Github user animeshtrivedi commented on a diff in the pull request:
https://github.com/apache/incubator-crail/pull/16#discussion_r180319636
--- Diff:
storage-nvmf/src/main/java/org/apache/crail/storage/nvmf/client/NvmfUnalignedWriteFuture.java
---
@@ -0,0 +1,183 @@
+/*
+ * Copyright (C) 2018, IBM Corporation
+ *
+ * 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.crail.storage.nvmf.client;
+
+import org.apache.crail.CrailBuffer;
+import org.apache.crail.metadata.BlockInfo;
+import org.apache.crail.storage.StorageFuture;
+import org.apache.crail.storage.StorageResult;
+
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+
+
+public class NvmfUnalignedWriteFuture implements StorageFuture {
+ private final NvmfStorageEndpoint endpoint;
+ private StorageFuture beginFuture;
+ private StorageFuture middleFuture;
+ private StorageFuture endFuture;
+ private final int written;
+ private NvmfStagingBufferCache.BufferCacheEntry beginBuffer;
+ private NvmfStagingBufferCache.BufferCacheEntry endBuffer;
+
+ private final boolean isSectorAligned(long address) {
+ return address % endpoint.getLBADataSize() == 0;
+ }
+
+ private final long floorToSectorSize(long address) {
+ return address - (address % endpoint.getLBADataSize());
+ }
+
+ private final int leftInSector(long address) {
+ return endpoint.getLBADataSize() - offsetInSector(address);
+ }
+
+ private final int offsetInSector(long address) {
+ return (int)(address % endpoint.getLBADataSize());
+ }
+
+ NvmfUnalignedWriteFuture(NvmfStorageEndpoint endpoint, CrailBuffer
buffer, BlockInfo blockInfo, long remoteOffset) throws Exception {
+ this.endpoint = endpoint;
+ this.written = buffer.remaining();
+ /* assume blockInfo.getAddr() is sector aligned */
+ assert isSectorAligned(blockInfo.getAddr());
+
+ long nextRemoteOffset = remoteOffset;
+ /* beginning */
+ if (!isSectorAligned(remoteOffset)) {
+ int copySize = Math.min(leftInSector(remoteOffset),
buffer.remaining());
+ nextRemoteOffset = remoteOffset + copySize;
+ int oldLimit = buffer.limit();
+ buffer.limit(buffer.position() + copySize);
+ long alignedRemoteOffset =
floorToSectorSize(remoteOffset);
+ long alignedRemoteAddress = blockInfo.getAddr() +
alignedRemoteOffset;
+ beginBuffer =
endpoint.getStagingBufferCache().getExisting(alignedRemoteAddress);
+ if (beginBuffer == null) {
+ /* we had to delete the old buffer because we
ran out of space. This should happen rarely. */
+ beginBuffer =
endpoint.getStagingBufferCache().get(alignedRemoteAddress);
+ endpoint.read(beginBuffer.getBuffer(),
blockInfo, alignedRemoteOffset).get();
+ } else {
+ /* Wait for previous end operation to finish */
+ beginBuffer.getFuture().get();
+ }
+ CrailBuffer stagingBuffer = beginBuffer.getBuffer();
+ stagingBuffer.position(offsetInSector(remoteOffset));
+
stagingBuffer.getByteBuffer().put(buffer.getByteBuffer());
+ buffer.limit(oldLimit);
+ stagingBuffer.position(0);
+ beginFuture = endpoint.write(stagingBuffer, blockInfo,
alignedRemoteOffset);
+ beginBuffer.setFuture(beginFuture);
+ stagingBuffer.position(offsetInSector(remoteOffset));
+ }
+
+ /* middle */
+ if (isSectorAligned(nextRemoteOffset) && buffer.remaining() >=
endpoint.getLBADataSize()) {
+ int oldLimit = buffer.limit();
+ buffer.limit(buffer.position() +
(int)floorToSectorSize(buffer.remaining()));
--- End diff --
this is just abusing the function ;)
---
