19.1.1.6. LoanableCollection

class fastdds.LoanableCollection(*args, **kwargs)

A collection of generic opaque pointers that can receive the buffer from outside (loan).

This is an abstract class. See ‘LoanableSequence’ for details.

buffer()

Get the pointer to the elements buffer.

The returned value may be nullptr if maximum() is 0. Otherwise it is guaranteed that up to maximum() elements can be accessed.

Return type:

void

Returns:

the pointer to the elements buffer.

has_ownership()

Get the ownership flag.

Return type:

boolean

Returns:

whether the collection has ownership of the buffer.

length(*args)

Overload 1:

Get the number of elements currently accessible.

Return type:

int

Returns:

the number of elements currently accessible.

Overload 2:

Set the number of elements currently accessible.

This method tells the collection that a certain number of elements should be accessible. If the new length is greater than the current ‘maximum()’ the collection should allocate space for the new elements. If this is the case and the collection does not own the buffer (i.e. ‘has_ownership()’ is false) then no allocation will be performed, the length will remain unchanged, and false will be returned.

Parameters:

[in] – new_length New number of elements to be accessible.

Return type:

boolean

Returns:

true if the new length was correctly set.

loan(buffer, new_maximum, new_length)

Loan a buffer to the collection.

Parameters:

• [in] – buffer pointer to the buffer to be loaned.

• [in] – new_maximum number of allocated elements in buffer.

• [in] – new_length number of accessible elements in buffer.

Return type:

boolean

Returns:

false if preconditions are not met.

Return type:

boolean

Returns:

true if operation succeeds.

maximum()

Get the maximum number of elements currently allocated.

Return type:

int

Returns:

the maximum number of elements currently allocated.

property thisown

The membership flag

unloan(*args)

Overload 1:

Remove the loan from the collection.

Parameters:

• [out] – maximum number of allocated elements on the returned buffer.

• [out] – length number of accessible elements on the returned buffer.

Return type:

void

Returns:

nullptr if preconditions are not met.

Return type:

void

Returns:

pointer to the previously loaned buffer of elements.

Overload 2:

Remove the loan from the collection.

Return type:

void

Returns:

nullptr if preconditions are not met.

Return type:

void

Returns:

pointer to the previously loaned buffer of elements.