Add HuntBugs static analyzer and fix warnings

HuntBugs is the unofficial successor to Findbugs on a clean code base.
The remaining warnings are all false positives and not sure how to
suppress individually. It did find a few mistakes where the array was
checked for null, rather than its element (weak key null guard).

See https://github.com/amaembo/huntbugs for details.

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

@@ -1634,7 +1634,7 @@ V putSlow(K key, V value, int newWeight, boolean notifyWriter, boolean onlyIfAbs
  nodeKey[0] = n.getKey();
  oldValue[0] = n.getValue();
  oldWeight[0] = n.getWeight();
- if ((nodeKey == null) || (oldValue[0] == null)) {
+ if ((nodeKey[0] == null) || (oldValue[0] == null)) {
  cause[0] = RemovalCause.COLLECTED;
  } else if (hasExpired(n, now)) {
  cause[0] = RemovalCause.EXPIRED;
@@ -1994,7 +1994,7 @@ V doComputeIfAbsent(K key, Object keyRef,
  nodeKey[0] = n.getKey();
  weight[0] = n.getWeight();
  oldValue[0] = n.getValue();
- if ((nodeKey == null) || (oldValue[0] == null)) {
+ if ((nodeKey[0] == null) || (oldValue[0] == null)) {
  cause[0] = RemovalCause.COLLECTED;
  } else if (hasExpired(n, now)) {
  cause[0] = RemovalCause.EXPIRED;
@@ -2141,7 +2141,7 @@ V remap(K key, Object keyRef, BiFunction<? super K, ? super V, ? extends V> rema
  synchronized (n) {
  nodeKey[0] = n.getKey();
  oldValue[0] = n.getValue();
- if ((nodeKey == null) || (oldValue[0] == null)) {
+ if ((nodeKey[0] == null) || (oldValue[0] == null)) {
  cause[0] = RemovalCause.COLLECTED;
  } else if (hasExpired(n, now)) {
  cause[0] = RemovalCause.EXPIRED;

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

@@ -182,7 +182,7 @@ void configure(String key, @Nullable String value) {
  maximumWeight(key, value);
  return;
  case "weakKeys":
- weakKeys(key, value);
+ weakKeys(value);
  return;
  case "weakValues":
  valueStrength(key, value, Strength.WEAK);
@@ -200,7 +200,7 @@ void configure(String key, @Nullable String value) {
  refreshAfterWrite(key, value);
  return;
  case "recordStats":
- recordStats(key, value);
+ recordStats(value);
  return;
  default:
  throw new IllegalArgumentException("Unknown key " + key);
@@ -233,7 +233,7 @@ void maximumWeight(String key, String value) {
  }
 
  /** Configures the keys as weak references. */
- void weakKeys(String key, @Nullable String value) {
+ void weakKeys(@Nullable String value) {
  requireArgument(value == null, "weak keys does not take a value");
  requireArgument(keyStrength == null, "weak keys was already set");
  keyStrength = Strength.WEAK;
@@ -268,7 +268,7 @@ void refreshAfterWrite(String key, String value) {
  }
 
  /** Configures the value as weak or soft references. */
- void recordStats(String key, @Nullable String value) {
+ void recordStats(@Nullable String value) {
  requireArgument(value == null, "record stats does not take a value");
  requireArgument(!recordStats, "record stats was already set");
  recordStats = true;

gradle/code_quality.gradle

@@ -2,6 +2,7 @@
  * Configurations for code quality analysis
  */
 apply plugin: 'org.kordamp.gradle.stats'
+apply plugin: 'one.util.huntbugs'
 apply plugin: 'checkstyle'
 apply plugin: 'findbugs'
 apply plugin: 'jacoco'
@@ -32,6 +33,12 @@ checkstyle {
  config = resources.text.fromArchiveEntry(configurations.checkstyleConfig, 'google_checks.xml')
 }
 
+huntbugs {
+ classSimpleFilter { classname ->
+ !classname.contains('Header') && !classname.contains('Mpsc') && !classname.contains('Factory')
+ }
+}
+
 findbugs {
  effort = 'max'
  excludeFilter = file("${rootDir}/config/findbugs/exclude.xml")

gradle/dependencies.gradle

@@ -73,6 +73,8 @@ ext {
  coveralls: '2.6.3',
  extra_conf: '3.1.0',
  error_prone: '0.0.8',
+ huntbugs_core: '0.0.11',
+ huntbugs_plugin: '0.3.5',
  jmh: '0.3.0',
  nexus: '2.3.1',
  pmd: '5.5.1',
@@ -164,6 +166,10 @@ ext {
  coveralls: "org.kt3k.gradle.plugin:coveralls-gradle-plugin:${plugin_versions.coveralls}",
  extra_conf: "com.netflix.nebula:gradle-extra-configurations-plugin:${plugin_versions.extra_conf}",
  error_prone: "net.ltgt.gradle:gradle-errorprone-plugin:${plugin_versions.error_prone}",
+ huntbugs: [
+ "one.util:huntbugs:${plugin_versions.huntbugs_core}",
+ "gradle.plugin.one.util.huntbugs:huntbugs-gradle-plugin:${plugin_versions.huntbugs_plugin}",
+ ],
  jmh: "gradle.plugin.me.champeau.gradle:jmh-gradle-plugin:${plugin_versions.jmh}",
  nexus: "com.bmuschko:gradle-nexus-plugin:${plugin_versions.nexus}",
  semantic_versioning: "io.ehdev:gradle-semantic-versioning:${plugin_versions.semantic_versioning}",

simulator/src/main/java/com/github/benmanes/caffeine/cache/simulator/admission/table/RandomRemovalFrequencyTable.java

@@ -81,7 +81,7 @@ public void increment(long e) {
  // just a model.
  if (currSum == maxSum) {
  List<Long> array = new ArrayList<>(table.keySet());
- long itemToRemove = array.get(random.nextInt(array.size()));
+ Long itemToRemove = array.get(random.nextInt(array.size()));
  value = table.remove(itemToRemove);
 
  if (value > 1) {

simulator/src/main/java/com/github/benmanes/caffeine/cache/simulator/admission/tinycache/HashFunctionParser.java

@@ -50,7 +50,7 @@ public HashedItem createHash(long item) {
  h ^= item;
  h *= m;
 
- fpaux.fingerprint = (byte) (h & fpMask);
+ fpaux.fingerprint = (byte) h;
  // the next line is a dirty fix as I do not want the value of 0 as a fingerprint.
  // It can be eliminated if we want very short fingerprints.
  fpaux.fingerprint = (fpaux.fingerprint == 0L) ? 1 : fpaux.fingerprint;

simulator/src/main/java/com/github/benmanes/caffeine/cache/simulator/admission/tinycache/TinyCacheAdapter.java

@@ -27,8 +27,6 @@
 public final class TinyCacheAdapter implements Frequency {
  // the actual data structure.
  TinyCacheSketch tcs;
- // number of (independent sets)
- int nrSets;
  // size between cache and sample.
  static final int sampleFactor = 10;
  // max frequency estimation of an item.
@@ -39,7 +37,7 @@ public final class TinyCacheAdapter implements Frequency {
  */
  public TinyCacheAdapter(Config config) {
  BasicSettings settings = new BasicSettings(config);
- nrSets = sampleFactor * settings.maximumSize() / 64;
+ int nrSets = sampleFactor * settings.maximumSize() / 64; // number of (independent sets)
  tcs = new TinyCacheSketch(nrSets, 64,settings.randomSeed());
  }
 

simulator/src/main/java/com/github/benmanes/caffeine/cache/simulator/admission/tinycache/TinyCacheWithGhostCache.java

@@ -26,13 +26,14 @@
  */
 @SuppressWarnings("PMD.AvoidDollarSigns")
 public final class TinyCacheWithGhostCache {
+ private static final int sampleSize = 10;
+
  public final long[] chainIndex;
  public final long[] isLastIndex;
  private final HashFunctionParser hashFunc;
  private final int itemsPerSet;
  private final long[] cache;
  private final Random rnd;
- private final int sampleSize;
  private final TinyCacheSketch ghostCache;
 
  public TinyCacheWithGhostCache(int nrSets, int itemsPerSet, int randomSeed) {
@@ -41,7 +42,6 @@ public TinyCacheWithGhostCache(int nrSets, int itemsPerSet, int randomSeed) {
  hashFunc = new HashFunctionParser(nrSets);
  this.itemsPerSet = itemsPerSet;
  cache = new long[nrSets * itemsPerSet];
- sampleSize = 10;
  ghostCache = new TinyCacheSketch(nrSets * sampleSize, itemsPerSet, randomSeed + 1);
  rnd = new Random(randomSeed);
  }

simulator/src/main/java/com/github/benmanes/caffeine/cache/simulator/policy/linked/MultiQueuePolicy.java

@@ -138,6 +138,10 @@ private void evict() {
  break;
  }
  }
+ if (victim == null) {
+ return;
+ }
+
  victim.remove();
  data.remove(victim.key);
  out.put(victim.key, victim);