Function holochain::core::check_prev_action

pub fn check_prev_action(action: &Action) -> SysValidationResult<()>

Check that the correct actions have the correct setting for prev_action:

• Dna can never have a prev_action, and must have seq == 0.
• All other actions must have prev_action, and seq > 0.

Examples found in repository

src/core/workflow/sys_validation_workflow.rs (line 568)

async fn register_agent_activity(
    action: &Action,
    workspace: &SysValidationWorkspace,
    network: HolochainP2pDna,
    incoming_dht_ops_sender: Option<IncomingDhtOpSender>,
) -> SysValidationResult<()> {
    // Get data ready to validate
    let prev_action_hash = action.prev_action();

    // Checks
    check_prev_action(action)?;
    check_valid_if_dna(action, workspace).await?;
    if let Some(prev_action_hash) = prev_action_hash {
        check_and_hold_register_agent_activity(
            prev_action_hash,
            workspace,
            network,
            incoming_dht_ops_sender,
            |_| Ok(()),
        )
        .await?;
    }
    check_chain_rollback(action, workspace).await?;
    Ok(())
}

async fn store_record(
    action: &Action,
    workspace: &SysValidationWorkspace,
    network: HolochainP2pDna,
) -> SysValidationResult<()> {
    // Get data ready to validate
    let prev_action_hash = action.prev_action();

    // Checks
    check_prev_action(action)?;
    if let Some(prev_action_hash) = prev_action_hash {
        let mut cascade = workspace.full_cascade(network);
        let prev_action = cascade
            .retrieve_action(prev_action_hash.clone(), Default::default())
            .await?
            .ok_or_else(|| ValidationOutcome::DepMissingFromDht(prev_action_hash.clone().into()))?;
        check_prev_timestamp(action, prev_action.action())?;
        check_prev_seq(action, prev_action.action())?;
    }
    Ok(())
}