| | | 1 | | using System.Collections.Concurrent; |
| | | 2 | | |
| | | 3 | | namespace AsyncResponse; |
| | | 4 | | |
| | | 5 | | /// <summary>Atomic process-local flow-state store for development, tests, and single-process apps.</summary> |
| | | 6 | | internal sealed class InMemoryFlowStateStore : IFlowStateStore |
| | | 7 | | { |
| | 3 | 8 | | private readonly ConcurrentDictionary<string, Entry> _entries = new(StringComparer.Ordinal); |
| | | 9 | | |
| | | 10 | | public Task<bool> TryCreateAsync( |
| | | 11 | | string flowId, |
| | | 12 | | FlowState state, |
| | | 13 | | TimeSpan ttl, |
| | | 14 | | CancellationToken cancellationToken = default) |
| | | 15 | | { |
| | 3 | 16 | | ValidateWrite(flowId, state, ttl); |
| | 3 | 17 | | cancellationToken.ThrowIfCancellationRequested(); |
| | 3 | 18 | | if (state.Revision != 0) |
| | 2 | 19 | | throw new ArgumentException("A new flow ledger must start at revision zero.", nameof(state)); |
| | | 20 | | |
| | 3 | 21 | | var now = DateTime.UtcNow; |
| | 3 | 22 | | var created = CreateEntry(state, now.Add(ttl)); |
| | | 23 | | while (true) |
| | | 24 | | { |
| | 3 | 25 | | if (_entries.TryAdd(flowId, created)) |
| | 3 | 26 | | return Task.FromResult(true); |
| | | 27 | | |
| | 3 | 28 | | if (!_entries.TryGetValue(flowId, out var existing)) |
| | | 29 | | continue; |
| | | 30 | | |
| | 3 | 31 | | if (existing.ExpiresAtUtc > now) |
| | 3 | 32 | | return Task.FromResult(false); |
| | | 33 | | |
| | 2 | 34 | | if (_entries.TryUpdate(flowId, created, existing)) |
| | 2 | 35 | | return Task.FromResult(true); |
| | | 36 | | } |
| | | 37 | | } |
| | | 38 | | |
| | | 39 | | public Task<FlowState?> LoadAsync(string flowId, CancellationToken cancellationToken = default) |
| | | 40 | | { |
| | 3 | 41 | | ArgumentException.ThrowIfNullOrWhiteSpace(flowId); |
| | 3 | 42 | | cancellationToken.ThrowIfCancellationRequested(); |
| | | 43 | | |
| | 3 | 44 | | while (_entries.TryGetValue(flowId, out var entry)) |
| | | 45 | | { |
| | 3 | 46 | | if (entry.ExpiresAtUtc <= DateTime.UtcNow) |
| | | 47 | | { |
| | 2 | 48 | | _entries.TryRemove(KeyValuePair.Create(flowId, entry)); |
| | 2 | 49 | | continue; |
| | | 50 | | } |
| | | 51 | | |
| | 3 | 52 | | var state = FlowStateJson.Deserialize(entry.StateJson); |
| | 3 | 53 | | return Task.FromResult( |
| | 3 | 54 | | state is not null |
| | 3 | 55 | | && FlowStateSchema.IsReadable(state.SchemaVersion) |
| | 3 | 56 | | && state.Revision == entry.Revision |
| | 3 | 57 | | && string.Equals(state.FlowId, flowId, StringComparison.Ordinal) |
| | 3 | 58 | | ? state |
| | 3 | 59 | | : null); |
| | | 60 | | } |
| | | 61 | | |
| | 3 | 62 | | return Task.FromResult<FlowState?>(null); |
| | | 63 | | } |
| | | 64 | | |
| | | 65 | | public Task<bool> TryUpdateAsync( |
| | | 66 | | string flowId, |
| | | 67 | | FlowState state, |
| | | 68 | | long expectedRevision, |
| | | 69 | | TimeSpan ttl, |
| | | 70 | | string? leaseId = null, |
| | | 71 | | CancellationToken cancellationToken = default) |
| | | 72 | | { |
| | 3 | 73 | | ValidateWrite(flowId, state, ttl); |
| | 3 | 74 | | cancellationToken.ThrowIfCancellationRequested(); |
| | 3 | 75 | | if (expectedRevision < 0) |
| | 2 | 76 | | throw new ArgumentOutOfRangeException(nameof(expectedRevision), "Expected revision cannot be negative."); |
| | 3 | 77 | | if (state.Revision != checked(expectedRevision + 1)) |
| | 2 | 78 | | throw new ArgumentException("The new flow-state revision must increment the expected revision by one.", name |
| | | 79 | | |
| | 3 | 80 | | while (_entries.TryGetValue(flowId, out var current)) |
| | | 81 | | { |
| | 3 | 82 | | var now = DateTime.UtcNow; |
| | 3 | 83 | | if (current.ExpiresAtUtc <= now || current.Revision != expectedRevision) |
| | 2 | 84 | | return Task.FromResult(false); |
| | 3 | 85 | | if (leaseId is not null |
| | 3 | 86 | | && (!string.Equals(current.LeaseId, leaseId, StringComparison.Ordinal) |
| | 3 | 87 | | || current.LeaseExpiresAtUtc <= now)) |
| | 2 | 88 | | return Task.FromResult(false); |
| | | 89 | | |
| | 3 | 90 | | var updated = CreateEntry( |
| | 3 | 91 | | state, |
| | 3 | 92 | | now.Add(ttl), |
| | 3 | 93 | | current.LeaseId, |
| | 3 | 94 | | current.LeaseExpiresAtUtc); |
| | 3 | 95 | | if (_entries.TryUpdate(flowId, updated, current)) |
| | 3 | 96 | | return Task.FromResult(true); |
| | | 97 | | } |
| | | 98 | | |
| | 2 | 99 | | return Task.FromResult(false); |
| | | 100 | | } |
| | | 101 | | |
| | | 102 | | public Task<bool> TryAcquireLeaseAsync( |
| | | 103 | | string flowId, |
| | | 104 | | string leaseId, |
| | | 105 | | TimeSpan leaseDuration, |
| | | 106 | | CancellationToken cancellationToken = default) |
| | 3 | 107 | | => TryChangeLeaseAsync(flowId, leaseId, leaseDuration, acquire: true, cancellationToken); |
| | | 108 | | |
| | | 109 | | public Task<bool> TryRenewLeaseAsync( |
| | | 110 | | string flowId, |
| | | 111 | | string leaseId, |
| | | 112 | | TimeSpan leaseDuration, |
| | | 113 | | CancellationToken cancellationToken = default) |
| | 2 | 114 | | => TryChangeLeaseAsync(flowId, leaseId, leaseDuration, acquire: false, cancellationToken); |
| | | 115 | | |
| | | 116 | | public Task ReleaseLeaseAsync( |
| | | 117 | | string flowId, |
| | | 118 | | string leaseId, |
| | | 119 | | CancellationToken cancellationToken = default) |
| | | 120 | | { |
| | 3 | 121 | | ArgumentException.ThrowIfNullOrWhiteSpace(flowId); |
| | 3 | 122 | | ArgumentException.ThrowIfNullOrWhiteSpace(leaseId); |
| | 3 | 123 | | cancellationToken.ThrowIfCancellationRequested(); |
| | | 124 | | |
| | 3 | 125 | | while (_entries.TryGetValue(flowId, out var current)) |
| | | 126 | | { |
| | 3 | 127 | | if (!string.Equals(current.LeaseId, leaseId, StringComparison.Ordinal)) |
| | | 128 | | break; |
| | | 129 | | |
| | 3 | 130 | | if (_entries.TryUpdate(flowId, current with { LeaseId = null, LeaseExpiresAtUtc = null }, current)) |
| | | 131 | | break; |
| | | 132 | | } |
| | | 133 | | |
| | 3 | 134 | | return Task.CompletedTask; |
| | | 135 | | } |
| | | 136 | | |
| | | 137 | | public Task<bool> TryDeleteAsync(string flowId, CancellationToken cancellationToken = default) |
| | | 138 | | { |
| | 2 | 139 | | ArgumentException.ThrowIfNullOrWhiteSpace(flowId); |
| | 2 | 140 | | cancellationToken.ThrowIfCancellationRequested(); |
| | 2 | 141 | | return Task.FromResult(_entries.TryRemove(flowId, out _)); |
| | | 142 | | } |
| | | 143 | | |
| | | 144 | | private Task<bool> TryChangeLeaseAsync( |
| | | 145 | | string flowId, |
| | | 146 | | string leaseId, |
| | | 147 | | TimeSpan leaseDuration, |
| | | 148 | | bool acquire, |
| | | 149 | | CancellationToken cancellationToken) |
| | | 150 | | { |
| | 3 | 151 | | ArgumentException.ThrowIfNullOrWhiteSpace(flowId); |
| | 3 | 152 | | ArgumentException.ThrowIfNullOrWhiteSpace(leaseId); |
| | 3 | 153 | | if (leaseDuration <= TimeSpan.Zero) |
| | 2 | 154 | | throw new ArgumentOutOfRangeException(nameof(leaseDuration), "Lease duration must be greater than zero."); |
| | 3 | 155 | | cancellationToken.ThrowIfCancellationRequested(); |
| | | 156 | | |
| | 3 | 157 | | while (_entries.TryGetValue(flowId, out var current)) |
| | | 158 | | { |
| | 3 | 159 | | var now = DateTime.UtcNow; |
| | 3 | 160 | | if (current.ExpiresAtUtc <= now) |
| | 2 | 161 | | return Task.FromResult(false); |
| | | 162 | | |
| | 3 | 163 | | var ownsLease = string.Equals(current.LeaseId, leaseId, StringComparison.Ordinal); |
| | 3 | 164 | | if (acquire ? current.LeaseId is not null && current.LeaseExpiresAtUtc > now && !ownsLease : !ownsLease || c |
| | 2 | 165 | | return Task.FromResult(false); |
| | | 166 | | |
| | 3 | 167 | | var updated = current with |
| | 3 | 168 | | { |
| | 3 | 169 | | LeaseId = leaseId, |
| | 3 | 170 | | LeaseExpiresAtUtc = now.Add(leaseDuration) |
| | 3 | 171 | | }; |
| | 3 | 172 | | if (_entries.TryUpdate(flowId, updated, current)) |
| | 3 | 173 | | return Task.FromResult(true); |
| | | 174 | | } |
| | | 175 | | |
| | 2 | 176 | | return Task.FromResult(false); |
| | | 177 | | } |
| | | 178 | | |
| | | 179 | | private static Entry CreateEntry( |
| | | 180 | | FlowState state, |
| | | 181 | | DateTime expiresAtUtc, |
| | | 182 | | string? leaseId = null, |
| | | 183 | | DateTime? leaseExpiresAtUtc = null) |
| | 3 | 184 | | => new(FlowStateJson.Serialize(state), state.Revision, expiresAtUtc, leaseId, leaseExpiresAtUtc); |
| | | 185 | | |
| | | 186 | | private static void ValidateWrite(string flowId, FlowState state, TimeSpan ttl) |
| | | 187 | | { |
| | 3 | 188 | | ArgumentException.ThrowIfNullOrWhiteSpace(flowId); |
| | 3 | 189 | | ArgumentNullException.ThrowIfNull(state); |
| | 3 | 190 | | if (!string.Equals(state.FlowId, flowId, StringComparison.Ordinal)) |
| | 2 | 191 | | throw new ArgumentException("The flow state id must match the store key.", nameof(state)); |
| | 3 | 192 | | if (state.SchemaVersion != FlowStateSchema.Current) |
| | 2 | 193 | | throw new ArgumentException("The flow state must use the current schema version.", nameof(state)); |
| | 3 | 194 | | if (ttl <= TimeSpan.Zero) |
| | 2 | 195 | | throw new ArgumentOutOfRangeException(nameof(ttl), "TTL must be greater than zero."); |
| | 3 | 196 | | } |
| | | 197 | | |
| | 3 | 198 | | private sealed record Entry( |
| | 3 | 199 | | string StateJson, |
| | 3 | 200 | | long Revision, |
| | 3 | 201 | | DateTime ExpiresAtUtc, |
| | 3 | 202 | | string? LeaseId = null, |
| | 3 | 203 | | DateTime? LeaseExpiresAtUtc = null); |
| | | 204 | | } |