Class RpcSessionImpl

src/rpc.ts:448–1081

};

class RpcSessionImpl implements Importer, Exporter {
  private exports: Array<ExportTableEntry> = [];
  private reverseExports: Map<StubHook, ExportId> = new Map();
  private imports: Array<ImportTableEntry> = [];
  private abortReason?: any;
  private cancelReadLoop?: (error: any) => void;

  // We assign positive numbers to imports we initiate, and negative numbers to exports we
  // initiate. So the next import ID is just `imports.length`, but the next export ID needs
  // to be tracked explicitly.
  private nextExportId = -1;

  // If set, call this when all incoming calls are complete.
  private onBatchDone?: Omit<PromiseWithResolvers<void>, "promise">;

  // How many promises is our peer expecting us to resolve?
  private pullCount = 0;

  // Sparse array of onBrokenCallback registrations. Items are strictly appended to the end but
  // may be deleted from the middle (hence leaving the array sparse).
  onBrokenCallbacks: ((error: any) => void)[] = [];

  // Encoding level from the transport (defaults to "string")
  private encodingLevel: EncodingLevel;

  constructor(private transport: AnyRpcTransport, mainHook: StubHook,
      private options: RpcSessionOptions) {
    // `RpcTransport` has no `encodingLevel` field, so its presence is what marks a custom-encoding
    // transport. Read it defensively: treat a present-but-`undefined` value (e.g. an uninitialized
    // class field) as the default string level rather than mis-routing it down the custom-encoding
    // path, and reject any other unrecognized value (e.g. a stale pre-rename level name) loudly
    // instead of silently corrupting the wire.
    let level: EncodingLevel = "string";
    if ('encodingLevel' in transport) {
      let raw = transport.encodingLevel as unknown;
      if (raw !== undefined) {
        if (raw !== "string" && raw !== "jsonCompatible" &&
            raw !== "jsonCompatibleWithBytes" && raw !== "structuredClonable") {
          throw new TypeError(`Unknown transport encodingLevel: ${String(raw)}`);
        }
        level = raw;
      }
    }
    this.encodingLevel = level;
    // Export zero is automatically the bootstrap object.
    this.exports.push({hook: mainHook, refcount: 1});

    // Import zero is the other side's bootstrap object.
    this.imports.push(new ImportTableEntry(this, 0, false));

    this.readLoop().catch(err => this.abort(err));
  }

  // Should only be called once immediately after construction.
  getMainImport(): RpcImportHook {
    return new RpcMainHook(this.imports[0]);
  }