Start working around components

[lgpl/argeo-commons.git] / org.argeo.enterprise / src / org / argeo / util / register / Singleton.java

diff --git a/org.argeo.enterprise/src/org/argeo/util/register/Singleton.java b/org.argeo.enterprise/src/org/argeo/util/register/Singleton.java
new file mode 100644 (file)
index 0000000..5d70e9a
--- /dev/null
+++ b/org.argeo.enterprise/src/org/argeo/util/register/Singleton.java
@@ -0,0 +1,41 @@
+package org.argeo.util.register;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CompletionStage;
+import java.util.concurrent.Future;
+import java.util.function.Consumer;
+
+public class Singleton<T> {
+       private final Class<T> clss;
+       private final CompletableFuture<T> registrationStage;
+       private final List<Consumer<T>> unregistrationHooks = new ArrayList<>();
+
+       public Singleton(Class<T> clss, CompletableFuture<T> registrationStage) {
+               this.clss = clss;
+               this.registrationStage = registrationStage;
+       }
+
+       CompletionStage<T> getRegistrationStage() {
+               return registrationStage.minimalCompletionStage();
+       }
+
+       public void addUnregistrationHook(Consumer<T> todo) {
+               unregistrationHooks.add(todo);
+       }
+
+       public Future<T> getValue() {
+               return registrationStage.copy();
+       }
+
+       public CompletableFuture<Void> prepareUnregistration(Void v) {
+               List<CompletableFuture<Void>> lst = new ArrayList<>();
+               for (Consumer<T> hook : unregistrationHooks) {
+                       lst.add(registrationStage.thenAcceptAsync(hook));
+               }
+               CompletableFuture<Void> prepareUnregistrationStage = CompletableFuture
+                               .allOf(lst.toArray(new CompletableFuture<?>[lst.size()]));
+               return prepareUnregistrationStage;
+       }
+}