Checkpoint
A header for a checkpoint on the Sui blockchain.
On the Sui network, checkpoints define the history of the blockchain. They are quite similar to the concept of blocks used by other blockchains like Bitcoin or Ethereum. The Sui blockchain, however, forms checkpoints after transaction execution has already happened to provide a certified history of the chain, instead of being formed before execution.
Checkpoints commit to a variety of state, including but not limited to:
The hash of the previous checkpoint.
The set of transaction digests, their corresponding effects digests, as well as the set of user signatures that authorized its execution.
The objects produced by a transaction.
The set of live objects that make up the current state of the chain.
On epoch transitions, the next validator committee.
CheckpointSummarys themselves don't directly include all of the previous information but they are the top-level type by which all the information is committed to transitively via cryptographic hashes included in the summary. CheckpointSummarys are signed and certified by a quorum of the validator committee in a given epoch to allow verification of the chain's state.
Properties
Commitments to checkpoint-specific state.
The hash of the CheckpointContents for this checkpoint.
Extra data only present in the final checkpoint of an epoch.
The running total gas costs of all transactions included in the current epoch so far until this checkpoint.
Returns the field-presence view for this CheckpointSummary instance.
The hash of the previous CheckpointSummary.
The height of this checkpoint.
Timestamp of the checkpoint - number of milliseconds from the Unix epoch Checkpoint timestamps are monotonic, but not strongly monotonic - subsequent checkpoints can have the same timestamp if they originate from the same underlining consensus commit.
Total number of transactions committed since genesis, including those in this checkpoint.
CheckpointSummary is not an evolvable structure - it must be readable by any version of the code. Therefore, to allow extensions to be added to CheckpointSummary, opaque data can be added to checkpoints, which can be deserialized based on the current protocol version.