davisusanibar commented on a change in pull request #137: URL: https://github.com/apache/arrow-cookbook/pull/137#discussion_r822069507
########## File path: java/source/flight.rst ########## @@ -0,0 +1,1061 @@ +.. Licensed to the Apache Software Foundation (ASF) under one +.. or more contributor license agreements. See the NOTICE file +.. distributed with this work for additional information +.. regarding copyright ownership. The ASF licenses this file +.. to you under the Apache License, Version 2.0 (the +.. "License"); you may not use this file except in compliance +.. with the License. You may obtain a copy of the License at + +.. http://www.apache.org/licenses/LICENSE-2.0 + +.. Unless required by applicable law or agreed to in writing, +.. software distributed under the License is distributed on an +.. "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY +.. KIND, either express or implied. See the License for the +.. specific language governing permissions and limitations +.. under the License. + +============ +Arrow Flight +============ + +This section contains a number of recipes for working with Arrow +Flight. For moreb about Flight. + +.. contents:: + +Simple VectorSchemaRoot storage service with Arrow Flight +========================================================= + +We'll implement a service to transfer batches flow through VectorSchemaRoot. + +Flight Client and Server +************************ + +.. code-block:: java + + import org.apache.arrow.flight.Action; + import org.apache.arrow.flight.AsyncPutListener; + import org.apache.arrow.flight.Criteria; + import org.apache.arrow.flight.FlightClient; + import org.apache.arrow.flight.FlightDescriptor; + import org.apache.arrow.flight.FlightEndpoint; + import org.apache.arrow.flight.FlightInfo; + import org.apache.arrow.flight.FlightServer; + import org.apache.arrow.flight.FlightStream; + import org.apache.arrow.flight.Location; + import org.apache.arrow.flight.NoOpFlightProducer; + import org.apache.arrow.flight.PutResult; + import org.apache.arrow.flight.Result; + import org.apache.arrow.flight.Ticket; + import org.apache.arrow.memory.RootAllocator; + import org.apache.arrow.vector.VarCharVector; + import org.apache.arrow.vector.VectorLoader; + import org.apache.arrow.vector.VectorSchemaRoot; + import org.apache.arrow.vector.VectorUnloader; + import org.apache.arrow.vector.ipc.message.ArrowRecordBatch; + import org.apache.arrow.vector.types.pojo.ArrowType; + import org.apache.arrow.vector.types.pojo.Field; + import org.apache.arrow.vector.types.pojo.FieldType; + import org.apache.arrow.vector.types.pojo.Schema; + + import java.io.IOException; + import java.nio.charset.StandardCharsets; + import java.util.ArrayList; + import java.util.Arrays; + import java.util.Collections; + import java.util.HashMap; + import java.util.Iterator; + import java.util.List; + import java.util.Map; + + class DataInMemory { + private List<ArrowRecordBatch> listArrowRecordBatch; + private Schema schema; + private Long rows; + public DataInMemory(List<ArrowRecordBatch> listArrowRecordBatch, Schema schema, Long rows) { + this.listArrowRecordBatch = listArrowRecordBatch; + this.schema = schema; + this.rows = rows; + } + public List<ArrowRecordBatch> getListArrowRecordBatch() { + return listArrowRecordBatch; + } + public Schema getSchema() { + return schema; + } + public Long getRows() { + return rows; + } + } + + // Server + Location location = Location.forGrpcInsecure("0.0.0.0", 33333); + Map<FlightDescriptor, DataInMemory> dataInMemory = new HashMap<>(); + Map<String, DataInMemory> mapPojoFlightDataInMemory = new HashMap<>(); + List<ArrowRecordBatch> listArrowRecordBatch = new ArrayList<>(); + try (RootAllocator allocator = new RootAllocator(Long.MAX_VALUE)){ + FlightServer flightServer = FlightServer.builder(allocator, location, new NoOpFlightProducer(){ + @Override + public Runnable acceptPut(CallContext context, FlightStream flightStream, StreamListener<PutResult> ackStream) { + return () -> { + long rows = 0; + while (flightStream.next()) { + VectorUnloader unloader = new VectorUnloader(flightStream.getRoot()); + try (final ArrowRecordBatch arb = unloader.getRecordBatch()) { + // Retain data information + listArrowRecordBatch.add(arb); + rows = rows + flightStream.getRoot().getRowCount(); + } + } + long finalRows = rows; + DataInMemory pojoFlightDataInMemory = new DataInMemory(listArrowRecordBatch, flightStream.getSchema(), finalRows); + dataInMemory.put(flightStream.getDescriptor(), pojoFlightDataInMemory); + ackStream.onCompleted(); + }; + } + + @Override + public void getStream(CallContext context, Ticket ticket, ServerStreamListener listener) { + FlightDescriptor flightDescriptor = FlightDescriptor.path(new String(ticket.getBytes(), StandardCharsets.UTF_8)); // Recover data for key configured + if(dataInMemory.containsKey(flightDescriptor)){ + VectorSchemaRoot vectorSchemaRoot = VectorSchemaRoot.create(dataInMemory.get(flightDescriptor).getSchema(), allocator); + listener.start(vectorSchemaRoot); + for(ArrowRecordBatch arrowRecordBatch : dataInMemory.get(flightDescriptor).getListArrowRecordBatch()){ + vectorSchemaRoot.allocateNew(); + VectorLoader loader = new VectorLoader(vectorSchemaRoot); + loader.load(arrowRecordBatch.cloneWithTransfer(allocator)); + listener.putNext(); + } + vectorSchemaRoot.clear(); + listener.completed(); + } + } + + @Override + public void doAction(CallContext context, Action action, StreamListener<Result> listener) { + FlightDescriptor flightDescriptor = FlightDescriptor.path(new String(action.getBody(), StandardCharsets.UTF_8)); // For recover data for key configured + if(dataInMemory.containsKey(flightDescriptor)) { Review comment: Thanks for the clarification. 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