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AccessQueueService
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Abstract queue and dictionary implementation to support alternative implementations

This commit is contained in:
henry 2025-05-09 19:41:07 -04:00
parent 6470ce21f3
commit c04a603d56
5 changed files with 149 additions and 78 deletions
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99
AccessQueueService/Data/DictionaryAccessQueueRepo.cs Normal file
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@ -0,0 +1,99 @@
using AccessQueueService.Models;
using Microsoft.Extensions.Configuration;
namespace AccessQueueService.Data
{
public class DictionaryAccessQueueRepo : IAccessQueueRepo
{
private readonly Dictionary<Guid, AccessTicket> _accessTickets = new();
private readonly Queue<AccessTicket> _accessQueue = new();
public int GetUnexpiredTicketsCount() => _accessTickets.Count(t => t.Value.ExpiresOn > DateTime.UtcNow);
public int GetActiveTicketsCount(DateTime activeCutoff) => _accessTickets
.Count(t => t.Value.ExpiresOn > DateTime.UtcNow && t.Value.LastActive >activeCutoff);
public int GetQueueCount() => _accessQueue.Count;
public int IndexOfTicket(Guid userId)
{
var index = 0;
foreach (var ticket in _accessQueue)
{
if (ticket.UserId == userId)
{
return index;
}
index++;
}
return -1;
}
public void Enqueue(AccessTicket ticket)
{
_accessQueue.Enqueue(ticket);
}
public int DeleteExpiredTickets()
{
var cutoff = DateTime.UtcNow;
var expiredTickets = _accessTickets.Where(t => t.Value.ExpiresOn < cutoff);
int count = 0;
foreach (var ticket in expiredTickets)
{
count++;
_accessTickets.Remove(ticket.Key);
}
return count;
}
public void RemoveUser(Guid userId)
{
_accessTickets.Remove(userId);
}
public bool DidDequeueUntilFull(int activeSeconds, int expirationSeconds, int capacityLimit)
{
var now = DateTime.UtcNow;
var activeCutoff = now.AddSeconds(-activeSeconds);
var numberOfActiveUsers = _accessTickets.Count(t => t.Value.ExpiresOn > now && t.Value.LastActive > activeCutoff);
var openSpots = capacityLimit - numberOfActiveUsers;
int filledSpots = 0;
while (filledSpots < openSpots)
{
if (_accessQueue.TryDequeue(out var nextUser))
{
if (nextUser.LastActive < activeCutoff)
{
// User is inactive, throw away their ticket
continue;
}
_accessTickets[nextUser.UserId] = new AccessTicket
{
UserId = nextUser.UserId,
ExpiresOn = now.AddSeconds(expirationSeconds),
LastActive = now
};
filledSpots++;
}
else
{
break;
}
}
return filledSpots == openSpots;
}
public AccessTicket? GetTicket(Guid userId)
{
return _accessTickets.TryGetValue(userId, out var ticket) ? ticket : null;
}
public void UpsertTicket(AccessTicket ticket)
{
_accessTickets[ticket.UserId] = ticket;
}
bool IAccessQueueRepo.RemoveUser(Guid userId)
{
return _accessTickets.Remove(userId);
}
}
}

22
AccessQueueService/Data/IAccessQueueRepo.cs Normal file
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@ -0,0 +1,22 @@
using AccessQueueService.Models;
using Microsoft.Extensions.Configuration;
namespace AccessQueueService.Data
{
public interface IAccessQueueRepo
{
public int GetUnexpiredTicketsCount();
public int GetActiveTicketsCount(DateTime activeCutoff);
public int GetQueueCount();
public AccessTicket? GetTicket(Guid userId);
public void UpsertTicket(AccessTicket ticket);
public int IndexOfTicket(Guid userId);
public void Enqueue(AccessTicket ticket);
public int DeleteExpiredTickets();
public bool RemoveUser(Guid userId);
public bool DidDequeueUntilFull(int activeSeconds, int expirationSeconds, int capacityLimit);
}
}

2
AccessQueueService/Program.cs
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@ -1,3 +1,4 @@
using AccessQueueService.Data;
using AccessQueueService.Services;
var builder = WebApplication.CreateBuilder(args);
@ -9,6 +10,7 @@ builder.Services.AddControllers();
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();
builder.Services.AddSingleton<IAccessService, AccessService>();
builder.Services.AddSingleton<IAccessQueueRepo, DictionaryAccessQueueRepo>();
var app = builder.Build();

100
AccessQueueService/Services/AccessService.cs
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@ -1,35 +1,39 @@
using AccessQueueService.Models;
using AccessQueueService.Data;
using AccessQueueService.Models;
namespace AccessQueueService.Services
{
public class AccessService : IAccessService
{
private readonly Dictionary<Guid, AccessTicket> _accessTickets = new();
private readonly Queue<AccessTicket> _accessQueue = new();
private readonly SemaphoreSlim _queueLock = new(1, 1);
private readonly IConfiguration _configuration;
private readonly IAccessQueueRepo _accessQueueRepo;
//private readonly Dictionary<Guid, AccessTicket> _accessTickets = new();
//private readonly Queue<AccessTicket> _accessQueue = new();
private readonly SemaphoreSlim _queueLock = new(1, 1);
private readonly int EXP_SECONDS;
private readonly int ACT_SECONDS;
private readonly int CAPACITY_LIMIT;
private readonly bool ROLLING_EXPIRATION;
public AccessService(IConfiguration configuration)
public AccessService(IConfiguration configuration, IAccessQueueRepo accessQueueRepo)
{
_configuration = configuration;
_accessQueueRepo = accessQueueRepo;
EXP_SECONDS = _configuration.GetValue<int>("AccessQueue:ExpirationSeconds");
ACT_SECONDS = _configuration.GetValue<int>("AccessQueue:ActivitySeconds");
CAPACITY_LIMIT = _configuration.GetValue<int>("AccessQueue:CapacityLimit");
ROLLING_EXPIRATION = _configuration.GetValue<bool>("AccessQueue:RollingExpiration");
}
public int UnexpiredTicketsCount => _accessTickets.Count(t => t.Value.ExpiresOn > DateTime.UtcNow);
public int ActiveTicketsCount => _accessTickets.Count(t => t.Value.ExpiresOn > DateTime.UtcNow && t.Value.LastActive > DateTime.UtcNow.AddSeconds(-_configuration.GetValue<int>("AccessQueue:ActivitySeconds")));
public int QueueCount => _accessQueue.Count;
public int UnexpiredTicketsCount => _accessQueueRepo.GetUnexpiredTicketsCount();
public int ActiveTicketsCount => _accessQueueRepo.GetActiveTicketsCount(DateTime.UtcNow.AddSeconds(-_configuration.GetValue<int>("AccessQueue:ActivitySeconds")));
public int QueueCount => _accessQueueRepo.GetQueueCount();
public async Task<AccessResponse> RequestAccess(Guid userId)
{
await _queueLock.WaitAsync();
try
{
var hasCapacity = !DidDequeueUntilFull();
var existingTicket = _accessTickets.GetValueOrDefault(userId);
var hasCapacity = !_accessQueueRepo.DidDequeueUntilFull(ACT_SECONDS, EXP_SECONDS, CAPACITY_LIMIT);
var existingTicket = _accessQueueRepo.GetTicket(userId);
if (existingTicket != null && existingTicket.ExpiresOn > DateTime.UtcNow)
{
var expiresOn = existingTicket.ExpiresOn;
@ -37,12 +41,12 @@ namespace AccessQueueService.Services
{
expiresOn = DateTime.UtcNow.AddSeconds(EXP_SECONDS);
}
_accessTickets[userId] = new AccessTicket
_accessQueueRepo.UpsertTicket(new AccessTicket
{
UserId = userId,
ExpiresOn = expiresOn,
LastActive = DateTime.UtcNow
};
});
return new AccessResponse
{
ExpiresOn = expiresOn
@ -56,20 +60,19 @@ namespace AccessQueueService.Services
ExpiresOn = DateTime.UtcNow.AddSeconds(EXP_SECONDS),
LastActive = DateTime.UtcNow
};
_accessTickets[userId] = accessTicket;
_accessQueueRepo.UpsertTicket(accessTicket);
return new AccessResponse
{
ExpiresOn = _accessTickets[userId].ExpiresOn,
RequestsAhead = _accessQueue.Count
ExpiresOn = accessTicket.ExpiresOn,
};
}
else
{
var indexOfTicket = IndexOfTicket(userId);
var requestsAhead = _accessQueue.Count - indexOfTicket - 1;
var indexOfTicket = _accessQueueRepo.IndexOfTicket(userId);
var requestsAhead = _accessQueueRepo.GetQueueCount() - indexOfTicket - 1;
if (indexOfTicket == -1)
{
_accessQueue.Enqueue(new AccessTicket
_accessQueueRepo.Enqueue(new AccessTicket
{
UserId = userId,
LastActive = DateTime.UtcNow,
@ -94,7 +97,7 @@ namespace AccessQueueService.Services
await _queueLock.WaitAsync();
try
{
return _accessTickets.Remove(userId);
return _accessQueueRepo.RemoveUser(userId);
}
finally
{
@ -102,63 +105,6 @@ namespace AccessQueueService.Services
}
}
public int DeleteExpiredTickets()
{
var now = DateTime.UtcNow;
var expiredTickets = _accessTickets.Where(t => t.Value.ExpiresOn < now);
int count = 0;
foreach (var ticket in expiredTickets)
{
count++;
_accessTickets.Remove(ticket.Key);
}
return count;
}
private bool DidDequeueUntilFull()
{
var now = DateTime.UtcNow;
var activeCutoff = now.AddSeconds(-ACT_SECONDS);
var numberOfActiveUsers = _accessTickets.Count(t => t.Value.ExpiresOn > now && t.Value.LastActive > activeCutoff);
var openSpots = CAPACITY_LIMIT - numberOfActiveUsers;
int filledSpots = 0;
while (filledSpots < openSpots)
{
if (_accessQueue.TryDequeue(out var nextUser))
{
if (nextUser.LastActive < activeCutoff)
{
// User is inactive, throw away their ticket
continue;
}
_accessTickets[nextUser.UserId] = new AccessTicket
{
UserId = nextUser.UserId,
ExpiresOn = now.AddSeconds(EXP_SECONDS),
LastActive = now
};
filledSpots++;
}
else
{
break;
}
}
return filledSpots == openSpots;
}
private int IndexOfTicket(Guid userId)
{
var index = 0;
foreach (var ticket in _accessQueue)
{
if (ticket.UserId == userId)
{
return index;
}
index++;
}
return -1;
}
public int DeleteExpiredTickets() => _accessQueueRepo.DeleteExpiredTickets();
}
}

4
AccessQueueServiceTests/AccessServiceTests.cs
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@ -1,5 +1,6 @@
namespace AccessQueueServiceTests
{
using global::AccessQueueService.Data;
using global::AccessQueueService.Services;
using Microsoft.Extensions.Configuration;
using System;
@ -32,8 +33,9 @@ namespace AccessQueueServiceTests
var configuration = new ConfigurationBuilder()
.AddInMemoryCollection(inMemorySettings)
.Build();
var accessQueueRepo = new DictionaryAccessQueueRepo();
_accessService = new AccessService(configuration);
_accessService = new AccessService(configuration, accessQueueRepo);
}
[Fact]