tkrzw::RemoteDBM::Stream Class Reference

Stream for better performance of intensive operations. More...

#include <tkrzw_dbm_remote.h>

Public Member Functions
	~Stream ()
	Destructor. More...
	Stream (const Stream &rhs)=delete
	Copy and assignment are disabled. More...
Stream &	operator= (const Stream &rhs)=delete
void	Cancel ()
	Cancels the current operation. More...
Status	Echo (std::string_view message, std::string *echo)
	Sends a message and gets back the echo message. More...
Status	Get (std::string_view key, std::string *value=nullptr)
	Gets the value of a record of a key. More...
std::string	GetSimple (std::string_view key, std::string_view default_value="")
	Gets the value of a record of a key, in a simple way. More...
Status	Set (std::string_view key, std::string_view value, bool overwrite=true, bool ignore_result=false)
	Sets a record of a key and a value. More...
Status	Remove (std::string_view key, bool ignore_result=false)
	Removes a record of a key. More...
Status	Append (std::string_view key, std::string_view value, std::string_view delim="", bool ignore_result=false)
	Appends data at the end of a record of a key. More...
Status	CompareExchange (std::string_view key, std::string_view expected, std::string_view desired, std::string *actual=nullptr, bool *found=nullptr, double retry_wait=0, bool notify=false)
	Compares the value of a record and exchanges if the condition meets. More...
Status	Increment (std::string_view key, int64_t increment=1, int64_t *current=nullptr, int64_t initial=0, bool ignore_result=false)
	Increments the numeric value of a record. More...
int64_t	IncrementSimple (std::string_view key, int64_t increment=1, int64_t initial=0)
	Increments the numeric value of a record, in a simple way. More...

Friends
class	tkrzw::RemoteDBM

Detailed Description

Stream for better performance of intensive operations.

An instance of this class dominates a thread on the server so you should destroy when it is no longer in use.

Constructor & Destructor Documentation

~Stream()

tkrzw::RemoteDBM::Stream::~Stream

(

)

Destructor.

Stream()

tkrzw::RemoteDBM::Stream::Stream ( const Stream &  rhs )

explicitdelete

Copy and assignment are disabled.

Member Function Documentation

Cancel()

void tkrzw::RemoteDBM::Stream::Cancel

(

)

Cancels the current operation.

This is called by another thread than the thread doing the operation.

Echo()

Status tkrzw::RemoteDBM::Stream::Echo	(	std::string_view	message,
		std::string *	echo
	)

Sends a message and gets back the echo message.

Parameters

message	The message to send.
echo	The pointer to a string object to contain the echo message.

Returns

The result status.

Get()

Status tkrzw::RemoteDBM::Stream::Get	(	std::string_view	key,
		std::string *	value = nullptr
	)

Gets the value of a record of a key.

Parameters

key	The key of the record.
value	The pointer to a string object to contain the result value. If it is nullptr, the value data is ignored.

Returns

The result status. If there's no matching record, NOT_FOUND_ERROR is returned.

GetSimple()

std::string tkrzw::RemoteDBM::Stream::GetSimple	(	std::string_view	key,
		std::string_view	default_value = ""
	)

Gets the value of a record of a key, in a simple way.

Parameters

key	The key of the record.
default_value	The value to be returned on failure.

Returns

The value of the matching record on success, or the default value on failure.

Set()

Status tkrzw::RemoteDBM::Stream::Set	(	std::string_view	key,
		std::string_view	value,
		bool	overwrite = true,
		bool	ignore_result = false
	)

Sets a record of a key and a value.

Parameters

key	The key of the record.
value	The value of the record.
overwrite	Whether to overwrite the existing value if there's a record with the same key. If true, the existing value is overwritten by the new value. If false, the operation is given up and an error status is returned.
ignore_result	If true, the result status is not checked.

Returns

The result status. If overwriting is abandoned, DUPLICATION_ERROR is returned.

Remove()

Status tkrzw::RemoteDBM::Stream::Remove	(	std::string_view	key,
		bool	ignore_result = false
	)

Removes a record of a key.

Parameters

key	The key of the record.
ignore_result	If true, the result status is not checked.

Returns

The result status. If there's no matching record, NOT_FOUND_ERROR is returned.

Append()

Status tkrzw::RemoteDBM::Stream::Append	(	std::string_view	key,
		std::string_view	value,
		std::string_view	delim = "",
		bool	ignore_result = false
	)

Appends data at the end of a record of a key.

Parameters

key	The key of the record.
value	The value to append.
delim	The delimiter to put after the existing record.
ignore_result	If true, the result status is not checked.

Returns

The result status.

If there's no existing record, the value is set without the delimiter.

CompareExchange()

Status tkrzw::RemoteDBM::Stream::CompareExchange	(	std::string_view	key,
		std::string_view	expected,
		std::string_view	desired,
		std::string *	actual = nullptr,
		bool *	found = nullptr,
		double	retry_wait = 0,
		bool	notify = false
	)

Compares the value of a record and exchanges if the condition meets.

Parameters

key	The key of the record.
expected	The expected value. If the data is nullptr, no existing record is expected. If it is DBM::ANY_DATA, an existing record with any value is expacted.
desired	The desired value. If the data is nullptr, the record is to be removed. If it is DBM::ANY_DATA, no update is done.
actual	The pointer to a string object to contain the actual value of the existing record. If it is nullptr, it is ignored.
found	The pointer to a variable to contain whether there is an existing record. If it is nullptr, it is ignored.
retry_wait	The maximum wait time in seconds before retrying. If it is zero, no retry is done. If it is positive, retry is done after waiting for the notifications of the next update for the time at most.
notify	If true, a notification signal is sent to wake up retrying threads.

Returns

The result status. If the condition doesn't meet, INFEASIBLE_ERROR is returned.

Increment()

Status tkrzw::RemoteDBM::Stream::Increment	(	std::string_view	key,
		int64_t	increment = 1,
		int64_t *	current = nullptr,
		int64_t	initial = 0,
		bool	ignore_result = false
	)

Increments the numeric value of a record.

Parameters

key	The key of the record.
increment	The incremental value. If it is INT64MIN, the current value is not changed and a new record is not created.
current	The pointer to an integer to contain the current value. If it is nullptr, it is ignored.
initial	The initial value.
ignore_result	If true, the result status is not checked.

Returns

The result status.

The record value is stored as an 8-byte big-endian integer. Negative is also supported.

IncrementSimple()

int64_t tkrzw::RemoteDBM::Stream::IncrementSimple	(	std::string_view	key,
		int64_t	increment = 1,
		int64_t	initial = 0
	)

Increments the numeric value of a record, in a simple way.

Parameters

key	The key of the record.
increment	The incremental value.
initial	The initial value.

Returns

The current value or INT64MIN on failure.

The record value is treated as a decimal integer. Negative is also supported.