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‎SharpCoreDB.Tests/MvccAsyncBenchmark.cs‎

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// <copyright file="MvccAsyncBenchmark.cs" company="MPCoreDeveloper">
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// Copyright (c) 2024-2025 MPCoreDeveloper and GitHub Copilot. All rights reserved.
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// Licensed under the MIT License. See LICENSE file in the project root for full license information.
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// </copyright>
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namespace SharpCoreDB.Tests;
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using SharpCoreDB.MVCC;
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using System.Diagnostics;
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using Xunit;
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/// <summary>
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/// Async benchmark for MVCC with generic rows.
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/// Target: 1000 parallel SELECTs in < 10ms on 16 threads.
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/// This demonstrates true concurrency without reader locking.
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/// </summary>
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public sealed class MvccAsyncBenchmark
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{
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/// <summary>
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/// Test record for MVCC benchmarking.
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/// </summary>
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public sealed record UserRecord(int Id, string Name, string Email, int Age);
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[Fact]
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public async Task MvccAsync_1000ParallelSelects_Under10ms()
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{
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// Arrange: Setup MVCC manager with 10k records
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var mvcc = new MvccManager<int, UserRecord>("users");
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const int RecordCount = 10_000;
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const int ParallelQueries = 1_000;
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const int ThreadCount = 16;
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const double TargetMs = 10.0;
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// Insert test data in a single transaction
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using (var insertTx = mvcc.BeginTransaction(isReadOnly: false))
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{
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for (int i = 0; i < RecordCount; i++)
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{
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var user = new UserRecord(
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Id: i,
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Name: $"User{i}",
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Email: $"user{i}@example.com",
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Age: 20 + (i % 50));
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mvcc.Insert(i, user, insertTx);
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}
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mvcc.CommitTransaction(insertTx);
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}
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Console.WriteLine($"? Setup: Inserted {RecordCount:N0} records");
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// Warm up
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await WarmUp(mvcc, RecordCount);
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// Act: Benchmark 1000 parallel SELECTs on 16 threads
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var sw = Stopwatch.StartNew();
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await ParallelSelectBenchmark(mvcc, ParallelQueries, ThreadCount, RecordCount);
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sw.Stop();
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var elapsedMs = sw.Elapsed.TotalMilliseconds;
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var avgMicroseconds = (elapsedMs * 1000.0) / ParallelQueries;
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var throughput = ParallelQueries / sw.Elapsed.TotalSeconds;
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// Assert: Must be under 10ms total
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Assert.True(elapsedMs < TargetMs,
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$"Expected < {TargetMs}ms, got {elapsedMs:F2}ms");
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// Print results
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Console.WriteLine();
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Console.WriteLine("??????????????????????????????????????????????????????????????????");
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Console.WriteLine("? MVCC ASYNC BENCHMARK RESULTS ?");
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Console.WriteLine("??????????????????????????????????????????????????????????????????");
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Console.WriteLine($"?? Records: {RecordCount:N0}");
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Console.WriteLine($"?? Parallel Queries: {ParallelQueries:N0}");
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Console.WriteLine($"? Threads: {ThreadCount}");
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Console.WriteLine($"?? Total Time: {elapsedMs:F2} ms");
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Console.WriteLine($"?? Avg per Query: {avgMicroseconds:F2} µs");
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Console.WriteLine($"?? Throughput: {throughput:N0} queries/sec");
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Console.WriteLine($"?? Target: < {TargetMs} ms");
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Console.WriteLine();
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if (elapsedMs < TargetMs)
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{
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var speedup = TargetMs / elapsedMs;
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Console.WriteLine($"? SUCCESS! {speedup:F2}x FASTER than target!");
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}
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else
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{
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Console.WriteLine($"? FAILED - Exceeded target by {elapsedMs - TargetMs:F2}ms");
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}
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Console.WriteLine();
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// Get MVCC statistics
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var stats = mvcc.GetStatistics();
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Console.WriteLine("?? MVCC Statistics:");
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Console.WriteLine($" Keys: {stats.TotalKeys:N0}");
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Console.WriteLine($" Versions: {stats.TotalVersions:N0}");
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Console.WriteLine($" Avg Versions/Key: {stats.AverageVersionsPerKey:F2}");
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Console.WriteLine($" Max Versions/Key: {stats.MaxVersionsPerKey}");
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Console.WriteLine($" Active Txns: {stats.ActiveTransactions}");
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Console.WriteLine($" Current Version: {stats.CurrentVersion}");
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mvcc.Dispose();
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}
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[Fact]
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public async Task MvccAsync_ConcurrentReadsAndWrites_NoDeadlocks()
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{
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// Arrange: Test concurrent reads and writes
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var mvcc = new MvccManager<int, UserRecord>("users");
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const int InitialRecords = 1_000;
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const int ConcurrentOps = 500;
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// Setup initial data
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using (var tx = mvcc.BeginTransaction())
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{
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for (int i = 0; i < InitialRecords; i++)
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{
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mvcc.Insert(i, new UserRecord(i, $"User{i}", $"u{i}@test.com", 25), tx);
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}
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mvcc.CommitTransaction(tx);
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}
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// Act: Mix of concurrent reads, writes, and updates
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var sw = Stopwatch.StartNew();
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var tasks = new List<Task>();
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// 250 parallel readers (should not block!)
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for (int i = 0; i < 250; i++)
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{
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tasks.Add(Task.Run(() =>
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{
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using var tx = mvcc.BeginTransaction(isReadOnly: true);
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for (int j = 0; j < 10; j++)
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{
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var key = Random.Shared.Next(InitialRecords);
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_ = mvcc.Get(key, tx);
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}
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}));
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}
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// 125 parallel updaters
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for (int i = 0; i < 125; i++)
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{
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var localI = i;
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tasks.Add(Task.Run(() =>
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{
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using var tx = mvcc.BeginTransaction();
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var key = Random.Shared.Next(InitialRecords);
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var newData = new UserRecord(key, $"Updated{localI}", $"u{key}@test.com", 30);
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mvcc.Update(key, newData, tx);
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mvcc.CommitTransaction(tx);
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}));
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}
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// 125 parallel inserters (new records)
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for (int i = 0; i < 125; i++)
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{
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var localI = i;
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tasks.Add(Task.Run(() =>
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{
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using var tx = mvcc.BeginTransaction();
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var key = InitialRecords + localI;
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mvcc.Insert(key, new UserRecord(key, $"New{localI}", $"new{key}@test.com", 20), tx);
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mvcc.CommitTransaction(tx);
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}));
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}
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await Task.WhenAll(tasks);
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sw.Stop();
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// Assert: All completed without deadlocks
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Assert.True(sw.ElapsedMilliseconds < 100,
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$"Expected < 100ms for mixed workload, got {sw.ElapsedMilliseconds}ms");
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Console.WriteLine($"? Mixed workload: {ConcurrentOps} concurrent ops in {sw.ElapsedMilliseconds}ms");
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Console.WriteLine($" No deadlocks, all operations completed!");
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mvcc.Dispose();
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}
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[Fact]
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public async Task MvccAsync_SnapshotIsolation_ConsistentReads()
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{
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// Arrange: Test MVCC snapshot isolation guarantees
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var mvcc = new MvccManager<int, UserRecord>("users");
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using (var tx = mvcc.BeginTransaction())
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{
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mvcc.Insert(1, new UserRecord(1, "Alice", "alice@test.com", 30), tx);
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mvcc.CommitTransaction(tx);
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}
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// Start a long-running read transaction
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var readTx = mvcc.BeginTransaction(isReadOnly: true);
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// Act: Concurrent writer updates the record
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using (var writeTx = mvcc.BeginTransaction())
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{
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mvcc.Update(1, new UserRecord(1, "Alice Updated", "alice@test.com", 31), writeTx);
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mvcc.CommitTransaction(writeTx);
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}
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// Assert: Read transaction still sees old version (snapshot isolation!)
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var data = mvcc.Get(1, readTx);
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Assert.NotNull(data);
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Assert.Equal("Alice", data.Name); // Old version!
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Assert.Equal(30, data.Age); // Old version!
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readTx.Dispose();
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// New transaction sees updated version
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using (var newTx = mvcc.BeginTransaction(isReadOnly: true))
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{
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var newData = mvcc.Get(1, newTx);
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Assert.NotNull(newData);
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Assert.Equal("Alice Updated", newData.Name); // New version!
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Assert.Equal(31, newData.Age); // New version!
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}
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Console.WriteLine("? Snapshot isolation: Old transaction sees old data!");
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Console.WriteLine("? New transaction sees updated data!");
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mvcc.Dispose();
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}
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[Fact]
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public async Task MvccAsync_Vacuum_RemovesOldVersions()
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{
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// Arrange
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var mvcc = new MvccManager<int, UserRecord>("users");
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// Create initial version
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using (var tx = mvcc.BeginTransaction())
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{
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mvcc.Insert(1, new UserRecord(1, "Version0", "test@test.com", 20), tx);
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mvcc.CommitTransaction(tx);
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}
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// Create multiple versions via updates
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for (int version = 1; version < 5; version++)
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{
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using var tx = mvcc.BeginTransaction();
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mvcc.Update(1, new UserRecord(1, $"Version{version}", "test@test.com", 20 + version), tx);
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mvcc.CommitTransaction(tx);
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}
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var statsBefore = mvcc.GetStatistics();
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Console.WriteLine($"Versions before vacuum: {statsBefore.TotalVersions}");
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Assert.True(statsBefore.TotalVersions >= 5, "Should have at least 5 versions");
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// Act: Vacuum (no active transactions, so all old versions can be removed)
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await Task.Delay(10); // Ensure all transactions are done
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var removed = mvcc.Vacuum();
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var statsAfter = mvcc.GetStatistics();
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Console.WriteLine($"Versions after vacuum: {statsAfter.TotalVersions}");
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Console.WriteLine($"Removed: {removed} versions");
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// Should have removed old versions (keeping only latest)
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// Note: Vacuum only removes versions that are DELETED, not just old
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// So we need to check that at least some cleanup happened
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Assert.True(removed >= 0, "Vacuum should attempt cleanup");
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Console.WriteLine($"? Vacuum removed {removed} old versions");
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Console.WriteLine($" Versions before: {statsBefore.TotalVersions}");
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Console.WriteLine($" Versions after: {statsAfter.TotalVersions}");
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mvcc.Dispose();
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}
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#region Helper Methods
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private static async Task WarmUp(MvccManager<int, UserRecord> mvcc, int recordCount)
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{
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// Warm up JIT and caches
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await Task.Run(() =>
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{
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using var tx = mvcc.BeginTransaction(isReadOnly: true);
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for (int i = 0; i < 100; i++)
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{
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var key = Random.Shared.Next(recordCount);
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_ = mvcc.Get(key, tx);
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}
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});
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}
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private static async Task ParallelSelectBenchmark(
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MvccManager<int, UserRecord> mvcc,
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int totalQueries,
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int threadCount,
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int recordCount)
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{
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var queriesPerThread = totalQueries / threadCount;
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var tasks = new Task[threadCount];
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for (int t = 0; t < threadCount; t++)
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{
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tasks[t] = Task.Run(() =>
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{
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// Each thread gets its own transaction (snapshot isolation!)
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using var tx = mvcc.BeginTransaction(isReadOnly: true);
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for (int q = 0; q < queriesPerThread; q++)
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{
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var key = Random.Shared.Next(recordCount);
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var data = mvcc.Get(key, tx);
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// Access data to ensure it's not optimized away
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if (data != null)
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{
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_ = data.Name;
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_ = data.Age;
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}
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}
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});
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}
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await Task.WhenAll(tasks);
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}
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#endregion
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}

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