Make RetryContext available to Callable of Promises.poll method

Author: vsilaev

src/main/java/net/tascalate/concurrent/Promises.java

@@ -566,7 +566,13 @@ private static <T> void pollOnce(Callable<Optional<? extends T>> codeBlock,
             Runnable doCall = () -> {
                 long startTime = System.currentTimeMillis();
                 try {
-                    Optional<? extends T> result = codeBlock.call();
+                    Optional<? extends T> result;
+                    ctx.enter();
+                    try {
+                        result = codeBlock.call();
+                    } finally {
+                        ctx.exit();
+                    }
                     if (result.isPresent()) {
                         resultPromise.onSuccess(result.get());
                     } else {

src/main/java/net/tascalate/concurrent/RetryContext.java

@@ -69,5 +69,21 @@ public RetryContext asPrevRetry() {
         }
         return new RetryContext(policy, retry - 1, lastCallDuration, lastThrowable);
     }
+    
+    public static RetryContext current() {
+        return CURRENT_CONTEXT.get();
+    }
+    
+    void enter() {
+        CURRENT_CONTEXT.set(this);
+    }
+    
+    void exit() {
+        if (CURRENT_CONTEXT.get() == this) {
+            CURRENT_CONTEXT.remove();
+        }
+    }
+    
+    private static final ThreadLocal<RetryContext> CURRENT_CONTEXT = new ThreadLocal<>();
 
 }

src/main/java/net/tascalate/concurrent/RetryException.java

@@ -1,3 +1,18 @@
+/**
+ * Copyright 2015-2017 Valery Silaev (http://vsilaev.com)
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 package net.tascalate.concurrent;
 
 public class RetryException extends Exception {