[GitHub] [kafka] ijuma commented on a change in pull request #9512: KAFKA-10394: generate snapshot

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

ijuma commented on a change in pull request #9512:
URL: https://github.com/apache/kafka/pull/9512#discussion_r535572033



##########
File path: raft/src/main/java/org/apache/kafka/snapshot/FileRawSnapshotWriter.java
##########
@@ -0,0 +1,108 @@
+/*
+ * 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.kafka.snapshot;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.FileChannel;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
+import java.nio.file.StandardOpenOption;
+import org.apache.kafka.common.utils.Utils;
+import org.apache.kafka.raft.OffsetAndEpoch;
+
+public final class FileRawSnapshotWriter implements RawSnapshotWriter {
+    private final Path tempSnapshotPath;
+    private final FileChannel channel;
+    private final OffsetAndEpoch snapshotId;
+    private boolean frozen = false;
+
+    private FileRawSnapshotWriter(
+        Path tempSnapshotPath,
+        FileChannel channel,
+        OffsetAndEpoch snapshotId
+    ) {
+        this.tempSnapshotPath = tempSnapshotPath;
+        this.channel = channel;
+        this.snapshotId = snapshotId;
+    }
+
+    @Override
+    public OffsetAndEpoch snapshotId() {
+        return snapshotId;
+    }
+
+    @Override
+    public long sizeInBytes() throws IOException {
+        return channel.size();
+    }
+
+    @Override
+    public void append(ByteBuffer buffer) throws IOException {
+        if (frozen) {
+            throw new IllegalStateException(
+                String.format("Append not supported. Snapshot is already frozen: id = %s; temp path = %s", snapshotId, tempSnapshotPath)
+            );
+        }
+
+        Utils.writeFully(channel, buffer);
+    }
+
+    @Override
+    public boolean isFrozen() {
+        return frozen;
+    }
+
+    @Override
+    public void freeze() throws IOException {
+        channel.close();
+        frozen = true;
+
+        // Set readonly and ignore the result
+        if (!tempSnapshotPath.toFile().setReadOnly()) {
+            throw new IOException(String.format("Unable to set file (%s) as read-only", tempSnapshotPath));
+        }
+
+        Path destination = Snapshots.moveRename(tempSnapshotPath, snapshotId);
+        Files.move(tempSnapshotPath, destination, StandardCopyOption.ATOMIC_MOVE);

Review comment:
       It's not only Windows, NFS also has some restrictions. Why don't you want to use the utility method?




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