...
| Name | Type | Unit | Description |
|---|
| numCachedRecord | Gauge | Records | The number of records in cache. |
| numCachedBytes | Gauge | Bytes | The number of bytes used by cache. |
| hitCount | Counter |
| The number of cache hits |
| missCount | Counter |
| The number of cache misses, which leads to loading operations |
| numBytesLoadedTotal | Counter | Bytes | The number of bytes totally loaded to the cache |
| numRecordsLoadedTotal | Counter | Records | The number of records totally loaded to the cache |
| numLoadFailure | Counter |
| The number of load failures |
| latestLoadTime | Gauge | ms | The time spent for the latest load operation |
...
| Code Block |
|---|
|
/**
* A semi-persistent mapping from keys to values. Cache entries are manually added using {@link
* #put(Object, Object)}, and are stored in the cache until either evicted or manually invalidated.
*
* <p>Implementations of this interface are expected to be thread-safe, and can be safely accessed
* by multiple concurrent threads.
*
* @param <K> key
* @param <V> value
*/
public interface Cache<K, V> {
/**
* Returns the value associated with the key in the cache, or obtain the value by loader if the
* key doesn't exist.
*
* @param key key - the key whose associated value is to be returned
* @param loader - the loader for loading associated values from external system
* @return The value associated with the key
* @throws IOException if any exception was thrown while loading the value
*/
V get(K key, Callable<? extends V> loader) throws IOException;
/**
* Associates the specified value with the specified key in the cache. If the cache previously
* contained a value associated with the key, the old value is replaced by the specified value.
*
* @return the previous value associated with key, or null if there was no mapping for key.
* @param key - key with which the specified value is to be associated
* @param value – value to be associated with the specified key
*/
V put(K key, V value);
/**
* Copies all the mappings from the specified map to the cache. The effect of this call is
* equivalent to that of calling {@code put(k, v)} on this map once for each mapping from key
* {@code k} to value {@code v} in the specified map. The behavior of this operation is
* undefined if the specified map is modified while the operation is in progress.
*/
void putAll(Map<? extends K, ? extends V> m);
/** Delete all entries in the cache. */
void clean();
/** Returns the number of key-value mappings in the cache. */
long size();
} |
CacheMetricGroup
An interface defining all cache related metric:
| Code Block |
|---|
| language | java |
|---|
| title | CacheMetricGroup |
|---|
|
/** Pre-defined metrics for {@code Cache}. */
public interface CacheMetricGroup {
/** The number of cache hits. */
Counter getHitCounter();
/** The number of cache misses. */
Counter getMissCounter();
/** The number of records totally loaded to the cache. */
Counter getNumRecordsLoadedTotalCounter();
/** The number of bytes totally loaded to the cache. */
Counter getNumBytesLoadedTotalCounter();
/** The time spent for the latest load operation. */
Gauge<Long> getLatestLoadTimeGauge();
/** The number of load failures. */
Counter getNumLoadFailureCounter();
/** The number of records in cache. */
void setNumCachedRecordsGauge(Gauge<Long> numCachedRecordsGauge);
/** The number of bytes used by cache. */
void setNumCachedBytesGauge(Gauge<Long> numCachedBytesGauge);
} |
CacheConfig
| Code Block |
|---|
| language | java |
|---|
| title | CacheConfig |
|---|
|
@PublicEvolving
/**
* Configuration for building caches.
*/
public class CacheConfig {
// Type of the cache
private CacheType cacheType;
// Time-to-live (TTL) of entries in cache
private Duration ttl;
// Maximum number of entries that the cache could contain
private long maxSize;
public enum CacheType {
ALL,
LRU,
NONE
}
}
|
CachingTableFunction
| Code Block |
|---|
| language | java |
|---|
| title | CachingTableFunction |
|---|
|
@PublicEvolving
public class CachingTableFunction<T, K, V> extends TableFunction<T> {
private Cache<K, V> cache;
private final CacheConfig cacheConfig;
public CachingTableFunction(CacheConfig cacheConfig) {
this.cacheConfig = cacheConfig;
}
@Override
public void open(FunctionContext context) throws Exception {
// Initialize cache with metric group
}
protected Cache<K, V> getCache() {
return cache;
}
}
|
Proposed Changes
Describe the new thing you want to do in appropriate detail. This may be fairly extensive and have large subsections of its own. Or it may be a few sentences. Use judgement based on the scope of the change.
...