/** {@inheritDoc} */
@Override
public ResultScanner<Row> readRows(ReadRowsRequest request) {
// Delegate all resumable operations to the scanner. It will request a non-resumable scanner
// during operation.
// TODO(sduskis): Figure out a way to perform operation level metrics with the
// AbstractBigtableResultScanner implementations.
return new ResumingStreamingResultScanner(
retryOptions, request, streamingScannerFactory, readRowsAsync.getRpcMetrics());
}
private ResultScanner<Row> streamRows(ReadRowsRequest request) {
final Timer.Context timerContext = readRowsAsync.getRpcMetrics().timeRpc();
final AtomicBoolean wasCanceled = new AtomicBoolean(false);
expandPoolIfNecessary(this.bigtableOptions.getChannelCount());
CallOptions callOptions = getCallOptions(readRowsAsync.getMethodDescriptor(), request);
final ClientCall<ReadRowsRequest, ReadRowsResponse> readRowsCall =
readRowsAsync.newCall(callOptions);
ResponseQueueReader reader =
new ResponseQueueReader(
retryOptions.getReadPartialRowTimeoutMillis(), retryOptions.getStreamingBufferSize());
final StreamObserverAdapter<ReadRowsResponse> listener =
new StreamObserverAdapter<>(readRowsCall, new RowMerger(reader));
readRowsAsync.start(readRowsCall, request, listener, createMetadata(request.getTableName()));
// If the scanner is closed before we're done streaming, we want to cancel the RPC.
CancellationToken cancellationToken = new CancellationToken();
cancellationToken.addListener(
new Runnable() {
@Override
public synchronized void run() {
if (!wasCanceled.get()) {
timerContext.close();
wasCanceled.set(true);
}
if (!listener.hasStatusBeenRecieved()) {
readRowsCall.cancel("User requested cancelation.", null);
}
}
},
MoreExecutors.directExecutor());
return new StreamingBigtableResultScanner(reader, cancellationToken);
}
private <ReqT, RespT> RetryingCollectingClientCallListener<ReqT, RespT> createStreamingListener(
ReqT request, BigtableAsyncRpc<ReqT, RespT> rpc, String tableName) {
CallOptions callOptions = getCallOptions(rpc.getMethodDescriptor(), request);
return new RetryingCollectingClientCallListener<>(
retryOptions, request, rpc, callOptions, retryExecutorService, createMetadata(tableName));
}