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osu-lazer/osu.Game/Database/DatabaseContextFactory.cs
Dean Herbert 587c0f965c Add more attempts to delete EF database
Just noticed in passing. Probably best we do this since it was known to
fail on windows in some rare cases.
2022-01-27 14:32:21 +09:00

213 lines
8.0 KiB
C#

// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
// See the LICENCE file in the repository root for full licence text.
using System;
using System.IO;
using System.Linq;
using System.Threading;
using Microsoft.EntityFrameworkCore.Storage;
using osu.Framework.Logging;
using osu.Framework.Platform;
using osu.Framework.Statistics;
namespace osu.Game.Database
{
public class DatabaseContextFactory : IDatabaseContextFactory
{
private readonly Storage storage;
public const string DATABASE_NAME = @"client.db";
private ThreadLocal<OsuDbContext> threadContexts;
private readonly object writeLock = new object();
private bool currentWriteDidWrite;
private bool currentWriteDidError;
private int currentWriteUsages;
private IDbContextTransaction currentWriteTransaction;
public DatabaseContextFactory(Storage storage)
{
this.storage = storage;
recycleThreadContexts();
}
private static readonly GlobalStatistic<int> reads = GlobalStatistics.Get<int>("Database", "Get (Read)");
private static readonly GlobalStatistic<int> writes = GlobalStatistics.Get<int>("Database", "Get (Write)");
private static readonly GlobalStatistic<int> commits = GlobalStatistics.Get<int>("Database", "Commits");
private static readonly GlobalStatistic<int> rollbacks = GlobalStatistics.Get<int>("Database", "Rollbacks");
/// <summary>
/// Get a context for the current thread for read-only usage.
/// If a <see cref="DatabaseWriteUsage"/> is in progress, the existing write-safe context will be returned.
/// </summary>
public OsuDbContext Get()
{
reads.Value++;
return threadContexts.Value;
}
/// <summary>
/// Request a context for write usage. Can be consumed in a nested fashion (and will return the same underlying context).
/// This method may block if a write is already active on a different thread.
/// </summary>
/// <param name="withTransaction">Whether to start a transaction for this write.</param>
/// <returns>A usage containing a usable context.</returns>
public DatabaseWriteUsage GetForWrite(bool withTransaction = true)
{
writes.Value++;
Monitor.Enter(writeLock);
OsuDbContext context;
try
{
if (currentWriteTransaction == null && withTransaction)
{
// this mitigates the fact that changes on tracked entities will not be rolled back with the transaction by ensuring write operations are always executed in isolated contexts.
// if this results in sub-optimal efficiency, we may need to look into removing Database-level transactions in favour of running SaveChanges where we currently commit the transaction.
if (threadContexts.IsValueCreated)
recycleThreadContexts();
context = threadContexts.Value;
currentWriteTransaction = context.Database.BeginTransaction();
}
else
{
// we want to try-catch the retrieval of the context because it could throw an error (in CreateContext).
context = threadContexts.Value;
}
}
catch
{
// retrieval of a context could trigger a fatal error.
Monitor.Exit(writeLock);
throw;
}
Interlocked.Increment(ref currentWriteUsages);
return new DatabaseWriteUsage(context, usageCompleted) { IsTransactionLeader = currentWriteTransaction != null && currentWriteUsages == 1 };
}
private void usageCompleted(DatabaseWriteUsage usage)
{
int usages = Interlocked.Decrement(ref currentWriteUsages);
try
{
currentWriteDidWrite |= usage.PerformedWrite;
currentWriteDidError |= usage.Errors.Any();
if (usages == 0)
{
if (currentWriteDidError)
{
rollbacks.Value++;
currentWriteTransaction?.Rollback();
}
else
{
commits.Value++;
currentWriteTransaction?.Commit();
}
if (currentWriteDidWrite || currentWriteDidError)
{
// explicitly dispose to ensure any outstanding flushes happen as soon as possible (and underlying resources are purged).
usage.Context.Dispose();
// once all writes are complete, we want to refresh thread-specific contexts to make sure they don't have stale local caches.
recycleThreadContexts();
}
currentWriteTransaction = null;
currentWriteDidWrite = false;
currentWriteDidError = false;
}
}
finally
{
Monitor.Exit(writeLock);
}
}
private void recycleThreadContexts()
{
// Contexts for other threads are not disposed as they may be in use elsewhere. Instead, fresh contexts are exposed
// for other threads to use, and we rely on the finalizer inside OsuDbContext to handle their previous contexts
threadContexts?.Value.Dispose();
threadContexts = new ThreadLocal<OsuDbContext>(CreateContext, true);
}
protected virtual OsuDbContext CreateContext() => new OsuDbContext(CreateDatabaseConnectionString(DATABASE_NAME, storage))
{
Database = { AutoTransactionsEnabled = false }
};
public void CreateBackup(string backupFilename)
{
Logger.Log($"Creating full EF database backup at {backupFilename}", LoggingTarget.Database);
using (var source = storage.GetStream(DATABASE_NAME))
using (var destination = storage.GetStream(backupFilename, FileAccess.Write, FileMode.CreateNew))
source.CopyTo(destination);
}
public void ResetDatabase()
{
lock (writeLock)
{
recycleThreadContexts();
try
{
int attempts = 10;
// Retry logic taken from MigratableStorage.AttemptOperation.
while (true)
{
try
{
storage.Delete(DATABASE_NAME);
return;
}
catch (Exception)
{
if (attempts-- == 0)
throw;
}
Thread.Sleep(250);
}
}
catch
{
// for now we are not sure why file handles are kept open by EF, but this is generally only used in testing
}
}
}
public void FlushConnections()
{
if (threadContexts != null)
{
foreach (var context in threadContexts.Values)
context.Dispose();
}
recycleThreadContexts();
}
public static string CreateDatabaseConnectionString(string filename, Storage storage) => string.Concat("Data Source=", storage.GetFullPath($@"{filename}", true));
private readonly ManualResetEventSlim migrationComplete = new ManualResetEventSlim();
public void SetMigrationCompletion() => migrationComplete.Set();
public void WaitForMigrationCompletion() => migrationComplete.Wait();
}
}