android和linux的休眠唤醒机制.pdf

android

和

linux

的休眠唤醒机制

四、 android 层源码解析

1.hardware/libhardware_legacy/power/power.c //HAI 层

2. frameworks/base/core/jni/android_os_Power.cpp //jni 层

3．frameworks/base/core/java/android/os/Power.java //java 层

在 linux 之上经过 android 的软件堆层层封装 ,最终在上层的 java 应用程序中使用。 休眠唤醒

也是从最上层发出的命令，然后一层一层地将参数解析，往最底层传，最后走上标准 linux

的休眠唤醒之路。

RELEASE_WAKE_LOCK,

REQUEST_STATE,

OUR_FD_COUNT

};

const char * const NEW_PATHS[] = {

"/sys/power/wake_lock",

"/sys/power/wake_unlock",

"/sys/power/state"

};

static int g_initialized = 0;

for (i=0; i<OUR_FD_COUNT; i++) {

int fd = open(paths[i], O_RDWR);

if (fd < 0) {

fprintf(stderr, "fatal error opening \"%s\"\n", paths[i]);

g_error = errno;

return -1;

}

g_fds[i] = fd;

}

g_error = 0;

{

if (g_initialized == 0) {

}

}

int acquire_wake_lock(int lock, const char* id)

{

initialize_fds();

if (g_error) return g_error;

int fd;

fd = g_fds[ACQUIRE_PARTIAL_WAKE_LOCK];

}

return write(fd, id, strlen(id));

}

return len >= 0;

}

int set_screen_state(int on)

{

QEMU_FALLBACK(set_screen_state(on));

LOGI("*** set_screen_state %d", on);

initialize_fds();

if (g_error) return g_error;

char buf[32];

int len;

len = sprintf(buf, off_state);

len = write(g_fds[REQUEST_STATE], buf, len);

static void acquireWakeLock(JNIEnv *env, jobject clazz, jint lock, jstring idObj)

{

if (idObj == NULL) {

throw_NullPointerException(env, "id is null");

return ;

}

const char *id = env->GetStringUTFChars(idObj, NULL);

acquire_wake_lock(lock, id);

env->ReleaseStringUTFChars(idObj, id);

}// 对 wakelock 加锁函数