Package com.wavefront.agent.histogram.accumulator

Class AccumulationCache

java.lang.Object

com.wavefront.agent.histogram.accumulator.AccumulationCache

All Implemented Interfaces:

Accumulator

public class AccumulationCache
extends Object
implements Accumulator

Expose a local cache of limited size along with a task to flush that cache to the backing store.

Author:

Tim Schmidt ([email protected]).

Constructor Summary

Constructors

Modifier	Constructor	Description
	AccumulationCache(ConcurrentMap<HistogramKey,AgentDigest> backingStore, AgentDigestFactory agentDigestFactory, long cacheSize, String metricPrefix, com.github.benmanes.caffeine.cache.Ticker ticker)	Constructs a new AccumulationCache instance around backingStore and builds an in-memory index maintaining dispatch times in milliseconds for all HistogramKeys in the backingStore.
protected	AccumulationCache(ConcurrentMap<HistogramKey,AgentDigest> backingStore, AgentDigestFactory agentDigestFactory, long cacheSize, String metricPrefix, com.github.benmanes.caffeine.cache.Ticker ticker, Runnable onFailure)	Constructs a new AccumulationCache instance around backingStore and builds an in-memory index maintaining dispatch times in milliseconds for all HistogramKeys in the backingStore.

Method Summary

Modifier and Type	Method	Description
AgentDigest	compute(HistogramKey key, BiFunction<? super HistogramKey,? super AgentDigest,? extends AgentDigest> remappingFunction)	Attempts to compute a mapping for the specified key and its current mapped value (or null if there is no current mapping).
void	flush()	Merge the contents of this cache with the corresponding backing store.
Iterator<HistogramKey>	getRipeDigestsIterator(com.wavefront.common.TimeProvider clock)	Returns an iterator over "ripe" digests ready to be shipped
void	put(HistogramKey key, double value)	Update AgentDigest in the cache with a double value.
void	put(HistogramKey key, AgentDigest value)	Update AgentDigest in the cache with another AgentDigest.
void	put(HistogramKey key, wavefront.report.Histogram value)	Update AgentDigest in the cache with a Histogram value.
long	size()	Returns the number of items in the storage behind the cache

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

AccumulationCache

public AccumulationCache(ConcurrentMap<HistogramKey,AgentDigest> backingStore,
                         AgentDigestFactory agentDigestFactory,
                         long cacheSize,
                         String metricPrefix,
                         @Nullable
                         com.github.benmanes.caffeine.cache.Ticker ticker)

Constructs a new AccumulationCache instance around backingStore and builds an in-memory index maintaining dispatch times in milliseconds for all HistogramKeys in the backingStore. Setting cacheSize to 0 disables in-memory caching so the cache only maintains the dispatch time index.

Parameters:

backingStore - a ConcurrentMap storing AgentDigests

agentDigestFactory - a factory that generates AgentDigests with pre-defined compression level and TTL time

cacheSize - maximum size of the cache

ticker - a nanosecond-precision time source

AccumulationCache

protected AccumulationCache(ConcurrentMap<HistogramKey,AgentDigest> backingStore,
                            AgentDigestFactory agentDigestFactory,
                            long cacheSize,
                            String metricPrefix,
                            @Nullable
                            com.github.benmanes.caffeine.cache.Ticker ticker,
                            @Nullable
                            Runnable onFailure)

Constructs a new AccumulationCache instance around backingStore and builds an in-memory index maintaining dispatch times in milliseconds for all HistogramKeys in the backingStore. Setting cacheSize to 0 disables in-memory caching, so the cache only maintains the dispatch time index.

Parameters:

backingStore - a ConcurrentMap storing AgentDigests

agentDigestFactory - a factory that generates AgentDigests with pre-defined compression level and TTL time

cacheSize - maximum size of the cache

ticker - a nanosecond-precision time source

onFailure - a Runnable that is invoked when backing store overflows

Method Detail

put

public void put(HistogramKey key,
                @Nonnull
                AgentDigest value)

Update AgentDigest in the cache with another AgentDigest.

Specified by:

put in interface Accumulator

Parameters:

key - histogram key

value - AgentDigest to be merged

put

public void put(HistogramKey key,
                double value)

Update AgentDigest in the cache with a double value. If such AgentDigest does not exist for the specified key, it will be created using AgentDigestFactory

Specified by:

put in interface Accumulator

Parameters:

key - histogram key

value - value to be merged into the AgentDigest

put

public void put(HistogramKey key,
                wavefront.report.Histogram value)

Update AgentDigest in the cache with a Histogram value. If such AgentDigest does not exist for the specified key, it will be created using AgentDigestFactory.

Specified by:

put in interface Accumulator

Parameters:

key - histogram key

value - a Histogram to be merged into the AgentDigest

getRipeDigestsIterator

public Iterator<HistogramKey> getRipeDigestsIterator(com.wavefront.common.TimeProvider clock)

Returns an iterator over "ripe" digests ready to be shipped

Specified by:

getRipeDigestsIterator in interface Accumulator

Parameters:

clock - a millisecond-precision epoch time source

Returns:

an iterator over "ripe" digests ready to be shipped

compute

public AgentDigest compute(HistogramKey key,
                           BiFunction<? super HistogramKey,? super AgentDigest,? extends AgentDigest> remappingFunction)

Attempts to compute a mapping for the specified key and its current mapped value (or null if there is no current mapping).

Specified by:

compute in interface Accumulator

Parameters:

key - key with which the specified value is to be associated

remappingFunction - the function to compute a value

Returns:

the new value associated with the specified key, or null if none

size

public long size()

Returns the number of items in the storage behind the cache

Specified by:

size in interface Accumulator

Returns:

number of items

flush

public void flush()

Merge the contents of this cache with the corresponding backing store.

Specified by:

flush in interface Accumulator