[GitHub] [iceberg] kbendick commented on a diff in pull request #4918: Core: Add InMemoryFileIO implementation

[GitBox <gi...@apache.org>]

kbendick commented on code in PR #4918:
URL: https://github.com/apache/iceberg/pull/4918#discussion_r912159458


##########
core/src/test/java/org/apache/iceberg/avro/TestAvroDeleteWriters.java:
##########
@@ -74,7 +75,7 @@ public void createDeleteRecords() {
 
   @Test
   public void testEqualityDeleteWriter() throws IOException {
-    OutputFile out = new InMemoryOutputFile();
+    OutputFile out = new InMemoryFileIO().newOutputFile(UUID.randomUUID().toString());

Review Comment:
   Same comment here about saving and reusing the `InMemoryFileIO`, especially as this class uses it multiple times.



##########
core/src/main/java/org/apache/iceberg/io/inmemory/InMemoryFileIO.java:
##########
@@ -0,0 +1,273 @@
+/*
+ * 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.
+ */
+
+package org.apache.iceberg.io.inmemory;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.nio.ByteBuffer;
+import org.apache.iceberg.io.FileIO;
+import org.apache.iceberg.io.InputFile;
+import org.apache.iceberg.io.OutputFile;
+import org.apache.iceberg.io.PositionOutputStream;
+import org.apache.iceberg.io.SeekableInputStream;
+import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
+import org.apache.iceberg.util.ByteBuffers;
+
+public class InMemoryFileIO implements FileIO {
+  private final InMemoryFileStore store;
+
+  public InMemoryFileIO() {
+    store = new InMemoryFileStore();
+  }
+
+  InMemoryFileStore getStore() {

Review Comment:
   Nit: We tend not to use `get` in Iceberg. The logic behind that being that there’s either a more specific verb available (like `fetch` etc) or that the `get` is simply unneeded.
   
   In this case for an accessor I think it’s simply not needed.



##########
core/src/test/java/org/apache/iceberg/TestScansAndSchemaEvolution.java:
##########
@@ -70,7 +70,8 @@ public TestScansAndSchemaEvolution(int formatVersion) {
   private DataFile createDataFile(String partValue) throws IOException {
     List<GenericData.Record> expected = RandomAvroData.generate(SCHEMA, 100, 0L);
 
-    OutputFile dataFile = new InMemoryOutputFile(FileFormat.AVRO.addExtension(UUID.randomUUID().toString()));
+    OutputFile dataFile =
+        new InMemoryFileIO().newOutputFile(FileFormat.AVRO.addExtension(UUID.randomUUID().toString()));

Review Comment:
   Should we store the `InMemoryFileIO` in its own variable so that the underlying `store` is only instantiated once?



##########
core/src/test/java/org/apache/iceberg/io/inmemory/InMemoryFileIOTest.java:
##########
@@ -0,0 +1,256 @@
+/*
+ * 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.
+ */
+
+package org.apache.iceberg.io.inmemory;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+import java.util.stream.IntStream;
+import org.apache.iceberg.io.InputFile;
+import org.apache.iceberg.io.OutputFile;
+import org.apache.iceberg.io.PositionOutputStream;
+import org.apache.iceberg.io.SeekableInputStream;
+import org.assertj.core.api.Assertions;
+import org.assertj.core.data.Offset;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static java.nio.charset.StandardCharsets.UTF_8;
+
+public class InMemoryFileIOTest {
+
+  private InMemoryFileIO fileIO;
+  private InMemoryFileStore store;
+
+  @BeforeEach
+  public void before() {
+    fileIO = new InMemoryFileIO();
+    store = fileIO.getStore();
+  }
+
+  @Test
+  public void testGetStore() {
+    Assertions.assertThat(store).isNotNull();
+  }
+
+  @Test
+  public void testDeleteFile() {
+    Assertions.assertThat(store.exists("file1")).isFalse();
+
+    // Create the file
+    store.put("file1", ByteBuffer.wrap(new byte[0]));
+    Assertions.assertThat(store.exists("file1")).isTrue();
+
+    // Delete the file
+    fileIO.deleteFile("file1");
+    // Verify that the file has been deleted
+    Assertions.assertThat(store.exists("file1")).isFalse();
+
+    Assertions.assertThatThrownBy(() -> fileIO.deleteFile("nonExisting"))
+        .isInstanceOf(IllegalArgumentException.class)
+        .hasMessage("File at location 'nonExisting' does not exist");
+  }
+
+  @Test
+  public void testNewInputFile() throws IOException {
+    String fileName = "file1";
+
+    store.put(fileName, ByteBuffer.wrap("data1".getBytes(UTF_8)));
+
+    InputFile inputFile = fileIO.newInputFile(fileName);
+    Assertions.assertThat(inputFile).isNotNull();
+
+    Assertions.assertThat(inputFile.exists()).isTrue();
+    Assertions.assertThat(inputFile.location()).isEqualTo(fileName);
+    Assertions.assertThat(inputFile.getLength()).isEqualTo(5);
+
+    try (SeekableInputStream inputStream = inputFile.newStream()) {
+      Assertions.assertThat(inputStream).isNotNull();
+
+      // Test read()
+      Assertions.assertThat(inputStream.getPos()).isEqualTo(0);
+      Assertions.assertThat(inputStream.read()).isEqualTo('d');
+
+      // Test read(byte[], index, len)
+      byte[] dataRead = new byte[3];
+      Assertions.assertThat(inputStream.read(dataRead, 0, 2)).isEqualTo(2);
+      Assertions.assertThat(new String(dataRead, 0, 2, UTF_8)).isEqualTo("at");
+    }
+  }
+
+  @Test
+  public void testSeek() throws IOException {
+    String fileName = "file1";
+
+    // Number of rows
+    int numRowsInChunk = 10;
+
+    // Emulate parquet file structure
+    ByteBuffer buffer = ByteBuffer.allocate(1024);
+    // Add magic number
+    buffer.put("par1".getBytes(UTF_8));
+    // Add column chunk 1 for int32
+    IntStream.range(0, numRowsInChunk).forEach(buffer::putInt);
+    // Add column chunk 2 for float64
+    IntStream.range(0, numRowsInChunk).forEach(buffer::putDouble);
+    // Add metadata footer (index to the start of chunks)
+    buffer.putInt(4);
+    buffer.putInt(4 + numRowsInChunk * 4);
+    // Add footer size
+    buffer.putInt(8);
+    // Add magic number
+    buffer.put("par1".getBytes(UTF_8));
+
+    // Put the data in the store
+    buffer.flip();
+    store.put(fileName, buffer);
+
+    // magic number, chunk1, chunk2, footer, footer size, magic number
+    int expectedFileSize = 4 + numRowsInChunk * 4 + numRowsInChunk * 8 + 8 + 4 + 4;

Review Comment:
   Nit: Some of these might be better off as constants. But since it's all in the same method and we'll defined above I'm ok either way.



##########
core/src/main/java/org/apache/iceberg/io/inmemory/InMemoryFileIO.java:
##########
@@ -0,0 +1,273 @@
+/*
+ * 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.
+ */
+
+package org.apache.iceberg.io.inmemory;
+
+import java.io.ByteArrayInputStream;
+import java.io.ByteArrayOutputStream;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.nio.ByteBuffer;
+import org.apache.iceberg.io.FileIO;
+import org.apache.iceberg.io.InputFile;
+import org.apache.iceberg.io.OutputFile;
+import org.apache.iceberg.io.PositionOutputStream;
+import org.apache.iceberg.io.SeekableInputStream;
+import org.apache.iceberg.relocated.com.google.common.base.Preconditions;
+import org.apache.iceberg.util.ByteBuffers;
+
+public class InMemoryFileIO implements FileIO {
+  private final InMemoryFileStore store;
+
+  public InMemoryFileIO() {
+    store = new InMemoryFileStore();
+  }
+
+  InMemoryFileStore getStore() {
+    return store;
+  }
+
+  @Override
+  public InputFile newInputFile(String path) {
+    return new InMemoryInputFile(path);
+  }
+
+  @Override
+  public OutputFile newOutputFile(String path) {
+    return new InMemoryOutputFile(path);
+  }
+
+  @Override
+  public void deleteFile(String path) {
+    Preconditions.checkArgument(store.remove(path), "File at location '%s' does not exist", path);
+  }
+
+  private class InMemoryInputFile implements InputFile {
+    private final String location;
+
+    InMemoryInputFile(String location) {
+      this.location = location;
+    }
+
+    @Override
+    public long getLength() {
+      return getOrThrow().remaining();
+    }
+
+    @Override
+    public SeekableInputStream newStream() {
+      return new InMemorySeekableInputStream(getOrThrow().duplicate());
+    }
+
+    @Override
+    public String location() {
+      return location;
+    }
+
+    @Override
+    public boolean exists() {
+      return store.exists(location);
+    }
+
+    private ByteBuffer getOrThrow() {

Review Comment:
   In this case, given that the `get` clearly lines up with the existing language and its private I feel it’s fine. 👍



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