进程创建与删除.cpp

操作系统实验中的进程创建与删除 1) 采用动态或静态方法生成一颗进程树（进程数目≥20）； 2) 设计进程撤销算法； 3) 实现进程撤销函数

//write by baisy//
#include "basic.h"
pnode *proot; //system process tree root
pnode *plink; //system process link head

void deletepc(pnode *parent,pnode *currect)             //delete process        
{
	if (currect->sub==NULL)                       //if the sub of the process which will be delete is NULL
	{
		if(parent->sub==currect)
		{		
			parent->sub=currect->brother;
		}
		else
		{
            for (pnode*p=parent->sub;p->brother!=currect;p=p->brother);
            p->brother=currect->brother;
		}
		pnode *tempperent;
		for (tempperent=plink;tempperent;tempperent=tempperent->next)  //delete the process from the plink
		{
			if (tempperent->next->node->pid==currect->node->pid)
			{				
				tempperent->next=tempperent->next->next;				
				break;
			}
		}
	}
	else                                         //recursion transfer
	{
		deletepc(currect,currect->sub);
		//deletepc(parent,currect);
	}
}
int createpc(int *para)          //create process
{
	//add your code here
	pnode *p,*p1,*pp;
	int pflag;
	pflag=0;
	for(p=plink;p;p=p->next)
	{
		if(p->node->pid == para[0]) //check if this pid is already exist
		{
			printf("pid %d is already exist!\n",para[0]);
			return -1;
		}
		if(p->node->pid == para[1]) //find parent pcb
		{
			pflag=1;
			pp = p;
		}
	}
	if(!pflag)
	{
		printf("parent id %d is not exist!\n",para[1]); 
		return -2;
	}
	//init new pcb
	p1 = new pnode;
	p1->node=new pcb;
	p1->node->pid = para[0];
	p1->node->ppid = para[1];
	p1->node->prio = para[2];
	p1->sub=NULL;
	p1->next=NULL;
	p1->brother=NULL;
	//add to process tree
	if(!pp->sub)
		pp->sub=p1;
	else
	{
		for(p=pp->sub;p->brother;p=p->brother);
		p->brother=p1;
	}
	// add to process link
	for(p=plink;p->next;p=p->next);
	p->next=p1;
	return 0;
}
//show process detail
void showdetail()
{
	//add your code here
	pnode *p,*p1;
	p=plink;
	for(;p;) //print all pcb info
	{
		printf("%d(prio %d): ",p->node->pid,p->node->prio);
		p1 = p->sub;
		for(;p1;) //print sub pcb
		{
			printf("%d(prio %d) ",p1->node->pid,p1->node->prio);
			p1 = p1->brother;
		}
		printf("\n");
		p = p->next;
	}
	printf("\n");
}
//don't change
void main()
{
	initerror();
	short cflag,pflag;
	char cmdstr[32];
	proot = new pnode;
	proot->node=new pcb;
	proot->node->pid=0;
	proot->node->ppid=-1;
	proot->node->prio=0;
	proot->next=NULL;
	proot->sub=NULL;
	proot->brother=NULL;
	plink=proot;
	for(;;)
	{
		cflag=0;
		pflag=0;
		printf("cmd:");
		scanf("%s",cmdstr);
		if(!strcmp(cmdstr,"exit")) //exit the program
			break;
		if(!strcmp(cmdstr,"showdetail"))
		{
			cflag = 1;
			pflag = 1;
			showdetail();
		}
		else
		{
			int *para;
			char *s,*s1,*s2;
			s = strstr(cmdstr,"createpc"); //create process
			s2 = strstr(cmdstr,"deletepc"); //delete process
			if(s)
			{
				cflag=1;
				para = (int *)malloc(3);
				//getparameter
				s1 = substr(s,instr(s,'(')+1,strlen(s)-2); //get param string
				para=strtoarray(s1); //get parameter
				createpc(para); //create process
				pflag=1;
			}	
			else if (s2)
			{
				cflag=1;
				para = (int *)malloc(2);
				//getparameter
				s1 = substr(s2,instr(s2,'(')+1,strlen(s2)-2); //get param string
				para=strtoarray(s1); //get parameter
				pnode *pp=plink;
				pnode *pc=plink;
				pnode *p,*p1;
				bool findflag=false;
				for (p=plink;p;p=p->next)
				{					
					if((p->node->pid)==para[1])       //search the process which will be delete from plink
					{
						for (p1=plink;p1;p1=p1->next)
						{
							if((p1->node->pid)==p->node->ppid) //search the parent process 
							{
								pp=p1;
								pc=p;
								break;
							}
						}
						
						findflag=true;
						break;
					}
				}
				if (findflag)
				{
					if (pp==pc)                 //if the process will be delete is 0 process
					{
						printf("you cann't delete the 0 process!\n");
					}
					else
						deletepc(pp,pc); //delete process
				}
				else
					geterror(2);
				
				pflag=1;
			}
			
		}
		if(!cflag)
			geterror(0);
		else if(!pflag)
			geterror(1);
	}
}