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feat: context propagation
Signed-off-by: Sviatoslav Sharaev <[email protected]>
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‎README.md

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@@ -120,16 +120,17 @@ See [here](https://javadoc.io/doc/dev.openfeature/sdk/latest/) for the Javadocs.
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## 🌟 Features
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| Status | Features | Description |
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| ------ | ------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------- |
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| ✅ | [Providers](#providers) | Integrate with a commercial, open source, or in-house feature management tool. |
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| ✅ | [Targeting](#targeting) | Contextually-aware flag evaluation using [evaluation context](https://openfeature.dev/docs/reference/concepts/evaluation-context). |
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| ✅ | [Hooks](#hooks) | Add functionality to various stages of the flag evaluation life-cycle. |
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| ✅ | [Logging](#logging) | Integrate with popular logging packages. |
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| ✅ | [Named clients](#named-clients) | Utilize multiple providers in a single application. |
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| ✅ | [Eventing](#eventing) | React to state changes in the provider or flag management system. |
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| ✅ | [Shutdown](#shutdown) | Gracefully clean up a provider during application shutdown. |
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| ✅ | [Extending](#extending) | Extend OpenFeature with custom providers and hooks. |
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| Status | Features | Description |
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| ------ |-----------------------------------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------|
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| ✅ | [Providers](#providers) | Integrate with a commercial, open source, or in-house feature management tool. |
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| ✅ | [Targeting](#targeting) | Contextually-aware flag evaluation using [evaluation context](https://openfeature.dev/docs/reference/concepts/evaluation-context). |
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| ✅ | [Hooks](#hooks) | Add functionality to various stages of the flag evaluation life-cycle. |
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| ✅ | [Logging](#logging) | Integrate with popular logging packages. |
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| ✅ | [Named clients](#named-clients) | Utilize multiple providers in a single application. |
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| ✅ | [Eventing](#eventing) | React to state changes in the provider or flag management system. |
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| ✅ | [Shutdown](#shutdown) | Gracefully clean up a provider during application shutdown. |
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| ✅ | [Transaction Context Propagation](#transaction-context-propagation) | Set a specific [evaluation context](https://openfeature.dev/docs/reference/concepts/evaluation-context) for a transaction (e.g. an HTTP request or a thread). |
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| ✅ | [Extending](#extending) | Extend OpenFeature with custom providers and hooks. |
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<sub>Implemented: ✅ | In-progress: ⚠️ | Not implemented yet: ❌</sub>
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‎src/main/java/dev/openfeature/sdk/NoOpTransactionContextPropagator.java

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package dev.openfeature.sdk;
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/**
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* A {@link TransactionContextPropagator} that simply returns null.
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*/
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public class NoOpTransactionContextPropagator implements TransactionContextPropagator {
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/**
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* {@inheritDoc}
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* @return null
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*/
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@Override
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public EvaluationContext getTransactionContext() {
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return null;
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}
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/**
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* {@inheritDoc}
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*/
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@Override
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public void setTransactionContext(EvaluationContext evaluationContext) {
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}
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}

‎src/main/java/dev/openfeature/sdk/OpenFeatureAPI.java

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@@ -27,11 +27,13 @@ public class OpenFeatureAPI implements EventBus<OpenFeatureAPI> {
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private ProviderRepository providerRepository;
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private EventSupport eventSupport;
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private EvaluationContext evaluationContext;
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private TransactionContextPropagator transactionContextPropagator;
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protected OpenFeatureAPI() {
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apiHooks = new ArrayList<>();
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providerRepository = new ProviderRepository();
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eventSupport = new EventSupport();
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transactionContextPropagator = new NoOpTransactionContextPropagator();
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}
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private static class SingletonHolder {
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}
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}
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/**
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* Return the transaction context propagator.
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*/
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public TransactionContextPropagator getTransactionContextPropagator() {
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try (AutoCloseableLock __ = lock.readLockAutoCloseable()) {
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return this.transactionContextPropagator;
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}
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}
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/**
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* Sets the transaction context propagator.
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*
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* @throws IllegalArgumentException if {@code transactionContextPropagator} is null
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*/
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public void setTransactionContextPropagator(TransactionContextPropagator transactionContextPropagator) {
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if (transactionContextPropagator == null) {
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throw new IllegalArgumentException("Transaction context propagator cannot be null");
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}
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try (AutoCloseableLock __ = lock.writeLockAutoCloseable()) {
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this.transactionContextPropagator = transactionContextPropagator;
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}
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}
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/**
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* Returns the currently defined transaction context using the registered transaction
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* context propagator.
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*
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* @return {@link EvaluationContext} The current transaction context
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*/
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public EvaluationContext getTransactionContext() {
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return this.transactionContextPropagator.getTransactionContext();
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}
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/**
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* Sets the transaction context using the registered transaction context propagator.
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*/
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void setTransactionContext(EvaluationContext evaluationContext) {
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this.transactionContextPropagator.setTransactionContext(evaluationContext);
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}
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/**
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* Set the default provider.
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*/

‎src/main/java/dev/openfeature/sdk/OpenFeatureClient.java

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@@ -105,9 +105,6 @@ private <T> FlagEvaluationDetails<T> evaluateFlag(FlagValueType type, String key
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FeatureProvider provider;
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try {
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final EvaluationContext apiContext;
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final EvaluationContext clientContext;
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// openfeatureApi.getProvider() must be called once to maintain a consistent reference
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provider = openfeatureApi.getProvider(this.name);
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hookCtx = HookContext.from(key, type, this.getMetadata(),
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provider.getMetadata(), ctx, defaultValue);
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// merge of: API.context, client.context, invocation.context
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apiContext = openfeatureApi.getEvaluationContext() != null
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? openfeatureApi.getEvaluationContext()
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: new ImmutableContext();
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clientContext = this.getEvaluationContext() != null
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? this.getEvaluationContext()
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: new ImmutableContext();
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EvaluationContext ctxFromHook = hookSupport.beforeHooks(type, hookCtx, mergedHooks, hints);
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EvaluationContext invocationCtx = ctx.merge(ctxFromHook);
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EvaluationContext mergedCtx = apiContext.merge(clientContext.merge(invocationCtx));
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EvaluationContext mergedCtx = mergeEvaluationContext(ctxFromHook, ctx);
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ProviderEvaluation<T> providerEval = (ProviderEvaluation<T>) createProviderEvaluation(type, key,
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defaultValue, provider, mergedCtx);
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return details;
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}
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/**
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* Merge hook and invocation contexts with API, transaction and client contexts.
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*
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* @param hookContext hook context
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* @param invocationContext invocation context
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* @return merged evaluation context
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*/
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private EvaluationContext mergeEvaluationContext(
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EvaluationContext hookContext,
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EvaluationContext invocationContext) {
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final EvaluationContext apiContext = openfeatureApi.getEvaluationContext() != null
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? openfeatureApi.getEvaluationContext()
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: new ImmutableContext();
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final EvaluationContext clientContext = this.getEvaluationContext() != null
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? this.getEvaluationContext()
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: new ImmutableContext();
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final EvaluationContext transactionContext = openfeatureApi.getTransactionContext() != null
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? openfeatureApi.getTransactionContext()
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: new ImmutableContext();
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EvaluationContext mergedInvocationCtx = invocationContext.merge(hookContext);
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return apiContext.merge(transactionContext.merge(clientContext.merge(mergedInvocationCtx)));
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}
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private <T> ProviderEvaluation<?> createProviderEvaluation(
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FlagValueType type,
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String key,

‎src/main/java/dev/openfeature/sdk/ThreadLocalTransactionContextPropagator.java

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package dev.openfeature.sdk;
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/**
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* A {@link ThreadLocalTransactionContextPropagator} is a transactional context propagator
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* that uses a ThreadLocal to persist a transactional context for the duration of a single thread.
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*
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* @see TransactionContextPropagator
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*/
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public class ThreadLocalTransactionContextPropagator implements TransactionContextPropagator {
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private final ThreadLocal<EvaluationContext> evaluationContextThreadLocal = new ThreadLocal<>();
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/**
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* {@inheritDoc}
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*/
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@Override
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public EvaluationContext getTransactionContext() {
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return this.evaluationContextThreadLocal.get();
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}
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/**
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* {@inheritDoc}
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*/
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@Override
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public void setTransactionContext(EvaluationContext evaluationContext) {
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this.evaluationContextThreadLocal.set(evaluationContext);
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}
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}

‎src/main/java/dev/openfeature/sdk/TransactionContextPropagator.java

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package dev.openfeature.sdk;
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/**
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* {@link TransactionContextPropagator} is responsible for persisting a transactional context
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* for the duration of a single transaction.
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* Examples of potential transaction specific context include: a user id, user agent, IP.
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* Transaction context is merged with evaluation context prior to flag evaluation.
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* <p>
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* The precedence of merging context can be seen in
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* <a href=https://openfeature.dev/specification/sections/evaluation-context#requirement-323>the specification</a>.
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* </p>
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*/
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public interface TransactionContextPropagator {
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/**
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* Returns the currently defined transaction context using the registered transaction
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* context propagator.
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*
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* @return {@link EvaluationContext} The current transaction context
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*/
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EvaluationContext getTransactionContext();
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/**
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* Sets the transaction context.
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*/
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void setTransactionContext(EvaluationContext evaluationContext);
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}

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