From 5570ae77e51ba29a03be4a8f6b5fc765a0067004 Mon Sep 17 00:00:00 2001
From: ajay_maddi <ajay_maddi@persistent.com>
Date: Thu, 19 Jan 2023 14:16:15 +0530
Subject: [PATCH] added changes for issue#2742

---
 .../internal/store/tiering/CacheStore.java    |  5 ++-
 .../store/tiering/CacheStoreTest.java         | 38 +++++++++++++++++++
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/impl/src/main/java/org/ehcache/internal/store/tiering/CacheStore.java b/impl/src/main/java/org/ehcache/internal/store/tiering/CacheStore.java
index 22a9838dfb..0a326aa808 100644
--- a/impl/src/main/java/org/ehcache/internal/store/tiering/CacheStore.java
+++ b/impl/src/main/java/org/ehcache/internal/store/tiering/CacheStore.java
@@ -439,7 +439,10 @@ public NoopCachingTier(final AuthoritativeTier<K, V> authoritativeTier) {
     @Override
     public ValueHolder<V> getOrComputeIfAbsent(final K key, final Function<K, ValueHolder<V>> source) throws CacheAccessException {
       final ValueHolder<V> apply = source.apply(key);
-      authoritativeTier.flush(key, apply);
+      if (apply != null) {
+        //immediately flushes any entries faulted from authority as this tier has no capacity
+        authoritativeTier.flush(key, apply);
+      }
       return apply;
     }
 
diff --git a/impl/src/test/java/org/ehcache/internal/store/tiering/CacheStoreTest.java b/impl/src/test/java/org/ehcache/internal/store/tiering/CacheStoreTest.java
index a5e468d288..b64c65ec75 100644
--- a/impl/src/test/java/org/ehcache/internal/store/tiering/CacheStoreTest.java
+++ b/impl/src/test/java/org/ehcache/internal/store/tiering/CacheStoreTest.java
@@ -639,6 +639,44 @@ public void run() {
         org.mockito.Matchers.<String>any(), org.mockito.Matchers.<Function<String, Store.ValueHolder<String>>>anyObject());
   }
 
+  @Test
+  public void AuthoritativeTierNullCheckDuringFlush() throws CacheAccessException, BrokenBarrierException, InterruptedException {
+
+
+    final CachingTier<String, String> cachingTier = mock(CachingTier.class);
+    final AuthoritativeTier<String, String> authoritativeTier = mock(AuthoritativeTier.class);
+
+    final CacheStore<String, String> cacheStore = new CacheStore<String, String>(cachingTier, authoritativeTier);
+
+    final CyclicBarrier barrier = new CyclicBarrier(2);
+
+    doAnswer(new Answer<Void>() {
+      @Override
+      public Void answer(final InvocationOnMock invocation) throws Throwable {
+        barrier.await();
+        barrier.await();
+        return null;
+      }
+    }).when(authoritativeTier).clear();
+    Thread t = new Thread(new Runnable() {
+      @Override
+      public void run() {
+        try {
+          cacheStore.clear();
+        } catch (Exception e) {
+          throw new RuntimeException(e);
+        }
+      }
+    });
+
+    t.start();
+    barrier.await();
+    cacheStore.get("foo");
+    barrier.await();
+    t.join();
+    verify(stringAuthoritativeTier, never()).flush("foo", null);
+  }
+
   public Map.Entry<? extends Number, ? extends CharSequence> newMapEntry(Number key, CharSequence value) {
     return new AbstractMap.SimpleEntry<Number, CharSequence>(key, value);
   }