yunfengzhou-hub commented on code in PR #97: URL: https://github.com/apache/flink-ml/pull/97#discussion_r888738791
########## flink-ml-iteration/src/main/java/org/apache/flink/iteration/datacache/nonkeyed/MemorySegmentWriter.java: ########## @@ -0,0 +1,170 @@ +/* + * 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.iteration.datacache.nonkeyed; + +import org.apache.flink.annotation.Internal; +import org.apache.flink.api.common.typeutils.TypeSerializer; +import org.apache.flink.core.fs.Path; +import org.apache.flink.core.memory.DataOutputView; +import org.apache.flink.core.memory.DataOutputViewStreamWrapper; +import org.apache.flink.core.memory.MemorySegment; +import org.apache.flink.runtime.memory.MemoryAllocationException; +import org.apache.flink.util.Preconditions; + +import java.io.IOException; +import java.io.OutputStream; +import java.util.ArrayList; +import java.util.List; +import java.util.Optional; + +/** A class that writes cache data to memory segments. */ +@Internal +public class MemorySegmentWriter<T> implements SegmentWriter<T> { + private final LimitedSizeMemoryManager memoryManager; + + private final Path path; + + private final TypeSerializer<T> serializer; + + private final ManagedMemoryOutputStream outputStream; + + private final DataOutputView outputView; + + private int count; + + public MemorySegmentWriter( + Path path, + LimitedSizeMemoryManager memoryManager, + TypeSerializer<T> serializer, + long expectedSize) + throws MemoryAllocationException { + this.serializer = serializer; + this.memoryManager = Preconditions.checkNotNull(memoryManager); + this.path = path; + this.outputStream = new ManagedMemoryOutputStream(memoryManager, expectedSize); + this.outputView = new DataOutputViewStreamWrapper(outputStream); + this.count = 0; + } + + @Override + public boolean addRecord(T record) { + try { + serializer.serialize(record, outputView); + count++; + return true; + } catch (IOException e) { + return false; + } + } + + @Override + public int getCount() { + return this.count; + } + + @Override + @SuppressWarnings("unchecked") + public Optional<Segment> finish() throws IOException { + if (count > 0) { + return Optional.of( + new Segment( + path, + count, + outputStream.getKey(), + outputStream.getSegments(), + (TypeSerializer<Object>) serializer)); + } else { + memoryManager.releaseAll(outputStream.getKey()); + return Optional.empty(); + } + } + + private static class ManagedMemoryOutputStream extends OutputStream { + private final LimitedSizeMemoryManager memoryManager; + + private final int pageSize; + + private final Object key = new Object(); + + private final List<MemorySegment> segments = new ArrayList<>(); + + private int segmentIndex; + + private int segmentOffset; + + private int globalOffset; + + public ManagedMemoryOutputStream(LimitedSizeMemoryManager memoryManager, long expectedSize) + throws MemoryAllocationException { + this.memoryManager = memoryManager; + this.pageSize = memoryManager.getPageSize(); + this.segmentIndex = 0; + this.segmentOffset = 0; + + Preconditions.checkArgument(expectedSize >= 0); + if (expectedSize > 0) { + int numPages = (int) ((expectedSize + pageSize - 1) / pageSize); + segments.addAll(memoryManager.allocatePages(getKey(), numPages)); + } + } + + public Object getKey() { + return key; + } + + public List<MemorySegment> getSegments() { + return segments; + } + + @Override + public void write(int b) throws IOException { + write(new byte[] {(byte) b}, 0, 1); + } + + @Override + public void write(byte[] b, int off, int len) throws IOException { + try { + ensureCapacity(globalOffset + len); + } catch (MemoryAllocationException e) { + throw new IOException(e); + } + writeRecursive(b, off, len); + } + + private void ensureCapacity(int capacity) throws MemoryAllocationException { + Preconditions.checkArgument(capacity > 0); + int requiredSegmentNum = (capacity - 1) / pageSize + 2 - segments.size(); + if (requiredSegmentNum > 0) { + segments.addAll(memoryManager.allocatePages(getKey(), requiredSegmentNum)); + } + } + + private void writeRecursive(byte[] b, int off, int len) { Review Comment: Do you mean we should allow `len` to be zero or prohibit it? I think we should allow such usage so as to correspond to lower-level implementation, and the code has already achieved it. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: issues-unsubscr...@flink.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
