軟件架構(gòu)之時(shí)間輪片法

程序架構(gòu)重要性很多人尤其是初學(xué)者在寫代碼的時(shí)候往往都是想一點(diǎn)寫一點(diǎn)，最開始沒有一個(gè)整體的規(guī)劃，導(dǎo)致后面代碼越寫越亂，bug不斷。最終代碼跑起來看似沒有問題(有可能也真的沒有問題)，但是要加一個(gè)功能的時(shí)候會(huì)浪費(fèi)大量的時(shí)間，甚至導(dǎo)致整個(gè)代碼的崩潰。所以，在一個(gè)項(xiàng)目開始的時(shí)候多花一些時(shí)間在代碼的架構(gòu)設(shè)計(jì)上是十分有必要的。代碼架構(gòu)確定好了之后你會(huì)發(fā)現(xiàn)敲代碼的時(shí)候會(huì)特別快，并且在后期調(diào)試的時(shí)候也不會(huì)像無頭蒼蠅一樣胡亂找問題。當(dāng)然，調(diào)試也是一門技術(shù)。在學(xué)習(xí)實(shí)時(shí)操作系統(tǒng)的過程中，發(fā)現(xiàn)實(shí)時(shí)操作系統(tǒng)框架與個(gè)人的業(yè)務(wù)代碼之間的耦合性就非常低，都是只需要將業(yè)務(wù)代碼通過一定的接口函數(shù)注冊(cè)好后就交給操作系統(tǒng)托管了，十分方便。但是操作系統(tǒng)的調(diào)度過于復(fù)雜，這里就使用操作系統(tǒng)的思維方式來重構(gòu)這個(gè)時(shí)間片輪詢框架。實(shí)現(xiàn)該框架的完全解耦，用戶只需要包含頭文件，并且在使用過程中不需要改動(dòng)已經(jīng)寫好的庫(kù)文件。Demo首先來個(gè)demo，該demo是使用電腦開兩個(gè)線程：一個(gè)線程模擬單片機(jī)的定時(shí)器中斷產(chǎn)生時(shí)間片輪詢個(gè)時(shí)鐘，另一個(gè)線程則模擬主函數(shù)中一直運(yùn)行的時(shí)間片輪詢調(diào)度程序。#include<thread>#include<stdio.h>#include<windows.h>#include"timeslice.h"http://創(chuàng)建5個(gè)任務(wù)對(duì)象TimesilceTaskObjtask_1,task_2,task_3,task_4,task_5;//具體的任務(wù)函數(shù)voidtask1_hdl(){printf(">>task1isrunning...\n");}voidtask2_hdl(){printf(">>task2isrunning...\n");}voidtask3_hdl(){printf(">>task3isrunning...\n");}voidtask4_hdl(){printf(">>task4isrunning...\n");}voidtask5_hdl(){printf(">>task5isrunning...\n");}//初始化任務(wù)對(duì)象，并且將任務(wù)添加到時(shí)間片輪詢調(diào)度中voidtask_init(){timeslice_task_init(&task_1,task1_hdl,1,10);timeslice_task_init(&task_2,task2_hdl,2,20);timeslice_task_init(&task_3,task3_hdl,3,30);timeslice_task_init(&task_4,task4_hdl,4,40);timeslice_task_init(&task_5,task5_hdl,5,50);timeslice_task_add(&task_1);timeslice_task_add(&task_2);timeslice_task_add(&task_3);timeslice_task_add(&task_4);timeslice_task_add(&task_5);}//開兩個(gè)線程模擬在單片機(jī)上的運(yùn)行過程voidtimeslice_exec_thread(){while(true){timeslice_exec();}}voidtimeslice_tick_thread(){while(true){timeslice_tick();Sleep(10);}}intmain(){task_init();printf(">>tasknum:%d\n",timeslice_get_task_num());printf(">>tasklen:%d\n",timeslice_get_task_timeslice_len(&task_3));timeslice_task_del(&task_2);printf(">>delettask2\n");printf(">>task2isexist:%d\n",timeslice_task_isexist(&task_2));printf(">>tasknum:%d\n",timeslice_get_task_num());timeslice_task_del(&task_5);printf(">>delettask5\n");printf(">>tasknum:%d\n",timeslice_get_task_num());printf(">>task3isexist:%d\n",timeslice_task_isexist(&task_3));timeslice_task_add(&task_2);printf(">>addtask2\n");printf(">>task2isexist:%d\n",timeslice_task_isexist(&task_2));timeslice_task_add(&task_5);printf(">>addtask5\n");printf(">>tasknum:%d\n",timeslice_get_task_num());printf("\n\n========timeslicerunning===========\n");std::threadthread_1(timeslice_exec_thread);std::threadthread_2(timeslice_tick_thread);thread_1.join();thread_2.join();return0;}運(yùn)行結(jié)果如下：由以上例子可見，這個(gè)框架使用十分方便，甚至可以完全不知道其原理，僅僅通過幾個(gè)簡(jiǎn)單的接口就可以迅速創(chuàng)建任務(wù)并加入到時(shí)間片輪詢的框架中，十分好用。時(shí)間片輪詢架構(gòu)其實(shí)該部分主要使用了面向?qū)ο蟮乃季S，使用結(jié)構(gòu)體作為對(duì)象，并使用結(jié)構(gòu)體指針作為參數(shù)傳遞，這樣作可以節(jié)省資源，并且有著極高的運(yùn)行效率。其中最難的部分是侵入式鏈表的使用，這種鏈表在一些操作系統(tǒng)內(nèi)核中使用十分廣泛，這里是參考RT-Thread實(shí)時(shí)操作系統(tǒng)中的侵入式鏈表實(shí)現(xiàn)。h文件：#ifndef_TIMESLICE_H#define_TIMESLICE_H#include"./list.h"typedefenum{TASK_STOP,TASK_RUN}IsTaskRun;typedefstructtimesilce{unsignedintid;void(*task_hdl)(void);IsTaskRunis_run;unsignedinttimer;unsignedinttimeslice_len;ListObjtimeslice_task_list;}TimesilceTaskObj;voidtimeslice_exec(void);voidtimeslice_tick(void);voidtimeslice_task_init(TimesilceTaskObj*obj,void(*task_hdl)(void),unsignedintid,unsignedinttimeslice_len);voidtimeslice_task_add(TimesilceTaskObj*obj);voidtimeslice_task_del(TimesilceTaskObj*obj);unsignedinttimeslice_get_task_timeslice_len(TimesilceTaskObj*obj);unsignedinttimeslice_get_task_num(void);unsignedchartimeslice_task_isexist(TimesilceTaskObj*obj);#endifc文件：#include"./timeslice.h"staticLIST_HEAD(timeslice_task_list);voidtimeslice_exec(){ListObj*node;TimesilceTaskObj*task;list_for_each(node,×lice_task_list){task=list_entry(node,TimesilceTaskObj,timeslice_task_list);if(task->is_run==TASK_RUN){task->task_hdl();task->is_run=TASK_STOP;}}}voidtimeslice_tick(){ListObj*node;TimesilceTaskObj*task;list_for_each(node,×lice_task_list){task=list_entry(node,TimesilceTaskObj,timeslice_task_list);if(task->timer!=0){task->timer--;if(task->timer==0){task->is_run=TASK_RUN;task->timer=task->timeslice_len;}}}}unsignedinttimeslice_get_task_num(){returnlist_len(×lice_task_list);}voidtimeslice_task_init(TimesilceTaskObj*obj,void(*task_hdl)(void),unsignedintid,unsignedinttimeslice_len){obj->id=id;obj->is_run=TASK_STOP;obj->task_hdl=task_hdl;obj->timer=timeslice_len;obj->timeslice_len=timeslice_len;}voidtimeslice_task_add(TimesilceTaskObj*obj){list_insert_before(×lice_task_list,&obj->timeslice_task_list);}voidtimeslice_task_del(TimesilceTaskObj*obj){if(timeslice_task_isexist(obj))list_remove(&obj->timeslice_task_list);elsereturn;}unsignedchartimeslice_task_isexist(TimesilceTaskObj*obj){unsignedcharisexist=0;ListObj*node;TimesilceTaskObj*task;list_for_each(node,×lice_task_list){task=list_entry(node,TimesilceTaskObj,timeslice_task_list);if(obj->id==task->id)isexist=1;}returnisexist;}unsignedinttimeslice_get_task_timeslice_len(TimesilceTaskObj*obj){returnobj->timeslice_len;}底層侵入式雙向鏈表h文件：#ifndef_LIST_H#define_LIST_H#defineoffset_of(type,member)(unsignedlong)&((type*)0)->member#definecontainer_of(ptr,type,member)((type*)((char*)(ptr)-offset_of(type,member)))typedefstructlist_structure{structlist_structure*next;structlist_structure*prev;}ListObj;#defineLIST_HEAD_INIT(name){&(name),&(name)}#defineLIST_HEAD(name)ListObjname=LIST_HEAD_INIT(name)voidlist_init(ListObj*list);voidlist_insert_after(ListObj*list,ListObj*node);voidlist_insert_before(ListObj*list,ListObj*node);voidlist_remove(ListObj*node);intlist_isempty(constListObj*list);unsignedintlist_len(constListObj*list);#definelist_entry(node,type,member)\container_of(node,type,member)#definelist_for_each(pos,head)\for(pos=(head)->next;pos!=(head);pos=pos->next)#definelist_for_each_safe(pos,n,head)\for(pos=(head)->next,n=pos->next;pos!=(head);\pos=n,n=pos->next)#endifc文件：#include"list.h"voidlist_init(ListObj*list){list->next=list->prev=list;}voidl