I/O Requests and Queues

Classes
class	disk_queues
class	request
	Request object encapsulating basic properties like file and offset. More...
class	request_interface
class	request_queue
	Interface of a request_queue to which requests can be added and canceled. More...
class	request_queue_impl_1q
class	request_queue_impl_qwqr
class	request_queue_impl_worker
class	request_with_state
	Request with completion shared_state. More...
class	request_with_waiters
	Request that is aware of threads waiting for it to complete. More...
class	serving_request
	Request which serves an I/O by calling the synchronous routine of the file. More...

Typedefs
using	completion_handler = tlx::delegate< void(request *r, bool success)>
	completion handler More...
using	file_ptr = tlx::counting_ptr< file >
	A reference counting pointer for file. More...
using	request_ptr = tlx::counting_ptr< request >
	A reference counting pointer for request. More...

Functions
template<class RequestIterator >
std::iterator_traits< RequestIterator >::difference_type	cancel_all (RequestIterator reqs_begin, RequestIterator reqs_end)
std::ostream &	operator<< (std::ostream &out, const request &req)
template<class RequestIterator >
RequestIterator	poll_any (RequestIterator reqs_begin, RequestIterator reqs_end)
static bool	poll_any (request_ptr req_array[], size_t count, size_t &index)
template<class RequestIterator >
void	wait_all (RequestIterator reqs_begin, RequestIterator reqs_end)
	Collection of functions to track statuses of a number of requests. More...
static void	wait_all (request_ptr req_array[], size_t count)
template<class RequestIterator >
RequestIterator	wait_any (RequestIterator reqs_begin, RequestIterator reqs_end)
static size_t	wait_any (request_ptr req_array[], size_t count)

Variables
constexpr size_t	BlockAlignment = 4096

Detailed Description

Encapsulation of an I/O request, queues for requests and threads to process them.

Typedef Documentation

completion_handler

using completion_handler = tlx::delegate<void(request* r, bool success)>

completion handler

Definition at line 46 of file request.hpp.

file_ptr

typedef tlx::counting_ptr< file > file_ptr

A reference counting pointer for file.

Definition at line 265 of file file.hpp.

request_ptr

using request_ptr = tlx::counting_ptr<request>

A reference counting pointer for request.

Definition at line 43 of file request.hpp.

Function Documentation

cancel_all()

std::iterator_traits<RequestIterator>::difference_type foxxll::cancel_all	(	RequestIterator	reqs_begin,
		RequestIterator	reqs_end
	)

Cancel requests. The specified requests are canceled unless already being processed. However, cancelation cannot be guaranteed. Cancelled requests must still be waited for in order to ensure correct operation.

Parameters

reqs_begin	begin of request sequence
reqs_end	end of request sequence

Returns

number of request canceled

Definition at line 57 of file request_operations.hpp.

operator<<()

std::ostream & operator<<	(	std::ostream &	out,
		const request &	req
	)

Definition at line 103 of file request.cpp.

References request::print().

poll_any() [1/2]

RequestIterator foxxll::poll_any	(	RequestIterator	reqs_begin,
		RequestIterator	reqs_end
	)

Polls requests.

Parameters

reqs_begin	begin of request sequence to poll
reqs_end	end of request sequence to poll

Returns

true if any of requests is completed, then index contains valid value, otherwise false

Definition at line 74 of file request_operations.hpp.

Referenced by foxxll::poll_any().

poll_any() [2/2]

static bool foxxll::poll_any ( request_ptr  req_array[], size_t  count, size_t &  index  )

inlinestatic

Polls requests.

Parameters

req_array	array of request_ptr objects
count	size of req_array
index	contains index of the first completed request if any

Returns

true if any of requests is completed, then index contains valid value, otherwise false

Definition at line 92 of file request_operations.hpp.

References foxxll::poll_any().

wait_all() [1/2]

void foxxll::wait_all	(	RequestIterator	reqs_begin,
		RequestIterator	reqs_end
	)

Collection of functions to track statuses of a number of requests.

Suspends calling thread until all given requests are completed.

Parameters

reqs_begin	begin of request sequence to wait for
reqs_end	end of request sequence to wait for

Definition at line 33 of file request_operations.hpp.

Referenced by foxxll::wait_all().

wait_all() [2/2]

static void foxxll::wait_all ( request_ptr  req_array[], size_t  count  )

inlinestatic

Suspends calling thread until all given requests are completed.

Parameters

req_array	array of request_ptr objects
count	size of req_array

Definition at line 42 of file request_operations.hpp.

References foxxll::wait_all().

wait_any() [1/2]

RequestIterator foxxll::wait_any	(	RequestIterator	reqs_begin,
		RequestIterator	reqs_end
	)

Suspends calling thread until any of requests is completed.

Parameters

reqs_begin	begin of request sequence to wait for
reqs_end	end of request sequence to wait for

Returns

index in req_array pointing to the first completed request

Definition at line 104 of file request_operations.hpp.

References onoff_switch::wait_for_on(), and stats::WAIT_OP_ANY.

Referenced by buffered_writer< block_type >::get_free_block(), write_pool< BlockType >::steal(), and foxxll::wait_any().

wait_any() [2/2]

static size_t foxxll::wait_any ( request_ptr  req_array[], size_t  count  )

inlinestatic

Suspends calling thread until any of requests is completed.

Parameters

req_array	array of request_ptr objects
count	size of req_array

Returns

index in req_array pointing to the first completed request

Definition at line 150 of file request_operations.hpp.

References foxxll::wait_any().

Variable Documentation

BlockAlignment

constexpr size_t BlockAlignment = 4096

Definition at line 34 of file request.hpp.

Referenced by request::check_alignment(), memory_file::discard(), fileperblock_file< base_file_type >::lock(), and typed_block< RawSize, Type, NRef, MetaInfoType >::typed_block().