touching-sol

high-level overview transaction lifecycle, block production, slot progression, PoH, BFT etc

graph TD

  subgraph Time
    Epoch_Start[Epoch Starts] --> Leader_Schedule[Leader Schedule Determined Stake-based]
    Leader_Schedule --> Slot_Start_N{Slot N Starts ~400ms}
    Slot_Start_N --> Slot_End_N[Slot N Ends]
    Slot_End_N --> Slot_Start_N_plus_1{Slot N+1 Starts}
    Slot_Start_N_plus_1 --> Slot_End_N_plus_1[Slot N+1 Ends]
    Slot_End_N_plus_1 --> Slot_Start_N
  end


  Client[User/Client Application] --> Tx_Submit[Submit Transaction]
  Tx_Submit --> Tx_Pending[Tx Status: Pending]


  Tx_Pending --> Validator_Receive_Tx[Validator Node Receives Tx e.g., RPC]
  Validator_Receive_Tx --> Leader_Forward_Tx[Forward Tx to Current Leader]

  Slot_Start_N --> Leader_Assign_N[Validator N Assigned as Leader for Slot N]


  Leader_Assign_N --> Leader_Fetch_Tx[Leader N: Fetch Transactions]
  Leader_Forward_Tx --> Leader_Fetch_Tx
  Leader_Fetch_Tx --> Leader_Process_Tx[Leader N: Process Transactions SigVerify, Banking]


  Leader_Process_Tx --> Tx_Valid_Leader{Tx Valid?}
  Tx_Valid_Leader -- Yes --> Tx_Processed[Tx Status: Processed by Leader]
  Tx_Valid_Leader -- No --> Tx_Failed_Leader[Tx Status: Failed Invalid Signature/State]


  Leader_Process_Tx --> Leader_PoH[Leader N: Add Events/Tx to PoH Sequence]
  Leader_PoH_ContinuousPoH[Generator Running Continuously] --- Leader_PoH


  Tx_Processed & Leader_PoH --> Leader_Create_Block[Leader N: Create Block N Bundle Tx, PoH, Prev Hash]


  Leader_Create_Block --> Leader_Propagate_Block[Leader N: Propagate Block N to Network]


  Leader_Propagate_Block --> Validators_Receive_Block[Other Validators: Receive Block N]
  Validators_Receive_Block --> Validators_Validate_Block[Other Validators: Validate Block N Tx Integrity, PoH Check]


  Validators_Validate_Block --> Block_Valid{Block N Valid?}
  Block_Valid -- No --> Block_Invalid[Block N Invalid]
  Block_Invalid --> Validators_Ignore_Block[Validators Ignore Invalid Block]

  Block_Valid -- Yes --> Validators_Vote[Other Validators: Vote on Block N Stake-Weighted]


  Validators_Vote --> Network_Accumulate_Votes[Network: Accumulate Votes Tower BFT]
  Network_Accumulate_Votes --> Block_Confirmed{Supermajority Vote 2/3+ for Block N?}


  Block_Confirmed -- Yes --> Block_Finalized[Block N Finalized]
  Block_Confirmed -- No --> Network_Accumulate_Votes


  Leader_Create_Block --> Tx_Included_in_Block[Tx Included in Block N]
  Tx_Included_in_Block --> Validators_Validate_Block

  Block_Confirmed -- Yes --> Tx_Confirmed_Status[Tx Status: Confirmed]
  Block_Finalized --> Tx_Finalized[Tx Status: Finalized]


  Leader_Fetch_Tx --> Tx_Not_Included{Tx Not Fetched/Included by Leader?}
  Tx_Not_Included -- Yes --> Tx_Still_Pending[Tx Status: Still Pending]
  Tx_Still_Pending --> Validator_Receive_Tx

  Block_Invalid --> Tx_Failed_Block[Tx Status: Failed In Invalid Block]


  Leader_Assign_N --> Leader_Fail{Leader N Fails to Produce Block?}
  Leader_Fail -- Yes --> Slot_End_N


  Slot_Start_N_plus_1 --> Leader_Assign_N_plus_1[Validator N+1 Assigned as Leader for Slot N+1]
  Leader_Assign_N_plus_1 --> Leader_Fetch_Tx


  classDef time fill:#e0e0e0,stroke:#333;
  class Epoch_Start,Slot_Start_N,Slot_End_N,Slot_Start_N_plus_1,Slot_End_N_plus_1,Leader_Schedule time;

  classDef tx fill:#ffc,stroke:#333;
  class Tx_Submit,Tx_Pending,Tx_Processed,Tx_Included_in_Block,Tx_Confirmed_Status,Tx_Finalized,Tx_Failed_Leader,Tx_Failed_Block,Tx_Still_Pending tx;

  classDef validator fill:#f9f,stroke:#333,stroke-width:2px;
  class Leader_Assign_N,Leader_Fetch_Tx,Leader_Process_Tx,Leader_Create_Block,Leader_Propagate_Block,Validators_Receive_Block,Validators_Validate_Block,Validators_Vote,Leader_Assign_N_plus_1 validator;

  classDef poh fill:#ccf,stroke:#333,stroke-width:2px;
  class Leader_PoH,Leader_PoH_Continuous poh;

  classDef consensus fill:#afa,stroke:#333,stroke-width:2px;
  class Network_Accumulate_Votes,Block_Confirmed,Block_Finalized consensus;

  classDef decision fill:#ff9,stroke:#333,stroke-width:2px;
  class Tx_Valid_Leader,Block_Valid,Block_Confirmed,Tx_Not_Included,Leader_Fail decision;

  classDef failure fill:#f99,stroke:#333;
  class Tx_Failed_Leader,Tx_Failed_Block,Block_Invalid,Validators_Ignore_Block failure;

  classDef process fill:#ddd,stroke:#333;
  class Client,Validator_Receive_Tx,Leader_Forward_Tx process;

  classDef note fill:#eee,stroke:#999,stroke-dasharray: 5 5;
  class Leader_PoH_Continuous note;

Loading

1. Time Subgraph: Shows the fundamental structure of Epochs and Slots, and how the Leader Schedule is determined per epoch. It illustrates the continuous progression of slots.
2. Transaction Origin: A transaction starts with a user/client and enters a pending state.
3. Propagation & Leader: The transaction is sent to a validator (like an RPC node) and forwarded towards the current slot's leader. The diagram shows the leader being assigned based on the schedule for the current slot (N).
4. Leader Pipeline: The assigned leader fetches transactions from its pool and puts them through its processing pipeline (SigVerify, Banking).
5. Tx Validation at Leader: Transactions are validated. Valid ones proceed; invalid ones lead to a "Failed (Invalid)" status.
6. Proof of History (PoH): The leader continuously generates the PoH sequence, incorporating processed transactions and events.
7. Block Creation: Valid, processed transactions and the current state of the PoH sequence are bundled into Block N.
8. Block Propagation: The leader sends Block N to other validators.
9. Validation by Others: Other validators receive Block N and validate its contents, including the transactions and the PoH sequence.
10. Block Validation Outcome: If the block is invalid (e.g., contains invalid transactions the leader missed, or a PoH discrepancy), validators ignore it, and transactions within it lead to a "Failed (In Invalid Block)" status. If valid, validators proceed to vote.
11. Consensus (Tower BFT): Validators cast stake-weighted votes. The network accumulates these votes.
12. Confirmation & Finality: If Block N receives a supermajority (>2/3) of stake votes, it becomes finalized.
13. Transaction Status Updates:
    • A transaction included in a block transitions from "Processed" to "Included in Block".
    • If the block is confirmed, the transaction status becomes "Confirmed".
    • If the block is finalized, the transaction status becomes "Finalized".
14. Alternative Cases:
    • Tx Not Included: A transaction might be valid but not fetched or included by the leader (e.g., arrived too late, network congestion). It remains "Pending" and re-enters the propagation pool to potentially be included by a future leader.
    • Leader Failure: If the assigned leader fails, the slot might end without a block from that leader.
    • Block Invalid: As mentioned, leads to Tx failure status.
15. Slot Progression: The diagram explicitly shows the transition to Slot N+1 and the assignment of the next leader, highlighting that this happens continuously, often before previous blocks are finalized.

Credits

• dhruvsol / git
• Arpita / git