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add doc (#4030)

This commit is contained in:
Jihoon Son 2017-03-11 05:49:20 +09:00 committed by Fangjin Yang
parent cab2e2f5d5
commit dfe4bda7fd
1 changed files with 45 additions and 0 deletions
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45
processing/src/main/java/io/druid/query/cache/CacheKeyBuilder.java vendored
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@ -37,6 +37,19 @@ import java.util.Collections;
import java.util.Iterator; import java.util.Iterator;
import java.util.List; import java.util.List;
/**
* CacheKeyBuilder is a tool for easily generating cache keys of {@link Cacheable} objects.
*
* The layout of the serialized cache key is like below.
*
* +--------------------------------------------------------+
* | ID (1 byte) |
* | type key (1 byte) | serialized value (variable length) |
* | type key (1 byte) | serialized value (variable length) |
* | ... |
* +--------------------------------------------------------+
*
*/
public class CacheKeyBuilder public class CacheKeyBuilder
{ {
static final byte BYTE_KEY = 0; static final byte BYTE_KEY = 0;
@ -188,12 +201,28 @@ public class CacheKeyBuilder
return this; return this;
} }
/**
* Add a collection of strings to the cache key.
* Strings in the collection are concatenated with a separator of '0xFF',
* and they appear in the cache key in their input order.
*
* @param input a collection of strings to be included in the cache key
* @return this instance
*/
public CacheKeyBuilder appendStrings(Collection<String> input) public CacheKeyBuilder appendStrings(Collection<String> input)
{ {
appendItem(STRING_LIST_KEY, stringCollectionToByteArray(input, true)); appendItem(STRING_LIST_KEY, stringCollectionToByteArray(input, true));
return this; return this;
} }
/**
* Add a collection of strings to the cache key.
* Strings in the collection are sorted by their byte representation and
* concatenated with a separator of '0xFF'.
*
* @param input a collection of strings to be included in the cache key
* @return this instance
*/
public CacheKeyBuilder appendStringsIgnoringOrder(Collection<String> input) public CacheKeyBuilder appendStringsIgnoringOrder(Collection<String> input)
{ {
appendItem(STRING_LIST_KEY, stringCollectionToByteArray(input, false)); appendItem(STRING_LIST_KEY, stringCollectionToByteArray(input, false));
@ -236,12 +265,28 @@ public class CacheKeyBuilder
return this; return this;
} }
/**
* Add a collection of Cacheables to the cache key.
* Cacheables in the collection are concatenated without any separator,
* and they appear in the cache key in their input order.
*
* @param input a collection of Cacheables to be included in the cache key
* @return this instance
*/
public CacheKeyBuilder appendCacheables(Collection<? extends Cacheable> input) public CacheKeyBuilder appendCacheables(Collection<? extends Cacheable> input)
{ {
appendItem(CACHEABLE_LIST_KEY, cacheableCollectionToByteArray(input, true)); appendItem(CACHEABLE_LIST_KEY, cacheableCollectionToByteArray(input, true));
return this; return this;
} }
/**
* Add a collection of Cacheables to the cache key.
* Cacheables in the collection are sorted by their byte representation and
* concatenated without any separator.
*
* @param input a collection of Cacheables to be included in the cache key
* @return this instance
*/
public CacheKeyBuilder appendCacheablesIgnoringOrder(Collection<? extends Cacheable> input) public CacheKeyBuilder appendCacheablesIgnoringOrder(Collection<? extends Cacheable> input)
{ {
appendItem(CACHEABLE_LIST_KEY, cacheableCollectionToByteArray(input, false)); appendItem(CACHEABLE_LIST_KEY, cacheableCollectionToByteArray(input, false));