Update Infinispan Cache Implementation to propagate Vert.x context co…

…rrectly (quarkusio#298)

extensions/infinispan-cache/runtime/src/main/java/io/quarkus/cache/infinispan/runtime/InfinispanCacheImpl.java

@@ -5,6 +5,7 @@
 import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.Executor;
 import java.util.concurrent.Flow;
 import java.util.concurrent.TimeUnit;
 import java.util.function.Function;
@@ -24,6 +25,10 @@
 import io.quarkus.infinispan.client.runtime.InfinispanClientUtil;
 import io.smallrye.mutiny.Multi;
 import io.smallrye.mutiny.Uni;
+import io.vertx.core.Context;
+import io.vertx.core.Handler;
+import io.vertx.core.Vertx;
+import io.vertx.core.impl.ContextInternal;
 
 /**
  * This class is an internal Quarkus cache implementation using Infinispan.
@@ -111,6 +116,8 @@ public <K, V> Uni<V> get(K key, Function<K, V> valueLoader) {
 
     @Override
     public <K, V> Uni<V> getAsync(K key, Function<K, Uni<V>> valueLoader) {
+        Context context = Vertx.currentContext();
+
         return Uni.createFrom().completionStage(CompletionStages.handleAndCompose(remoteCache.getAsync(key), (v1, ex1) -> {
             if (ex1 != null) {
                 return CompletableFuture.failedFuture(ex1);
@@ -145,7 +152,49 @@ public <K, V> Uni<V> getAsync(K key, Function<K, Uni<V>> valueLoader) {
                         }
                     });
             return resultAsync;
-        }));
+        })).emitOn(new Executor() {
+            // We need make sure we go back to the original context when the cache value is computed.
+            // Otherwise, we would always emit on the context having computed the value, which could
+            // break the duplicated context isolation.
+            @Override
+            public void execute(Runnable command) {
+                Context ctx = Vertx.currentContext();
+                if (context == null) {
+                    // We didn't capture a context
+                    if (ctx == null) {
+                        // We are not on a context => we can execute immediately.
+                        command.run();
+                    } else {
+                        // We are on a context.
+                        // We cannot continue on the current context as we may share a duplicated context.
+                        // We need a new one. Note that duplicate() does not duplicate the duplicated context,
+                        // but the root context.
+                        ((ContextInternal) ctx).duplicate()
+                                .runOnContext(new Handler<Void>() {
+                                    @Override
+                                    public void handle(Void ignored) {
+                                        command.run();
+                                    }
+                                });
+                    }
+                } else {
+                    // We captured a context.
+                    if (ctx == context) {
+                        // We are on the same context => we can execute immediately
+                        command.run();
+                    } else {
+                        // 1) We are not on a context (ctx == null) => we need to switch to the captured context.
+                        // 2) We are on a different context (ctx != null) => we need to switch to the captured context.
+                        context.runOnContext(new Handler<Void>() {
+                            @Override
+                            public void handle(Void ignored) {
+                                command.run();
+                            }
+                        });
+                    }
+                }
+            }
+        });
     }
 
     @Override