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lzljs3620320 pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/flink-table-store.git
commit 6194ecba528d0d257bc1123ee1b1e3f5666b493e
Author: JingsongLi <lzljs3620...@aliyun.com>
AuthorDate: Wed Jan 12 19:40:12 2022 +0800
[FLINK-25628] Introduce RecordReader interface
Co-authored-by: tsreaper <tsreape...@gmail.com>
Co-authored-by: Jane Chan <55568005+ladyfor...@users.noreply.github.com>
---
.../flink/table/store/file/utils/RecordReader.java | 64 +++++++++++++++
.../store/file/utils/RecordReaderIterator.java | 95 ++++++++++++++++++++++
2 files changed, 159 insertions(+)
diff --git
a/flink-table-store-core/src/main/java/org/apache/flink/table/store/file/utils/RecordReader.java
b/flink-table-store-core/src/main/java/org/apache/flink/table/store/file/utils/RecordReader.java
new file mode 100644
index 0000000..89194e1
--- /dev/null
+++
b/flink-table-store-core/src/main/java/org/apache/flink/table/store/file/utils/RecordReader.java
@@ -0,0 +1,64 @@
+/*
+ * 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.flink.table.store.file.utils;
+
+import org.apache.flink.table.store.file.KeyValue;
+
+
+import javax.annotation.Nullable;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.util.Iterator;
+
+/** The reader that reads the batches of records. */
+public interface RecordReader extends Closeable {
+
+ /**
+ * Reads one batch. The method should return null when reaching the end of
the input.
+ *
+ * <p>The returned iterator object and any contained objects may be held
onto by the source for
+ * some time, so it should not be immediately reused by the reader.
+ */
+ @Nullable
+ RecordIterator readBatch() throws IOException;
+
+ /** Closes the reader and should release all resources. */
+ @Override
+ void close() throws IOException;
+
+ /**
+ * An internal iterator interface which presents a more restrictive API
than {@link Iterator}.
+ */
+ interface RecordIterator {
+
+ /**
+ * Gets the next record from the iterator. Returns null if this
iterator has no more
+ * elements.
+ */
+ KeyValue next() throws IOException;
+
+ /**
+ * Releases the batch that this iterator iterated over. This is not
supposed to close the
+ * reader and its resources, but is simply a signal that this iterator
is not used anymore.
+ * This method can be used as a hook to recycle/reuse heavyweight
object structures.
+ */
+ void releaseBatch();
+ }
+}
diff --git
a/flink-table-store-core/src/main/java/org/apache/flink/table/store/file/utils/RecordReaderIterator.java
b/flink-table-store-core/src/main/java/org/apache/flink/table/store/file/utils/RecordReaderIterator.java
new file mode 100644
index 0000000..58ad8e2
--- /dev/null
+++
b/flink-table-store-core/src/main/java/org/apache/flink/table/store/file/utils/RecordReaderIterator.java
@@ -0,0 +1,95 @@
+/*
+ * 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.flink.table.store.file.utils;
+
+import org.apache.flink.table.store.file.KeyValue;
+import org.apache.flink.util.CloseableIterator;
+
+
+import java.io.IOException;
+
+/** Wrap a {@link RecordReader} as an {@link CloseableIterator}. */
+public class RecordReaderIterator implements CloseableIterator<KeyValue> {
+
+ private final RecordReader reader;
+ private RecordReader.RecordIterator currentIterator;
+ private boolean advanced;
+ private KeyValue currentResult;
+
+ public RecordReaderIterator(RecordReader reader) {
+ this.reader = reader;
+ try {
+ this.currentIterator = reader.readBatch();
+ } catch (IOException e) {
+ throw new RuntimeException(e);
+ }
+ this.advanced = false;
+ this.currentResult = null;
+ }
+
+ @Override
+ public boolean hasNext() {
+ if (currentIterator == null) {
+ return false;
+ }
+ advanceIfNeeded();
+ return currentResult != null;
+ }
+
+ @Override
+ public KeyValue next() {
+ if (!hasNext()) {
+ return null;
+ }
+ advanced = false;
+ return currentResult;
+ }
+
+ private void advanceIfNeeded() {
+ if (advanced) {
+ return;
+ }
+ advanced = true;
+
+ try {
+ while (true) {
+ currentResult = currentIterator.next();
+ if (currentResult != null) {
+ break;
+ } else {
+ currentIterator.releaseBatch();
+ currentIterator = reader.readBatch();
+ if (currentIterator == null) {
+ break;
+ }
+ }
+ }
+ } catch (IOException e) {
+ throw new RuntimeException(e);
+ }
+ }
+
+ @Override
+ public void close() throws Exception {
+ if (currentIterator != null) {
+ currentIterator.releaseBatch();
+ }
+ reader.close();
+ }
+}
