solana_kit_sysvars 0.1.0

System variable access for the Solana Kit Dart SDK.

solana_kit_sysvars

System variable (sysvar) account access for the Solana Kit Dart SDK -- provides typed access to Solana runtime sysvar accounts like Clock, Rent, EpochSchedule, and more.

This is the Dart port of @solana/sysvars from the Solana TypeScript SDK.

Installation

Add solana_kit_sysvars to your pubspec.yaml:

dependencies:
  solana_kit_sysvars:

Or, if you are using the umbrella package:

dependencies:
  solana_kit:

Documentation

• Package page: https://pub.dev/packages/solana_kit_sysvars
• API reference: https://pub.dev/documentation/solana_kit_sysvars/latest/

Usage

Sysvar addresses

All Solana sysvar account addresses are available as const Address values.

import 'package:solana_kit_sysvars/solana_kit_sysvars.dart';

void main() {
  print(sysvarClockAddress);
  // Address('SysvarC1ock11111111111111111111111111111111')

  print(sysvarRentAddress);
  // Address('SysvarRent111111111111111111111111111111111')

  print(sysvarEpochScheduleAddress);
  // Address('SysvarEpochSchedu1e111111111111111111111111')

  print(sysvarSlotHashesAddress);
  // Address('SysvarS1otHashes111111111111111111111111111')

  print(sysvarSlotHistoryAddress);
  // Address('SysvarS1otHistory11111111111111111111111111')

  print(sysvarStakeHistoryAddress);
  // Address('SysvarStakeHistory1111111111111111111111111')

  print(sysvarRecentBlockhashesAddress);
  // Address('SysvarRecentB1ockHashes11111111111111111111')

  print(sysvarInstructionsAddress);
  // Address('Sysvar1nstructions1111111111111111111111111')

  print(sysvarEpochRewardsAddress);
  // Address('SysvarEpochRewards1111111111111111111111111')

  print(sysvarLastRestartSlotAddress);
  // Address('SysvarLastRestartS1ot1111111111111111111111')
}

Fetching the Clock sysvar

The Clock sysvar contains data about the current slot, epoch, and Unix timestamp. It is updated every slot.

import 'package:solana_kit_rpc/solana_kit_rpc.dart';
import 'package:solana_kit_sysvars/solana_kit_sysvars.dart';

Future<void> main() async {
  final rpc = createSolanaRpc('https://api.devnet.solana.com');

  final clock = await fetchSysvarClock(rpc);
  print('Current slot: ${clock.slot}');
  print('Current epoch: ${clock.epoch}');
  print('Unix timestamp: ${clock.unixTimestamp}');
  print('Epoch start timestamp: ${clock.epochStartTimestamp}');
  print('Leader schedule epoch: ${clock.leaderScheduleEpoch}');
}

The SysvarClock class contains:

import 'package:solana_kit_sysvars/solana_kit_sysvars.dart';

void main() {
  // Construct a SysvarClock value directly (e.g. for testing).
  final clock = SysvarClock(
    slot: BigInt.from(100),
    epochStartTimestamp: BigInt.from(1700000000),
    epoch: BigInt.from(5),
    leaderScheduleEpoch: BigInt.from(6),
    unixTimestamp: BigInt.from(1700001000),
  );

  print(clock.slot); // 100
  print(clock.epoch); // 5
}

Fetching the Rent sysvar

The Rent sysvar contains rent configuration for the cluster.

import 'package:solana_kit_rpc/solana_kit_rpc.dart';
import 'package:solana_kit_sysvars/solana_kit_sysvars.dart';

Future<void> main() async {
  final rpc = createSolanaRpc('https://api.devnet.solana.com');

  final rent = await fetchSysvarRent(rpc);
  print('Lamports per byte-year: ${rent.lamportsPerByteYear}');
  print('Exemption threshold: ${rent.exemptionThreshold} years');
  print('Burn percent: ${rent.burnPercent}%');
}

Fetching the EpochSchedule sysvar

The EpochSchedule sysvar includes the number of slots per epoch, leader schedule timing, and warmup information.

import 'package:solana_kit_rpc/solana_kit_rpc.dart';
import 'package:solana_kit_sysvars/solana_kit_sysvars.dart';

Future<void> main() async {
  final rpc = createSolanaRpc('https://api.devnet.solana.com');

  final schedule = await fetchSysvarEpochSchedule(rpc);
  print('Slots per epoch: ${schedule.slotsPerEpoch}');
  print('Leader schedule slot offset: ${schedule.leaderScheduleSlotOffset}');
  print('Warmup: ${schedule.warmup}');
  print('First normal epoch: ${schedule.firstNormalEpoch}');
  print('First normal slot: ${schedule.firstNormalSlot}');
}

Fetching encoded sysvar accounts

For sysvars that do not yet have a dedicated fetch function, or when you need the raw encoded bytes, use fetchEncodedSysvarAccount.

import 'dart:typed_data';

import 'package:solana_kit_accounts/solana_kit_accounts.dart';
import 'package:solana_kit_rpc/solana_kit_rpc.dart';
import 'package:solana_kit_sysvars/solana_kit_sysvars.dart';

Future<void> main() async {
  final rpc = createSolanaRpc('https://api.devnet.solana.com');

  // Fetch the raw encoded data for any sysvar.
  final maybeAccount = await fetchEncodedSysvarAccount(
    rpc,
    sysvarSlotHashesAddress,
  );

  switch (maybeAccount) {
    case ExistingAccount<Uint8List>(:final account):
      print('SlotHashes data: ${account.data.length} bytes');
    case NonExistingAccount():
      print('Sysvar account not found');
  }
}

Using sysvar codecs

Each sysvar type has encoder, decoder, and codec factory functions for binary serialization.

import 'dart:typed_data';

import 'package:solana_kit_sysvars/solana_kit_sysvars.dart';

void main() {
  // Encode a Clock sysvar value to bytes.
  final encoder = getSysvarClockEncoder();
  final clock = SysvarClock(
    slot: BigInt.from(42),
    epochStartTimestamp: BigInt.from(1700000000),
    epoch: BigInt.from(5),
    leaderScheduleEpoch: BigInt.from(6),
    unixTimestamp: BigInt.from(1700001000),
  );
  final bytes = encoder.encode(clock);
  print(bytes.length); // 40 (sysvarClockSize)

  // Decode bytes back to a SysvarClock.
  final decoder = getSysvarClockDecoder();
  final (decoded, _) = decoder.read(bytes, 0);
  print(decoded.slot); // 42

  // Use the combined codec.
  final codec = getSysvarClockCodec();
  final roundTripped = codec.decode(codec.encode(clock));
  print(roundTripped == clock); // true
}

API Reference

Sysvar addresses

Constant	Address
sysvarClockAddress	SysvarC1ock11111111111111111111111111111111
sysvarRentAddress	SysvarRent111111111111111111111111111111111
sysvarEpochScheduleAddress	SysvarEpochSchedu1e111111111111111111111111
sysvarEpochRewardsAddress	SysvarEpochRewards1111111111111111111111111
sysvarInstructionsAddress	Sysvar1nstructions1111111111111111111111111
sysvarLastRestartSlotAddress	SysvarLastRestartS1ot1111111111111111111111
sysvarRecentBlockhashesAddress	SysvarRecentB1ockHashes11111111111111111111
sysvarSlotHashesAddress	SysvarS1otHashes111111111111111111111111111
sysvarSlotHistoryAddress	SysvarS1otHistory11111111111111111111111111
sysvarStakeHistoryAddress	SysvarStakeHistory1111111111111111111111111

Sysvar types

Class	Fields
SysvarClock	slot, epochStartTimestamp, epoch, leaderScheduleEpoch, unixTimestamp
SysvarRent	lamportsPerByteYear, exemptionThreshold, burnPercent
SysvarEpochSchedule	slotsPerEpoch, leaderScheduleSlotOffset, warmup, firstNormalEpoch, firstNormalSlot

Fetch functions

Function	Description
fetchSysvarClock(rpc, {config?})	Fetches and decodes the Clock sysvar. Returns Future<SysvarClock>.
fetchSysvarRent(rpc, {config?})	Fetches and decodes the Rent sysvar. Returns Future<SysvarRent>.
fetchSysvarEpochSchedule(rpc, {config?})	Fetches and decodes the EpochSchedule sysvar. Returns Future<SysvarEpochSchedule>.
fetchEncodedSysvarAccount(rpc, address, {config?})	Fetches any sysvar as a MaybeEncodedAccount.

Codec functions

Sysvar	Encoder	Decoder	Codec
Clock	getSysvarClockEncoder()	getSysvarClockDecoder()	getSysvarClockCodec()
Rent	getSysvarRentEncoder()	getSysvarRentDecoder()	getSysvarRentCodec()
EpochSchedule	getSysvarEpochScheduleEncoder()	getSysvarEpochScheduleDecoder()	getSysvarEpochScheduleCodec()

Size constants

Constant	Value	Description
sysvarClockSize	40	Size of the Clock sysvar data in bytes.
sysvarRentSize	17	Size of the Rent sysvar data in bytes.
sysvarEpochScheduleSize	33	Size of the EpochSchedule sysvar data in bytes.