DDS::LoanableSequence< E > Class Template Reference

A sequence implementation used internally by the middleware to efficiently manage memory during DDS::TypedDataReader::read and DDS::TypedDataReader::take operations. More...

#include <managed_sequence.h>

Inheritance diagram for DDS::LoanableSequence< E >:

Public Member Functions
virtual E	get_at (System::Int32 i) overridesealed
	Get the i-th element for a const sequence.
virtual System::Boolean	copy_from_no_alloc (Sequence< E >^src) overridesealed
	Copy elements from another sequence, only if the destination sequence has enough capacity.
virtual void	unloan () overridesealed
	Return the loaned buffer in the sequence and set the maximum to 0.
Public Member Functions inherited from DDS::Sequence< E >
System::Boolean	ensure_length (System::Int32 length, System::Int32 max)
	Set the sequence to the desired length, and resize the sequence if necessary.
virtual void	set_at (System::Int32 i, Eval)
	Set the i-th element of the sequence.
void	loan (array< E >^buffer, System::Int32 new_length)
	Loan a contiguous buffer to this sequence.
void	from_array (array< E >^arr)
	Copy elements from an array of elements, resizing the sequence if necessary. The original contents of the sequence (if any) are replaced.
void	to_array (array< E >^arr)
	Copy elements to an array of elements. The original contents of the array (if any) are replaced.
System::Boolean	copy_from (Sequence< E >^src_seq)
	Copy elements from another sequence, resizing the sequence if necessary.

Additional Inherited Members
Properties inherited from DDS::Sequence< E >
System::Int32	length [get, set]
	The logical length of this sequence.
virtual System::Int32	maximum [get, set]
	The current maximum number of elements that can be stored in this sequence.
array< E >^	buffer [get]
	Return the contiguous buffer of the sequence.
System::Boolean	has_ownership [get]
	Return the value of the owned flag.

Detailed Description

template<typename E>
class DDS::LoanableSequence< E >

A sequence implementation used internally by the middleware to efficiently manage memory during DDS::TypedDataReader::read and DDS::TypedDataReader::take operations.

Applications are not expected to use this type directly.

Member Function Documentation

template<typename E>

virtual E DDS::LoanableSequence< E >::get_at ( System::Int32  i )

overridesealedvirtual

Get the i-th element for a const sequence.

Parameters

i	index of element to access, must be >= 0 and less than DDS::Sequence::length

Returns

the i-th element

Reimplemented from DDS::Sequence< E >.

template<typename E>

virtual System::Boolean DDS::LoanableSequence< E >::copy_from_no_alloc ( Sequence< E >^  src_seq )

overridesealedvirtual

Copy elements from another sequence, only if the destination sequence has enough capacity.

Fill the elements in this sequence by copying the corresponding elements in src_seq. The original contents in this sequence are replaced via the element assignment operation (Foo_copy() function). By default, elements are discarded; 'delete' is not invoked on the discarded elements.

Precondition

this::maximum >= src_seq::length

this::owned == true

Postcondition

this::length == src_seq::length

this[i] == src_seq[i] for 0 <= i < target_seq::length

this::owned == true

Parameters

src_seq

<<in>> the sequence from which to copy

Returns

true if the sequence was successfully copied; false otherwise.

Note

If the pre-conditions are not met, the operator will print a message to stdout and leave this sequence unchanged.

See Also

DDS::Sequence::copy_from_no_alloc(DDS::Sequence<T>^)

Reimplemented from DDS::Sequence< E >.

template<typename E>

virtual void DDS::LoanableSequence< E >::unloan ( )

overridesealedvirtual

Return the loaned buffer in the sequence and set the maximum to 0.

This method affects only the state of this sequence; it does not change the contents of the buffer in any way.

Only the user who originally loaned a buffer should return that loan, as the user may have dependencies on that memory known only to them. Unloaning someone else's buffer may cause unspecified problems. For example, suppose a sequence is loaning memory from a custom memory pool. A user of the sequence likely has no way to release the memory back into the pool, so unloaning the sequence buffer would result in a resource leak. If the user were to then re-loan a different buffer, the original creator of the sequence would have no way to discover, when freeing the sequence, that the loan no longer referred to its own memory and would thus not free the user's memory properly, exacerbating the situation and leading to undefined behavior.

Precondition

owned == false

Postcondition

owned == true

maximum == 0

Returns

true if the preconditions were met. Otherwise false. The function only fails if the pre-conditions are not met, in which case it leaves the sequence unmodified.

See Also

DDS::Sequence<T>::loan(array<T>^, System::Int32), ::DDS::Sequence::loan_discontiguous, DDS::Sequence::maximum

Reimplemented from DDS::Sequence< E >.