122 lines
5.2 KiB
Markdown
122 lines
5.2 KiB
Markdown
---
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title: Sysvar Cluster Data
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---
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Solana exposes a variety of cluster state data to programs via
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[`sysvar`](terminology.md#sysvar) accounts. These accounts are populated at
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known addresses published along with the account layouts in the
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[`solana-program`
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crate](https://docs.rs/solana-program/VERSION_FOR_DOCS_RS/solana_program/sysvar/index.html),
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and outlined below.
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To include sysvar data in program operations, pass the sysvar account address in
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the list of accounts in a transaction. The account can be read in your
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instruction processor like any other account. Access to sysvars accounts ßis
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always _readonly_.
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## Clock
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The Clock sysvar contains data on cluster time, including the current slot,
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epoch, and estimated wall-clock Unix timestamp. It is updated every slot.
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- Address: `SysvarC1ock11111111111111111111111111111111`
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- Layout: [Clock](https://docs.rs/solana-program/VERSION_FOR_DOCS_RS/solana_program/clock/struct.Clock.html)
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- Fields:
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- `slot`: the current slot
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- `epoch_start_timestamp`: the Unix timestamp of the first slot in this epoch. In the first slot of an epoch, this timestamp is identical to the `unix_timestamp` (below).
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- `epoch`: the current epoch
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- `leader_schedule_epoch`: the most recent epoch for which the leader schedule has already been generated
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- `unix_timestamp`: the Unix timestamp of this slot.
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Each slot has an estimated duration based on Proof of History. But in reality,
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slots may elapse faster and slower than this estimate. As a result, the Unix
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timestamp of a slot is generated based on oracle input from voting validators.
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This timestamp is calculated as the stake-weighted median of timestamp
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estimates provided by votes, bounded by the expected time elapsed since the
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start of the epoch.
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More explicitly: for each slot, the most recent vote timestamp provided by
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each validator is used to generate a timestamp estimate for the current slot
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(the elapsed slots since the vote timestamp are assumed to be
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Bank::ns_per_slot). Each timestamp estimate is associated with the stake
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delegated to that vote account to create a distribution of timestamps by
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stake. The median timestamp is used as the `unix_timestamp`, unless the
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elapsed time since the `epoch_start_timestamp` has deviated from the expected
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elapsed time by more than 25%.
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## EpochSchedule
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The EpochSchedule sysvar contains epoch scheduling constants that are set in
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genesis, and enables calculating the number of slots in a given epoch, the epoch
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for a given slot, etc. (Note: the epoch schedule is distinct from the [`leader schedule`](terminology.md#leader-schedule))
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- Address: `SysvarEpochSchedu1e111111111111111111111111`
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- Layout:
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[EpochSchedule](https://docs.rs/solana-program/VERSION_FOR_DOCS_RS/solana_program/epoch_schedule/struct.EpochSchedule.html)
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## Fees
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The Fees sysvar contains the fee calculator for the current slot. It is updated
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every slot, based on the fee-rate governor.
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- Address: `SysvarFees111111111111111111111111111111111`
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- Layout:
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[Fees](https://docs.rs/solana-program/VERSION_FOR_DOCS_RS/solana_program/sysvar/fees/struct.Fees.html)
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## Instructions
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The Instructions sysvar contains the serialized instructions in a Message while
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that Message is being processed. This allows program instructions to reference
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other instructions in the same transaction. Read more information on
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[instruction introspection](implemented-proposals/instruction_introspection.md).
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- Address: `Sysvar1nstructions1111111111111111111111111`
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- Layout:
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[Instructions](https://docs.rs/solana-program/VERSION_FOR_DOCS_RS/solana_program/sysvar/instructions/type.Instructions.html)
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## RecentBlockhashes
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The RecentBlockhashes sysvar contains the active recent blockhashes as well as
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their associated fee calculators. It is updated every slot.
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- Address: `SysvarRecentB1ockHashes11111111111111111111`
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- Layout:
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[RecentBlockhashes](https://docs.rs/solana-program/VERSION_FOR_DOCS_RS/solana_program/sysvar/recent_blockhashes/struct.RecentBlockhashes.html)
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## Rent
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The Rent sysvar contains the rental rate. Currently, the rate is static and set
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in genesis. The Rent burn percentage is modified by manual feature activation.
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- Address: `SysvarRent111111111111111111111111111111111`
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- Layout:
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[Rent](https://docs.rs/solana-program/VERSION_FOR_DOCS_RS/solana_program/rent/struct.Rent.html)
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## SlotHashes
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The SlotHashes sysvar contains the most recent hashes of the slot's parent
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banks. It is updated every slot.
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- Address: `SysvarS1otHashes111111111111111111111111111`
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- Layout:
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[SlotHashes](https://docs.rs/solana-program/VERSION_FOR_DOCS_RS/solana_program/slot_hashes/struct.SlotHashes.html)
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## SlotHistory
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The SlotHistory sysvar contains a bitvector of slots present over the last
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epoch. It is updated every slot.
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- Address: `SysvarS1otHistory11111111111111111111111111`
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- Layout:
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[SlotHistory](https://docs.rs/solana-program/VERSION_FOR_DOCS_RS/solana_program/slot_history/struct.SlotHistory.html)
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## StakeHistory
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The StakeHistory sysvar contains the history of cluster-wide stake activations
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and de-activations per epoch. It is updated at the start of every epoch.
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- Address: `SysvarStakeHistory1111111111111111111111111`
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- Layout:
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[StakeHistory](https://docs.rs/solana-program/VERSION_FOR_DOCS_RS/solana_program/stake_history/struct.StakeHistory.html)
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