Add @CanIgnoreReturnValue annotations

caffeine/src/main/java/com/github/benmanes/caffeine/cache/Caffeine.java

@@ -46,6 +46,7 @@
 import com.github.benmanes.caffeine.cache.stats.CacheStats;
 import com.github.benmanes.caffeine.cache.stats.ConcurrentStatsCounter;
 import com.github.benmanes.caffeine.cache.stats.StatsCounter;
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.FormatMethod;
 
 /**
@@ -291,6 +292,7 @@ public static Caffeine<Object, Object> from(String spec) {
    * @throws IllegalArgumentException if {@code initialCapacity} is negative
    * @throws IllegalStateException if an initial capacity was already set
    */
+  @CanIgnoreReturnValue
   public Caffeine<K, V> initialCapacity(@NonNegative int initialCapacity) {
     requireState(this.initialCapacity == UNSET_INT,
         "initial capacity was already set to %s", this.initialCapacity);
@@ -324,6 +326,7 @@ int getInitialCapacity() {
    * @return this {@code Caffeine} instance (for chaining)
    * @throws NullPointerException if the specified executor is null
    */
+  @CanIgnoreReturnValue
   public Caffeine<K, V> executor(Executor executor) {
     requireState(this.executor == null, "executor was already set to %s", this.executor);
     this.executor = requireNonNull(executor);
@@ -355,6 +358,7 @@ Executor getExecutor() {
    * @return this {@code Caffeine} instance (for chaining)
    * @throws NullPointerException if the specified scheduler is null
    */
+  @CanIgnoreReturnValue
   public Caffeine<K, V> scheduler(Scheduler scheduler) {
     requireState(this.scheduler == null, "scheduler was already set to %s", this.scheduler);
     this.scheduler = requireNonNull(scheduler);
@@ -389,6 +393,7 @@ Scheduler getScheduler() {
    * @throws IllegalArgumentException if {@code size} is negative
    * @throws IllegalStateException if a maximum size or weight was already set
    */
+  @CanIgnoreReturnValue
   public Caffeine<K, V> maximumSize(@NonNegative long maximumSize) {
     requireState(this.maximumSize == UNSET_INT,
         "maximum size was already set to %s", this.maximumSize);
@@ -425,6 +430,7 @@ public Caffeine<K, V> maximumSize(@NonNegative long maximumSize) {
    * @throws IllegalArgumentException if {@code maximumWeight} is negative
    * @throws IllegalStateException if a maximum weight or size was already set
    */
+  @CanIgnoreReturnValue
   public Caffeine<K, V> maximumWeight(@NonNegative long maximumWeight) {
     requireState(this.maximumWeight == UNSET_INT,
         "maximum weight was already set to %s", this.maximumWeight);
@@ -465,6 +471,7 @@ public Caffeine<K, V> maximumWeight(@NonNegative long maximumWeight) {
    *         remaining configuration and cache building
    * @throws IllegalStateException if a weigher was already set
    */
+  @CanIgnoreReturnValue
   public <K1 extends K, V1 extends V> Caffeine<K1, V1> weigher(
       Weigher<? super K1, ? super V1> weigher) {
     requireNonNull(weigher);
@@ -517,6 +524,7 @@ <K1 extends K, V1 extends V> Weigher<K1, V1> getWeigher(boolean isAsync) {
    * @return this {@code Caffeine} instance (for chaining)
    * @throws IllegalStateException if the key strength was already set
    */
+  @CanIgnoreReturnValue
   public Caffeine<K, V> weakKeys() {
     requireState(keyStrength == null, "Key strength was already set to %s", keyStrength);
     keyStrength = Strength.WEAK;
@@ -546,6 +554,7 @@ boolean isStrongKeys() {
    * @return this {@code Caffeine} instance (for chaining)
    * @throws IllegalStateException if the value strength was already set
    */
+  @CanIgnoreReturnValue
   public Caffeine<K, V> weakValues() {
     requireState(valueStrength == null, "Value strength was already set to %s", valueStrength);
     valueStrength = Strength.WEAK;
@@ -582,6 +591,7 @@ boolean isWeakValues() {
    * @return this {@code Caffeine} instance (for chaining)
    * @throws IllegalStateException if the value strength was already set
    */
+  @CanIgnoreReturnValue
   public Caffeine<K, V> softValues() {
     requireState(valueStrength == null, "Value strength was already set to %s", valueStrength);
     valueStrength = Strength.SOFT;
@@ -604,6 +614,7 @@ public Caffeine<K, V> softValues() {
    * @throws IllegalStateException if the time to live or variable expiration was already set
    * @throws ArithmeticException for durations greater than +/- approximately 292 years
    */
+  @CanIgnoreReturnValue
   public Caffeine<K, V> expireAfterWrite(Duration duration) {
     return expireAfterWrite(saturatedToNanos(duration), TimeUnit.NANOSECONDS);
   }
@@ -627,6 +638,7 @@ public Caffeine<K, V> expireAfterWrite(Duration duration) {
    * @throws IllegalArgumentException if {@code duration} is negative
    * @throws IllegalStateException if the time to live or variable expiration was already set
    */
+  @CanIgnoreReturnValue
   public Caffeine<K, V> expireAfterWrite(@NonNegative long duration, TimeUnit unit) {
     requireState(expireAfterWriteNanos == UNSET_INT,
         "expireAfterWrite was already set to %s ns", expireAfterWriteNanos);
@@ -663,6 +675,7 @@ boolean expiresAfterWrite() {
    * @throws IllegalStateException if the time to idle or variable expiration was already set
    * @throws ArithmeticException for durations greater than +/- approximately 292 years
    */
+  @CanIgnoreReturnValue
   public Caffeine<K, V> expireAfterAccess(Duration duration) {
     return expireAfterAccess(saturatedToNanos(duration), TimeUnit.NANOSECONDS);
   }
@@ -689,6 +702,7 @@ public Caffeine<K, V> expireAfterAccess(Duration duration) {
    * @throws IllegalArgumentException if {@code duration} is negative
    * @throws IllegalStateException if the time to idle or variable expiration was already set
    */
+  @CanIgnoreReturnValue
   public Caffeine<K, V> expireAfterAccess(@NonNegative long duration, TimeUnit unit) {
     requireState(expireAfterAccessNanos == UNSET_INT,
         "expireAfterAccess was already set to %s ns", expireAfterAccessNanos);
@@ -733,6 +747,7 @@ boolean expiresAfterAccess() {
    * @return this {@code Caffeine} instance (for chaining)
    * @throws IllegalStateException if expiration was already set
    */
+  @CanIgnoreReturnValue
   public <K1 extends K, V1 extends V> Caffeine<K1, V1> expireAfter(
       Expiry<? super K1, ? super V1> expiry) {
     requireNonNull(expiry);
@@ -779,6 +794,7 @@ boolean expiresVariable() {
    * @throws IllegalStateException if the refresh interval was already set
    * @throws ArithmeticException for durations greater than +/- approximately 292 years
    */
+  @CanIgnoreReturnValue
   public Caffeine<K, V> refreshAfterWrite(Duration duration) {
     return refreshAfterWrite(saturatedToNanos(duration), TimeUnit.NANOSECONDS);
   }
@@ -806,6 +822,7 @@ public Caffeine<K, V> refreshAfterWrite(Duration duration) {
    * @throws IllegalArgumentException if {@code duration} is zero or negative
    * @throws IllegalStateException if the refresh interval was already set
    */
+  @CanIgnoreReturnValue
   public Caffeine<K, V> refreshAfterWrite(@NonNegative long duration, TimeUnit unit) {
     requireNonNull(unit);
     requireState(refreshAfterWriteNanos == UNSET_INT,
@@ -835,6 +852,7 @@ boolean refreshAfterWrite() {
    * @throws IllegalStateException if a ticker was already set
    * @throws NullPointerException if the specified ticker is null
    */
+  @CanIgnoreReturnValue
   public Caffeine<K, V> ticker(Ticker ticker) {
     requireState(this.ticker == null, "Ticker was already set to %s", this.ticker);
     this.ticker = requireNonNull(ticker);
@@ -883,6 +901,7 @@ Ticker getTicker() {
    * @throws IllegalStateException if a removal listener was already set
    * @throws NullPointerException if the specified removal listener is null
    */
+  @CanIgnoreReturnValue
   public <K1 extends K, V1 extends V> Caffeine<K1, V1> evictionListener(
       RemovalListener<? super K1, ? super V1> evictionListener) {
     requireState(this.evictionListener == null,
@@ -934,6 +953,7 @@ public <K1 extends K, V1 extends V> Caffeine<K1, V1> evictionListener(
    * @throws IllegalStateException if a removal listener was already set
    * @throws NullPointerException if the specified removal listener is null
    */
+  @CanIgnoreReturnValue
   public <K1 extends K, V1 extends V> Caffeine<K1, V1> removalListener(
       RemovalListener<? super K1, ? super V1> removalListener) {
     requireState(this.removalListener == null,
@@ -961,6 +981,7 @@ public <K1 extends K, V1 extends V> Caffeine<K1, V1> removalListener(
    *
    * @return this {@code Caffeine} instance (for chaining)
    */
+  @CanIgnoreReturnValue
   public Caffeine<K, V> recordStats() {
     requireState(this.statsCounterSupplier == null, "Statistics recording was already set");
     statsCounterSupplier = ENABLED_STATS_COUNTER_SUPPLIER;
@@ -977,6 +998,7 @@ public Caffeine<K, V> recordStats() {
    * @param statsCounterSupplier a supplier instance that returns a new {@link StatsCounter}
    * @return this {@code Caffeine} instance (for chaining)
    */
+  @CanIgnoreReturnValue
   public Caffeine<K, V> recordStats(Supplier<? extends StatsCounter> statsCounterSupplier) {
     requireState(this.statsCounterSupplier == null, "Statistics recording was already set");
     requireNonNull(statsCounterSupplier);

caffeine/src/main/java/com/github/benmanes/caffeine/cache/Weigher.java

@@ -53,8 +53,8 @@ public interface Weigher<K, V> {
    */
   static <K, V> Weigher<K, V> singletonWeigher() {
     @SuppressWarnings("unchecked")
-    Weigher<K, V> self = (Weigher<K, V>) SingletonWeigher.INSTANCE;
-    return self;
+    Weigher<K, V> instance = (Weigher<K, V>) SingletonWeigher.INSTANCE;
+    return instance;
   }
 
   /**

caffeine/src/test/java/com/github/benmanes/caffeine/cache/CaffeineSpecGuavaTest.java

@@ -32,7 +32,7 @@
  *
  * @author Adam Winer
  */
-@SuppressWarnings({"CheckReturnValue", "PreferJavaTimeOverload"})
+@SuppressWarnings("PreferJavaTimeOverload")
 public class CaffeineSpecGuavaTest extends TestCase {
 
   public void testParse_empty() {

caffeine/src/test/java/com/github/benmanes/caffeine/cache/testing/CacheContextSubject.java

@@ -55,6 +55,7 @@
 import com.google.common.truth.FailureMetadata;
 import com.google.common.truth.StandardSubjectBuilder;
 import com.google.common.truth.Subject;
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
 
 /**
  * Propositions for {@link CacheContext} subjects.
@@ -219,30 +220,37 @@ private StatsSubject(FailureMetadata metadata, CacheContext context) {
           || (context.executorType() == CacheExecutor.DIRECT);
     }
 
+    @CanIgnoreReturnValue
     public StatsSubject hits(long count) {
       return awaitStatistic("hitCount", CacheStats::hitCount, count);
     }
 
+    @CanIgnoreReturnValue
     public StatsSubject misses(long count) {
       return awaitStatistic("missCount", CacheStats::missCount, count);
     }
 
+    @CanIgnoreReturnValue
     public StatsSubject evictions(long count) {
       return awaitStatistic("evictionCount", CacheStats::evictionCount, count);
     }
 
+    @CanIgnoreReturnValue
     public StatsSubject evictionWeight(long count) {
       return awaitStatistic("evictionWeight", CacheStats::evictionWeight, count);
     }
 
+    @CanIgnoreReturnValue
     public StatsSubject success(long count) {
       return awaitStatistic("loadSuccessCount", CacheStats::loadSuccessCount, count);
     }
 
+    @CanIgnoreReturnValue
     public StatsSubject failures(long count) {
       return awaitStatistic("loadFailureCount", CacheStats::loadFailureCount, count);
     }
 
+    @CanIgnoreReturnValue
     private StatsSubject awaitStatistic(String label,
         ToLongFunction<CacheStats> supplier, long expectedValue) {
       if (isDirect) {

caffeine/src/test/java/com/github/benmanes/caffeine/cache/testing/ExpiryBuilder.java

@@ -20,6 +20,7 @@
 import java.io.Serializable;
 
 import com.github.benmanes.caffeine.cache.Expiry;
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
 
 /**
  * A builder for unit test convenience.
@@ -45,12 +46,14 @@ public static ExpiryBuilder expiringAfterCreate(long nanos) {
   }
 
   /** Sets the fixed update expiration time. */
+  @CanIgnoreReturnValue
   public ExpiryBuilder expiringAfterUpdate(long nanos) {
     updateNanos = nanos;
     return this;
   }
 
   /** Sets the fixed read expiration time. */
+  @CanIgnoreReturnValue
   public ExpiryBuilder expiringAfterRead(long nanos) {
     readNanos = nanos;
     return this;

examples/write-behind-rxjava/src/main/java/com/github/benmanes/caffeine/examples/writebehind/rxjava/WriteBehindCacheWriter.java

@@ -27,6 +27,8 @@
 
 import io.reactivex.subjects.PublishSubject;
 
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
+
 /**
  * This class allows a cache to have "write-behind" semantics. The passed in writeAction will only
  * be called every 'bufferTime' time with a Map containing the keys and the values that have been
@@ -67,18 +69,21 @@ public static final class Builder<K, V> {
      * The duration that the calls to the cache should be buffered before calling the
      * <code>writeAction</code>.
      */
+    @CanIgnoreReturnValue
     public Builder<K, V> bufferTime(long duration, TimeUnit unit) {
       this.bufferTimeNanos = TimeUnit.NANOSECONDS.convert(duration, unit);
       return this;
     }
 
     /** The callback to perform the writing to the database or repository. */
+    @CanIgnoreReturnValue
     public Builder<K, V> writeAction(Consumer<Map<K, V>> writeAction) {
       this.writeAction = requireNonNull(writeAction);
       return this;
     }
 
     /** The action that decides which value to take in case a key was updated multiple times. */
+    @CanIgnoreReturnValue
     public Builder<K, V> coalesce(BinaryOperator<V> coalescer) {
       this.coalescer = requireNonNull(coalescer);
       return this;

gradle/codeQuality.gradle

@@ -170,7 +170,7 @@ tasks.withType(JavaCompile).configureEach {
       'LexicographicalAnnotationListing', 'MissingSummary', 'StaticImport' ]
     disabledChecks.each { disable(it) }
 
-    def errorChecks = [ 'NullAway' ]
+    def errorChecks = [ 'CanIgnoreReturnValueSuggester', 'NullAway' ]
     errorChecks.each { error(it) }
 
     nullaway {

guava/src/main/java/com/github/benmanes/caffeine/guava/CaffeinatedGuavaCache.java

@@ -40,6 +40,7 @@
 import com.google.common.collect.ImmutableMap;
 import com.google.common.util.concurrent.ExecutionError;
 import com.google.common.util.concurrent.UncheckedExecutionException;
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
 
 /**
  * A Caffeine-backed cache through a Guava facade.
@@ -240,6 +241,7 @@ static final class CacheLoaderException extends RuntimeException {
     CacheLoaderException(Exception e) {
       super(e);
     }
+    @CanIgnoreReturnValue
     @SuppressWarnings({"lgtm [java/non-sync-override]", "UnsynchronizedOverridesSynchronized"})
     @Override public Throwable fillInStackTrace() {
       return this;

guava/src/main/java/com/github/benmanes/caffeine/guava/CaffeinatedGuavaLoadingCache.java

@@ -123,7 +123,7 @@ public V apply(K key) {
   }
 
   @Override
-  @SuppressWarnings({"CheckReturnValue", "FutureReturnValueIgnored"})
+  @SuppressWarnings("FutureReturnValueIgnored")
   public void refresh(K key) {
     cache.refresh(key);
   }

guava/src/test/java/com/github/benmanes/caffeine/guava/compatibility/CacheBuilderFactory.java

@@ -29,14 +29,14 @@
 import com.google.common.collect.Lists;
 import com.google.common.collect.Sets;
 import com.google.common.util.concurrent.MoreExecutors;
+import com.google.errorprone.annotations.CanIgnoreReturnValue;
 
 /**
  * Helper class for creating {@link CacheBuilder} instances with all combinations of several sets of
  * parameters.
  *
  * @author mike nonemacher
  */
-@SuppressWarnings({"CanIgnoreReturnValueSuggester", "CheckReturnValue"})
 class CacheBuilderFactory {
   // Default values contain only 'null', which means don't call the CacheBuilder method (just give
   // the CacheBuilder default).
@@ -49,42 +49,50 @@ class CacheBuilderFactory {
   private Set<Strength> keyStrengths = Sets.newHashSet((Strength) null);
   private Set<Strength> valueStrengths = Sets.newHashSet((Strength) null);
 
+  @CanIgnoreReturnValue
   CacheBuilderFactory withConcurrencyLevels(Set<Integer> concurrencyLevels) {
     this.concurrencyLevels = Sets.newLinkedHashSet(concurrencyLevels);
     return this;
   }
 
+  @CanIgnoreReturnValue
   CacheBuilderFactory withInitialCapacities(Set<Integer> initialCapacities) {
     this.initialCapacities = Sets.newLinkedHashSet(initialCapacities);
     return this;
   }
 
+  @CanIgnoreReturnValue
   CacheBuilderFactory withMaximumSizes(Set<Integer> maximumSizes) {
     this.maximumSizes = Sets.newLinkedHashSet(maximumSizes);
     return this;
   }
 
+  @CanIgnoreReturnValue
   CacheBuilderFactory withExpireAfterWrites(Set<DurationSpec> durations) {
     this.expireAfterWrites = Sets.newLinkedHashSet(durations);
     return this;
   }
 
+  @CanIgnoreReturnValue
   CacheBuilderFactory withExpireAfterAccesses(Set<DurationSpec> durations) {
     this.expireAfterAccesses = Sets.newLinkedHashSet(durations);
     return this;
   }
 
+  @CanIgnoreReturnValue
   CacheBuilderFactory withRefreshes(Set<DurationSpec> durations) {
     this.refreshes = Sets.newLinkedHashSet(durations);
     return this;
   }
 
+  @CanIgnoreReturnValue
   CacheBuilderFactory withKeyStrengths(Set<Strength> keyStrengths) {
     this.keyStrengths = Sets.newLinkedHashSet(keyStrengths);
     Preconditions.checkArgument(!this.keyStrengths.contains(Strength.SOFT));
     return this;
   }
 
+  @CanIgnoreReturnValue
   CacheBuilderFactory withValueStrengths(Set<Strength> valueStrengths) {
     this.valueStrengths = Sets.newLinkedHashSet(valueStrengths);
     return this;