Support prepopulating/warming the blob cache (#10298)
Summary: Many workloads have temporal locality, where recently written items are read back in a short period of time. When using remote file systems, this is inefficient since it involves network traffic and higher latencies. Because of this, we would like to support prepopulating the blob cache during flush. This task is a part of https://github.com/facebook/rocksdb/issues/10156 Pull Request resolved: https://github.com/facebook/rocksdb/pull/10298 Reviewed By: ltamasi Differential Revision: D37908743 Pulled By: gangliao fbshipit-source-id: 9feaed234bc719d38f0c02975c1ad19fa4bb37d1main
Gang Liao
2 years ago
committed by
Facebook GitHub Bot
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// Copyright (c) Meta Platforms, Inc. and affiliates.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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package org.rocksdb; |
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/** |
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* Enum PrepopulateBlobCache |
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* |
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* <p>Prepopulate warm/hot blobs which are already in memory into blob |
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* cache at the time of flush. On a flush, the blob that is in memory |
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* (in memtables) get flushed to the device. If using Direct IO, |
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* additional IO is incurred to read this blob back into memory again, |
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* which is avoided by enabling this option. This further helps if the |
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* workload exhibits high temporal locality, where most of the reads go |
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* to recently written data. This also helps in case of the remote file |
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* system since it involves network traffic and higher latencies.</p> |
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*/ |
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public enum PrepopulateBlobCache { |
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PREPOPULATE_BLOB_DISABLE((byte) 0x0, "prepopulate_blob_disable", "kDisable"), |
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PREPOPULATE_BLOB_FLUSH_ONLY((byte) 0x1, "prepopulate_blob_flush_only", "kFlushOnly"); |
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/** |
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* <p>Get the PrepopulateBlobCache enumeration value by |
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* passing the library name to this method.</p> |
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* |
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* <p>If library cannot be found the enumeration |
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* value {@code PREPOPULATE_BLOB_DISABLE} will be returned.</p> |
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* |
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* @param libraryName prepopulate blob cache library name. |
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* |
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* @return PrepopulateBlobCache instance. |
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*/ |
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public static PrepopulateBlobCache getPrepopulateBlobCache(String libraryName) { |
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if (libraryName != null) { |
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for (PrepopulateBlobCache prepopulateBlobCache : PrepopulateBlobCache.values()) { |
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if (prepopulateBlobCache.getLibraryName() != null |
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&& prepopulateBlobCache.getLibraryName().equals(libraryName)) { |
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return prepopulateBlobCache; |
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} |
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} |
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} |
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return PrepopulateBlobCache.PREPOPULATE_BLOB_DISABLE; |
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} |
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/** |
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* <p>Get the PrepopulateBlobCache enumeration value by |
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* passing the byte identifier to this method.</p> |
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* |
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* @param byteIdentifier of PrepopulateBlobCache. |
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* |
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* @return PrepopulateBlobCache instance. |
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* |
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* @throws IllegalArgumentException If PrepopulateBlobCache cannot be found for the |
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* provided byteIdentifier |
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*/ |
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public static PrepopulateBlobCache getPrepopulateBlobCache(byte byteIdentifier) { |
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for (final PrepopulateBlobCache prepopulateBlobCache : PrepopulateBlobCache.values()) { |
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if (prepopulateBlobCache.getValue() == byteIdentifier) { |
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return prepopulateBlobCache; |
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} |
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} |
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throw new IllegalArgumentException("Illegal value provided for PrepopulateBlobCache."); |
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} |
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/** |
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* <p>Get a PrepopulateBlobCache value based on the string key in the C++ options output. |
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* This gets used in support of getting options into Java from an options string, |
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* which is generated at the C++ level. |
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* </p> |
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* |
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* @param internalName the internal (C++) name by which the option is known. |
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* |
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* @return PrepopulateBlobCache instance (optional) |
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*/ |
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static PrepopulateBlobCache getFromInternal(final String internalName) { |
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for (final PrepopulateBlobCache prepopulateBlobCache : PrepopulateBlobCache.values()) { |
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if (prepopulateBlobCache.internalName_.equals(internalName)) { |
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return prepopulateBlobCache; |
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} |
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} |
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throw new IllegalArgumentException( |
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"Illegal internalName '" + internalName + " ' provided for PrepopulateBlobCache."); |
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} |
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/** |
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* <p>Returns the byte value of the enumerations value.</p> |
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* |
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* @return byte representation |
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*/ |
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public byte getValue() { |
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return value_; |
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} |
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/** |
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* <p>Returns the library name of the prepopulate blob cache mode |
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* identified by the enumeration value.</p> |
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* |
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* @return library name |
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*/ |
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public String getLibraryName() { |
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return libraryName_; |
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} |
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PrepopulateBlobCache(final byte value, final String libraryName, final String internalName) { |
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value_ = value; |
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libraryName_ = libraryName; |
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internalName_ = internalName; |
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} |
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private final byte value_; |
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private final String libraryName_; |
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private final String internalName_; |
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} |
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