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Annotate DDCache/SimpleUtf8Cache/GenerationalUtf8Cache with @ForegroundSafe / @BackgroundOnly #12472

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Annotate DDCache/SimpleUtf8Cache/GenerationalUtf8Cache with @ForegroundSafe / @BackgroundOnly #12472

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6 changes: 6 additions & 0 deletions communication/src/main/java/datadog/communication/serialization/GenerationalUtf8Cache.java
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
package datadog.communication.serialization;

import datadog.trace.api.function.BackgroundOnly;
import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
import java.nio.charset.StandardCharsets;
import javax.annotation.concurrent.ThreadSafe;
Expand All @@ -15,6 +16,11 @@
* String#getBytes(java.nio.charset.Charset)}.
*
* <p>The cache is thread safe.
*
* <p>{@link BackgroundOnly}: the eden/tenured promotion and recalibration bookkeeping costs more
* than the {@code getBytes} call it replaces, so the saving only shows up as reduced allocation/GC
* pressure on the thread that pays it -- confine it to the background serializer thread, not an
* application thread.
*/
/*
* Cache works by using a 2-level promotion based scheme.
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6 changes: 6 additions & 0 deletions communication/src/main/java/datadog/communication/serialization/SimpleUtf8Cache.java
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Original file line number Diff line number Diff line change
@@ -1,5 +1,6 @@
package datadog.communication.serialization;

import datadog.trace.api.function.BackgroundOnly;
import java.nio.charset.StandardCharsets;
import javax.annotation.concurrent.ThreadSafe;

Expand All @@ -13,6 +14,11 @@
* String#getBytes(java.nio.charset.Charset)}.
*
* <p>The cache is thread safe.
*
* <p>{@link BackgroundOnly}: the bookkeeping (hit counting, LFU eviction scan) costs more than the
* {@code getBytes} call it replaces, so the saving only shows up as reduced allocation/GC pressure
* on the thread that pays it -- confine it to the background serializer thread, not an application
* thread.
*/
/*
* Thread safety is achieved through using CacheEntry objects where the key data
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7 changes: 7 additions & 0 deletions internal-api/src/main/java/datadog/trace/api/cache/DDCache.java
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@@ -1,8 +1,15 @@
package datadog.trace.api.cache;

import datadog.trace.api.function.ForegroundSafe;
import java.util.function.BiConsumer;
import java.util.function.Function;

/**
* {@link ForegroundSafe}: every implementation looks up a key via a small, bounded number of probes
* (no growth, no eviction bookkeeping beyond overwriting a slot) -- cheap enough to call from an
* application thread.
*/
@ForegroundSafe
public interface DDCache<K, V> {
/**
* Look up or create and store a value in the cache.
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