kagome::telemetry::MessagePool Class Reference

#include <message_pool.hpp>

Collaboration diagram for kagome::telemetry::MessagePool:

Classes
struct	Record

Public Types
using	RefCount = int16_t

Public Member Functions
	MessagePool (std::size_t entry_size_bytes, std::size_t entries_count)
std::optional< MessageHandle >	push (const std::string &message, int16_t ref_count)
RefCount	add_ref (MessageHandle handle)
RefCount	release (MessageHandle handle)
boost::asio::mutable_buffer	operator[] (MessageHandle handle) const
std::size_t	capacity () const

Private Member Functions
std::optional< MessageHandle >	nextFreeSlot ()
	performs quick lookup for a free slot More...

Private Attributes
const std::size_t	entry_size_
const std::size_t	entries_count_
std::vector< Record >	pool_
std::unordered_set< std::size_t >	free_slots_
common::spin_lock	mutex_

Detailed Description

Message pool used to deduplicate and hold the data till async write operations are in progress.

The pool is designed to be extremely fast against data-copy operations. That is why all the storage buffers are pre-allocated during the construction. All the copy operations are performed in a fastest manner via memcpy.

Access operations to shared data where data race is possible are synchronized via spin locks. Locking is performed for a smallest possible set of lines of code. Spin locks let us avoid expensive context switches and performance degradation.

Definition at line 36 of file message_pool.hpp.

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Class Documentation

struct kagome::telemetry::MessagePool::Record

Definition at line 99 of file message_pool.hpp.

Collaboration diagram for kagome::telemetry::MessagePool::Record:

Class Members
vector< uint8_t >	data
size_t	data_size
size_t	ref_count

Member Typedef Documentation

using kagome::telemetry::MessagePool::RefCount = int16_t

Type for reference external reference counters. Normally cannot be negative. That sized and signed type is chosen to easily catch illegal cases (negative and too hign numbers -> will more likely result in an overflow).

Definition at line 45 of file message_pool.hpp.

Constructor & Destructor Documentation

kagome::telemetry::MessagePool::MessagePool	(	std::size_t	entry_size_bytes,
		std::size_t	entries_count
	)

Contruct the pool

Parameters

entry_size_bytes	- max size of a single record
entries_count	- max amount of records to hold at the same time

Definition at line 13 of file message_pool.cpp.

Member Function Documentation

MessagePool::RefCount kagome::telemetry::MessagePool::add_ref

(

MessageHandle

handle

)

Increase reference counter for the specified handle

Parameters

handle

- handle to the record

Would be useful in case when many verbosity level would be developed.

Definition at line 52 of file message_pool.cpp.

std::size_t kagome::telemetry::MessagePool::capacity

(

)

const

Reports a number of records the pool was initialized for.

Returns

pool capacity

Definition at line 99 of file message_pool.cpp.

std::optional< MessageHandle > kagome::telemetry::MessagePool::nextFreeSlot ( )

private

performs quick lookup for a free slot

Definition at line 103 of file message_pool.cpp.

boost::asio::mutable_buffer kagome::telemetry::MessagePool::operator[]

(

MessageHandle

handle

)

const

Access the record by the handle.

Parameters

handle

- handle to the record

Returns

- boost::asio::buffer with the contents ready to be passed to boost::asio::async_write call

Definition at line 81 of file message_pool.cpp.

std::optional< MessageHandle > kagome::telemetry::MessagePool::push	(	const std::string &	message,
		int16_t	ref_count
	)

Put a message to the pool

Parameters

message	- the data, could be disposed immediately after returning
ref_count	- initial reference counter value for the record

Returns

- handle to the record or std::nullopt when the pool is full

Note: the record will be freed from the pool as soon as an handle-owner calls the release method for the handle ref_count-many times

Definition at line 27 of file message_pool.cpp.

MessagePool::RefCount kagome::telemetry::MessagePool::release

(

MessageHandle

handle

)

Decrement reference counter for the handled record.

Parameters

handle

- handle to the record

The record would be disposed when counter decreases to zero.

Definition at line 65 of file message_pool.cpp.

Member Data Documentation

const std::size_t kagome::telemetry::MessagePool::entries_count_

private

Definition at line 106 of file message_pool.hpp.

const std::size_t kagome::telemetry::MessagePool::entry_size_

private

Definition at line 105 of file message_pool.hpp.

std::unordered_set<std::size_t> kagome::telemetry::MessagePool::free_slots_

private

Definition at line 108 of file message_pool.hpp.

common::spin_lock kagome::telemetry::MessagePool::mutex_

private

Definition at line 109 of file message_pool.hpp.

std::vector<Record> kagome::telemetry::MessagePool::pool_

private

Definition at line 107 of file message_pool.hpp.

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The documentation for this class was generated from the following files:

• core/telemetry/impl/message_pool.hpp
• core/telemetry/impl/message_pool.cpp