telltale-vm 2.1.0

Bytecode VM for choreographic session type protocols
Documentation 
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//! Shared commit-phase helpers used by cooperative and threaded backends.

use serde_json::json;

use crate::coroutine::Fault;
use crate::effect::EffectTraceEntry;
use crate::output_condition::{
    verify_output_condition, OutputConditionCheck, OutputConditionHint, OutputConditionMeta,
    OutputConditionPolicy,
};
use crate::vm::ObsEvent;

/// Apply output-condition verification for a commit and record diagnostics.
pub(crate) fn apply_output_condition_gate(
    policy: &OutputConditionPolicy,
    checks: &mut Vec<OutputConditionCheck>,
    trace: &mut Vec<ObsEvent>,
    tick: u64,
    output_hint: Option<OutputConditionHint>,
) -> Result<(), Fault> {
    let digest = "vm.output_digest.unspecified".to_string();
    let meta = match output_hint {
        Some(h) => OutputConditionMeta::from_hint(h, digest),
        None => OutputConditionMeta::default_observable(digest),
    };
    let passed = verify_output_condition(policy, &meta);
    checks.push(OutputConditionCheck {
        meta: meta.clone(),
        passed,
    });
    trace.push(ObsEvent::OutputConditionChecked {
        tick,
        predicate_ref: meta.predicate_ref.clone(),
        witness_ref: meta.witness_ref.clone(),
        output_digest: meta.output_digest.clone(),
        passed,
    });
    if passed {
        Ok(())
    } else {
        Err(Fault::OutputCondition {
            predicate_ref: meta.predicate_ref,
        })
    }
}

/// Build canonical effect-trace entry from an observable event, if applicable.
pub(crate) fn effect_trace_entry_for_event(
    ev: &ObsEvent,
    effect_id: u64,
    handler_identity: &str,
    ordering_key: u64,
) -> Option<EffectTraceEntry> {
    match ev {
        ObsEvent::Sent {
            session,
            from,
            to,
            label,
            ..
        } => Some(EffectTraceEntry {
            effect_id,
            effect_kind: "send_decision".to_string(),
            inputs: json!({
                "session": session,
                "from": from,
                "to": to,
                "label": label,
            }),
            outputs: json!({"committed": true}),
            handler_identity: handler_identity.to_string(),
            ordering_key,
            topology: None,
        }),
        ObsEvent::Received {
            session,
            from,
            to,
            label,
            ..
        } => Some(EffectTraceEntry {
            effect_id,
            effect_kind: "handle_recv".to_string(),
            inputs: json!({
                "session": session,
                "from": from,
                "to": to,
                "label": label,
            }),
            outputs: json!({"committed": true}),
            handler_identity: handler_identity.to_string(),
            ordering_key,
            topology: None,
        }),
        ObsEvent::Invoked { coro_id, role, .. } => Some(EffectTraceEntry {
            effect_id,
            effect_kind: "invoke_step".to_string(),
            inputs: json!({
                "coro_id": coro_id,
                "role": role,
            }),
            outputs: json!({"ok": true}),
            handler_identity: handler_identity.to_string(),
            ordering_key,
            topology: None,
        }),
        ObsEvent::Acquired {
            session,
            role,
            layer,
            ..
        } => Some(EffectTraceEntry {
            effect_id,
            effect_kind: "handle_acquire".to_string(),
            inputs: json!({
                "session": session,
                "role": role,
                "layer": layer,
            }),
            outputs: json!({"granted": true}),
            handler_identity: handler_identity.to_string(),
            ordering_key,
            topology: None,
        }),
        ObsEvent::Released {
            session,
            role,
            layer,
            ..
        } => Some(EffectTraceEntry {
            effect_id,
            effect_kind: "handle_release".to_string(),
            inputs: json!({
                "session": session,
                "role": role,
                "layer": layer,
            }),
            outputs: json!({"ok": true}),
            handler_identity: handler_identity.to_string(),
            ordering_key,
            topology: None,
        }),
        _ => None,
    }
}