Chunks¶

Description¶

Chunk is the abstract base class representing a simple typed data buffer. These buffers are used to pass data to and from the library, e.g. as arguments to FillChunk or FillFromChunk.

The concrete implementing classes are defined by the templated class GenericChunk. For convenience we provide typedefs which instantiate GenericChunk on all the Deephaven types: Int8Chunk, Int16Chunk, Int32Chunk, Int64Chunk, FloatChunk, DoubleChunk, BooleanChunk, StringChunk, and DateTimeChunk.

GenericChunk also supports the methods Take and Drop to take slices of the GenericChunk.

AnyChunk¶

The AnyChunk class is a variant value type that can hold one of the concrete Chunk types described above. AnyChunk is useful in certain limited cases where a factory method needs to create a Chunk having a dynamically-determined type, not known at compile time. Of course this could also be accomplished by returning a heap-allocated pointer to a Chunk. The rationale for using the variant approach rather than the heap-allocated object approach is for the sake of simplicity and efficiency when using these small objects. One example method that returns an AnyChunk is CreateChunkFor, which creates a Chunk with a type appropriate to the passed-in ColumnSource, and wraps that dynamicaly-determined Chunk in an AnyChunk value.

Chunk Declarations¶

class Chunk¶

Abstract base class for Deephaven chunks. A Chunk represents a simple typed data buffer. It is used as an argument to methods like ColumnSource::FillChunk() and MutableColumnSource::FillFromChunk.

Subclassed by deephaven::dhcore::chunk::GenericChunk< T >

Public Functions

virtual void AcceptVisitor(ChunkVisitor *visitor) const = 0¶: Implementation of the visitor pattern.

inline size_t Size() const¶: The size of the Chunk.

template<typename T> class GenericChunk : public deephaven::dhcore::chunk::Chunk ¶

Concrete implementing class for Deephaven chunks.

Public Functions

GenericChunk() = default¶: Constructor.

GenericChunk(GenericChunk &&other) noexcept = default¶: Move constructor.

GenericChunk &operator=(GenericChunk &&other) noexcept = default¶: Move assignment operator.

~GenericChunk() final = default¶: Destructor.

GenericChunk Take(size_t size) const¶: Create a new GenericChunk that is a prefix of the current GenericChunk. The new object shares the same underlying buffer, but has new size ‘size’. ‘size’ is required to be less than or equal to the size of this object.

GenericChunk Drop(size_t size) const¶: Create a new GenericChunk that is a suffix of the current GenericChunk. The new object shares the same underlying buffer, but has new size (this->size() - size). ‘size’ is required to be less than or equal to the size of this object.

virtual void AcceptVisitor(ChunkVisitor *visitor) const final¶: Implementation of the visitor pattern.

inline T *data()¶: Returns a pointer to the start of the data represented by this GenericChunk.

inline const T *data() const¶: Returns a pointer to the start of the data represented by this GenericChunk.

inline T *begin()¶: Returns a pointer to the start of the data represented by this GenericChunk.

inline const T *begin() const¶: Returns a pointer to the start of the data represented by this GenericChunk.

inline T *end()¶: Returns a pointer to the (exlusive) end of the data represented by this GenericChunk.

inline const T *end() const¶: Returns a pointer to the (exlusive) end of the data represented by this GenericChunk.

inline T &operator[](size_t index)¶: Indexing operator.

inline const T &operator[](size_t index) const¶: Indexing operator.

Public Static Functions

static GenericChunk<T> Create(size_t size)¶: Factory method. Create a Chunk having the specified size, with a privately allocated buffer.

static GenericChunk<T> CreateView(T *data, size_t size)¶: Factory method. Create a Chunk on a buffer owned by the caller. The buffer must outlive this Chunk and all Chunks derived from this chunk (e.g. via take/drop).

using deephaven::dhcore::chunk::Int8Chunk = GenericChunk<int8_t>¶: Convenience typedef.

using deephaven::dhcore::chunk::Int16Chunk = GenericChunk<int16_t>¶: Convenience typedef.

using deephaven::dhcore::chunk::Int32Chunk = GenericChunk<int32_t>¶: Convenience typedef.

using deephaven::dhcore::chunk::Int64Chunk = GenericChunk<int64_t>¶: Convenience typedef.

using deephaven::dhcore::chunk::FloatChunk = GenericChunk<float>¶: Convenience typedef.

using deephaven::dhcore::chunk::DoubleChunk = GenericChunk<double>¶: Convenience typedef.

using deephaven::dhcore::chunk::BooleanChunk = GenericChunk<bool>¶: Convenience typedef.

using deephaven::dhcore::chunk::StringChunk = GenericChunk<std::string>¶: Convenience typedef.

using deephaven::dhcore::chunk::DateTimeChunk = GenericChunk<deephaven::dhcore::DateTime>¶: Convenience typedef.

Utility Declarations¶

class AnyChunk¶

Typesafe union of all the Chunk types. This is used when you need to have a method that creates a Chunk (with a type determined at runtime) or for example you need to have a vector of such Chunk objects.

Public Functions

template<typename T> inline AnyChunk &operator=(T &&chunk)¶: Move assignment operator.

template<typename Visitor> inline void Visit(Visitor &&visitor) const¶: Implementation of the visitor pattern.

const Chunk &Unwrap() const¶: Gets the abstract base type of the contained Chunk.

Chunk &Unwrap()¶: Gets the abstract base type of the contained Chunk.

template<typename T> inline const T &Get() const¶: Gets the contained Chunk as specified by T, or throws an exception if the contained Chunk is not of type T.

template<typename T> inline T &Get()¶: Gets the contained Chunk as specified by T, or throws an exception if the contained Chunk is not of type T.

class ChunkVisitor¶

Abstract base class that implements the visitor pattern for Chunk.

Public Functions

virtual void Visit(const CharChunk&) = 0¶: Implements the visitor pattern.

virtual void Visit(const Int8Chunk&) = 0¶: Implements the visitor pattern.

virtual void Visit(const Int16Chunk&) = 0¶: Implements the visitor pattern.

virtual void Visit(const Int32Chunk&) = 0¶: Implements the visitor pattern.

virtual void Visit(const Int64Chunk&) = 0¶: Implements the visitor pattern.

virtual void Visit(const UInt16Chunk&) = 0¶: Implements the visitor pattern.

virtual void Visit(const UInt64Chunk&) = 0¶: Implements the visitor pattern.

virtual void Visit(const FloatChunk&) = 0¶: Implements the visitor pattern.

virtual void Visit(const DoubleChunk&) = 0¶: Implements the visitor pattern.

virtual void Visit(const BooleanChunk&) = 0¶: Implements the visitor pattern.

virtual void Visit(const StringChunk&) = 0¶: Implements the visitor pattern.

virtual void Visit(const DateTimeChunk&) = 0¶: Implements the visitor pattern.

class ChunkMaker¶

Factory class for creating Chunk objects.

Public Static Functions

static AnyChunk CreateChunkFor(const ColumnSource &column_source, size_t chunk_size)¶

Create a Chunk compatible with the specified ColumnSource. For example if the underlying element type of the ColumnSource is int32_t, this method will Create an Int32Chunk.

Parameters:

column_source – The column source whose underlying element type will be inspected.
chunk_size – The requested size of the chunk.

Returns:

An AnyChunk, which is a variant value containing the requested chunk.