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https://github.com/OpenHFT/Chronicle-Map.git
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HCOLL-164 Exctracted ChronicleHashBuilder interface and pulled some classes up from n.o.chronicle.map package to n.o.chronicle. Fixed ChronicleSetBuilder.equals() implementation.
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leventov
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package net.openhft.chronicle;
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import net.openhft.chronicle.map.*;
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import net.openhft.chronicle.set.ChronicleSetBuilder;
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import org.jetbrains.annotations.NotNull;
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import net.openhft.lang.io.serialization.*;
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import net.openhft.lang.model.Byteable;
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import java.io.File;
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import java.io.IOException;
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import java.util.HashMap;
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import java.util.HashSet;
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import java.util.Map;
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import java.util.Set;
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import java.util.concurrent.ConcurrentHashMap;
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import java.util.concurrent.TimeUnit;
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/**
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* This interface defines the meaning of configurations, common to {@link ChronicleMapBuilder}
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* and {@link ChronicleSetBuilder}, i. e. <i>Chronicle hash container</i> configurations.
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*
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* @param <K> the type of keys in hash containers, created by this builder
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* @param <C> the container type, created by this builder, i. e. {@link ChronicleMap}
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* or {@link ChronicleSet}
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* @param <B> the concrete builder type, i. e. {@link ChronicleMapBuilder}
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* or {@link ChronicleSetBuilder}
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*/
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public interface ChronicleHashBuilder<K, C, B extends ChronicleHashBuilder<K, C, B>>
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extends Cloneable {
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B clone();
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/**
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* Set minimum number of segments. See concurrencyLevel in {@link ConcurrentHashMap}.
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*
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* @param minSegments the minimum number of segments in containers, constructed by this builder
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* @return this builder object back
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*/
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B minSegments(int minSegments);
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/**
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* Configures the optimal number of bytes, taken by serialized form of keys, put into hash
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* containers, created by this builder. If key size is always the same, call
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* {@link #constantKeySizeBySample(Object)} method instead of this one.
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*
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* <p>If key size varies moderately, specify the size higher than average, but lower than
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* the maximum possible, to minimize average memory overuse. If key size varies in a wide range,
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* it's better to use {@linkplain #entrySize(int) entry size} in "chunk" mode and configure it
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* directly.
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*
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* @param keySize number of bytes, taken by serialized form of keys
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* @return this builder back
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* @see #constantKeySizeBySample(Object)
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* @see #entrySize(int)
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*/
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B keySize(int keySize);
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/**
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* Configures the constant number of bytes, taken by serialized form of keys, put into hash
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* containers, created by this builder. This is done by providing the {@code sampleKey},
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* all keys should take the same number of bytes in serialized form, as this sample object.
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*
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* <p>If keys are of boxed primitive type or {@link Byteable} subclass, i. e. if key size
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* is known statically, it is automatically accounted and this method shouldn't be called.
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*
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* <p>If key size varies, method {@link #keySize(int)} or {@link #entrySize(int)} should be
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* called instead of this one.
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*
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* @param sampleKey the sample key
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* @return this builder back
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* @see #keySize(int)
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*/
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B constantKeySizeBySample(K sampleKey);
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/**
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* Configures the size in bytes of allocation unit of hash container instances, created by
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* this builder.
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*
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* <p>{@link ChronicleMap} and {@link ChronicleSet} store their data off-heap, so it is required
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* to serialize key (and values, in {@code ChronicleMap} case) (unless they are direct
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* {@link Byteable} instances). Serialized key bytes (+ serialized value bytes,
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* in {@code ChronicleMap} case) + some metadata bytes comprise "entry space", which
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* {@code ChronicleMap} or {@code ChronicleSet} should allocate. So <i>entry size</i>
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* is a minimum allocation portion in the hash containers, created by this builder.
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* E. g. if entry size is 100, the created container could only allocate 100, 200, 300... bytes
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* for an entry. If say 150 bytes of entry space are required by the entry, 200 bytes
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* will be allocated, 150 used and 50 wasted. To minimize memory overuse and improve speed, you
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* should pay decent attention to this configuration.
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*
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* <p>There are three major patterns of this configuration usage:
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* <ol>
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* <li>Key (and value, in {@code ChronicleMap} case) sizes are constant. Configure them
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* via {@link #constantKeySizeBySample(Object)} and
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* {@link ChronicleMapBuilder#constantValueSizeBySample(Object)} methods, and you will
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* experience no memory waste at all.</li>
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* <li>Key (and/or value size, in {@code ChronicleMap} case) varies moderately. Specify them
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* using corresponding methods, or specify entry size directly by calling this method,
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* by sizes somewhere between average and maximum possible. The idea is to have most
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* (90% or more) entries to fit a single "entry size" with moderate memory waste
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* (10-20% on average), rest 10% or less of entries should take 2 "entry sizes", thus with
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* ~50% memory overuse.</li>
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* <li>Key (and/or value size, in {@code ChronicleMap} case) varies in a wide range.
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* Then it's best to use entry size configuration in <i>chunk mode</i>. Specify entry size
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* so that most entries should take from 5 to several dozens of "chunks". With this
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* approach, average memory waste should be very low.
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*
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* <p>However, remember that
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* <ul>
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* <li>Operations with entries that span several "entry sizes" are a bit slower, than
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* entries which take a single "entry size". That is why "chunk" approach
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* is not recommended, when key (and/or value size) varies moderately.</li>
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* <li>The maximum number of chunks could be taken by an entry is 64.
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* {@link IllegalArgumentException} is thrown on attempt to insert too large entry,
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* compared to the configured or computed entry size.</li>
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* <li>The number of "entries" {@linkplain #entries(long) in the whole map} and
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* {@linkplain #actualEntriesPerSegment(int) per segment} is actually the number
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* "chunks".</li>
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* </ul>
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*
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* <p>Example: if values in your {@code ChronicleMap} are adjacency lists of some social
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* graph, where nodes are represented as {@code long} ids, and adjacency lists
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* are serialized in efficient manner, for example as {@code long[]} arrays. Typical number
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* of connections is 100-300, maximum is 3000. In this case entry size of
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* 50 * (8 bytes for each id) = 400 bytes would be a good choice: <pre>{@code
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* Map<Long, long[]> socialGraph = ChronicleMapBuilder
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* .of(Long.class, long[].class)
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* // given that graph should have of 1 billion nodes, and 150 average adjacency list size
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* // => values takes 3 chuncks on average
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* .entries(1_000_000_000L * (150 / 50))
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* .entrySize(50 * 8)
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* .create();}</pre>
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* It is minimum possible (because 3000 friends / 50 friends = 60 is close to 64 "max
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* chunks by single entry" limit, and ensures moderate average memory overuse (not more
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* than 20%).
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* </li>
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* </ol>
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*
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* @param entrySize the "chunk size" in bytes
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* @return this builder back
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* @see #entries(long)
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*/
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B entrySize(int entrySize);
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/**
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* Configures the maximum number of {@linkplain #entrySize(int) "entry size chunks"}, which
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* could be taken by the maximum number of entries, inserted into the hash containers, created
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* by this builder. If you try to insert more data, {@link IllegalStateException} might be
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* thrown, because currently {@link ChronicleMap} and {@link ChronicleSet} doesn't support
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* resizing.
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*
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* <ol>
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* <li>If key size (and value size, in {@code ChronicleMap} case) is constant, this number
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* is equal to the maximum number of entries (because each entry takes exactly one
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* "entry size" memory unit).</li>
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* <li>If key (and/or value, in {@code ChronicleMap} case) size varies moderately, you
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* should pass to this method the maximum number of entries + 5-25%, depending on your data
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* properties and configured {@linkplain #keySize(int) key}/{@linkplain
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* ChronicleMapBuilder#valueSize(int) value}/{@linkplain #entrySize(int) entry} sizes.</li>
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* <li>If your data size varies in a wide range, pass the maximum number of entries
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* multiplied by average data size and divided by the configured "entry size" (i. e. chunk
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* size). See an example in the documentation to {@link #entrySize(int)} method.</li>
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* </ol>
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*
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* <p>You shouldn't put additional margin over the number, computed according the rules above.
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* This bad practice was popularized by {@link HashMap#HashMap(int)}
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* and {@link HashSet#HashSet(int)} constructors, which accept "capacity", that should
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* be multiplied by "load factor" to obtain actual maximum expected number of entries.
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* {@code ChronicleMap} and {@code ChronicleSet} don't have a notion of load factor.
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*
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* <p>Default value is 2^20 (~ 1 million).
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*
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* @param entries maximum size of the created maps, in memory allocation units,
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* so-called "entry size"
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* @return this builder back
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* @see #entrySize(int)
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*/
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B entries(long entries);
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B actualEntriesPerSegment(int actualEntriesPerSegment);
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B actualSegments(int actualSegments);
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B lockTimeOut(long lockTimeOut, TimeUnit unit);
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B errorListener(ChronicleHashErrorListener errorListener);
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B largeSegments(boolean largeSegments);
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B metaDataBytes(int metaDataBytes);
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B addReplicator(Replicator replicator);
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B setReplicators(Replicator... replicators);
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B timeProvider(TimeProvider timeProvider);
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B bytesMarshallerFactory(BytesMarshallerFactory bytesMarshallerFactory);
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B objectSerializer(ObjectSerializer objectSerializer);
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B keyMarshaller(@NotNull BytesMarshaller<K> keyMarshaller);
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/**
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* Specifies that key objects, queried with the hash containers, created by this builder,
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* are inherently immutable. Keys in {@link ChronicleMap} or {@link ChronicleSet}
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* are not required to be immutable, as in ordinary {@link Map} or {@link Set} implementations,
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* because they are serialized off-heap. However, {@code ChronicleMap} and {@code ChronicleSet}
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* implementations can benefit from the knowledge that keys are not mutated between queries.
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*
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* <p>By default, {@code ChronicleHashBuilder}s detects immutability automatically
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* only for very few standard JDK types (for example, for {@link String}), it is not recommended
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* to rely on {@code ChronicleHashBuilder} to be smart enough about this.
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*
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* @return this builder back
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*/
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B immutableKeys();
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C create(File file) throws IOException;
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C create() throws IOException;
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}
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