| /** |
| * 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.hadoop.fs; |
| |
| import org.apache.hadoop.classification.InterfaceAudience; |
| import org.apache.hadoop.classification.InterfaceStability; |
| |
| /** |
| * Interface to query streams for supported capabilities. |
| * |
| * Capability strings must be in lower case. |
| * |
| * Constant strings are chosen over enums in order to allow other file systems |
| * to define their own capabilities. |
| */ |
| @InterfaceAudience.Public |
| @InterfaceStability.Evolving |
| public interface StreamCapabilities { |
| /** |
| * Stream hflush capability implemented by {@link Syncable#hflush()}. |
| * |
| * Use the {@link #HSYNC} probe to check for the support of Syncable; |
| * it's that presence of {@code hsync()} which matters. |
| */ |
| @Deprecated |
| String HFLUSH = "hflush"; |
| |
| /** |
| * Stream hsync capability implemented by {@link Syncable#hsync()}. |
| */ |
| String HSYNC = "hsync"; |
| |
| /** |
| * Stream setReadahead capability implemented by |
| * {@link CanSetReadahead#setReadahead(Long)}. |
| */ |
| String READAHEAD = "in:readahead"; |
| |
| /** |
| * Stream setDropBehind capability implemented by |
| * {@link CanSetDropBehind#setDropBehind(Boolean)}. |
| */ |
| String DROPBEHIND = "dropbehind"; |
| |
| /** |
| * Stream unbuffer capability implemented by {@link CanUnbuffer#unbuffer()}. |
| */ |
| String UNBUFFER = "in:unbuffer"; |
| |
| /** |
| * Stream read(ByteBuffer) capability implemented by |
| * {@link ByteBufferReadable#read(java.nio.ByteBuffer)}. |
| */ |
| String READBYTEBUFFER = "in:readbytebuffer"; |
| |
| /** |
| * Stream read(long, ByteBuffer) capability implemented by |
| * {@link ByteBufferPositionedReadable#read(long, java.nio.ByteBuffer)}. |
| */ |
| String PREADBYTEBUFFER = "in:preadbytebuffer"; |
| |
| /** |
| * IOStatisticsSource API. |
| */ |
| String IOSTATISTICS = "iostatistics"; |
| |
| /** |
| * Support for vectored IO api. |
| * See {@code PositionedReadable#readVectored(List, IntFunction)}. |
| */ |
| String VECTOREDIO = "readvectored"; |
| |
| /** |
| * Stream abort() capability implemented by {@link Abortable#abort()}. |
| * This matches the Path Capability |
| * {@link CommonPathCapabilities#ABORTABLE_STREAM}. |
| */ |
| String ABORTABLE_STREAM = CommonPathCapabilities.ABORTABLE_STREAM; |
| |
| /** |
| * Streams that support IOStatistics context and capture thread-level |
| * IOStatistics. |
| */ |
| String IOSTATISTICS_CONTEXT = "fs.capability.iocontext.supported"; |
| |
| /** |
| * Capabilities that a stream can support and be queried for. |
| */ |
| @Deprecated |
| enum StreamCapability { |
| HFLUSH(StreamCapabilities.HFLUSH), |
| HSYNC(StreamCapabilities.HSYNC); |
| |
| private final String capability; |
| |
| StreamCapability(String value) { |
| this.capability = value; |
| } |
| |
| public final String getValue() { |
| return capability; |
| } |
| } |
| |
| /** |
| * Query the stream for a specific capability. |
| * |
| * @param capability string to query the stream support for. |
| * @return True if the stream supports capability. |
| */ |
| boolean hasCapability(String capability); |
| } |
| |