Support for retries in AtomicCounter. Enabled counter operation retries in ConsistentApplicationIdStore

Change-Id: I705c51b2efd7ecd928c64c7f8a16d1965198253c
diff --git a/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultAsyncAtomicCounter.java b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultAsyncAtomicCounter.java
index a69c0cc..cdaf792 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultAsyncAtomicCounter.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultAsyncAtomicCounter.java
@@ -16,10 +16,20 @@
 package org.onosproject.store.consistent.impl;
 
 import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.TimeUnit;
+import java.util.function.BiFunction;
 
 import org.onosproject.store.service.AsyncAtomicCounter;
 
+
+
+
+
+import org.slf4j.Logger;
+
 import static com.google.common.base.Preconditions.*;
+import static org.slf4j.LoggerFactory.getLogger;
 
 /**
  * Default implementation for a distributed AsyncAtomicCounter backed by
@@ -31,10 +41,20 @@
 
     private final String name;
     private final Database database;
+    private final boolean retryOnFailure;
+    private final ScheduledExecutorService retryExecutor;
+    // TODO: configure delay via builder
+    private static final int DELAY_BETWEEN_RETRY_SEC = 1;
+    private final Logger log = getLogger(getClass());
 
-    public DefaultAsyncAtomicCounter(String name, Database database) {
+    public DefaultAsyncAtomicCounter(String name,
+            Database database,
+            boolean retryOnException,
+            ScheduledExecutorService retryExecutor) {
         this.name = checkNotNull(name);
         this.database = checkNotNull(database);
+        this.retryOnFailure = retryOnException;
+        this.retryExecutor = retryExecutor;
     }
 
     @Override
@@ -54,11 +74,70 @@
 
     @Override
     public CompletableFuture<Long> getAndAdd(long delta) {
-        return database.counterGetAndAdd(name, delta);
+        CompletableFuture<Long> result = database.counterGetAndAdd(name, delta);
+        if (!retryOnFailure) {
+            return result;
+        }
+
+        CompletableFuture<Long> future = new CompletableFuture<>();
+        return result.whenComplete((r, e) -> {
+            if (e != null) {
+                log.warn("getAndAdd failed due to {}. Will retry", e.getMessage());
+                retryExecutor.schedule(new RetryTask(database::counterGetAndAdd, delta, future),
+                                                     DELAY_BETWEEN_RETRY_SEC,
+                                                     TimeUnit.SECONDS);
+            } else {
+                future.complete(r);
+            }
+         }).thenCompose(v -> future);
     }
 
     @Override
     public CompletableFuture<Long> addAndGet(long delta) {
-        return database.counterAddAndGet(name, delta);
+        CompletableFuture<Long> result = database.counterAddAndGet(name, delta);
+        if (!retryOnFailure) {
+            return result;
+        }
+
+        CompletableFuture<Long> future = new CompletableFuture<>();
+        return result.whenComplete((r, e) -> {
+            if (e != null) {
+                log.warn("addAndGet failed due to {}. Will retry", e.getMessage());
+                retryExecutor.schedule(new RetryTask(database::counterAddAndGet, delta, future),
+                                                     DELAY_BETWEEN_RETRY_SEC,
+                                                     TimeUnit.SECONDS);
+            } else {
+                future.complete(r);
+            }
+        }).thenCompose(v -> future);
     }
-}
+
+    private class RetryTask implements Runnable {
+
+        private final BiFunction<String, Long, CompletableFuture<Long>> function;
+        private final Long delta;
+        private final CompletableFuture<Long> result;
+
+        public RetryTask(BiFunction<String, Long, CompletableFuture<Long>> function,
+                Long delta,
+                CompletableFuture<Long> result) {
+            this.function = function;
+            this.delta = delta;
+            this.result = result;
+        }
+
+        @Override
+        public void run() {
+            function.apply(name, delta).whenComplete((r, e) -> {
+                if (e == null) {
+                    result.complete(r);
+                } else {
+                    log.warn("{} retry failed due to {}. Will try again...", function, e.getMessage());
+                    // TODO: Exponential backoff
+                    // TODO: limit retries
+                    retryExecutor.schedule(this, DELAY_BETWEEN_RETRY_SEC, TimeUnit.SECONDS);
+                }
+            });
+        }
+    }
+}
\ No newline at end of file
diff --git a/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultAtomicCounter.java b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultAtomicCounter.java
index fee91fa..18120bb 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultAtomicCounter.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultAtomicCounter.java
@@ -17,6 +17,7 @@
 
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 
@@ -36,8 +37,11 @@
 
     private final AsyncAtomicCounter asyncCounter;
 
-    public DefaultAtomicCounter(String name, Database database) {
-        asyncCounter = new DefaultAsyncAtomicCounter(name, database);
+    public DefaultAtomicCounter(String name,
+            Database database,
+            boolean retryOnException,
+            ScheduledExecutorService retryExecutor) {
+        asyncCounter = new DefaultAsyncAtomicCounter(name, database, retryOnException, retryExecutor);
     }
 
     @Override
diff --git a/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultAtomicCounterBuilder.java b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultAtomicCounterBuilder.java
index c84cff0..97361db 100644
--- a/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultAtomicCounterBuilder.java
+++ b/core/store/dist/src/main/java/org/onosproject/store/consistent/impl/DefaultAtomicCounterBuilder.java
@@ -1,5 +1,7 @@
 package org.onosproject.store.consistent.impl;
 
+import java.util.concurrent.ScheduledExecutorService;
+
 import org.onosproject.store.service.AsyncAtomicCounter;
 import org.onosproject.store.service.AtomicCounter;
 import org.onosproject.store.service.AtomicCounterBuilder;
@@ -15,6 +17,8 @@
     private boolean partitionsEnabled = true;
     private final Database partitionedDatabase;
     private final Database inMemoryDatabase;
+    private boolean retryOnFailure = false;
+    private ScheduledExecutorService retryExecutor = null;
 
     public DefaultAtomicCounterBuilder(Database inMemoryDatabase, Database partitionedDatabase) {
         this.inMemoryDatabase = inMemoryDatabase;
@@ -36,13 +40,35 @@
 
     @Override
     public AtomicCounter build() {
+        validateInputs();
         Database database = partitionsEnabled ? partitionedDatabase : inMemoryDatabase;
-        return new DefaultAtomicCounter(name, database);
+        return new DefaultAtomicCounter(name, database, retryOnFailure, retryExecutor);
     }
 
     @Override
     public AsyncAtomicCounter buildAsyncCounter() {
+        validateInputs();
         Database database = partitionsEnabled ? partitionedDatabase : inMemoryDatabase;
-        return new DefaultAsyncAtomicCounter(name, database);
+        return new DefaultAsyncAtomicCounter(name, database, retryOnFailure, retryExecutor);
+    }
+
+    @Override
+    public AtomicCounterBuilder withRetryOnFailure() {
+        retryOnFailure = true;
+        return this;
+    }
+
+    @Override
+    public AtomicCounterBuilder withRetryExecutor(ScheduledExecutorService executor) {
+        this.retryExecutor = executor;
+        return this;
+    }
+
+    private void validateInputs() {
+        if (retryOnFailure) {
+            if (retryExecutor == null) {
+                throw new IllegalArgumentException("RetryExecutor must be specified when retries are enabled");
+            }
+        }
     }
 }