Package org.apache.druid.segment.column

Class ObjectStrategyComplexTypeStrategy<T>

java.lang.Object

org.apache.druid.segment.column.ObjectStrategyComplexTypeStrategy<T>

All Implemented Interfaces:

Comparator<Object>, TypeStrategy<T>

public class ObjectStrategyComplexTypeStrategy<T>
extends Object
implements TypeStrategy<T>

Default implementation of TypeStrategy for all ComplexMetricSerde implementations that just wraps the ObjectStrategy they are required to implement. This is not likely to be the most efficient way to do things, especially since writing must first produce a byte array before it can be written to the buffer, but it is cheap and should work correctly, which is important.

Constructor Summary

Constructors

Constructor	Description
ObjectStrategyComplexTypeStrategy(ObjectStrategy<T> objectStrategy, TypeSignature<?> signature)

Method Summary

Modifier and Type	Method	Description
int	compare(Object o1, Object o2)
int	estimateSizeBytes(T value)	Estimate the size in bytes that writing this value to memory would require.
T	fromBytes(byte[] value)	Translate raw byte array into a value.
T	read(ByteBuffer buffer)	Read a non-null value from the ByteBuffer at the current Buffer.position().
boolean	readRetainsBufferReference()	Whether the TypeStrategy.read(java.nio.ByteBuffer) methods return an object that may retain a reference to the provided ByteBuffer.
int	write(ByteBuffer buffer, T value, int maxSizeBytes)	Write a non-null value to the ByteBuffer at position Buffer.position().

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.util.Comparator

equals, reversed, thenComparing, thenComparing, thenComparing, thenComparingDouble, thenComparingInt, thenComparingLong

Methods inherited from interface org.apache.druid.segment.column.TypeStrategy

read, write

Constructor Detail

ObjectStrategyComplexTypeStrategy

public ObjectStrategyComplexTypeStrategy(ObjectStrategy<T> objectStrategy,
                                         TypeSignature<?> signature)

Method Detail

estimateSizeBytes

public int estimateSizeBytes(@Nullable
                             T value)

Description copied from interface: TypeStrategy

Estimate the size in bytes that writing this value to memory would require. This method is not required to be exactly correct, but many implementations might be. Implementations should err on the side of over-estimating if exact sizing is not efficient. Example usage of this method is estimating heap memory usage for an aggregator or the amount of buffer which might need allocated to then TypeStrategy.write(java.nio.ByteBuffer, T, int) a value

Specified by:

estimateSizeBytes in interface TypeStrategy<T>

read

public T read(ByteBuffer buffer)

Description copied from interface: TypeStrategy

Read a non-null value from the ByteBuffer at the current Buffer.position(). This will move the underlying position by the size of the value read. The value returned from this method may retain a reference to the provided ByteBuffer. If it does, then TypeStrategy.readRetainsBufferReference() returns true.

Specified by:

read in interface TypeStrategy<T>

readRetainsBufferReference

public boolean readRetainsBufferReference()

Description copied from interface: TypeStrategy

Whether the TypeStrategy.read(java.nio.ByteBuffer) methods return an object that may retain a reference to the provided ByteBuffer. If a reference is sometimes retained, this method returns true. It returns false if, and only if, a reference is *never* retained.

Specified by:

readRetainsBufferReference in interface TypeStrategy<T>

write

public int write(ByteBuffer buffer,
                 T value,
                 int maxSizeBytes)

Description copied from interface: TypeStrategy

Write a non-null value to the ByteBuffer at position Buffer.position(). This will move the underlying position by the size of the value written. This method returns the number of bytes written. If writing the value would take more than 'maxSizeBytes', this method will return a negative value indicating the number of additional bytes that would be required to fully write the value. Partial results may be written to the buffer when in this state, and the position may be left at whatever point the implementation ran out of space while writing the value. Callers should save the starting position if it is necessary to 'rewind' after a partial write. Callers MUST check that the return value is positive which indicates a successful write, while a negative response a partial write.

Specified by:

write in interface TypeStrategy<T>

Returns:

number of bytes written

compare

public int compare(Object o1,
                   Object o2)

Specified by:

compare in interface Comparator<T>

fromBytes

public T fromBytes(byte[] value)

Description copied from interface: TypeStrategy

Translate raw byte array into a value. This is primarily useful for transforming self contained values that are serialized into byte arrays, such as happens with 'COMPLEX' types which serialize to base64 strings in JSON responses. 'COMPLEX' types should implement this method to participate in the expression systems built-in function to deserialize base64 encoded values, BuiltInExprMacros.ComplexDecodeBase64ExprMacro.

Specified by:

fromBytes in interface TypeStrategy<T>