org.rocksdb.HashLinkedListMemTableConfig Maven / Gradle / Ivy
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// Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.
package org.rocksdb;
/**
* The config for hash linked list memtable representation
* Such memtable contains a fix-sized array of buckets, where
* each bucket points to a sorted singly-linked
* list (or null if the bucket is empty).
*
* Note that since this mem-table representation relies on the
* key prefix, it is required to invoke one of the usePrefixExtractor
* functions to specify how to extract key prefix given a key.
* If proper prefix-extractor is not set, then RocksDB will
* use the default memtable representation (SkipList) instead
* and post a warning in the LOG.
*/
public class HashLinkedListMemTableConfig extends MemTableConfig {
public static final long DEFAULT_BUCKET_COUNT = 50_000;
public static final long DEFAULT_HUGE_PAGE_TLB_SIZE = 0;
public static final int DEFAULT_BUCKET_ENTRIES_LOG_THRES = 4096;
public static final boolean
DEFAULT_IF_LOG_BUCKET_DIST_WHEN_FLUSH = true;
public static final int DEFAUL_THRESHOLD_USE_SKIPLIST = 256;
/**
* HashLinkedListMemTableConfig constructor
*/
public HashLinkedListMemTableConfig() {
bucketCount_ = DEFAULT_BUCKET_COUNT;
hugePageTlbSize_ = DEFAULT_HUGE_PAGE_TLB_SIZE;
bucketEntriesLoggingThreshold_ = DEFAULT_BUCKET_ENTRIES_LOG_THRES;
ifLogBucketDistWhenFlush_ = DEFAULT_IF_LOG_BUCKET_DIST_WHEN_FLUSH;
thresholdUseSkiplist_ = DEFAUL_THRESHOLD_USE_SKIPLIST;
}
/**
* Set the number of buckets in the fixed-size array used
* in the hash linked-list mem-table.
*
* @param count the number of hash buckets.
* @return the reference to the current HashLinkedListMemTableConfig.
*/
public HashLinkedListMemTableConfig setBucketCount(
final long count) {
bucketCount_ = count;
return this;
}
/**
* Returns the number of buckets that will be used in the memtable
* created based on this config.
*
* @return the number of buckets
*/
public long bucketCount() {
return bucketCount_;
}
/**
*
Set the size of huge tlb or allocate the hashtable bytes from
* malloc if {@code size <= 0}.
*
* The user needs to reserve huge pages for it to be allocated,
* like: {@code sysctl -w vm.nr_hugepages=20}
*
* See linux documentation/vm/hugetlbpage.txt
*
* @param size if set to {@code <= 0} hashtable bytes from malloc
* @return the reference to the current HashLinkedListMemTableConfig.
*/
public HashLinkedListMemTableConfig setHugePageTlbSize(
final long size) {
hugePageTlbSize_ = size;
return this;
}
/**
* Returns the size value of hugePageTlbSize.
*
* @return the hugePageTlbSize.
*/
public long hugePageTlbSize() {
return hugePageTlbSize_;
}
/**
* If number of entries in one bucket exceeds that setting, log
* about it.
*
* @param threshold - number of entries in a single bucket before
* logging starts.
* @return the reference to the current HashLinkedListMemTableConfig.
*/
public HashLinkedListMemTableConfig
setBucketEntriesLoggingThreshold(final int threshold) {
bucketEntriesLoggingThreshold_ = threshold;
return this;
}
/**
* Returns the maximum number of entries in one bucket before
* logging starts.
*
* @return maximum number of entries in one bucket before logging
* starts.
*/
public int bucketEntriesLoggingThreshold() {
return bucketEntriesLoggingThreshold_;
}
/**
* If true the distrubition of number of entries will be logged.
*
* @param logDistribution - boolean parameter indicating if number
* of entry distribution shall be logged.
* @return the reference to the current HashLinkedListMemTableConfig.
*/
public HashLinkedListMemTableConfig
setIfLogBucketDistWhenFlush(final boolean logDistribution) {
ifLogBucketDistWhenFlush_ = logDistribution;
return this;
}
/**
* Returns information about logging the distribution of
* number of entries on flush.
*
* @return if distribution of number of entries shall be logged.
*/
public boolean ifLogBucketDistWhenFlush() {
return ifLogBucketDistWhenFlush_;
}
/**
* Set maximum number of entries in one bucket. Exceeding this val
* leads to a switch from LinkedList to SkipList.
*
* @param threshold maximum number of entries before SkipList is
* used.
* @return the reference to the current HashLinkedListMemTableConfig.
*/
public HashLinkedListMemTableConfig
setThresholdUseSkiplist(final int threshold) {
thresholdUseSkiplist_ = threshold;
return this;
}
/**
* Returns entries per bucket threshold before LinkedList is
* replaced by SkipList usage for that bucket.
*
* @return entries per bucket threshold before SkipList is used.
*/
public int thresholdUseSkiplist() {
return thresholdUseSkiplist_;
}
@Override protected long newMemTableFactoryHandle() {
return newMemTableFactoryHandle(bucketCount_, hugePageTlbSize_,
bucketEntriesLoggingThreshold_, ifLogBucketDistWhenFlush_,
thresholdUseSkiplist_);
}
private static native long newMemTableFactoryHandle(long bucketCount, long hugePageTlbSize,
int bucketEntriesLoggingThreshold, boolean ifLogBucketDistWhenFlush, int thresholdUseSkiplist)
throws IllegalArgumentException;
private long bucketCount_;
private long hugePageTlbSize_;
private int bucketEntriesLoggingThreshold_;
private boolean ifLogBucketDistWhenFlush_;
private int thresholdUseSkiplist_;
}