Status FBIDBServiceHandler::log()

in idb_companion/Server/FBIDBServiceHandler.mm [1188:1232]
31 lines of code
7 McCabe index (conditional complexity)

Status FBIDBServiceHandler::log(ServerContext *context, const idb::LogRequest *request, grpc::ServerWriter<idb::LogResponse> *response)
{@autoreleasepool{
  // In the background, write out the log data. Prevent future writes if the client write fails.
  // This will happen asynchronously with the server thread.
  FBMutableFuture<NSNull *> *writingDone = FBMutableFuture.future;
  id<FBDataConsumer, FBDataConsumerLifecycle, FBDataConsumerSync> consumer = [FBBlockDataConsumer synchronousDataConsumerWithBlock:^(NSData *data) {
    idb::LogResponse item;
    item.set_output(data.bytes, data.length);
    if (writingDone.hasCompleted) {
      return;
    }
    bool success = response->Write(item);
    if (success) {
      return;
    }
    // The client write failed, the client has gone so don't write again.
    [writingDone resolveWithResult:NSNull.null];
  }];

  // Setup the log operation.
  NSError *error = nil;
  BOOL logFromCompanion = request->source() == idb::LogRequest::Source::LogRequest_Source_COMPANION;
  NSArray<NSString *> *arguments = extract_string_array(request->arguments());
  id<FBLogOperation> operation = [(logFromCompanion ? [_commandExecutor tail_companion_logs:consumer] : [_target tailLog:arguments consumer:consumer]) block:&error];
  if (!operation) {
    return Status(grpc::StatusCode::INTERNAL, error.localizedDescription.UTF8String);
  }

  // Poll on completion (logging happens asynchronously). This occurs when the stream is cancelled, the log operation is done, or the last write failed.
  FBFuture<NSNull *> *completed = [FBFuture race:@[writingDone, operation.completed]];
  while (completed.hasCompleted == NO && context->IsCancelled() == false) {
    // Sleep for 200ms before polling again.
    usleep(1000 * 200);
  }

  // Signal that we're done writing due to the operation completion or the client going away.
  // This will also prevent the polling of the ClientContext.
  [writingDone resolveWithResult:NSNull.null];

  // Teardown the log operation now that we're done with it
  FBFuture<NSNull *> *teardown = [operation.completed cancel];
  [teardown block:nil];

  return Status::OK;
}}