banker.cpp

操作系统中的经典问题：银行家算法

//#define _DEBUG
#include "file.h"


//执行某条指令
void exec(char instruction)
{
	cout << instruction;
}

//程序开始执行
void run()
{
	int instruction;//指令，其中#为申请资源指令，*为释放资源指令
	int res_id;//资源的ID
	list< list<int> >::iterator thread_ptr;//当前执行的进程指针
	list< string >::iterator thread_name_ptr;//进程名称指针
	int counter = 0;
	g_already_ptr = g_already.begin();
	g_needed_ptr = g_needed.begin();
	thread_ptr = g_thread.begin();
	thread_name_ptr = g_thread_name.begin();

	while (g_thread.size())
	{
		int out = 0;
		cout << endl << *thread_name_ptr << " is runing" << endl;

		for (int i=0; i < MAX_INSTRUCTION && (*thread_ptr).size()>1; i++)
		{
    		instruction = (*thread_ptr).front();//读取指令

    		(*thread_ptr).pop_front();

    		if (instruction == '#')
    		{
#ifdef _DEBUG
how_res();
cout << *thread_name_ptr << " request resource " << res_id << endl;
#endif
    			res_id = (*thread_ptr).front();
    			(*thread_ptr).pop_front();
    			int result = request_res(res_id);

    			if (result == -1)
    			{
    				cout << endl << *thread_name_ptr << " REQUEST resource " << res_id << " which is a error resource, it will be end!" << endl;
    				free_all_res();

    				if (g_thread.size() == 1)
					{
						g_already.erase(g_already_ptr);
						g_needed.erase(g_needed_ptr);
						g_thread.erase(thread_ptr);
						g_thread_name.erase(thread_name_ptr);
					}
					else
					{
						if (counter == (int)g_thread.size() -1)
						{
							g_already_ptr = g_already.begin();
							g_needed_ptr = g_needed.begin();
							thread_ptr = g_thread.begin();
							thread_name_ptr = g_thread_name.begin();
							counter = 0;
							g_already.pop_back();
							g_needed.pop_back();
							g_thread.pop_back();
							g_thread_name.pop_back();
						}
						else
						{
							list< vector<int> >::iterator templv;
							list<string>::iterator templs;
							list< list<int> >::iterator templl;

							templv = g_already_ptr++;
							g_already.erase(templv);
							templv = g_needed_ptr++;
							g_needed.erase(templv);
							templl = thread_ptr++;
							g_thread.erase(templl);
							templs = thread_name_ptr++;
							g_thread_name.erase(templs);
						}
					}
					out = 1;
    				break;
    			}
     			else if (result == 0)
    			{
    				cout << endl << *thread_name_ptr << " REQUEST resource " << g_res[res_id] << " failed, it will try the next time!" << endl;
    				(*thread_ptr).push_front(res_id);
    				(*thread_ptr).push_front('#');
    				break;
    			}
    			else
    				cout << endl << *thread_name_ptr << " REQUEST resource " << g_res[res_id] << " succeed!" << endl;
    		}
    		else if (instruction == '*')
    		{
    			res_id = (*thread_ptr).front();
    			(*thread_ptr).pop_front();
				if (free_res(res_id))
    				cout << endl << *thread_name_ptr << " RELEASE resource " << g_res[res_id] << " succeed!" << endl;
				else
				{
					cout << endl << *thread_name_ptr << " RELEASE resource " << res_id << " which is a error resource, it will be end!" << endl;
    				free_all_res();

    				if (g_thread.size() == 1)
					{
						g_already.erase(g_already_ptr);
						g_needed.erase(g_needed_ptr);
						g_thread.erase(thread_ptr);
						g_thread_name.erase(thread_name_ptr);
					}
					else
					{
						if (counter == (int)g_thread.size() -1)
						{
							g_already_ptr = g_already.begin();
							g_needed_ptr = g_needed.begin();
							thread_ptr = g_thread.begin();
							thread_name_ptr = g_thread_name.begin();
							counter = 0;
							g_already.pop_back();
							g_needed.pop_back();
							g_thread.pop_back();
							g_thread_name.pop_back();
						}
						else
						{
							list< vector<int> >::iterator templv;
							list<string>::iterator templs;
							list< list<int> >::iterator templl;

							templv = g_already_ptr++;
							g_already.erase(templv);
							templv = g_needed_ptr++;
							g_needed.erase(templv);
							templl = thread_ptr++;
							g_thread.erase(templl);
							templs = thread_name_ptr++;
							g_thread_name.erase(templs);
						}
					}
					out = 1;
    				break;
				}
    		}
    		else
    			exec( (char)instruction );
    	}
    	if (out)
    		continue;
		//如果线程执行完毕，清理资源
		else if ((*thread_ptr).size()<=1)
		{
			cout << endl << *thread_name_ptr << " finished, it will release all the resources!" << endl;
			free_all_res();

			if (g_thread.size() == 1)
			{
				g_already.erase(g_already_ptr);
				g_needed.erase(g_needed_ptr);
				g_thread.erase(thread_ptr);
				g_thread_name.erase(thread_name_ptr);
			}
			else
			{
				if (counter == (int)g_thread.size() -1)
				{
					g_already_ptr = g_already.begin();
					g_needed_ptr = g_needed.begin();
					thread_ptr = g_thread.begin();
					thread_name_ptr = g_thread_name.begin();
					counter = 0;
					g_already.pop_back();
					g_needed.pop_back();
					g_thread.pop_back();
					g_thread_name.pop_back();
				}
				else
				{
					list< vector<int> >::iterator templv;
					list<string>::iterator templs;
					list< list<int> >::iterator templl;

					templv = g_already_ptr++;
					g_already.erase(templv);
					templv = g_needed_ptr++;
					g_needed.erase(templv);
					templl = thread_ptr++;
					g_thread.erase(templl);
					templs = thread_name_ptr++;
					g_thread_name.erase(templs);
				}
			}
		}
		else if (counter == (int)g_thread.size() -1)
		{
			g_already_ptr = g_already.begin();
			g_needed_ptr = g_needed.begin();
			thread_ptr = g_thread.begin();
			thread_name_ptr = g_thread_name.begin();
			counter = 0;
		}
		else
		{
			g_already_ptr++;
			g_needed_ptr++;
			thread_ptr++;
			thread_name_ptr++;
			counter++;
		}
	}
}


main(int argc,char *argv[])
{
	init();
	what_are_res();
	cout << "Computer init over,now it is going to run!" << endl << endl;

	if (argc < 2)
	{
		cout << "no thread is going to run ,the computer will shut down!";
		exit(2);
	}
	for (int i = 1; i < argc; i++)
	{
		add_thread(*(argv+i));
	}

	how_res();

	//此处加入测试代码，测试文件内容是否正确
	#ifdef _DEBUG

	list< list<int> >::iterator thread_test_ptr = g_thread.begin();
	for (; thread_test_ptr != g_thread.end(); thread_test_ptr++)
	{
		list<int>::iterator thread_text_test_ptr = (*thread_test_ptr).begin();
		for (; thread_text_test_ptr != (*thread_test_ptr).end(); thread_text_test_ptr++)
		{
			cout << (char)*thread_text_test_ptr;
		}
		cout << endl;
	}

	#endif
	if (allow())
	{
		run();
	}
	else
	{
		cout << "The System now is not in safe, maybe some thread request too much resources, the computer will shut down!";
	}
}