g1701_1800.s1797_design_authentication_manager

Class AuthenticationManager

java.lang.Object

g1701_1800.s1797_design_authentication_manager.AuthenticationManager

public class AuthenticationManager
extends Object

1797 - Design Authentication Manager.

Medium

There is an authentication system that works with authentication tokens. For each session, the user will receive a new authentication token that will expire timeToLive seconds after the currentTime. If the token is renewed, the expiry time will be extended to expire timeToLive seconds after the (potentially different) currentTime.

Implement the AuthenticationManager class:

• AuthenticationManager(int timeToLive) constructs the AuthenticationManager and sets the timeToLive.
• generate(string tokenId, int currentTime) generates a new token with the given tokenId at the given currentTime in seconds.
• renew(string tokenId, int currentTime) renews the unexpired token with the given tokenId at the given currentTime in seconds. If there are no unexpired tokens with the given tokenId, the request is ignored, and nothing happens.
• countUnexpiredTokens(int currentTime) returns the number of unexpired tokens at the given currentTime.

Note that if a token expires at time t, and another action happens on time t (renew or countUnexpiredTokens), the expiration takes place before the other actions.

Example 1:

Input

[“AuthenticationManager”, “renew”, “generate”, “countUnexpiredTokens”, “generate”, “renew”, “renew”, “countUnexpiredTokens”]

["aaa", 1], ["aaa", 2], [6], ["bbb", 7], ["aaa", 8], ["bbb", 10], [15

Output: [null, null, null, 1, null, null, null, 0]

Explanation:

AuthenticationManager authenticationManager = new AuthenticationManager(5); // Constructs the AuthenticationManager with timeToLive = 5 seconds.

authenticationManager.renew(“aaa”, 1); // No token exists with tokenId “aaa” at time 1, so nothing happens.

authenticationManager.generate(“aaa”, 2); // Generates a new token with tokenId “aaa” at time 2.

authenticationManager.countUnexpiredTokens(6); // The token with tokenId “aaa” is the only unexpired one at time 6, so return 1.

authenticationManager.generate(“bbb”, 7); // Generates a new token with tokenId “bbb” at time 7.

authenticationManager.renew(“aaa”, 8); // The token with tokenId “aaa” expired at time 7, and 8 >= 7, so at time 8 the renew request is ignored, and nothing happens.

authenticationManager.renew(“bbb”, 10); // The token with tokenId “bbb” is unexpired at time 10, so the renew request is fulfilled and now the token will expire at time 15.

authenticationManager.countUnexpiredTokens(15); // The token with tokenId “bbb” expires at time 15, and the token with tokenId “aaa” expired at time 7, so currently no token is unexpired, so return 0.

Constraints:

• 1 <= timeToLive <= 108
• 1 <= currentTime <= 108
• 1 <= tokenId.length <= 5
• tokenId consists only of lowercase letters.
• All calls to generate will contain unique values of tokenId.
• The values of currentTime across all the function calls will be strictly increasing.
• At most 2000 calls will be made to all functions combined.

Constructor Summary

Constructors

Constructor and Description
AuthenticationManager(int timeToLive)

Method Summary

Modifier and Type	Method and Description
int	countUnexpiredTokens(int currentTime)
void	generate(String tokenId, int currentTime)
void	renew(String tokenId, int currentTime)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AuthenticationManager

public AuthenticationManager(int timeToLive)

Method Detail

generate

public void generate(String tokenId,
                     int currentTime)

renew

public void renew(String tokenId,
                  int currentTime)

countUnexpiredTokens

public int countUnexpiredTokens(int currentTime)