bddec0fe4d
An exception thrown inside a `when` filter is swallowed as false, so a manifest re-read failing mid-File.Replace turned a race that should retry into a thrown torn-page error. The re-read now runs in the handler, and a failed re-read counts as moved. Parallel.For's AggregateException is unwrapped where the pages are read, so the page's own failure propagates and the torn check no longer walks wrappers. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
604 lines
24 KiB
C#
604 lines
24 KiB
C#
using System;
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using System.Collections.Concurrent;
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using System.Collections.Generic;
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using System.Diagnostics;
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using System.IO;
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using System.Linq;
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using System.Runtime.ExceptionServices;
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using System.Security.Cryptography;
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using System.Threading;
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using System.Threading.Tasks;
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using MessagePack;
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namespace GameCult.Caching.MessagePack;
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// A small hot manifest indexes the store; each record lives in one cold content-addressed page.
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public sealed class DirectoryMessagePackBackingStore : CacheBackingStore
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{
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private const string IndexedFormatVersion = "cultcache.store.v4.directory-content-addressed-pages";
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// An unleased load that has not settled after this many attempts throws.
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private const int UnleasedLoadAttempts = 5;
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private readonly FileInfo _manifestFile;
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private readonly DirectoryInfo _recordDirectory;
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private readonly ConcurrentDictionary<string, bool> _dirtyKeys = new(StringComparer.Ordinal);
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private readonly ConcurrentDictionary<string, bool> _deletedKeys = new(StringComparer.Ordinal);
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private readonly HashSet<string> _hydratedKeys = new(StringComparer.Ordinal);
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private CultSchemaCatalogEntry[] _durableCatalog = Array.Empty<CultSchemaCatalogEntry>();
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public DirectoryMessagePackBackingStore(string manifestPath, string? recordDirectoryPath = null, bool readOnly = false)
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: base(readOnly)
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{
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if (string.IsNullOrWhiteSpace(manifestPath))
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{
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throw new ArgumentException("Manifest path must be non-empty.", nameof(manifestPath));
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}
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_manifestFile = new FileInfo(manifestPath);
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_recordDirectory = new DirectoryInfo(recordDirectoryPath ?? DefaultRecordDirectoryPath(manifestPath));
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}
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public static string DefaultRecordDirectoryPath(string manifestPath) => manifestPath + ".records";
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// Test seam: runs between an unleased load's manifest read and its page reads.
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internal Action? UnleasedManifestRead { get; set; }
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public override string ToString() => _manifestFile.FullName;
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public override void PullAll() => Held(PullAllCore);
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private void PullAllCore()
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{
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var traceStartup = string.Equals(
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Environment.GetEnvironmentVariable("CULTCACHE_TRACE_STARTUP_PHASES"),
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"1",
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StringComparison.Ordinal);
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var startupPhase = Stopwatch.StartNew();
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void Trace(string phase)
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{
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if (traceStartup)
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Console.WriteLine($"CultCache directory-pull phase {phase} took {startupPhase.Elapsed.TotalMilliseconds:0.###}ms.");
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startupPhase.Restart();
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}
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var reports = new List<CultSchemaMigrationReport>();
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var loaded = new Dictionary<string, CultStoredDocument>(StringComparer.Ordinal);
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CultSchemaCatalogEntry[] catalog;
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for (var attempt = 1; ; attempt++)
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{
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loaded.Clear();
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reports.Clear();
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// Only pages named by the manifest read under the lease are loaded; orphaned pages are never loaded. With no
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// lock to lease (none created yet, or a store copied without it) a writer may commit mid-load, so an unleased
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// load stands only if its manifest is still current; if the manifest moved it reloads, under the lease the
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// writer created. A page that fails under an unmoved manifest is corruption, not a race.
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using var lease = AcquireCommitLease(wait: true, create: false);
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var manifestBytes = ReadManifestBytes();
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var manifest = ParseManifest(manifestBytes);
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Trace($"manifest records={manifest.Records.Length}");
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try
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{
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if (lease == null)
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UnleasedManifestRead?.Invoke();
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LoadRecordPages(
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manifest.Records.OrderBy(record => record.Key, StringComparer.Ordinal).ToArray(),
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manifest.SchemaCatalog,
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loaded,
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reports);
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if (lease != null || !ManifestMoved(manifestBytes))
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{
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catalog = manifest.SchemaCatalog;
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Trace($"indexed-pages loaded={loaded.Count}");
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break;
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}
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}
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catch (Exception exception) when (lease == null && IsTornGeneration(exception))
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{
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// The re-read stays out of the filter: an exception thrown inside a filter is swallowed as false.
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if (!ManifestMoved(manifestBytes))
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throw;
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if (attempt == UnleasedLoadAttempts)
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throw Unsettled(exception);
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continue;
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}
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if (attempt == UnleasedLoadAttempts)
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throw Unsettled(null);
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}
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bool Staged(string key) => _dirtyKeys.ContainsKey(key) || _deletedKeys.ContainsKey(key);
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var arrived = loaded
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.Where(pair => !Staged(pair.Key) &&
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(!Entries.TryGetValue(pair.Key, out var existing) ||
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existing.StoredAt != pair.Value.StoredAt ||
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existing.Descriptor.SchemaId != pair.Value.Descriptor.SchemaId))
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.Select(pair => pair.Value)
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.ToArray();
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var departed = _hydratedKeys
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.Where(key => !loaded.ContainsKey(key) && !Staged(key) && Entries.ContainsKey(key))
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.Select(key => Entries[key])
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.ToArray();
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if (arrived.Length > 0 || departed.Length > 0)
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Loaded?.Invoke(arrived, departed);
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// Adopted only once the cache admitted the load; a refused load leaves the store's durable view untouched.
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_durableCatalog = catalog;
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foreach (var stored in departed)
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Entries.TryRemove(stored.Key.Value, out _);
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_hydratedKeys.RemoveWhere(key => !loaded.ContainsKey(key) && !Staged(key));
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foreach (var stored in arrived)
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Entries[stored.Key.Value] = stored;
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foreach (var key in loaded.Keys)
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_hydratedKeys.Add(key);
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SetLastSchemaMigrationReports(reports);
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IsDirty = !_dirtyKeys.IsEmpty || !_deletedKeys.IsEmpty;
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Trace("publish");
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}
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public override void Push(CultStoredDocument entry)
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{
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ThrowIfReadOnly();
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Held(() =>
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{
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Entries[entry.Key.Value] = entry;
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_dirtyKeys[entry.Key.Value] = true;
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_deletedKeys.TryRemove(entry.Key.Value, out _);
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IsDirty = true;
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});
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}
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public override void Delete(CultStoredDocument entry)
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{
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ThrowIfReadOnly();
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Held(() =>
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{
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Entries.TryRemove(entry.Key.Value, out _);
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_dirtyKeys.TryRemove(entry.Key.Value, out _);
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_deletedKeys[entry.Key.Value] = true;
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IsDirty = true;
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});
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}
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public override CultCommitOutcome CommitBatch(CultCommitRequest request, bool wait)
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{
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ThrowIfReadOnly();
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return Held(() =>
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{
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Directory.CreateDirectory(_manifestFile.DirectoryName!);
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using var commitLease = AcquireCommitLease(wait, create: true);
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if (commitLease == null)
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return CultCommitOutcome.Contended;
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var manifest = ReadManifest();
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if (!request.ConditionsHold(manifest.Records, Entries.Values))
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return CultCommitOutcome.Mismatch;
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var previousEntries = Entries.ToDictionary(pair => pair.Key, pair => pair.Value, StringComparer.Ordinal);
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var previousDirtyKeys = _dirtyKeys.Keys.ToArray();
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var previousDeletedKeys = _deletedKeys.Keys.ToArray();
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var wasDirty = IsDirty;
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try
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{
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foreach (var entry in request.Deletes)
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{
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Entries.TryRemove(entry.Key.Value, out _);
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_dirtyKeys.TryRemove(entry.Key.Value, out _);
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_deletedKeys[entry.Key.Value] = true;
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}
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foreach (var entry in request.Upserts)
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{
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Entries[entry.Key.Value] = entry;
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_dirtyKeys[entry.Key.Value] = true;
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_deletedKeys.TryRemove(entry.Key.Value, out _);
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}
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IsDirty = true;
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WriteGeneration(manifest);
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return CultCommitOutcome.Committed;
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}
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catch
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{
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Entries.Clear();
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foreach (var pair in previousEntries)
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Entries[pair.Key] = pair.Value;
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_dirtyKeys.Clear();
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foreach (var key in previousDirtyKeys)
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_dirtyKeys[key] = true;
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_deletedKeys.Clear();
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foreach (var key in previousDeletedKeys)
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_deletedKeys[key] = true;
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IsDirty = wasDirty;
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throw;
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}
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});
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}
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public override void PushAll()
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{
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ThrowIfReadOnly();
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Held(() =>
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{
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if (!IsDirty)
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return;
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Directory.CreateDirectory(_manifestFile.DirectoryName!);
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using var commitLease = AcquireCommitLease(wait: true, create: true);
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WriteGeneration(ReadManifest());
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});
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}
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// Runs under the commit lease: pages first, then the manifest that names them.
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private void WriteGeneration(CultPersistedStoreSnapshot currentManifest)
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{
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Directory.CreateDirectory(_recordDirectory.FullName);
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var currentIndex = currentManifest.Records.ToDictionary(record => record.Key, record => record, StringComparer.Ordinal);
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foreach (var key in _deletedKeys.Keys)
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currentIndex.Remove(key);
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foreach (var key in _dirtyKeys.Keys)
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{
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if (Entries.TryGetValue(key, out var stored))
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currentIndex[key] = ToIndexRecord(stored);
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}
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var catalogCandidates = currentManifest.SchemaCatalog
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.Concat(_durableCatalog)
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.Concat(Entries.Values.Select(entry => entry.Descriptor.ToCatalogEntry()))
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.GroupBy(entry => entry.SchemaId, StringComparer.Ordinal)
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.Select(group => group.Last())
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.ToArray();
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var usedSchemaIds = currentIndex.Values.Select(record => record.SchemaId).ToHashSet(StringComparer.Ordinal);
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var targetCatalog = catalogCandidates
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.Where(entry => usedSchemaIds.Contains(entry.SchemaId))
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.OrderBy(entry => entry.SchemaName, StringComparer.Ordinal)
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.ToArray();
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var keysToWrite = _dirtyKeys.Keys
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.OrderBy(value => value, StringComparer.Ordinal)
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.ToArray();
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foreach (var key in keysToWrite)
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{
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if (!Entries.TryGetValue(key, out var stored))
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{
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continue;
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}
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var record = ToPersistedRecord(stored, document =>
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CultDocumentMessagePackSerialization.SerializeUntyped(
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document,
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stored.Descriptor.DocumentType,
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Registry));
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var pagePayload = CultDocumentMessagePackSerialization.SerializePersistedRecord(record);
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var indexRecord = ToContentAddressedIndexRecord(record, pagePayload);
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currentIndex[key] = indexRecord;
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WriteFileAtomically(
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ContentAddressedRecordPath(indexRecord),
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pagePayload);
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}
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WriteManifest(targetCatalog, currentIndex.Values
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.OrderBy(record => record.Key, StringComparer.Ordinal)
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.ToArray());
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DeleteUnreferencedRecordPages(currentIndex.Values);
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_durableCatalog = targetCatalog;
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_dirtyKeys.Clear();
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_deletedKeys.Clear();
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MarkFlushSucceeded();
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}
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private void WriteManifest(CultSchemaCatalogEntry[] catalog, CultPersistedRecord[] index)
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{
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var manifest = new CultPersistedStoreSnapshot
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{
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FormatVersion = IndexedFormatVersion,
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SchemaCatalog = catalog,
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Records = index
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};
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WriteFileAtomically(_manifestFile.FullName, CultDocumentMessagePackSerialization.SerializeSnapshot(manifest));
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}
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private void LoadRecordPages(
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CultPersistedRecord[] records,
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IReadOnlyCollection<CultSchemaCatalogEntry> catalogEntries,
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Dictionary<string, CultStoredDocument> loaded,
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List<CultSchemaMigrationReport> reports)
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{
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var tracePages = string.Equals(
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Environment.GetEnvironmentVariable("CULTCACHE_TRACE_STARTUP_PHASES"),
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"1",
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StringComparison.Ordinal);
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var recordReports = new CultSchemaMigrationReport[records.Length];
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var storedRecords = new CultStoredDocument?[records.Length];
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var pageBytes = tracePages ? new long[records.Length] : Array.Empty<long>();
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var pageElapsedTicks = tracePages ? new long[records.Length] : Array.Empty<long>();
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try
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{
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ReadPages();
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}
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catch (AggregateException aggregate)
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{
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// The page's own failure propagates, not Parallel.For's wrapper.
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ExceptionDispatchInfo.Capture(aggregate.Flatten().InnerExceptions[0]).Throw();
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}
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void ReadPages() => Parallel.For(
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0,
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records.Length,
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new ParallelOptions { MaxDegreeOfParallelism = Math.Min(Environment.ProcessorCount, 8) },
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index =>
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{
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var started = tracePages ? Stopwatch.GetTimestamp() : 0L;
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var metadata = records[index];
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var record = ReadPersistedRecordPage(metadata, out var pagePayload);
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recordReports[index] = Registry.ResolvePersistedSchemaReport(record.SchemaId, catalogEntries);
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storedRecords[index] = ToStoredDocument(
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record,
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catalogEntries,
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(type, payload) => CultDocumentMessagePackSerialization.DeserializeUntyped(type, payload, Registry));
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if (tracePages)
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{
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pageBytes[index] = pagePayload.LongLength;
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pageElapsedTicks[index] = Stopwatch.GetTimestamp() - started;
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}
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});
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if (tracePages)
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{
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var schemaNames = catalogEntries.ToDictionary(entry => entry.SchemaId, entry => entry.SchemaName, StringComparer.Ordinal);
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foreach (var group in records
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.Select((record, index) => new { record.SchemaId, Index = index })
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.Where(item => pageElapsedTicks[item.Index] > 0)
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.GroupBy(item => item.SchemaId, StringComparer.Ordinal)
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.Select(group => new
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{
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SchemaId = group.Key,
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Count = group.Count(),
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Bytes = group.Sum(item => pageBytes[item.Index]),
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TotalMs = group.Sum(item => pageElapsedTicks[item.Index]) * 1000d / Stopwatch.Frequency,
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MaxMs = group.Max(item => pageElapsedTicks[item.Index]) * 1000d / Stopwatch.Frequency
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})
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.OrderByDescending(group => group.TotalMs)
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.Take(10))
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{
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var schemaName = schemaNames.TryGetValue(group.SchemaId, out var name) ? name : group.SchemaId;
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Console.WriteLine(
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$"CultCache directory-page schema={schemaName} count={group.Count} bytes={group.Bytes} " +
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$"cumulative={group.TotalMs:0.###}ms max={group.MaxMs:0.###}ms.");
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}
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}
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for (var index = 0; index < storedRecords.Length; index++)
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{
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var stored = storedRecords[index];
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if (stored == null)
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continue;
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reports.Add(recordReports[index]);
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loaded[stored.Key.Value] = stored;
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}
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}
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private static CultPersistedRecord ToIndexRecord(CultStoredDocument stored) => new()
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{
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Key = stored.Key.Value,
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SchemaId = stored.Descriptor.SchemaId,
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StoredAt = stored.StoredAt,
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Payload = Array.Empty<byte>()
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};
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private static CultPersistedRecord ToContentAddressedIndexRecord(
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CultPersistedRecord record,
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byte[] pagePayload) => new()
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{
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Key = record.Key,
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SchemaId = record.SchemaId,
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StoredAt = record.StoredAt,
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Payload = HashPayload(pagePayload)
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};
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private CultPersistedStoreSnapshot ReadManifest() => ParseManifest(ReadManifestBytes());
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private byte[]? ReadManifestBytes() => File.Exists(_manifestFile.FullName) ? ReadAllBytesShared(_manifestFile.FullName) : null;
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// A manifest that cannot be re-read (a writer mid-replace) has moved.
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private bool ManifestMoved(byte[]? read)
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{
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try
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{
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var current = ReadManifestBytes();
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return read == null ? current != null : current == null || !read.SequenceEqual(current);
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}
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catch (Exception)
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{
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return true;
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}
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}
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// A page the manifest named that vanished or was replaced. It is a writer committing mid-load only when the manifest
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// moved too; under an unchanged manifest the same failure is corruption and is thrown as it is.
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private static bool IsTornGeneration(Exception exception) =>
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exception is InvalidDataException or FileNotFoundException or DirectoryNotFoundException;
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private InvalidOperationException Unsettled(Exception? last) => new(
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$"Directory store {_manifestFile.FullName} changed under every one of {UnleasedLoadAttempts} unlocked loads; it did not settle.", last);
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// A missing manifest is an empty store. An existing manifest in any other format is refused.
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private CultPersistedStoreSnapshot ParseManifest(byte[]? manifestBytes)
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{
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if (manifestBytes == null)
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{
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return new CultPersistedStoreSnapshot
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{
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FormatVersion = IndexedFormatVersion,
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SchemaCatalog = Array.Empty<CultSchemaCatalogEntry>(),
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Records = Array.Empty<CultPersistedRecord>()
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};
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}
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var snapshot = CultDocumentMessagePackSerialization.DeserializeSnapshot(manifestBytes);
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if (!string.Equals(snapshot.FormatVersion, IndexedFormatVersion, StringComparison.Ordinal))
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{
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throw new InvalidOperationException(
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$"Directory store {_manifestFile.FullName} is {snapshot.FormatVersion}; only {IndexedFormatVersion} is readable.");
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}
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return snapshot;
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}
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private string ContentAddressedRecordPath(CultPersistedRecord metadata)
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{
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if (metadata.Payload == null || metadata.Payload.Length != 32)
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throw new InvalidDataException($"Record '{metadata.Key}' has no committed SHA-256 page identity.");
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var hash = BitConverter.ToString(metadata.Payload).Replace("-", string.Empty).ToLowerInvariant();
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return Path.Combine(_recordDirectory.FullName, $"{hash}.msgpack");
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}
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private static byte[] HashPayload(byte[] payload)
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{
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using var sha256 = SHA256.Create();
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return sha256.ComputeHash(payload);
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}
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private void DeleteUnreferencedRecordPages(IEnumerable<CultPersistedRecord> durableRecords)
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{
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var referenced = durableRecords
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.Select(ContentAddressedRecordPath)
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.ToHashSet(StringComparer.OrdinalIgnoreCase);
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foreach (var file in _recordDirectory.EnumerateFiles("*.msgpack"))
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{
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if (referenced.Contains(file.FullName))
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continue;
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try
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{
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File.Delete(file.FullName);
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}
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catch (IOException)
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{
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// An orphan is harmless: no committed manifest references it.
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}
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catch (UnauthorizedAccessException)
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{
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// Cleanup is best effort and never changes the committed generation.
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}
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}
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}
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private CultPersistedRecord ReadPersistedRecordPage(CultPersistedRecord metadata, out byte[] pagePayload)
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{
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var path = ContentAddressedRecordPath(metadata);
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if (!File.Exists(path))
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throw new InvalidDataException($"Committed record page '{path}' is missing from the selected manifest generation.");
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pagePayload = ReadAllBytesShared(path);
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if (!HashPayload(pagePayload).SequenceEqual(metadata.Payload))
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throw new InvalidDataException($"Record page '{path}' does not match its committed content hash.");
|
|
var record = CultDocumentMessagePackSerialization.DeserializePersistedRecord(pagePayload);
|
|
if (!string.Equals(record.Key, metadata.Key, StringComparison.Ordinal))
|
|
throw new InvalidDataException($"Record page '{path}' contains key '{record.Key}', expected '{metadata.Key}'.");
|
|
return record;
|
|
}
|
|
|
|
private static void WriteFileAtomically(string path, byte[] payload)
|
|
{
|
|
var directory = Path.GetDirectoryName(path)!;
|
|
Directory.CreateDirectory(directory);
|
|
var tempPath = Path.Combine(directory, $".{Path.GetFileName(path)}.{Guid.NewGuid():N}.tmp");
|
|
|
|
try
|
|
{
|
|
using (var stream = new FileStream(
|
|
tempPath,
|
|
FileMode.CreateNew,
|
|
FileAccess.Write,
|
|
FileShare.None,
|
|
bufferSize: 4096,
|
|
FileOptions.WriteThrough))
|
|
{
|
|
stream.Write(payload, 0, payload.Length);
|
|
stream.Flush(true);
|
|
}
|
|
|
|
if (File.Exists(path))
|
|
{
|
|
ReplaceExistingFile(tempPath, path);
|
|
}
|
|
else
|
|
{
|
|
File.Move(tempPath, path);
|
|
}
|
|
}
|
|
finally
|
|
{
|
|
if (File.Exists(tempPath))
|
|
{
|
|
File.Delete(tempPath);
|
|
}
|
|
}
|
|
}
|
|
|
|
private static byte[] ReadAllBytesShared(string path)
|
|
{
|
|
using var stream = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.ReadWrite | FileShare.Delete);
|
|
using var buffer = new MemoryStream();
|
|
stream.CopyTo(buffer);
|
|
return buffer.ToArray();
|
|
}
|
|
|
|
// Only a writer creates the records folder and the lock, so opening the store creates nothing. A reader opens an
|
|
// existing lock and returns null when there is none; that does not mean no writer committed (a store may be copied
|
|
// without its lock, and a first writer may create it mid-load), so an unleased load checks that it settled.
|
|
private FileStream? AcquireCommitLease(bool wait, bool create)
|
|
{
|
|
if (create)
|
|
Directory.CreateDirectory(_recordDirectory.FullName);
|
|
var lockPath = Path.Combine(_recordDirectory.FullName, ".commit.lock");
|
|
var started = Stopwatch.StartNew();
|
|
while (true)
|
|
{
|
|
try
|
|
{
|
|
return new FileStream(
|
|
lockPath,
|
|
create ? FileMode.OpenOrCreate : FileMode.Open,
|
|
FileAccess.ReadWrite,
|
|
FileShare.None,
|
|
bufferSize: 1,
|
|
FileOptions.WriteThrough);
|
|
}
|
|
catch (FileNotFoundException) when (!create)
|
|
{
|
|
return null;
|
|
}
|
|
catch (DirectoryNotFoundException) when (!create)
|
|
{
|
|
return null;
|
|
}
|
|
catch (IOException) when (!wait)
|
|
{
|
|
return null;
|
|
}
|
|
catch (IOException) when (started.Elapsed < TimeSpan.FromSeconds(30))
|
|
{
|
|
Thread.Sleep(10);
|
|
}
|
|
}
|
|
}
|
|
|
|
private static void ReplaceExistingFile(string sourcePath, string destinationPath)
|
|
{
|
|
for (var attempt = 0; attempt < 3; attempt++)
|
|
{
|
|
try
|
|
{
|
|
File.Replace(sourcePath, destinationPath, null);
|
|
return;
|
|
}
|
|
catch (IOException) when (attempt < 2)
|
|
{
|
|
Thread.Sleep(10 * (attempt + 1));
|
|
}
|
|
catch (UnauthorizedAccessException) when (attempt < 2)
|
|
{
|
|
Thread.Sleep(10 * (attempt + 1));
|
|
}
|
|
}
|
|
|
|
File.Replace(sourcePath, destinationPath, null);
|
|
}
|
|
}
|