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| 1 | +package immortalstreams |
| 2 | + |
| 3 | +import ( |
| 4 | + "context" |
| 5 | + "fmt" |
| 6 | + "io" |
| 7 | + "net" |
| 8 | + "sync" |
| 9 | + "time" |
| 10 | + |
| 11 | + "github.com/google/uuid" |
| 12 | + "github.com/moby/moby/pkg/namesgenerator" |
| 13 | + "golang.org/x/xerrors" |
| 14 | + |
| 15 | + "cdr.dev/slog" |
| 16 | + "github.com/coder/coder/v2/codersdk" |
| 17 | +) |
| 18 | + |
| 19 | +const ( |
| 20 | + // MaxStreams is the maximum number of immortal streams allowed per agent |
| 21 | + MaxStreams = 32 |
| 22 | + // BufferSize is the size of the ring buffer for each stream (64 MiB) |
| 23 | + BufferSize = 64 * 1024 * 1024 |
| 24 | +) |
| 25 | + |
| 26 | +// Manager manages immortal streams for an agent |
| 27 | +type Manager struct { |
| 28 | + logger slog.Logger |
| 29 | + |
| 30 | + mu sync.RWMutex |
| 31 | + streams map[uuid.UUID]*Stream |
| 32 | + |
| 33 | + // dialer is used to dial local services |
| 34 | + dialer Dialer |
| 35 | +} |
| 36 | + |
| 37 | +// Dialer dials a local service |
| 38 | +type Dialer interface { |
| 39 | + DialContext(ctx context.Context, network, address string) (net.Conn, error) |
| 40 | +} |
| 41 | + |
| 42 | +// New creates a new immortal streams manager |
| 43 | +func New(logger slog.Logger, dialer Dialer) *Manager { |
| 44 | + return &Manager{ |
| 45 | + logger: logger, |
| 46 | + streams: make(map[uuid.UUID]*Stream), |
| 47 | + dialer: dialer, |
| 48 | + } |
| 49 | +} |
| 50 | + |
| 51 | +// CreateStream creates a new immortal stream |
| 52 | +func (m *Manager) CreateStream(ctx context.Context, port int) (*codersdk.ImmortalStream, error) { |
| 53 | + m.mu.Lock() |
| 54 | + defer m.mu.Unlock() |
| 55 | + |
| 56 | + // Check if we're at the limit |
| 57 | + if len(m.streams) >= MaxStreams { |
| 58 | + // Try to evict a disconnected stream |
| 59 | + evicted := m.evictOldestDisconnectedLocked() |
| 60 | + if !evicted { |
| 61 | + return nil, xerrors.New("too many immortal streams") |
| 62 | + } |
| 63 | + } |
| 64 | + |
| 65 | + // Dial the local service |
| 66 | + addr := fmt.Sprintf("localhost:%d", port) |
| 67 | + conn, err := m.dialer.DialContext(ctx, "tcp", addr) |
| 68 | + if err != nil { |
| 69 | + if isConnectionRefused(err) { |
| 70 | + return nil, xerrors.Errorf("the connection was refused") |
| 71 | + } |
| 72 | + return nil, xerrors.Errorf("dial local service: %w", err) |
| 73 | + } |
| 74 | + |
| 75 | + // Create the stream |
| 76 | + id := uuid.New() |
| 77 | + name := namesgenerator.GetRandomName(0) |
| 78 | + stream := NewStream( |
| 79 | + id, |
| 80 | + name, |
| 81 | + port, |
| 82 | + m.logger.With(slog.F("stream_id", id), slog.F("stream_name", name)), |
| 83 | + ) |
| 84 | + |
| 85 | + // Start the stream |
| 86 | + if err := stream.Start(conn); err != nil { |
| 87 | + _ = conn.Close() |
| 88 | + return nil, xerrors.Errorf("start stream: %w", err) |
| 89 | + } |
| 90 | + |
| 91 | + m.streams[id] = stream |
| 92 | + |
| 93 | + return &codersdk.ImmortalStream{ |
| 94 | + ID: id, |
| 95 | + Name: name, |
| 96 | + TCPPort: port, |
| 97 | + CreatedAt: stream.createdAt, |
| 98 | + LastConnectionAt: stream.createdAt, |
| 99 | + }, nil |
| 100 | +} |
| 101 | + |
| 102 | +// GetStream returns a stream by ID |
| 103 | +func (m *Manager) GetStream(id uuid.UUID) (*Stream, bool) { |
| 104 | + m.mu.RLock() |
| 105 | + defer m.mu.RUnlock() |
| 106 | + stream, ok := m.streams[id] |
| 107 | + return stream, ok |
| 108 | +} |
| 109 | + |
| 110 | +// ListStreams returns all streams |
| 111 | +func (m *Manager) ListStreams() []codersdk.ImmortalStream { |
| 112 | + m.mu.RLock() |
| 113 | + defer m.mu.RUnlock() |
| 114 | + |
| 115 | + streams := make([]codersdk.ImmortalStream, 0, len(m.streams)) |
| 116 | + for _, stream := range m.streams { |
| 117 | + streams = append(streams, stream.ToAPI()) |
| 118 | + } |
| 119 | + return streams |
| 120 | +} |
| 121 | + |
| 122 | +// DeleteStream deletes a stream by ID |
| 123 | +func (m *Manager) DeleteStream(id uuid.UUID) error { |
| 124 | + m.mu.Lock() |
| 125 | + defer m.mu.Unlock() |
| 126 | + |
| 127 | + stream, ok := m.streams[id] |
| 128 | + if !ok { |
| 129 | + return xerrors.New("stream not found") |
| 130 | + } |
| 131 | + |
| 132 | + if err := stream.Close(); err != nil { |
| 133 | + m.logger.Warn(context.Background(), "failed to close stream", slog.Error(err)) |
| 134 | + } |
| 135 | + |
| 136 | + delete(m.streams, id) |
| 137 | + return nil |
| 138 | +} |
| 139 | + |
| 140 | +// Close closes all streams |
| 141 | +func (m *Manager) Close() error { |
| 142 | + m.mu.Lock() |
| 143 | + defer m.mu.Unlock() |
| 144 | + |
| 145 | + var firstErr error |
| 146 | + for id, stream := range m.streams { |
| 147 | + if err := stream.Close(); err != nil && firstErr == nil { |
| 148 | + firstErr = err |
| 149 | + } |
| 150 | + delete(m.streams, id) |
| 151 | + } |
| 152 | + return firstErr |
| 153 | +} |
| 154 | + |
| 155 | +// evictOldestDisconnectedLocked evicts the oldest disconnected stream |
| 156 | +// Must be called with mu held |
| 157 | +func (m *Manager) evictOldestDisconnectedLocked() bool { |
| 158 | + var ( |
| 159 | + oldestID uuid.UUID |
| 160 | + oldestDisconnected time.Time |
| 161 | + found bool |
| 162 | + ) |
| 163 | + |
| 164 | + for id, stream := range m.streams { |
| 165 | + if stream.IsConnected() { |
| 166 | + continue |
| 167 | + } |
| 168 | + |
| 169 | + disconnectedAt := stream.LastDisconnectionAt() |
| 170 | + |
| 171 | + // Prioritize streams that have actually been disconnected over never-connected streams |
| 172 | + switch { |
| 173 | + case !found: |
| 174 | + oldestID = id |
| 175 | + oldestDisconnected = disconnectedAt |
| 176 | + found = true |
| 177 | + case disconnectedAt.IsZero() && !oldestDisconnected.IsZero(): |
| 178 | + // Keep the current choice (it was actually disconnected) |
| 179 | + continue |
| 180 | + case !disconnectedAt.IsZero() && oldestDisconnected.IsZero(): |
| 181 | + // Prefer this stream (it was actually disconnected) over never-connected |
| 182 | + oldestID = id |
| 183 | + oldestDisconnected = disconnectedAt |
| 184 | + case !disconnectedAt.IsZero() && !oldestDisconnected.IsZero(): |
| 185 | + // Both were actually disconnected, pick the oldest |
| 186 | + if disconnectedAt.Before(oldestDisconnected) { |
| 187 | + oldestID = id |
| 188 | + oldestDisconnected = disconnectedAt |
| 189 | + } |
| 190 | + } |
| 191 | + // If both are zero time, keep the first one found |
| 192 | + } |
| 193 | + |
| 194 | + if !found { |
| 195 | + return false |
| 196 | + } |
| 197 | + |
| 198 | + // Close and remove the oldest disconnected stream |
| 199 | + if stream, ok := m.streams[oldestID]; ok { |
| 200 | + m.logger.Info(context.Background(), "evicting oldest disconnected stream", |
| 201 | + slog.F("stream_id", oldestID), |
| 202 | + slog.F("stream_name", stream.name), |
| 203 | + slog.F("disconnected_at", oldestDisconnected)) |
| 204 | + |
| 205 | + if err := stream.Close(); err != nil { |
| 206 | + m.logger.Warn(context.Background(), "failed to close evicted stream", slog.Error(err)) |
| 207 | + } |
| 208 | + delete(m.streams, oldestID) |
| 209 | + } |
| 210 | + |
| 211 | + return true |
| 212 | +} |
| 213 | + |
| 214 | +// HandleConnection handles a new connection for an existing stream |
| 215 | +func (m *Manager) HandleConnection(id uuid.UUID, conn io.ReadWriteCloser, readSeqNum uint64) error { |
| 216 | + m.mu.RLock() |
| 217 | + stream, ok := m.streams[id] |
| 218 | + m.mu.RUnlock() |
| 219 | + |
| 220 | + if !ok { |
| 221 | + return xerrors.New("stream not found") |
| 222 | + } |
| 223 | + |
| 224 | + return stream.HandleReconnect(conn, readSeqNum) |
| 225 | +} |
| 226 | + |
| 227 | +// isConnectionRefused checks if an error is a connection refused error |
| 228 | +func isConnectionRefused(err error) bool { |
| 229 | + var opErr *net.OpError |
| 230 | + if xerrors.As(err, &opErr) { |
| 231 | + return opErr.Op == "dial" |
| 232 | + } |
| 233 | + return false |
| 234 | +} |
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