Package com.apple.foundationdb.record

Interface PlanHashable

All Known Subinterfaces:

AtomKeyExpression, Comparisons.Comparison, ComponentWithChildren, ComponentWithComparison, ComponentWithNoChildren, ComponentWithSingleChild, KeyExpression, KeyExpressionWithChild, KeyExpressionWithChildren, KeyExpressionWithoutChildren, KeyExpressionWithValue, PredicateWithValue, QueryableKeyExpression, QueryComponent, QueryPlan<T>, QueryPredicate, RecordQueryLoadByKeysPlan.KeysSource, RecordQueryPlan, RecordQueryPlanWithChild, RecordQueryPlanWithChildren, RecordQueryPlanWithComparisons, RecordQueryPlanWithIndex, RecordQueryPlanWithNoChildren, RecordQueryPlanWithRequiredFields, SyntheticRecordFromStoredRecordPlan, SyntheticRecordPlan, Value

All Known Implementing Classes:

AndComponent, AndOrComponent, AndOrPredicate, AndPredicate, BaseField, BaseKeyExpression, BaseNestedField, BaseValue, CollateFunctionKeyExpression, CollateFunctionKeyExpressionFactoryJRE.CollateFunctionKeyExpressionJRE, ComparisonRange, Comparisons.ListComparison, Comparisons.MultiColumnComparison, Comparisons.NullComparison, Comparisons.ParameterComparison, Comparisons.SimpleComparison, Comparisons.TextComparison, Comparisons.TextContainsAllPrefixesComparison, Comparisons.TextWithMaxDistanceComparison, ComposedBitmapIndexQueryPlan, ComposedBitmapIndexQueryPlan.ComposerBase, ConstantPredicate, EmptyComparison, EmptyKeyExpression, ExistsPredicate, FieldKeyExpression, FieldValue, FieldWithComparison, FunctionKeyExpression, GroupingKeyExpression, IndexAggregateFunction, IndexRecordFunction, IndexScanType, KeyWithValueExpression, ListKeyExpression, LiteralKeyExpression, LiteralValue, NestedField, NestingKeyExpression, NotComponent, NotPredicate, ObjectPlanHash, OneOfThemWithComparison, OneOfThemWithComponent, OrComponent, OrPredicate, QuantifiedColumnValue, QuantifiedObjectValue, QueryComponentPredicate, QueryKeyExpressionWithComparison, QueryPlanResult, QueryRecordFunction, QueryRecordFunctionWithComparison, RecordFunction, RecordQueryCoveringIndexPlan, RecordQueryFetchFromPartialRecordPlan, RecordQueryFilterPlan, RecordQueryIndexPlan, RecordQueryInJoinPlan, RecordQueryInParameterJoinPlan, RecordQueryIntersectionPlan, RecordQueryInValuesJoinPlan, RecordQueryLoadByKeysPlan, RecordQueryPredicateFilterPlan, RecordQueryScanPlan, RecordQueryScoreForRankPlan, RecordQueryScoreForRankPlan.ScoreForRank, RecordQueryTextIndexPlan, RecordQueryTypeFilterPlan, RecordQueryUnionPlan, RecordQueryUnionPlanBase, RecordQueryUnorderedDistinctPlan, RecordQueryUnorderedPrimaryKeyDistinctPlan, RecordQueryUnorderedUnionPlan, RecordTypeKeyComparison, RecordTypeKeyExpression, RecordTypeValue, ScanComparisons, ScanComparisons.Builder, SplitKeyExpression, StoreRecordFunction, TextScan, ThenKeyExpression, TimeWindowAggregateFunction, TimeWindowRecordFunction, ValueComparisonRangePredicate, ValueComparisonRangePredicate.Placeholder, ValueComparisonRangePredicate.Sargable, ValuePredicate, VersionKeyExpression, VersionValue

@API(UNSTABLE)
public interface PlanHashable

A more stable version of Object.hashCode(). The planHash semantics are different than Object.hashCode() in a few ways:

• planHash() values should be stable across runtime instance changes. The reason is that these values can be used to validate outstanding continuations, and a change in hash value caused by an application restart or refactoring will invalidate all those outstanding continuations
• planHash() supports multiple flavors of hash calculations (See PlanHashable.PlanHashKind). The various kinds of plan hash algorithms are used for different purposes and include/exclude different parts of the target query plan
• planHash() is meant to imply a certain identity of a plan, and reflects on the entire structure of the plan. The intent is to be able to correlate various plans for "identity" (using different definitions for this identity as specified by PlanHashable.PlanHashKind). This requirement drives a desire to reduce collisions as much as possible since not in all cases can we actually use "equals" to verify identity (e.g. log messages)

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static class	PlanHashable.PlanHashKind	The "kinds" of planHash calculations.

Method Summary

Modifier and Type	Method	Description
static int	combineHashes(List<Integer> hashes)
static int	iterablePlanHash(PlanHashable.PlanHashKind hashKind, Iterable<?> objects)
static int	objectPlanHash(PlanHashable.PlanHashKind hashKind, Object obj)
static int	objectsPlanHash(PlanHashable.PlanHashKind hashKind, Object... objects)
default int	planHash()
int	planHash(PlanHashable.PlanHashKind hashKind)	Return a hash similar to hashCode, but with the additional guarantee that is is stable across JVMs.
static int	planHash(PlanHashable.PlanHashKind hashKind, PlanHashable... hashables)
static int	planHash(PlanHashable.PlanHashKind hashKind, Iterable<? extends PlanHashable> hashables)
static int	planHashUnordered(PlanHashable.PlanHashKind hashKind, Iterable<? extends PlanHashable> hashables)
static int	primitiveArrayHash(Object primitiveArray)
static int	stringHashUnordered(Iterable<String> strings)

Method Detail

planHash

int planHash(@Nonnull
             PlanHashable.PlanHashKind hashKind)

Return a hash similar to hashCode, but with the additional guarantee that is is stable across JVMs.

Parameters:

hashKind - the "kind" of hash to calculate. Each kind of hash has a particular logic with regards to included and excluded items.

Returns:

a stable hash code

planHash

default int planHash()

planHash

static int planHash(@Nonnull
                    PlanHashable.PlanHashKind hashKind,
                    @Nonnull
                    Iterable<? extends PlanHashable> hashables)

planHash

static int planHash(@Nonnull
                    PlanHashable.PlanHashKind hashKind,
                    PlanHashable... hashables)

planHashUnordered

static int planHashUnordered(@Nonnull
                             PlanHashable.PlanHashKind hashKind,
                             @Nonnull
                             Iterable<? extends PlanHashable> hashables)

stringHashUnordered

static int stringHashUnordered(@Nonnull
                               Iterable<String> strings)

combineHashes

static int combineHashes(@Nonnull
                         List<Integer> hashes)

objectPlanHash

static int objectPlanHash(@Nonnull
                          PlanHashable.PlanHashKind hashKind,
                          @Nullable
                          Object obj)

iterablePlanHash

static int iterablePlanHash(@Nonnull
                            PlanHashable.PlanHashKind hashKind,
                            @Nonnull
                            Iterable<?> objects)

objectsPlanHash

static int objectsPlanHash(@Nonnull
                           PlanHashable.PlanHashKind hashKind,
                           Object... objects)

primitiveArrayHash

static int primitiveArrayHash(Object primitiveArray)