Class Engine

tfjs-core/src/engine.ts:168–1282

}

export class Engine implements TensorTracker, DataMover {
  state: EngineState;
  backendName: string;
  registry: {[id: string]: KernelBackend} = {};
  registryFactory: {
    [id: string]: {
      factory: () => KernelBackend | Promise<KernelBackend>,
      priority: number
    }
  } = {};

  private profiler: Profiler;
  private backendInstance: KernelBackend;
  private pendingBackendInit: Promise<boolean>;
  private pendingBackendInitId = 0;

  constructor(public ENV: Environment) {
    this.state = new EngineState();
  }

  async ready(): Promise<void> {
    if (this.pendingBackendInit != null) {
      return this.pendingBackendInit.then(() => {});
    }
    if (this.backendInstance != null) {
      return;
    }
    const sortedBackends = this.getSortedBackends();

    for (let i = 0; i < sortedBackends.length; i++) {
      const backendName = sortedBackends[i];
      const success = await this.initializeBackend(backendName).success;
      if (success) {
        await this.setBackend(backendName);
        return;
      }
    }

    throw new Error(
        `Could not initialize any backends, all backend initializations ` +
        `failed.`);
  }

  get backend(): KernelBackend {
    if (this.pendingBackendInit != null) {
      throw new Error(
          `Backend '${this.backendName}' has not yet been initialized. Make ` +
          `sure to await tf.ready() or await tf.setBackend() before calling ` +
          `other methods`);
    }
    if (this.backendInstance == null) {
      const {name, asyncInit} = this.initializeBackendsAndReturnBest();
      if (asyncInit) {
        throw new Error(
            `The highest priority backend '${name}' has not yet been ` +
            `initialized. Make sure to await tf.ready() or ` +
            `await tf.setBackend() before calling other methods`);
      }