterPath.isEmpty()) {
path.clear();
path.appendFormat("%s/%s/charge_counter",
POWER_SUPPLY_SYSFS_PATH, name);
if (access(path, R_OK) == 0)
mHealthdConfig->batteryChargeCounterPath = path;
}
if (mHealthdConfig->batteryTemperaturePath.isEmpty()) {
path.clear();
path.appendFormat("%s/%s/temp", POWER_SUPPLY_SYSFS_PATH,
name);
if (access(path, R_OK) == 0) {
mHealthdConfig->batteryTemperaturePath = path;
} else {
path.clear();
path.appendFormat("%s/%s/batt_temp",
POWER_SUPPLY_SYSFS_PATH, name);
if (access(path, R_OK) == 0)
mHealthdConfig->batteryTemperaturePath = path;
}
}
if (mHealthdConfig->batteryTechnologyPath.isEmpty()) {
path.clear();
path.appendFormat("%s/%s/technology",
POWER_SUPPLY_SYSFS_PATH, name);
if (access(path, R_OK) == 0)
mHealthdConfig->batteryTechnologyPath = path;
}
break;
case ANDROID_POWER_SUPPLY_TYPE_UNKNOWN:
break;
}
}
closedir(dir);
}
if (!mChargerNames.size())
KLOG_ERROR(LOG_TAG, "No charger supplies found\n");
if (!mBatteryDevicePresent) {//主要由battery该成员变量就为true
KLOG_WARNING(LOG_TAG, "No battery devices found\n");
hc->periodic_chores_interval_fast = -1;
hc->periodic_chores_interval_slow = -1;
} else {
if (mHealthdConfig->batteryStatusPath.isEmpty())
KLOG_WARNING(LOG_TAG, "BatteryStatusPath not found\n");
。。。。。。。。。。。。。//这里都是一些警告
}
if (property_get("ro.boot.fake_battery", pval, NULL) > 0
&& strtol(pval, NULL, 10) != 0) {
mBatteryFixedCapacity = FAKE_BATTERY_CAPACITY;
mBatteryFixedTemperature = FAKE_BATTERY_TEMPERATURE;
}
}
下面就是update函数，将数据封装在BatteryProperties 中，并且通过healthd_mode_ops->battery_update把BatteryProperties 发给上层
bool BatteryMonitor::update(void) {
bool logthis;
props.chargerAcOnline = false;
props.chargerUsbOnline = false;
props.chargerWirelessOnline = false;
props.batteryStatus = BATTERY_STATUS_UNKNOWN;
props.batteryHealth = BATTERY_HEALTH_UNKNOWN;
//都是从之前配置的mHealthd中取地址，读取节点信息，保存到props成员变量中
if (!mHealthdConfig->batteryPresentPath.isEmpty())
props.batteryPresent = getBooleanField(mHealthdConfig->batteryPresentPath);
else
props.batteryPresent = mBatteryDevicePresent;
props.batteryLevel = mBatteryFixedCapacity ?
mBatteryFixedCapacity :
getIntField(mHealthdConfig->batteryCapacityPath);
props.batteryVoltage = getIntField(mHealthdConfig->batteryVoltagePath) / 1000;
props.batteryTemperature = mBatteryFixedTemperature ?
mBatteryFixedTemperature :
getIntField(mHealthdConfig->batteryTemperaturePath);
const int SIZE = 128;
char buf[SIZE];
String8 btech;
if (readFromFile(mHealthdConfig->batteryStatusPath, buf, SIZE) > 0)
props.batteryStatus = getBatteryStatus(buf);
if (readFromFile(mHealthdConfig->batteryHealthPath, buf, SIZE) > 0)
props.batteryHealth = getBatteryHealth(buf);
if (readFromFile(mHealthdConfig->batteryTechnologyPath, buf, SIZE) > 0)
props.batteryTechnology = String8(buf);
if (readFromFile(mHealthdConfig->acChargeHeathPath, buf, SIZE) > 0)
props.acChargeHeath= String8(buf);
if (readFromFile(mHealthdConfig->usbChargeHeathPath, buf, SIZE) > 0)
props.usbChargeHeath= String8(buf);
unsigned int i;
for (i = 0; i < mChargerNames.size(); i++) {//遍历之前保存的各个充电方式
String8 path;
path.appendFormat("%s/%s/online", POWER_SUPPLY_SYSFS_PATH,
mChargerNames[i].string());//路径就是每个目录下的online字段，比如/sys/class/power_supply/usb 下的online
if (readFromFile(path, buf, SIZE) > 0) {
if (buf[0] != '0') {//读取online里面的内容，如果当前在usb线上充电，那么usb下online里面的内容为1
path.clear();
path.appendFormat("%s/%s/type", POWER_SUPPLY_SYSFS_PATH,
mChargerNames[i].string());//这里看看是哪个type的
switch(readPowerSupplyType(path)) {
case ANDROID_POWER_SUPPLY_TYPE_AC:
props.chargerAcOnline = true;
break;
case ANDROID_POWER_SUPPLY_TYPE_USB://将其值赋成true
props.chargerUsbOnline = true;
break;
case ANDROID_POWER_SUPPLY_TYPE_WIRELESS:
props.chargerWirelessOnline = true;
break;
default:
KLOG_WARNING(LOG_TAG, "%s: Unknown power supply type\n",
mChargerNames[i].string());
}
}
}
}
logthis = !healthd_board_battery_update(&props);
if (logthis) {
char dmesgline[256];
if (props.batteryPresent) {
snprintf(dmesgline, sizeof(dmesgline),
"battery l=%d v=%d t=%s%d.%d h=%d st=%d",
props.batteryLevel, props.batteryVoltage,
props.batteryTemperature < 0 ? "-" : "",
abs(props.batteryTemperature / 10),
abs(props.batteryTemperature % 10), props.batteryHealth,
props.batteryStatus);
if (!mHealthdConfig->batteryCurrentNowPath.isEmpty()) {
int c = getIntField(mHealthdConfig->batteryCurrentNowPath);
char b[20];
snprintf(b, sizeof(b), " c=%d", c / 1000);
strlcat(dmesgline, b, sizeof(dmesgline));
}
} else {
snprintf(dmesgline, sizeof(dmesgline),
"battery none");
}
KLOG_WARNING(LOG_TAG, "%s chg=%s%s%s\n", dmesgline,
props.chargerAcOnline ? "a" : "",
props.chargerUsbOnline ? "u" : "",
props.chargerWirelessOnline ? "w" : "");
}
healthd_mode_ops->battery_update(&props);//将数据传到上层的BatteryService
return props.chargerAcOnline | props.chargerUsbOnline |//返回当前是否属于充电
props.chargerWirelessOnline;
}
healthd_mode_ops->battery_update是把数据传到上层
void healthd_mode_android_battery_update(
struct android::BatteryProperties *props) {
if (gBatteryPropertiesRegistrar != NULL)
gBatteryPropertiesRegistrar->notifyListeners(*props);
return;
}
上层会通过binder通信，注册一个回调到BatteryPropertiesRegistrar
void BatteryPropertiesRegistrar::registerListener(const sp<IBatteryPropertiesListener>& listener) {
{
if (listener == NULL)
return;
Mutex::Autolock _l(mRegistrationLock);
// check whether this is a duplicate
for (size_t i = 0; i < mListeners.size(); i++) {
if (IInterface::asBinder(mListeners[i]) == IInterface::asBinder(listener)) {
return;
}
}
mListeners.add(listener);
IInterface::asBinder(listener)->linkToDeath(this);
}
healthd_battery_update();
}
而update函数就是调用了notifyListeners遍历各个listener传到上层BatteryService
void BatteryPropertiesRegistrar::notifyListeners(struct BatteryProperties props) {
Mutex::Autolock _l(mRegistrationLock);
for (size_t i = 0; i < mListeners.size(); i++) {
mListeners[i]->batteryPropertiesChanged(props);
}
}
再来看看BatteryService中，在onStart中通过ServiceManager，和batteryproperties这个Service通信，将BatteryListener这个listenter注册到batteryproperties中去
public void onStart() {
IBinder b = ServiceManager.getService("batteryproperties");
final IBatteryPropertiesRegistrar batteryPropertiesRegistrar =
IBatteryPropertiesRegistrar.Stub.asInterface(b);
try {
batteryPropertiesRegistrar.registerListener(new BatteryListener());
} catch (RemoteException e) {
// Should never happen.
}
publishBinderService("battery", new BinderService());
publishLocalService(BatteryManagerInternal.class, new LocalService());
}
再来看看BatteryListener 的batteryPropertiesChanged接口，当下面调这个接口，就会调用BatteryService的update函数
private final class BatteryListener extends IBatteryPropertiesListener.Stub {
@Override
public void batteryPropertiesChanged(BatteryProperties props) {
final long identity = Binder.clearCallingIdentity();
try {
BatteryService.this.update(props);
} finally {
Binder.restoreCallingIdentity(identity);
}
}
}
BatteryService接受healthd的数据都是被动的，healthd传过来的。有没有主动去healthd查询的
扩展
主动查询数据
private long queryProperty(int id) {
long ret;
if (mBatteryPropertiesRegistrar == null) {
IBinder b = ServiceManager.getService("batteryproperties");//获取batteryproperties Service
mBatteryPropertiesRegistrar =
IBatteryPropertiesRegistrar.Stub.asInterface(b);//接口转化下
if (mBatteryPropertiesRegistrar == null)
return Long.MIN_VALUE;
}
try {
BatteryProperty prop = new BatteryProperty();
if (mBatteryPropertiesRegistrar.getProperty(id, prop) == 0)//prop是输出
ret = prop.getLong();
else
ret = Long.MIN_VALUE;
} catch (RemoteException e) {
ret = Long.MIN_VALUE;
}
return ret;
}
status_t BatteryPropertiesRegistrar::getProperty(int id, struct BatteryProperty *val) {
return healthd_get_property(id, val);
}
status_t healthd_get_property(int id, struct BatteryProperty *val) {
return gBatteryMonitor->getProperty(id, val);
}
status_t BatteryMonitor::getProperty(int id, struct BatteryProperty *val) {
status_t ret = BAD_VALUE;
val->valueInt64 = LONG_MIN;
switch(id) {
case BATTERY_PROP_CHARGE_COUNTER://根据不同ID，返回不同值
if (!mHealthdConfig->batteryChargeCounterPath.isEmpty()) {
val->valueInt64 =
getIntField(mHealthdConfig->batteryChargeCounterPath);
ret = NO_ERROR;
} else {
ret = NAME_NOT_FOUND;
}
break;
case BATTERY_PROP_CURRENT_NOW:
if (!mHealthdConfig->batteryCurrentNowPath.isEmpty()) {
val->valueInt64 =
getIntField(mHealthdConfig->batteryCurrentNowPath);
ret = NO_ERROR;
} else {
ret = NAME_NOT_FOUND;
}
break;
case BATTERY_PROP_CURRENT_AVG:
if (!mHealthdConfig->batteryCurrentAvgPath.isEmpty()) {
val->valueInt64 =
getIntField(mHealthdConfig->batteryCurrentAvgPath);
ret = NO_ERROR;
} else {
ret = NAME_NOT_FOUND;
}
break;
case BATTERY_PROP_CAPACITY:
if (!mHealthdConfig->batteryCapacityPath.isEmpty()) {
val->valueInt64 =
getIntField(mHealthdConfig->batteryCapacityPath);
ret = NO_ERROR;
} else {
ret = NAME_NOT_FOUND;
}
break;
case BATTERY_PROP_ENERGY_COUNTER:
if (mHealthdConfig->energyCounter) {
ret = mHealthdConfig->energyCounter(&val->valueInt64);
} else {
ret = NAME_NOT_FOUND;
}
break;
default:
break;
}
return ret;
}