Cubietruck---19.andorid进程创建过程分析

init.rc

service zygote /system/bin/app_process -Xzygote /system/bin --zygote --start-system-server
    class main
    socket zygote stream 660 root system
    onrestart write /sys/android_power/request_state wake
    onrestart write /sys/power/state on
    onrestart restart media
    onrestart restart netd

1.
app_process是通过下面这个文件编译出来的,
在./frameworks/base/cmds/app_process/app_main.cpp中

int main(int argc, const char* const argv[])
{
    //将进程名改为zygote
    if (niceName && *niceName) {
        setArgv0(argv0, niceName);
        set_process_name(niceName);
    }
    //调用AndroidRuntime的start
    AppRuntime runtime;
    runtime.addVmArguments(argc, argv);
    runtime.mParentDir = parentDir;
    runtime.start("com.android.internal.os.ZygoteInit", "start-system-server" );
}

其中class AppRuntime : public AndroidRuntime,所以上面的start就是调用AndroidRuntime的start
a.运行的进程是app_process为什么看到的却是zygote呢?
    set_process_name
       --> prctl(PR_SET_NAME, (unsigned long) new_name, 0, 0, 0);   ;;system/core/libcutils/process_name.c
    将进程的名字改为zygote了
2.
在./frameworks/base/core/jni/AndroidRuntime.cpp中

void AndroidRuntime::start(const char* className, const char* options)
{
    if (strcmp(options, "start-system-server") == 0)
        const int LOG_BOOT_PROGRESS_START = 3000;

    JNIEnv* env;
    startVm(&mJavaVM, &env);   //创建java虚拟机
        --> JNI_CreateJavaVM

    onVmCreated(env);

    startReg(env);

    //将 "com.android.internal.os.ZygoteInit", "start-system-server"都放在strArray中
     ...

    //找到"com.android.internal.os.ZygoteInit"这个类
    char* slashClassName = toSlashClassName(className);
    jclass startClass = env->FindClass(slashClassName);
    //并找到"com.android.internal.os.ZygoteInit"这个类的main方法
    jmethodID startMeth = env->GetStaticMethodID(startClass, "main", "([Ljava/lang/String;)V");
    //调用"com.android.internal.os.ZygoteInit"这个类的main方法
    env->CallStaticVoidMethod(startClass, startMeth, strArray);
}