use std::collections::{BTreeMap, BTreeSet};
use rustev_contract::definition::{Definition, StepBody};
use rustev_contract::descriptor::BackendDescriptor;
use rustev_contract::execution::{
AttemptTimeout, CostPolicy, Delay, ExecutionPolicy, MAX_ATTEMPTS_PER_TARGET, MAX_DELAY_MS,
MAX_FALLBACKS,
};
use rustev_contract::optimization::OptimizationPolicy;
use rustev_contract::plan::{
BoundCalibration, DeclaredExecution, FallbackBinding, PlanExecution, PlanStepDetail,
};
use rustev_contract::{Identified, schema};
use crate::compile::{Category, Refusal, Shortfall, check_candidate};
fn refuse<T>(subject: impl Into<String>, detail: impl Into<String>) -> Result<T, Refusal> {
Err(Refusal {
category: Category::InvalidExecution,
subject: subject.into(),
detail: detail.into(),
shortfalls: vec![],
})
}
fn unique<T: Ord>(items: &[T]) -> bool {
items.iter().collect::<BTreeSet<_>>().len() == items.len()
}
fn validate_optimization(policy: &OptimizationPolicy) -> Result<(), Refusal> {
let subject = "execution.optimization";
if policy.key_schema_version == 0 {
return refuse(subject, "key_schema_version must be positive");
}
if policy.cache_namespace_version == 0 {
return refuse(subject, "cache_namespace_version must be positive");
}
if policy.batch.is_none() && policy.memory_cache.is_none() {
return refuse(subject, "at least one optimization mechanism is enabled");
}
if let Some(p) = &policy.batch
&& (p.max_members < 2
|| p.max_canonical_bytes == 0
|| p.max_members_per_scope == 0
|| p.max_members_per_scope > p.max_members
|| p.max_backend_work == 0)
{
return refuse(
subject,
"batch bounds must be positive and internally consistent",
);
}
if let Some(p) = &policy.memory_cache
&& (p.max_bytes == 0
|| p.max_entries == 0
|| p.max_entry_bytes == 0
|| p.max_scope_bytes == 0
|| p.ttl_ms == 0
|| p.max_entry_bytes > p.max_scope_bytes
|| p.max_scope_bytes > p.max_bytes)
{
return refuse(
subject,
"memory cache bounds must be positive and internally consistent",
);
}
Ok(())
}
pub(crate) fn validate(
policy: &ExecutionPolicy,
def: &Definition,
sorted: &[&BackendDescriptor],
details: &BTreeMap<String, PlanStepDetail>,
bind_ctx: &BTreeMap<String, (u64, u64)>,
) -> Result<PlanExecution, Refusal> {
if policy.schema != schema::EXECUTION {
return Err(Refusal {
category: Category::Parse,
subject: "execution".into(),
detail: format!("schema {:?} is not {}", policy.schema, schema::EXECUTION),
shortfalls: vec![],
});
}
match policy.cost {
CostPolicy::Hard { max_units: 0 } | CostPolicy::Estimated { max_units: 0 } => {
return refuse("execution", "a cost budget of 0 units admits nothing");
}
_ => {}
}
if let Some(optimization) = &policy.optimization {
validate_optimization(optimization)?;
}
let mut seen = BTreeSet::new();
let mut fallbacks = Vec::new();
for sp in &policy.steps {
let subject = format!("step:{}", sp.step);
let decl = def.steps.iter().find(|s| s.id == sp.step);
let binding = match (decl.map(|s| &s.body), details.get(&sp.step)) {
(None, _) => return refuse(subject, "no such step"),
(Some(StepBody::Exact(_)), _) => {
return refuse(subject, "an exact step has no runtime execution");
}
(Some(StepBody::Semantic(_)), Some(PlanStepDetail::Unsupported { .. })) => {
return refuse(
subject,
"the step's compile-time fallback `unsupported` was taken",
);
}
(Some(StepBody::Semantic(_)), Some(PlanStepDetail::Semantic(_)))
| (Some(StepBody::Generate(_)), Some(PlanStepDetail::Generate(_))) => {
(decl.unwrap(), details.get(&sp.step).unwrap())
}
(Some(StepBody::Acquire(_)), Some(PlanStepDetail::Acquire))
| (Some(StepBody::Widen(_)), Some(PlanStepDetail::Widen)) => {
if !seen.insert(sp.step.as_str()) {
return refuse(subject, "a step has at most one execution entry");
}
if sp.attempt_timeout == AttemptTimeout::Ms(0) {
return refuse(subject, "an attempt timeout of 0 admits nothing");
}
if sp.retry != rustev_contract::execution::RetryPolicy::none()
|| !sp.fallback.backends.is_empty()
|| !sp.fallback.on.is_empty()
{
return refuse(
subject,
"acquisition retries and sources are declared in the step",
);
}
continue;
}
_ => return refuse(subject, "the step is not bound"),
};
if !seen.insert(sp.step.as_str()) {
return refuse(subject, "a step has at most one execution entry");
}
let r = &sp.retry;
if !(1..=MAX_ATTEMPTS_PER_TARGET).contains(&r.max_attempts) {
return refuse(
subject,
format!("retry.max_attempts must be in 1..={MAX_ATTEMPTS_PER_TARGET}"),
);
}
if (r.max_attempts == 1) != r.on.is_empty() {
return refuse(
subject,
"retry.on is empty exactly when retry.max_attempts is 1",
);
}
if !unique(&r.on) {
return refuse(subject, "retry.on repeats a class");
}
if let Some(c) = r.on.iter().find(|c| !c.retryable()) {
return refuse(subject, format!("{} is never retried", c.name()));
}
match r.delay {
Delay::None => {}
Delay::Fixed { ms } if (1..=MAX_DELAY_MS).contains(&ms) => {}
Delay::Exponential { initial_ms, max_ms }
if 1 <= initial_ms && initial_ms <= max_ms && max_ms <= MAX_DELAY_MS => {}
_ => return refuse(subject, "a retry delay is outside its bounds"),
}
if sp.attempt_timeout == AttemptTimeout::Ms(0) {
return refuse(subject, "an attempt timeout of 0 admits nothing");
}
let f = &sp.fallback;
if f.backends.len() > MAX_FALLBACKS {
return refuse(
subject,
format!("at most {MAX_FALLBACKS} fallback backends"),
);
}
if f.backends.is_empty() != f.on.is_empty() {
return refuse(
subject,
"fallback.on is empty exactly when no fallback backend is declared",
);
}
if !unique(&f.on) {
return refuse(subject, "fallback.on repeats a class");
}
let (decl, detail) = binding;
let (primary_id, primary_output, calibration) = match detail {
PlanStepDetail::Semantic(b) => (&b.backend_id, b.output.clone(), b.calibration.clone()),
PlanStepDetail::Generate(b) => {
let Some(backend) = sorted.iter().find(|d| d.backend_id == b.backend_id) else {
return refuse(
subject,
format!("bound backend {:?} was not supplied", b.backend_id),
);
};
let StepBody::Generate(g) = &decl.body else {
unreachable!()
};
let checked = crate::generation::checked_binding(&decl.id, g, b)?;
let output =
crate::generation::candidate(g, &checked, backend).map_err(|reasons| {
Refusal {
category: Category::InvalidExecution,
subject: subject.clone(),
detail: "generation binding changed".into(),
shortfalls: vec![Shortfall {
backend_id: b.backend_id.clone(),
reasons,
}],
}
})?;
(&b.backend_id, output, BoundCalibration::None)
}
_ => unreachable!(),
};
let mut chain: BTreeSet<&str> = [primary_id.as_str()].into();
let (options_needed, bound) = bind_ctx
.get(&sp.step)
.copied()
.unwrap_or((u64::MAX, u64::MAX));
for (i, id) in f.backends.iter().enumerate() {
if !chain.insert(id.as_str()) {
return refuse(
subject,
format!("fallback {id:?} is the bound backend or repeats one (a cycle)"),
);
}
let Some(b) = sorted.iter().find(|b| &b.backend_id == id) else {
return refuse(subject, format!("fallback {id:?} was not supplied"));
};
let candidate = match (&decl.body, detail) {
(StepBody::Semantic(d), PlanStepDetail::Semantic(primary)) => {
check_candidate(d, b, primary.requires, options_needed, bound)
}
(StepBody::Generate(g), PlanStepDetail::Generate(primary)) => {
crate::generation::candidate(
g,
&crate::generation::checked_binding(&decl.id, g, primary)?,
b,
)
}
_ => unreachable!(),
};
let output = match candidate {
Ok(o) => o,
Err(reasons) => {
return Err(Refusal {
category: Category::InvalidExecution,
subject,
detail: format!("fallback {id:?} cannot serve the step"),
shortfalls: vec![Shortfall {
backend_id: id.clone(),
reasons,
}],
});
}
};
if matches!(detail, PlanStepDetail::Semantic(_)) && output != primary_output {
return refuse(
subject,
format!(
"fallback {id:?} returns {output:?}; the bound backend returns {:?}",
primary_output
),
);
}
if let BoundCalibration::Bound { binding, .. } = &calibration
&& binding.artifact != b.artifact
{
return refuse(
subject,
format!(
"fallback {id:?} is artifact {}; the calibration is bound to {}",
b.artifact, binding.artifact
),
);
}
let descriptor = b.id().map_err(|e| Refusal {
category: Category::Parse,
subject: subject.clone(),
detail: e.to_string(),
shortfalls: vec![],
})?;
fallbacks.push(FallbackBinding {
step: sp.step.clone(),
target: i as u32 + 1,
backend_id: b.backend_id.clone(),
artifact: b.artifact.clone(),
descriptor,
output,
});
}
}
let mut worst: u64 = 0;
for s in &def.steps {
let requests = match details.get(&s.id) {
Some(PlanStepDetail::Semantic(b)) => b.max_requests,
Some(PlanStepDetail::Generate(b)) => b.worst_case_requests,
_ => continue,
};
{
let per_request = match policy.steps.iter().find(|p| p.step == s.id) {
Some(p) => u64::from(p.retry.max_attempts)
.saturating_mul(1 + p.fallback.backends.len() as u64),
None => 1,
};
worst = worst.saturating_add(requests.saturating_mul(per_request));
}
}
if worst > policy.max_attempts_per_decision {
return refuse(
"execution",
format!(
"worst case {worst} attempts exceeds max_attempts_per_decision {}",
policy.max_attempts_per_decision
),
);
}
let id = policy.id().map_err(|e| Refusal {
category: Category::Parse,
subject: "execution".into(),
detail: e.to_string(),
shortfalls: vec![],
})?;
Ok(PlanExecution::Declared(Box::new(DeclaredExecution {
id,
policy: policy.clone(),
fallbacks,
})))
}
#[cfg(test)]
mod tests {
use super::*;
use rustev_contract::execution::{FallbackPolicy, RetryPolicy, StepExecution};
use rustev_contract::plan::Plan;
#[test]
fn missing_primary_generate_backend_is_refused() {
let plan: Plan =
serde_json::from_str(include_str!("testdata/generation.plan.json")).unwrap();
let step = &plan.steps[0];
let PlanStepDetail::Generate(binding) = &step.detail else {
panic!("expected a generation binding");
};
let policy = ExecutionPolicy {
schema: schema::EXECUTION.into(),
max_attempts_per_decision: binding.worst_case_requests,
cost: CostPolicy::Unlimited,
optimization: None,
steps: vec![StepExecution {
step: step.id.clone(),
retry: RetryPolicy::none(),
attempt_timeout: AttemptTimeout::None,
fallback: FallbackPolicy {
backends: vec![],
on: vec![],
},
}],
};
let details = BTreeMap::from([(step.id.clone(), step.detail.clone())]);
let refusal = validate(&policy, &plan.definition, &[], &details, &BTreeMap::new())
.expect_err("a missing primary descriptor must be refused");
assert_eq!(refusal.category, Category::InvalidExecution);
assert_eq!(refusal.subject, format!("step:{}", step.id));
assert_eq!(
refusal.detail,
format!("bound backend {:?} was not supplied", binding.backend_id)
);
assert!(refusal.shortfalls.is_empty());
}
}