1808 Alipay System 1 user(Eden)

本文介绍了一个模拟支付宝用户模块的设计与实现过程,包括用户名、密码、电话号码等信息的有效性验证,性别设置,余额操作等功能。并通过一系列单元测试案例确保各功能正确实现。

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Introduction

You must have heard alipay(“Zhi Fu Bao” for Chinese). Now in this topic, we will do a series of practice to develop such a online payment system. This Time we are going to focus on the core of the system, the user part. If you have an account in alipay, you will have some basic knowledge about the architecture of the class, user.

Requirements

I have already build a hpp file for the class architecture, and your job is to implement the specific functions.

In order to prevent name conflicts, I have already declared a namespace for alipay. You should notice that while you are going to coding.

There will be some more details:

// username should be a combination of letters and numbers and the length should be in [6,20]
// correct: ["Alice1995", "Heart2you", "love2you", "5201314"]
// incorrect: ["222@_@222", "12306", "abc12?"]
std::string username;

// password should be a combination of letters and numbers and the length should be in [8,20]
// correct: ["12345678", "abc00000000"]
// incorrect: ["123", "21?=_=?12"]
std::string password;

// phone should be a number and the length should be fixed 13
// correct: ["8618819473230"]
// incorrect: ["110", "330"]
std::string phone;

Gender::Gender gender;

// because soil-rich use this system, so no decimal.
long long int balance;

// auxiliary function for format checking
inline bool verifyPasswordFormat(const std::string & password);
inline bool verifyUsernameFormat(const std::string & username);
inline bool verifyPhoneFormat(const std::string & phone);
// Because of the mistake of the architect of alibaba,
// all the parameters of these function use c strings(char *).
// you are smart, the transformation is not a problem

// if the input is a valid username, set it and return true
bool setUsername(const char * username);

// You should confirm the old password and the new_password's format
bool setPassword(const char * new_password, const char * old_password);

bool setPhone(const char * new_phone);

// You can not set the Gender to unknown again
bool setGender(Gender::Gender gender);

std::string getUsername(void);
std::string getPhone(void);
alipay::Gender::Gender getGender(void);

long long int getMoneyAmount(const char * password);

bool deposit(long long int amount);

// password check is needed when withdraw
bool withdraw(long long int amount, const char * password);

Deep Thinking and Discuss

What’s the disadvantages of this design?
Why “using namespace std” is not a good way in c++ programming?

More

If you have any ideas or thoughts about alipay system. Just leave a message below or send me a mail.

Next we will have some practice which is more detailed with the teaching process.

Copy from 叶嘉祺

Provided Codes

main.cpp

#include "user.hpp"
#include "test.hpp"

int main() {
  unittest::TEST t;
  t.runAllCases();
  return 0;
}

test.hpp

#ifndef TEST_H_
#define TEST_H_
#include "user.hpp"
#include <iostream>
#include <string>

using std::cin;
using std::cout;
using std::endl;
using std::cerr;
using std::string;

namespace unittest {
class TEST {
 public:
  // complete legal operations
  void TestCase1() {
    cout << "Test1" << endl;
    alipay::User u;

    char username[20];
    cin >> username;
    u.setUsername(username) ? cout << "Pass" : cout << "Fail";
    cout << "\tsetting a legal username." << username << endl;

    char password[20];
    cin >> password;
    u.setPassword(password, "") ? cout << "Pass" : cout << "Fail";
    cout << "\tsetting a legal password for a blank password." << password
         << endl;

    char phone[20];
    cin >> phone;
    u.setPhone(phone) ? cout << "Pass" : cout << "Fail";
    cout << "\tsetting a legal phone." << phone << endl;

    int gender;
    cin >> gender;
    u.setGender(gender == 0 ? alipay::Gender::Female : alipay::Gender::Male)
        ? cout << "Pass"
        : cout << "Fail";
    cout << "\tsetting a legal gender: " << (gender == 0 ? "Female." : "Male.")
         << endl;

    string username_s = u.getUsername();
    username_s == username ? cout << "Pass" : cout << "Fail";
    cout << "\tusername should be equal: (" << username << "," << username_s
         << ")." << endl;

    string phone_s = u.getPhone();
    phone == phone_s ? cout << "Pass" : cout << "Fail";
    cout << "\tphone should be equal: (" << phone << "," << phone_s << ")."
         << endl;

    int money;
    cin >> money;
    u.deposit(money) ? cout << "Pass" : cout << "Fail";
    cout << "\ttry to deposit." << endl;

    cin >> money;
    u.withdraw(money, password) ? cout << "Pass" : cout << "Fail";
    cout << "\ttry to withdraw." << endl;

    cout << endl;
  }

  // complete illegal operations
  void TestCase2() {
    cout << "Test2" << endl;
    alipay::User u;

    char wrong_username[20];
    cin >> wrong_username;
    !u.setUsername(wrong_username) ? cout << "Pass" : cout << "Fail";
    cout << "\tsetting an illegal username." << wrong_username << endl;

    char wrong_phone[20];
    cin >> wrong_phone;
    !u.setPhone(wrong_phone) ? cout << "Pass" : cout << "Fail";
    cout << "\tsetting an illegal phone." << wrong_phone << endl;

    char wrong_password[20];
    cin >> wrong_password;
    !u.setPassword(wrong_password, "") ? cout << "Pass" : cout << "Fail";
    cout << "\tsetting an illegal password." << wrong_password << endl;

    u.setPassword("20482048123", "");

    !u.setPassword("123", "123") ? cout << "Pass" : cout << "Fail";
    cout << "\tsetting a new password using wrong old password." << endl;

    cout << endl;
  }

  // complete illegal operations2
  void TestCase3() {
    cout << "Test3" << endl;
    alipay::User u;

    u.setPassword("123456789", "");

    !u.withdraw(-1000, "123456789") ? cout << "Pass" : cout << "Fail";
    cout << "\ttry to cheat money using negative number." << endl;

    u.deposit(1000);
    !u.withdraw(10000, "123456789") ? cout << "Pass" : cout << "Fail";
    cout << "\ttry to cheat money using loan which is not supported." << endl;

    cout << endl;
  }

  void runAllCases() {
    TestCase1();
    TestCase2();
    TestCase3();
  }
};
}

#endif  // TEST_H_

user.hpp

#include <string>

#ifndef USER_H_
#define USER_H_

namespace alipay {

namespace Gender {
enum Gender { Female = 0, Male = 1, Unknown = 2 };
}

class User {
  std::string username;
  std::string password;
  std::string phone;
  Gender::Gender gender;
  long long int balance;

  inline bool verifyPasswordFormat(const std::string &password);
  inline bool verifyUsernameFormat(const std::string &username);
  inline bool verifyPhoneFormat(const std::string &phone);

 public:
  User() {
    this->gender = Gender::Unknown;
    this->balance = 0;
  }

  bool setUsername(const char *username);
  bool setPassword(const char *new_password, const char *old_password);
  bool setPhone(const char *new_phone);
  bool setGender(Gender::Gender gender);

  std::string getUsername(void);
  std::string getPhone(void);
  alipay::Gender::Gender getGender(void);

  // if passowrd is in correct, return -1
  long long int getMoneyAmount(const char *password);
  bool deposit(long long int amount);
  bool withdraw(long long int amount, const char *password);
};
}

#endif  // USER_H_

Submission

user.cpp

#include<string.h>
#include<iostream>
#include<string>
#include"user.hpp"
#include"test.hpp"
using namespace std;
using namespace alipay;
bool alipay::User::setUsername(const char * user){
    int len=strlen(user);
    if(len<6||len>20)
        return false;
    for(int i=0;i<len;i++){
        if((user[i]>='a'&&user[i]<='z')||(user[i]>='A'&&user[i]<='Z')||(user[i]>='0'&&user[i]<='9'));           
        else
            return false;
    }
    username=user;
    return true;
}

bool alipay::User::setPassword(const char *new_password, const char *old_password){
    string temp=old_password;
    if(password!=temp)
        return false;
    int len=strlen(new_password);
    if(len<8||len>20)
        return false;
    for(int i=0;i<len;i++){
        if(new_password[i]<48||(new_password[i]>57&&new_password[i]<65)||(new_password[i]>90&&new_password[i]<97)||new_password[i]>122)         
            return false;
    }
    password=new_password;
    return true;
}

bool alipay::User::setPhone(const char * new_phone){
    if(strlen(new_phone)!=13)
        return false;
    phone=new_phone;
    return true;
}

bool alipay::User::setGender(Gender::Gender gende){
    if(gende==Gender::Unknown)
        return false;
    gender=gende;
    return true;
}

std::string alipay::User::getUsername(void){
    return username;
}

std::string alipay::User::getPhone(void){
    return phone;
}

alipay::Gender::Gender alipay::User::getGender(void){
    return gender;
}

long long int alipay::User::getMoneyAmount(const char *passwor){
    string temp=passwor;
    if(password!=temp)
        return -1;
    return balance;
}

bool alipay::User::deposit(long long int amount){
    if(amount<=0)
        return false;
    balance+=amount;
    return true;
}

bool alipay::User::withdraw(long long int amount, const char *passwor){
    string temp=passwor;
    if(password!=temp||balance<amount||amount<0)
        return false;
    balance-=amount;
    return true;
}
<think>嗯,用户想了解G1垃圾回收器中Eden区内存增长过快的原因及解决方法。首先,我需要回忆G1垃圾回收器的工作原理,特别是内存划分和回收机制。G1将堆分成多个区域,包括Eden、Survivor和Old区,采用分代收集。Eden区用于新对象分配,当Eden满时会触发Young GC,存活的对象移到Survivor或晋升到Old区。 接下来,用户提到Eden区增长过快,可能的原因有哪些呢?首先,可能是对象分配速率过高,比如短时间内大量创建对象,导致Eden快速填满。这时候需要检查应用是否存在内存泄漏,或者是否有不必要的大量临时对象生成。比如代码中的循环频繁创建对象,或者缓存未正确清理。 其次,Young GC的频率可能不够,导致Eden区无法及时回收。这可能是因为GC参数设置不当,比如-XX:MaxGCPauseMillis设置过长,导致JVM为了达到暂停时间目标而增大Eden区。或者-XX:G1NewSizePercent和-XX:G1MaxNewSizePercent参数设置不合理,使得Eden区动态调整的范围过大,导致在需要时扩张过快。 另外,Survivor区空间不足也可能导致对象过早晋升到Old区,从而影响Eden区的回收效率。如果Survivor区太小,存活对象无法容纳,就会直接进入Old区,这可能导致Old区快速填满,进而触发Mixed GC,但Eden区的回收可能因此不够及时。 还有可能是大对象直接进入Old区,虽然这主要影响的是Humongous区域,但如果大对象分配频繁,也可能间接影响Eden区的行为,因为G1可能需要调整区域分配策略,影响整体回收效率。 在排查步骤方面,首先需要监控GC日志,使用-XX:+PrintGCDetails参数来查看每次GC的情况,包括Eden区的使用情况、GC暂停时间、对象晋升情况等。同时,使用jstat工具实时监控内存各区域的变化,比如jstat -gc <pid> 可以查看各个内存区域的容量和使用量。 分析对象分配模式,使用堆转储或者Profiling工具如JProfiler、VisualVM,查看哪些类或方法占用了大量内存,是否有内存泄漏。检查代码中是否存在不合理的大量对象创建,比如在循环中不断生成临时对象,或者缓存未有效管理。 调整JVM参数也是关键,比如调整-XX:MaxGCPauseMillis为一个合理的值,平衡吞吐量和暂停时间。适当限制Eden区的动态范围,设置G1NewSizePercent和G1MaxNewSizePercent,避免Eden区无限制扩大。增加Survivor区的比例,避免过早晋升,可以通过-XX:SurvivorRatio来调整。 另外,检查是否有内存泄漏,特别是长时间存活的对象意外滞留在年轻代,或者某些对象被错误地强引用持有,无法被回收。使用弱引用或软引用来管理缓存,或者定期清理无用的缓存对象。 参考引用中的内容,当分配大内存(如10GB)时,GC调优可能变得困难,因此如果应用确实需要大内存,必须仔细分析内存使用情况。如果遇到OutOfMemoryError,应该生成堆转储分析原因。分代垃圾收集的特点也需要考虑,不同代的内存管理策略会影响Eden区的行为。 可能用户的应用中存在高频率的对象分配,或者存在内存泄漏,导致Eden区快速增长。需要结合日志和监控工具具体分析,调整JVM参数优化GC行为,同时优化代码减少不必要的对象创建。</think>### G1垃圾回收器中Eden区内存增长过快的原因分析及排查步骤 #### 一、Eden区内存增长过快的常见原因 1. **对象分配速率过高** - 应用短时间内创建大量对象,导致Eden区快速填满。例如高频循环中生成临时对象,或缓存未合理清理。 - 可通过监控工具(如`jstat`)观察对象分配速率: $$ \text{分配速率} = \frac{\text{Eden区占用增量}}{\text{时间间隔}} \quad \text{(单位:MB/s)} $$ 若速率超过1GB/s,可能触发问题[^1]。 2. **Young GC触发频率不足** - G1通过`-XX:MaxGCPauseMillis`控制GC暂停时间。若设置过长(如200ms),JVM可能增大Eden区以减少GC次数,导致内存占用升高[^2]。 3. **Survivor区空间不足** - 存活对象无法容纳在Survivor区,直接晋升到Old区,导致Eden区回收效率降低。需检查`-XX:SurvivorRatio`参数。 4. **大对象直接进入Old区** - 大于`G1HeapRegionSize`50%的对象会分配到Humongous区(属于Old代),若频繁分配大对象,可能间接影响Eden区回收节奏。 --- #### 二、排查步骤 1. **启用GC日志分析** 添加JVM参数: ```bash -XX:+PrintGCDetails -XX:+PrintGCDateStamps -Xloggc:/path/to/gc.log ``` 观察日志中`Eden`区的变化: ``` 2023-10-01T12:00:00.123+0800: [GC (Allocation Failure) [PSYoungGen: 1024K->512K(2048K)]...] ``` 2. **使用`jstat`实时监控** 执行命令: ```bash jstat -gc <pid> 1000 # 每秒输出一次GC数据 ``` 关注以下指标: - `EU`(Eden区使用量) - `YGCT`(Young GC总耗时) - `OGC`(Old区容量) 3. **检查JVM参数合理性** - `-XX:MaxGCPauseMillis`:建议设置为50-150ms(默认200ms可能过大) - `-XX:G1NewSizePercent`/`-XX:G1MaxNewSizePercent`:限制Eden区占比范围(默认5%-60%) - `-XX:G1HeapRegionSize`:调整Region大小(1MB-32MB) 4. **对象分配模式分析** 通过堆转储(Heap Dump)和Profiling工具(如MAT、JProfiler)定位高频分配点: ```bash jmap -dump:live,format=b,file=heap.hprof <pid> ``` --- #### 三、优化方案 1. **调整GC参数** ```bash -XX:MaxGCPauseMillis=100 -XX:G1NewSizePercent=20 -XX:G1MaxNewSizePercent=40 ``` 2. **减少对象分配** - 复用对象(如对象池) - 避免在循环中创建临时对象 - 使用`WeakReference`管理缓存 3. **避免过早晋升** 增加Survivor区容量: ```bash -XX:SurvivorRatio=6 # Eden/Survivor=6:1:1 ``` ---
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