Android IPC 通讯机制源码分析

核心提示：.......................................}} else {//这一段我们获取到了service_mananger process 注册在binder kernle的进程信息target_node = binder_context_mgr_node; //BINDER_SET_CON

.......................................

}

} else {//这一段我们获取到了service_mananger process 注册在binder kernle的进程信息

target_node = binder_context_mgr_node; //BINDER_SET_CONTEXT_MGR 注册了service

if (target_node == NULL) { //manager

return_error = BR_DEAD_REPLY;

goto err_no_context_mgr_node;

}

}

e->to_node = target_node->debug_id;

target_proc = target_node->proc; //得到目标进程service_mananger 的结构

if (target_proc == NULL) {

return_error = BR_DEAD_REPLY;

goto err_dead_binder;

}

....................

}

if (target_thread) {

e->to_thread = target_thread->pid;

target_list = &target_thread->todo;

target_wait = &target_thread->wait; //得到service manager挂起的线程

} else {

target_list = &target_proc->todo;

target_wait = &target_proc->wait;

}

............................................

case BINDER_TYPE_BINDER:

case BINDER_TYPE_WEAK_BINDER: {

..........................

ref = binder_get_ref_for_node(target_proc, node); //在Binder kernel中创建

.......................... //查找到的service参考

} break;

............................................

if (target_wait)

wake_up_interruptible(target_wait); //唤醒挂起的线程 处理caller process请求

............................................//处理命令可以看svcmgr_handler

}

到这里我们已经通过getService连接到service manager进程了，service manager进程得到请求后，如果他的状态是挂起的话，将被唤醒。现在我们来看一下service manager中的binder_loop函数。

Service_manager.c

void binder_loop(struct binder_state *bs, binder_handler func)