Add putIfAbsent optimistic fastpath (#506)

ben-manes · Feb 23, 2021 · f5a5e32 · f5a5e32
1 parent 9cc266a
commit f5a5e32
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Showing 2 changed files with 23 additions and 1 deletion.
diff --git a/build.gradle b/build.gradle
@@ -42,7 +42,7 @@ allprojects {
   version.with {
     major = 2 // incompatible API changes
     minor = 9 // backwards-compatible additions
-    patch = 0 // backwards-compatible bug fixes
+    patch = 1 // backwards-compatible bug fixes
     releaseBuild = rootProject.hasProperty('release')
   }
 }

diff --git a/caffeine/src/main/java/com/github/benmanes/caffeine/cache/BoundedLocalCache.java b/caffeine/src/main/java/com/github/benmanes/caffeine/cache/BoundedLocalCache.java
@@ -2029,12 +2029,34 @@ public Map<K, V> getAllPresent(Iterable<?> keys) {
           if (prior == node) {
             afterWrite(new AddTask(node, newWeight));
             return null;
+          } else if (onlyIfAbsent) {
+            // An optimistic fast path to avoid unnecessary locking
+            V currentValue = prior.getValue();
+            if ((currentValue != null) && !hasExpired(prior, now)) {
+              if (!isComputingAsync(prior)) {
+                tryExpireAfterRead(prior, key, currentValue, expiry(), now);
+                setAccessTime(prior, now);
+              }
+              afterRead(prior, now, /* recordHit */ false);
+              return currentValue;
+            }
           }
         } else {
           prior = data.putIfAbsent(node.getKeyReference(), node);
           if (prior == null) {
             afterWrite(new AddTask(node, newWeight));
             return null;
+          } else if (onlyIfAbsent) {
+            // An optimistic fast path to avoid unnecessary locking
+            V currentValue = prior.getValue();
+            if ((currentValue != null) && !hasExpired(prior, now)) {
+              if (!isComputingAsync(prior)) {
+                tryExpireAfterRead(prior, key, currentValue, expiry(), now);
+                setAccessTime(prior, now);
+              }
+              afterRead(prior, now, /* recordHit */ false);
+              return currentValue;
+            }
           }
         }
       } else if (onlyIfAbsent) {