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Separate per-store context storage from boxed store-ids that forward to ObjectStoreDispatch
Selects the context-store implementation at startup and emits direct references to its concrete type so the JIT can optimize store access. Static ObjectStoreDispatch which uses just a store-id is moved into BoxedContextStore, while FieldBackedContextStore retains the per-store weak-map fallback. Updates instrumentation rewriting, OpenTelemetry mapping, and native-image initialization to use the selected implementation. Adds concurrent allocation tests and JMH benchmarks for store operations and a variety of workloads.
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37 files changed

Lines changed: 2246 additions & 100 deletions

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‎dd-java-agent/agent-bootstrap/src/main/java/datadog/trace/bootstrap/BoxedContextStore.java‎

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package datadog.trace.bootstrap;
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import datadog.instrument.fieldinject.ObjectStoreDispatch;
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import java.util.function.Function;
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/** Boxes a store-id and dispatches context operations through {@link ObjectStoreDispatch}. */
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public final class BoxedContextStore implements ContextStore<Object, Object> {
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final int storeId;
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BoxedContextStore(final int storeId) {
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this.storeId = storeId;
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}
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@Override
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public Object get(final Object key) {
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return ObjectStoreDispatch.get(key, storeId);
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}
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@Override
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public void put(final Object key, final Object context) {
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ObjectStoreDispatch.put(key, storeId, context);
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}
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@Override
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public Object getOrPut(final Object key, final Object context) {
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return ObjectStoreDispatch.getOrPut(key, storeId, context);
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}
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@Override
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public Object getOrCompute(
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final Object key, final Function<? super Object, Object> contextFactory) {
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return ObjectStoreDispatch.getOrCompute(key, storeId, contextFactory);
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}
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@Override
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public Object remove(final Object key) {
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return ObjectStoreDispatch.remove(key, storeId);
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}
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}

‎dd-java-agent/agent-bootstrap/src/main/java/datadog/trace/bootstrap/BoxedContextStores.java‎

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package datadog.trace.bootstrap;
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import java.util.Arrays;
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import java.util.concurrent.ConcurrentHashMap;
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import org.slf4j.Logger;
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import org.slf4j.LoggerFactory;
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/**
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* Intentional copy of FieldBackedContextStores but for {@link BoxedContextStore}.
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*
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* <p>Only one is loaded at runtime; the explicit field type helps the JIT optimize.
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*/
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public final class BoxedContextStores {
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private static final Logger log = LoggerFactory.getLogger(BoxedContextStores.class);
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// these fields will be accessed directly from field-injected instrumentation
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public static final BoxedContextStore contextStore0 = new BoxedContextStore(0);
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public static final BoxedContextStore contextStore1 = new BoxedContextStore(1);
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public static final BoxedContextStore contextStore2 = new BoxedContextStore(2);
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public static final BoxedContextStore contextStore3 = new BoxedContextStore(3);
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public static final BoxedContextStore contextStore4 = new BoxedContextStore(4);
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public static final BoxedContextStore contextStore5 = new BoxedContextStore(5);
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public static final BoxedContextStore contextStore6 = new BoxedContextStore(6);
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public static final BoxedContextStore contextStore7 = new BoxedContextStore(7);
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public static final BoxedContextStore contextStore8 = new BoxedContextStore(8);
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public static final BoxedContextStore contextStore9 = new BoxedContextStore(9);
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public static final BoxedContextStore contextStore10 = new BoxedContextStore(10);
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public static final BoxedContextStore contextStore11 = new BoxedContextStore(11);
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public static final BoxedContextStore contextStore12 = new BoxedContextStore(12);
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public static final BoxedContextStore contextStore13 = new BoxedContextStore(13);
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public static final BoxedContextStore contextStore14 = new BoxedContextStore(14);
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public static final BoxedContextStore contextStore15 = new BoxedContextStore(15);
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public static final BoxedContextStore contextStore16 = new BoxedContextStore(16);
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public static final BoxedContextStore contextStore17 = new BoxedContextStore(17);
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public static final BoxedContextStore contextStore18 = new BoxedContextStore(18);
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public static final BoxedContextStore contextStore19 = new BoxedContextStore(19);
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public static final BoxedContextStore contextStore20 = new BoxedContextStore(20);
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public static final BoxedContextStore contextStore21 = new BoxedContextStore(21);
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public static final BoxedContextStore contextStore22 = new BoxedContextStore(22);
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public static final BoxedContextStore contextStore23 = new BoxedContextStore(23);
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public static final BoxedContextStore contextStore24 = new BoxedContextStore(24);
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public static final BoxedContextStore contextStore25 = new BoxedContextStore(25);
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public static final BoxedContextStore contextStore26 = new BoxedContextStore(26);
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public static final BoxedContextStore contextStore27 = new BoxedContextStore(27);
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public static final BoxedContextStore contextStore28 = new BoxedContextStore(28);
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public static final BoxedContextStore contextStore29 = new BoxedContextStore(29);
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public static final BoxedContextStore contextStore30 = new BoxedContextStore(30);
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public static final BoxedContextStore contextStore31 = new BoxedContextStore(31);
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// keep track of all allocated stores so far
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private static volatile BoxedContextStore[] stores = {
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contextStore0,
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contextStore1,
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contextStore2,
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contextStore3,
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contextStore4,
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contextStore5,
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contextStore6,
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contextStore7,
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contextStore8,
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contextStore9,
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contextStore10,
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contextStore11,
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contextStore12,
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contextStore13,
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contextStore14,
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contextStore15,
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contextStore16,
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contextStore17,
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contextStore18,
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contextStore19,
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contextStore20,
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contextStore21,
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contextStore22,
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contextStore23,
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contextStore24,
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contextStore25,
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contextStore26,
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contextStore27,
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contextStore28,
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contextStore29,
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contextStore30,
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contextStore31
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};
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private static final ConcurrentHashMap<String, BoxedContextStore> storesByName =
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new ConcurrentHashMap<>();
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private static final Object allocationLock = new Object();
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private static int nextStoreId;
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public static int getContextStoreId(String keyClassName, String contextClassName) {
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String storeName = keyClassName + ';' + contextClassName;
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BoxedContextStore store = storesByName.get(storeName);
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if (store == null) {
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synchronized (allocationLock) {
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// speculatively create the next store in the sequence and attempt to map this name to it;
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// if another thread has mapped this name then the store will be kept for the next mapping
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BoxedContextStore existing =
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storesByName.putIfAbsent(storeName, store = allocateStore(nextStoreId));
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if (existing != null) {
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return existing.storeId;
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}
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nextStoreId++;
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}
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log.debug(
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"Allocated ContextStore #{} - instrumentation.target.context={}->{}",
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store.storeId,
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keyClassName,
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contextClassName);
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}
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return store.storeId;
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}
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public static BoxedContextStore getContextStore(final int storeId) {
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return stores[storeId]; // guaranteed to be populated by getContextStoreId
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}
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// this method should only be called while holding the allocation lock
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private static BoxedContextStore allocateStore(int storeId) {
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BoxedContextStore[] snapshot = stores;
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if (storeId >= snapshot.length) {
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stores = snapshot = Arrays.copyOf(snapshot, storeId + 16);
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}
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// check for pre-allocated / speculatively allocated stores
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BoxedContextStore store = snapshot[storeId];
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if (store == null) {
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snapshot[storeId] = store = new BoxedContextStore(storeId);
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}
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return store;
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}
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}

‎dd-java-agent/agent-bootstrap/src/main/java/datadog/trace/bootstrap/ContextStores.java‎

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package datadog.trace.bootstrap;
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import datadog.trace.api.InstrumenterConfig;
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/** Allocates {@link ContextStore}s. */
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public final class ContextStores {
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// fast lookup available for fixed number of stores
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public static final int FAST_STORE_ID_LIMIT = 32;
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private static final boolean MAP_PER_STORE =
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InstrumenterConfig.get().isRuntimeContextMapPerStore();
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public static final String STORES_DESCRIPTOR =
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MAP_PER_STORE
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? "Ldatadog/trace/bootstrap/FieldBackedContextStores;"
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: "Ldatadog/trace/bootstrap/BoxedContextStores;";
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public static final String STORE_DESCRIPTOR =
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MAP_PER_STORE
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? "Ldatadog/trace/bootstrap/FieldBackedContextStore;"
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: "Ldatadog/trace/bootstrap/BoxedContextStore;";
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public static int getContextStoreId(String keyClassName, String contextClassName) {
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if (MAP_PER_STORE) {
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return FieldBackedContextStores.getContextStoreId(keyClassName, contextClassName);
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} else {
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return BoxedContextStores.getContextStoreId(keyClassName, contextClassName);
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}
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}
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public static ContextStore<?, ?> getContextStore(final int storeId) {
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if (MAP_PER_STORE) {
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return FieldBackedContextStores.getContextStore(storeId);
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} else {
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return BoxedContextStores.getContextStore(storeId);
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}
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}
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}

‎dd-java-agent/agent-bootstrap/src/main/java/datadog/trace/bootstrap/FieldBackedContextStore.java‎

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package datadog.trace.bootstrap;
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import datadog.instrument.fieldinject.KeyWithValue;
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import datadog.instrument.fieldinject.ObjectStoreDispatch;
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import datadog.trace.api.InstrumenterConfig;
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import java.util.function.Function;
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/**
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* {@link ContextStore} that attempts to store context in its keys by using bytecode-injected
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* fields. Delegates to a lazy {@link WeakMap} for keys that don't have a field for this store.
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*/
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public final class FieldBackedContextStore implements ContextStore<Object, Object> {
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private static final boolean MAP_PER_STORE =
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InstrumenterConfig.get().isRuntimeContextMapPerStore();
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final int storeId;
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FieldBackedContextStore(final int storeId) {
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public Object get(final Object key) {
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if (key instanceof KeyWithValue) {
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return ((KeyWithValue) key).$get$__dd_instrument$(storeId);
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} else if (MAP_PER_STORE) {
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return weakStore().get(key);
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} else {
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return ObjectStoreDispatch.get(key, storeId);
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return weakStore().get(key);
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}
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}
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@Override
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public void put(final Object key, final Object context) {
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if (key instanceof KeyWithValue) {
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((KeyWithValue) key).$put$__dd_instrument$(storeId, context);
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} else if (MAP_PER_STORE) {
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weakStore().put(key, context);
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} else {
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ObjectStoreDispatch.put(key, storeId, context);
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weakStore().put(key, context);
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}
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}
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@@ -56,15 +47,14 @@ public Object getOrPut(final Object key, final Object context) {
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}
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}
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return existingContext;
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} else if (MAP_PER_STORE) {
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return weakStore().getOrPut(key, context);
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} else {
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return ObjectStoreDispatch.getOrPut(key, storeId, context);
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return weakStore().getOrPut(key, context);
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}
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}
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@Override
67-
public Object getOrCompute(Object key, Function<? super Object, Object> contextFactory) {
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public Object getOrCompute(
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final Object key, final Function<? super Object, Object> contextFactory) {
6858
if (key instanceof KeyWithValue) {
6959
final KeyWithValue accessor = (KeyWithValue) key;
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Object existingContext = accessor.$get$__dd_instrument$(storeId);
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}
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}
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return existingContext;
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} else if (MAP_PER_STORE) {
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return weakStore().getOrCompute(key, contextFactory);
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} else {
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return ObjectStoreDispatch.getOrCompute(key, storeId, contextFactory);
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return weakStore().getOrCompute(key, contextFactory);
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}
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}
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8876
@Override
89-
public Object remove(Object key) {
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public Object remove(final Object key) {
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if (key instanceof KeyWithValue) {
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final KeyWithValue accessor = (KeyWithValue) key;
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Object existingContext = accessor.$get$__dd_instrument$(storeId);
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}
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}
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return existingContext;
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} else if (MAP_PER_STORE) {
103-
return weakStore().remove(key);
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} else {
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return ObjectStoreDispatch.remove(key, storeId);
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return weakStore().remove(key);
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}
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}
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‎dd-java-agent/agent-bootstrap/src/main/java/datadog/trace/bootstrap/FieldBackedContextStores.java‎

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private static final Logger log = LoggerFactory.getLogger(FieldBackedContextStores.class);
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// provide fast lookup for a fixed number of stores
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public static final int FAST_STORE_ID_LIMIT = 32;
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// these fields will be accessed directly from field-injected instrumentation
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public static final FieldBackedContextStore contextStore0 = new FieldBackedContextStore(0);
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public static final FieldBackedContextStore contextStore1 = new FieldBackedContextStore(1);

‎dd-java-agent/agent-bootstrap/src/test/groovy/datadog/trace/bootstrap/FieldBackedContextStoresTest.groovy‎

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