@genkit-ai/core/lib/streaming.mjs.map

Genkit AI framework core libraries.

{"version":3,"sources":["../src/streaming.ts"],"sourcesContent":["/**\n * Copyright 2024 Google LLC\n *\n * Licensed under the Apache License, Version 2.0 (the \"License\");\n * you may not use this file except in compliance with the License.\n * You may obtain a copy of the License at\n *\n *     http://www.apache.org/licenses/LICENSE-2.0\n *\n * Unless required by applicable law or agreed to in writing, software\n * distributed under the License is distributed on an \"AS IS\" BASIS,\n * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.\n * See the License for the specific language governing permissions and\n * limitations under the License.\n */\n\nimport { GenkitError } from './error';\n\n/**\n * Error thrown when a stream cannot be found.\n */\nexport class StreamNotFoundError extends GenkitError {\n  constructor(message: string) {\n    super({ status: 'NOT_FOUND', message });\n    this.name = 'StreamNotFoundError';\n  }\n}\n\n/**\n * Interface for writing content to a stream.\n * @template S The type of the stream chunks.\n * @template O The type of the final output.\n */\nexport interface ActionStreamInput<S, O> {\n  /**\n   * Writes a chunk to the stream.\n   * @param chunk The chunk data to write.\n   */\n  write(chunk: S): Promise<void>;\n  /**\n   * Closes the stream with a final output.\n   * @param output The final output data.\n   */\n  done(output: O): Promise<void>;\n  /**\n   * Closes the stream with an error.\n   * @param err The error that occurred.\n   */\n  error(err: any): Promise<void>;\n}\n\n/**\n * Subscriber callbacks for receiving stream events.\n * @template S The type of the stream chunks.\n * @template O The type of the final output.\n */\nexport type ActionStreamSubscriber<S, O> = {\n  /** Called when a chunk is received. */\n  onChunk: (chunk: S) => void;\n  /** Called when the stream completes successfully. */\n  onDone: (output: O) => void;\n  /** Called when the stream encounters an error. */\n  onError: (error: any) => void;\n};\n\n/**\n * Interface for managing streaming actions, allowing creation and subscription to streams.\n * Implementations can provide different storage backends (e.g., in-memory, database, cache).\n */\nexport interface StreamManager {\n  /**\n   * Opens a stream for writing.\n   * @param streamId The unique identifier for the stream.\n   * @returns An object to write to the stream.\n   */\n  open<S, O>(streamId: string): Promise<ActionStreamInput<S, O>>;\n  /**\n   * Subscribes to a stream to receive its events.\n   * @param streamId The unique identifier for the stream.\n   * @param options The subscriber callbacks.\n   * @returns A promise resolving to an object containing an unsubscribe function.\n   */\n  subscribe<S, O>(\n    streamId: string,\n    options: ActionStreamSubscriber<S, O>\n  ): Promise<{ unsubscribe: () => void }>;\n}\n\ntype StreamState<S, O> =\n  | {\n      status: 'open';\n      chunks: S[];\n      subscribers: ActionStreamSubscriber<S, O>[];\n      lastTouched: number;\n    }\n  | { status: 'done'; chunks: S[]; output: O; lastTouched: number }\n  | { status: 'error'; chunks: S[]; error: any; lastTouched: number };\n\n/**\n * An in-memory implementation of StreamManager.\n * Useful for testing or single-instance deployments where persistence is not required.\n */\nexport class InMemoryStreamManager implements StreamManager {\n  private streams: Map<string, StreamState<any, any>> = new Map();\n\n  /**\n   * @param options Configuration options.\n   * @param options.ttlSeconds Time-to-live for streams in seconds. Defaults to 5 minutes.\n   */\n  constructor(private options: { ttlSeconds?: number } = {}) {}\n\n  private _cleanup() {\n    const ttl = (this.options.ttlSeconds ?? 5 * 60) * 1000;\n    const now = Date.now();\n    for (const [streamId, stream] of this.streams.entries()) {\n      if (stream.status !== 'open' && now - stream.lastTouched > ttl) {\n        this.streams.delete(streamId);\n      }\n    }\n  }\n\n  async open<S, O>(streamId: string): Promise<ActionStreamInput<S, O>> {\n    this._cleanup();\n    if (this.streams.has(streamId)) {\n      throw new Error(`Stream with id ${streamId} already exists.`);\n    }\n    this.streams.set(streamId, {\n      status: 'open',\n      chunks: [],\n      subscribers: [],\n      lastTouched: Date.now(),\n    });\n\n    return {\n      write: async (chunk: S) => {\n        const stream = this.streams.get(streamId);\n        if (stream?.status === 'open') {\n          stream.chunks.push(chunk);\n          stream.subscribers.forEach((s) => s.onChunk(chunk));\n          stream.lastTouched = Date.now();\n        }\n      },\n      done: async (output: O) => {\n        const stream = this.streams.get(streamId);\n        if (stream?.status === 'open') {\n          this.streams.set(streamId, {\n            status: 'done',\n            chunks: stream.chunks,\n            output,\n            lastTouched: Date.now(),\n          });\n          stream.subscribers.forEach((s) => s.onDone(output));\n        }\n      },\n      error: async (err: any) => {\n        const stream = this.streams.get(streamId);\n        if (stream?.status === 'open') {\n          stream.subscribers.forEach((s) => s.onError(err));\n          this.streams.set(streamId, {\n            status: 'error',\n            chunks: stream.chunks,\n            error: err,\n            lastTouched: Date.now(),\n          });\n        }\n      },\n    };\n  }\n\n  async subscribe<S, O>(\n    streamId: string,\n    subscriber: ActionStreamSubscriber<S, O>\n  ): Promise<{ unsubscribe: () => void }> {\n    const stream = this.streams.get(streamId);\n    if (!stream) {\n      throw new StreamNotFoundError(`Stream with id ${streamId} not found.`);\n    }\n\n    if (stream.status === 'done') {\n      for (const chunk of stream.chunks) {\n        subscriber.onChunk(chunk);\n      }\n      subscriber.onDone(stream.output);\n    } else if (stream.status === 'error') {\n      for (const chunk of stream.chunks) {\n        subscriber.onChunk(chunk);\n      }\n      subscriber.onError(stream.error);\n    } else {\n      stream.chunks.forEach((chunk) => subscriber.onChunk(chunk));\n      stream.subscribers.push(subscriber);\n    }\n\n    return {\n      unsubscribe: () => {\n        const currentStream = this.streams.get(streamId);\n        if (currentStream?.status === 'open') {\n          const index = currentStream.subscribers.indexOf(subscriber);\n          if (index > -1) {\n            currentStream.subscribers.splice(index, 1);\n          }\n        }\n      },\n    };\n  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