Qt——银行家算法的分
1.研究一个银行家如何将总数一定的资金安全地借给若干个顾客使顾客既能满足对资金的需求也使银行家可以收回自己的全部资金不至于破产一些限制条件每次顾客在借款前必须提前说明所需资金总额每次借钱都是以一个单位进行顾客在拿到一个单位的借款前可能需要等待银行保证顾客的等待时间是有限的借或不借2.Qt中的算法实现方案使用多线程机制模拟客户和银行银行优先分配资源给最小需求的客户当客户的资源需求无法满足的时候收回已分配的资源强制结束线程#include QCoreApplication #include QThread #include QMutex #include QList #include QDebug class Customer : public QThread { protected: int m_need; //所需金额总额 int m_current; //当前有的金额数 QMutex m_mutex; void run() { bool condition false; qDebug() objectName() begin to apply money; do { m_mutex.lock(); condition (m_current m_need); m_mutex.unlock(); msleep(10); } while( condition ); qDebug() objectName() end (get enough money); } public: Customer(int current, int need) { m_current current; m_need need; } void addMoney(int m) { m_mutex.lock(); m_current m; m_mutex.unlock(); } int backMoney() //需要还的钱 { int ret 0; m_mutex.lock(); ret m_current; m_current 0; m_mutex.unlock(); return ret; } int current() { int ret 0; m_mutex.lock(); ret m_current; m_mutex.unlock(); return ret; } int need() { return m_need; } }; class Bank : public QThread { protected: QListCustomer* m_list; //需要借款的对象列表 int m_total; //总额 void run() { int index -1; qDebug() objectName() begin: m_total; do { index -1; for(int i0; im_list.count(); i) { if( m_list[i]-current() m_list[i]-need()) { qDebug() objectName() take back money from m_list[i]-objectName() m_list[i]-need(); m_total m_list[i]-backMoney(); } } qDebug() objectName() current: m_total; int toGet 0x00FFFFFF; //初始化一个很大的值 //找到需求量最小的消费者 for(int i0; im_list.count(); i) { if( m_list[i]-isRunning() ) { int tmp m_list[i]-need() - m_list[i]-current(); if( toGet tmp ) { index i; toGet tmp; } } } if( index 0 ) //找到了 { if( toGet m_total ) { qDebug() objectName() give money to: m_list[index]-objectName(); m_total--; m_list[index]-addMoney(1); } else { qDebug() objectName() terminate: m_list[index]-objectName(); m_total m_list[index]-backMoney(); m_list[index]-terminate(); } } } while( index 0 ); } public: Bank(int total) { m_total total; } void addCustomer(Customer* customer) { m_list.append(customer); } }; int main(int argc, char *argv[]) { QCoreApplication a(argc, argv); Customer p(4, 8); Customer q(2, 3); Customer r(2, 9); Bank bank(2); p.setObjectName(P); q.setObjectName(Q); r.setObjectName(R); bank.setObjectName(Bank); bank.addCustomer(p); bank.addCustomer(q); bank.addCustomer(r); p.start(); q.start(); r.start(); bank.start(); return QCoreApplication::exec(); }
