Files
sglang/experimental/sgl-router/tests/proxy/bucket_routing.rs
T

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35 KiB
Rust

// SPDX-FileCopyrightText: Copyright (c) 2026 The SGLang Authors
// SPDX-License-Identifier: Apache-2.0
//! HTTP contract for static P/D buckets.
//!
//! Buckets narrow the candidate domain before policy selection. Prefill SLO
//! profiles may override rank, while decode uses `input_tokens + max_tokens`.
use axum::body::Body;
use axum::http::{Request, StatusCode};
use sgl_kv_indexer::{PrefixIndex, PrefixIndexError, PrefixMatch, PrefixOutcome};
use sgl_router::config::{
ActiveLoadConfig, AffinityConfig, BucketConfig, BucketSpec, BucketStage, CacheAwareConfig,
CachePrefixProvider, Config, DiscoveryBackend, KvIndexerEndpointConfig, ModelConfig,
ObservabilityConfig, PolicyKind, ProxyConfig, ServerConfig, SessionAffinityMode,
SloBucketPolicy, StaticUrlsDiscoveryConfig,
};
use sgl_router::discovery::{ModelId, WorkerId, WorkerMode, WorkerSpec};
use sgl_router::policies::engine_load::{LoadStat, NativeCacheRankLoad};
use sgl_router::policies::factory::build_registry_with_defaults;
use sgl_router::proxy::Proxy;
use sgl_router::server::app::build_router;
use sgl_router::server::app_context::AppContext;
use sgl_router::tokenizer::TokenizerRegistry;
use sgl_router::workers::WorkerRegistry;
use std::sync::atomic::{AtomicUsize, Ordering};
use std::sync::Arc;
use std::time::{Duration, Instant};
use tower::ServiceExt;
fn bucket(id: &str, stage: BucketStage, rank: u32, worker_id: &str) -> BucketSpec {
BucketSpec {
id: id.into(),
stage,
rank,
worker_ids: vec![worker_id.into()],
min_extend_tokens: None,
max_extend_tokens: None,
min_sequence_tokens: None,
max_sequence_tokens: None,
max_context_tokens: Some(16_384),
ttft_p95_at_capacity_ms: None,
tps_p05_at_capacity: None,
max_pending_prefill_tokens: None,
}
}
fn build_app_context(
specs: Vec<WorkerSpec>,
bucket_config: BucketConfig,
policy: PolicyKind,
affinity: Option<AffinityConfig>,
) -> AppContext {
let config = Config {
server: ServerConfig {
host: "0".into(),
port: 0,
},
observability: ObservabilityConfig::default(),
model: ModelConfig {
id: "tiny".into(),
tokenizer_path: "tests/fixtures/tiny_tokenizer.json".into(),
policy,
decode_policy: Default::default(),
bucket_config: Some(bucket_config),
circuit_breaker: None,
cache_aware: None,
sticky: None,
affinity,
fused: None,
eligibility: None,
},
discovery: DiscoveryBackend::StaticUrls(StaticUrlsDiscoveryConfig {
urls: vec!["http://placeholder:0".into()],
}),
proxy: ProxyConfig::default(),
active_load: ActiveLoadConfig::default(),
};
let tokenizers = Arc::new(TokenizerRegistry::load_from_config(&config).unwrap());
let registry = Arc::new(WorkerRegistry::default());
for spec in specs {
let _ = registry.add(spec);
}
let policies = Arc::new(build_registry_with_defaults(&config).unwrap());
let proxy = Arc::new(Proxy::new(Duration::from_secs(5)).unwrap());
AppContext::new(config, tokenizers, proxy, registry, policies)
}
fn build_ctx(
specs: Vec<WorkerSpec>,
bucket_config: BucketConfig,
policy: PolicyKind,
affinity: Option<AffinityConfig>,
) -> Arc<AppContext> {
Arc::new(build_app_context(specs, bucket_config, policy, affinity))
}
struct FakePrefixIndex {
address: Option<String>,
calls: AtomicUsize,
}
impl FakePrefixIndex {
fn matched(address: String) -> Arc<Self> {
Arc::new(Self {
address: Some(address),
calls: AtomicUsize::new(0),
})
}
fn no_signal() -> Arc<Self> {
Arc::new(Self {
address: None,
calls: AtomicUsize::new(0),
})
}
}
#[tonic::async_trait]
impl PrefixIndex for FakePrefixIndex {
async fn match_prefix(&self, hashes: Vec<i64>) -> Result<PrefixOutcome, PrefixIndexError> {
self.calls.fetch_add(1, Ordering::Relaxed);
let Some(address) = &self.address else {
return Ok(PrefixOutcome::Empty);
};
let matched_prefix_blocks =
u32::try_from(hashes.len().saturating_sub(1)).unwrap_or(u32::MAX);
Ok(PrefixOutcome::Matched {
matches: vec![PrefixMatch {
address: address.clone(),
matched_prefix_blocks,
worker_id: "fake-index-worker".into(),
}],
best_prefix_blocks: matched_prefix_blocks,
})
}
}
struct TwoPrefixIndex {
best_address: String,
lower_ranked_address: String,
}
impl TwoPrefixIndex {
fn new(best_address: String, lower_ranked_address: String) -> Arc<Self> {
Arc::new(Self {
best_address,
lower_ranked_address,
})
}
}
#[tonic::async_trait]
impl PrefixIndex for TwoPrefixIndex {
async fn match_prefix(&self, hashes: Vec<i64>) -> Result<PrefixOutcome, PrefixIndexError> {
let best_prefix_blocks = u32::try_from(hashes.len().saturating_sub(1)).unwrap_or(u32::MAX);
let lower_ranked_prefix_blocks = (best_prefix_blocks / 2).max(1);
Ok(PrefixOutcome::Matched {
matches: vec![
PrefixMatch {
address: self.best_address.clone(),
matched_prefix_blocks: best_prefix_blocks,
worker_id: "best-index-worker".into(),
},
PrefixMatch {
address: self.lower_ranked_address.clone(),
matched_prefix_blocks: lower_ranked_prefix_blocks,
worker_id: "lower-index-worker".into(),
},
],
best_prefix_blocks,
})
}
}
fn build_cache_ctx(
specs: Vec<WorkerSpec>,
bucket_config: BucketConfig,
prefix_index: Arc<dyn PrefixIndex>,
) -> Arc<AppContext> {
build_cache_ctx_with_affinity(
specs,
bucket_config,
prefix_index,
AffinityConfig::default(),
)
}
fn build_cache_ctx_with_affinity(
specs: Vec<WorkerSpec>,
bucket_config: BucketConfig,
prefix_index: Arc<dyn PrefixIndex>,
affinity: AffinityConfig,
) -> Arc<AppContext> {
let mut context =
build_app_context(specs, bucket_config, PolicyKind::CacheAware, Some(affinity));
context.config.model.cache_aware = Some(CacheAwareConfig {
prefix_provider: CachePrefixProvider::Indexer,
kv_indexer_endpoint: Some(KvIndexerEndpointConfig {
url: "http://fake-indexer".into(),
query_timeout_ms: 100,
query_max_inflight: 32,
}),
});
context.prefix_index = Some(prefix_index);
context.block_size_oracle.try_set(1).unwrap();
Arc::new(context)
}
fn worker_spec(id: &str, url: String, mode: WorkerMode) -> WorkerSpec {
WorkerSpec {
id: WorkerId(id.into()),
url,
mode,
model_ids: vec![ModelId("tiny".into())],
bootstrap_port: (mode == WorkerMode::Prefill).then_some(8997),
}
}
fn set_native_load(
ctx: &AppContext,
worker_url: &str,
num_total_tokens: u64,
max_total_num_tokens: u64,
) {
set_native_load_with_waiting(ctx, worker_url, num_total_tokens, max_total_num_tokens, 0);
}
fn set_native_load_with_waiting(
ctx: &AppContext,
worker_url: &str,
num_total_tokens: u64,
max_total_num_tokens: u64,
num_waiting_uncached_tokens: u64,
) {
ctx.engine_load.set(
worker_url,
0,
LoadStat {
num_running_reqs: 0,
num_waiting_reqs: 0,
num_tokens: num_total_tokens,
max_total_num_tokens,
native_cache: Some(NativeCacheRankLoad {
num_waiting_uncached_tokens,
num_total_tokens,
max_running_requests: 64,
total_prefill_uncached_tokens: 1,
total_prefill_busy_us: 1,
}),
},
Instant::now(),
);
}
fn chat_request(ttft_slo_ms: Option<u64>, max_tokens: Option<u64>) -> Request<Body> {
chat_request_with_content("bucket routing", ttft_slo_ms, max_tokens, None)
}
fn chat_request_with_content(
content: &str,
ttft_slo_ms: Option<u64>,
max_tokens: Option<u64>,
session_id: Option<&str>,
) -> Request<Body> {
let mut builder = Request::builder()
.method("POST")
.uri("/v1/chat/completions")
.header("content-type", "application/json");
if let Some(ttft_slo_ms) = ttft_slo_ms {
builder = builder.header("x-sgl-ttft-slo-ms", ttft_slo_ms.to_string());
}
if let Some(session_id) = session_id {
builder = builder.header("x-session-id", session_id);
}
builder
.body(Body::from(
serde_json::to_vec(&serde_json::json!({
"model": "tiny",
"messages": [{"role": "user", "content": content}],
"max_tokens": max_tokens,
}))
.unwrap(),
))
.unwrap()
}
async fn wait_for_prefill(mock: &crate::common::mock_worker::MockWorker) {
tokio::time::timeout(Duration::from_secs(2), async {
loop {
if mock.captured.lock().unwrap().last_body.is_some() {
return;
}
tokio::time::sleep(Duration::from_millis(5)).await;
}
})
.await
.expect("selected prefill worker must receive the detached request");
}
async fn wait_for_prefill_body_containing(
mock: &crate::common::mock_worker::MockWorker,
expected: &str,
) -> Vec<u8> {
tokio::time::timeout(Duration::from_secs(2), async {
loop {
let captured = mock.captured.lock().unwrap().last_body.clone();
if let Some(body) = captured {
if String::from_utf8_lossy(&body).contains(expected) {
return body.to_vec();
}
}
tokio::time::sleep(Duration::from_millis(5)).await;
}
})
.await
.expect("selected prefill worker must receive the expected request body")
}
#[tokio::test]
async fn prefill_slo_first_uses_eligible_ttft_bucket_before_lower_rank_bucket() {
let cheap = crate::common::mock_worker::MockWorker::start(vec![]).await;
let fast = crate::common::mock_worker::MockWorker::start(vec![]).await;
let decode = crate::common::mock_worker::MockWorker::start(vec![]).await;
let mut cheap_bucket = bucket("p-cheap", BucketStage::Prefill, 10, "p-cheap");
cheap_bucket.ttft_p95_at_capacity_ms = Some(400);
let mut fast_bucket = bucket("p-fast", BucketStage::Prefill, 20, "p-fast");
fast_bucket.ttft_p95_at_capacity_ms = Some(100);
let bucket_config = BucketConfig {
buckets: vec![
cheap_bucket,
fast_bucket,
bucket("d-catch-all", BucketStage::Decode, 30, "d"),
],
ttft_slo_policy: SloBucketPolicy::SloFirst,
tps_slo_policy: SloBucketPolicy::Disabled,
};
let ctx = build_ctx(
vec![
worker_spec("p-cheap", cheap.url.clone(), WorkerMode::Prefill),
worker_spec("p-fast", fast.url.clone(), WorkerMode::Prefill),
worker_spec("d", decode.url.clone(), WorkerMode::Decode),
],
bucket_config,
PolicyKind::PowerOfTwo,
None,
);
let response = build_router(ctx)
.oneshot(chat_request(Some(200), Some(16)))
.await
.unwrap();
assert_eq!(response.status(), StatusCode::OK);
wait_for_prefill(&fast).await;
assert!(
cheap.captured.lock().unwrap().last_body.is_none(),
"lower-rank but TTFT-ineligible P Bucket must not be dispatched first"
);
}
#[tokio::test]
async fn prefill_tries_later_compatible_bucket_before_capacity_fallback() {
let full = crate::common::mock_worker::MockWorker::start(vec![]).await;
let available = crate::common::mock_worker::MockWorker::start(vec![]).await;
let decode = crate::common::mock_worker::MockWorker::start(vec![]).await;
let bucket_config = BucketConfig {
buckets: vec![
bucket("p-full", BucketStage::Prefill, 10, "p-full"),
bucket("p-available", BucketStage::Prefill, 20, "p-available"),
bucket("d", BucketStage::Decode, 30, "d"),
],
ttft_slo_policy: SloBucketPolicy::Disabled,
tps_slo_policy: SloBucketPolicy::Disabled,
};
let ctx = build_ctx(
vec![
worker_spec("p-full", full.url.clone(), WorkerMode::Prefill),
worker_spec("p-available", available.url.clone(), WorkerMode::Prefill),
worker_spec("d", decode.url.clone(), WorkerMode::Decode),
],
bucket_config,
PolicyKind::PowerOfTwo,
None,
);
set_native_load(&ctx, &full.url, 100, 100);
set_native_load(&ctx, &available.url, 0, 10_000);
let response = build_router(ctx)
.oneshot(chat_request(None, Some(16)))
.await
.unwrap();
assert_eq!(response.status(), StatusCode::OK);
wait_for_prefill(&available).await;
assert!(
full.captured.lock().unwrap().last_body.is_none(),
"capacity fallback must wait until all compatible prefill buckets are exhausted"
);
}
#[tokio::test]
async fn decode_bucket_uses_input_plus_requested_output_budget() {
let prefill = crate::common::mock_worker::MockWorker::start(vec![]).await;
let short_decode = crate::common::mock_worker::MockWorker::start(vec![]).await;
let long_decode = crate::common::mock_worker::MockWorker::start(vec![]).await;
let mut short_bucket = bucket("d-short", BucketStage::Decode, 20, "d-short");
short_bucket.max_sequence_tokens = Some(1_024);
let mut long_bucket = bucket("d-long", BucketStage::Decode, 30, "d-long");
long_bucket.min_sequence_tokens = Some(1_025);
let bucket_config = BucketConfig {
buckets: vec![
bucket("p", BucketStage::Prefill, 10, "p"),
short_bucket,
long_bucket,
],
ttft_slo_policy: SloBucketPolicy::Disabled,
tps_slo_policy: SloBucketPolicy::Disabled,
};
let ctx = build_ctx(
vec![
worker_spec("p", prefill.url.clone(), WorkerMode::Prefill),
worker_spec("d-short", short_decode.url.clone(), WorkerMode::Decode),
worker_spec("d-long", long_decode.url.clone(), WorkerMode::Decode),
],
bucket_config,
PolicyKind::PowerOfTwo,
None,
);
let response = build_router(ctx)
.oneshot(chat_request(None, Some(2_000)))
.await
.unwrap();
assert_eq!(response.status(), StatusCode::OK);
assert_eq!(
response
.headers()
.get("x-sgl-decode-url")
.and_then(|value| value.to_str().ok()),
Some(long_decode.url.as_str()),
"peak sequence length must exclude the short Decode Bucket"
);
assert!(
long_decode.captured.lock().unwrap().last_body.is_some(),
"the selected long Decode worker is awaited before the response"
);
assert!(
short_decode.captured.lock().unwrap().last_body.is_none(),
"the incompatible short Decode Bucket must not receive the request"
);
}
#[tokio::test]
async fn decode_tries_later_compatible_bucket_before_capacity_fallback() {
let prefill = crate::common::mock_worker::MockWorker::start(vec![]).await;
let full = crate::common::mock_worker::MockWorker::start(vec![]).await;
let available = crate::common::mock_worker::MockWorker::start(vec![]).await;
let bucket_config = BucketConfig {
buckets: vec![
bucket("p", BucketStage::Prefill, 10, "p"),
bucket("d-full", BucketStage::Decode, 20, "d-full"),
bucket("d-available", BucketStage::Decode, 30, "d-available"),
],
ttft_slo_policy: SloBucketPolicy::Disabled,
tps_slo_policy: SloBucketPolicy::Disabled,
};
let ctx = build_ctx(
vec![
worker_spec("p", prefill.url.clone(), WorkerMode::Prefill),
worker_spec("d-full", full.url.clone(), WorkerMode::Decode),
worker_spec("d-available", available.url.clone(), WorkerMode::Decode),
],
bucket_config,
PolicyKind::PowerOfTwo,
None,
);
set_native_load(&ctx, &full.url, 100, 100);
set_native_load(&ctx, &available.url, 0, 10_000);
let response = build_router(ctx)
.oneshot(chat_request(None, Some(16)))
.await
.unwrap();
assert_eq!(response.status(), StatusCode::OK);
assert_eq!(
response
.headers()
.get("x-sgl-decode-url")
.and_then(|value| value.to_str().ok()),
Some(available.url.as_str()),
"capacity fallback must wait until all compatible decode buckets are exhausted"
);
}
#[tokio::test]
async fn prefill_only_bucket_configuration_keeps_global_decode_routing() {
let prefill = crate::common::mock_worker::MockWorker::start(vec![]).await;
let decode = crate::common::mock_worker::MockWorker::start(vec![]).await;
let bucket_config = BucketConfig {
buckets: vec![bucket("p", BucketStage::Prefill, 10, "p")],
ttft_slo_policy: SloBucketPolicy::Disabled,
tps_slo_policy: SloBucketPolicy::Disabled,
};
let ctx = build_ctx(
vec![
worker_spec("p", prefill.url.clone(), WorkerMode::Prefill),
worker_spec("d", decode.url.clone(), WorkerMode::Decode),
],
bucket_config,
PolicyKind::PowerOfTwo,
None,
);
let response = build_router(ctx)
.oneshot(chat_request(None, Some(16)))
.await
.unwrap();
assert_eq!(response.status(), StatusCode::OK);
assert_eq!(
response
.headers()
.get("x-sgl-decode-url")
.and_then(|value| value.to_str().ok()),
Some(decode.url.as_str()),
"a Prefill-only Bucket rollout must retain the Step 1 global Decode domain"
);
}
#[tokio::test]
async fn global_rebind_session_affinity_can_keep_a_cross_length_bucket_primary() {
let short = crate::common::mock_worker::MockWorker::start(vec![]).await;
let long = crate::common::mock_worker::MockWorker::start(vec![]).await;
let decode = crate::common::mock_worker::MockWorker::start(vec![]).await;
let mut short_bucket = bucket("p-short", BucketStage::Prefill, 10, "p-short");
short_bucket.max_extend_tokens = Some(256);
short_bucket.max_context_tokens = Some(16_384);
short_bucket.ttft_p95_at_capacity_ms = Some(80);
let mut long_bucket = bucket("p-long", BucketStage::Prefill, 20, "p-long");
long_bucket.min_extend_tokens = Some(257);
long_bucket.max_context_tokens = Some(16_384);
long_bucket.ttft_p95_at_capacity_ms = Some(300);
let bucket_config = BucketConfig {
buckets: vec![
short_bucket,
long_bucket,
bucket("d-catch-all", BucketStage::Decode, 30, "d"),
],
ttft_slo_policy: SloBucketPolicy::SloFirst,
tps_slo_policy: SloBucketPolicy::Disabled,
};
let ctx = build_ctx(
vec![
worker_spec("p-short", short.url.clone(), WorkerMode::Prefill),
worker_spec("p-long", long.url.clone(), WorkerMode::Prefill),
worker_spec("d", decode.url.clone(), WorkerMode::Decode),
],
bucket_config,
PolicyKind::SessionAware,
Some(AffinityConfig {
session_affinity_mode: SessionAffinityMode::GlobalRebind,
..Default::default()
}),
);
let app = build_router(ctx);
let first = app
.clone()
.oneshot(chat_request_with_content(
"short",
Some(120),
Some(8),
Some("s-1"),
))
.await
.unwrap();
assert_eq!(first.status(), StatusCode::OK);
wait_for_prefill(&short).await;
let long_content = "length ".repeat(128);
let second = app
.oneshot(chat_request_with_content(
&long_content,
Some(120),
Some(8),
Some("s-1"),
))
.await
.unwrap();
assert_eq!(second.status(), StatusCode::OK);
let short_body = wait_for_prefill_body_containing(&short, &long_content).await;
assert!(
String::from_utf8_lossy(&short_body).contains(&long_content),
"the second, long request must retain the existing cross-Bucket session primary"
);
assert!(
long.captured.lock().unwrap().last_body.is_none(),
"target length Bucket is skipped only because the primary's own Hard TTFT profile is eligible"
);
}
#[tokio::test]
async fn global_preserve_establishes_then_reuses_a_new_assignment() {
let prefill = crate::common::mock_worker::MockWorker::start(vec![]).await;
let decode = crate::common::mock_worker::MockWorker::start(vec![]).await;
let bucket_config = BucketConfig {
buckets: vec![
bucket("p", BucketStage::Prefill, 10, "p"),
bucket("d", BucketStage::Decode, 20, "d"),
],
ttft_slo_policy: SloBucketPolicy::Disabled,
tps_slo_policy: SloBucketPolicy::Disabled,
};
let ctx = build_ctx(
vec![
worker_spec("p", prefill.url.clone(), WorkerMode::Prefill),
worker_spec("d", decode.url.clone(), WorkerMode::Decode),
],
bucket_config,
PolicyKind::SessionAware,
Some(AffinityConfig {
session_affinity_mode: SessionAffinityMode::GlobalPreserve,
..Default::default()
}),
);
let app = build_router(Arc::clone(&ctx));
for content in ["first global request", "second global request"] {
let response = app
.clone()
.oneshot(chat_request_with_content(
content,
None,
Some(8),
Some("global-session"),
))
.await
.unwrap();
assert_eq!(response.status(), StatusCode::OK);
}
let metrics = ctx.metrics.render();
assert!(
metrics.contains(
r#"sgl_router_policy_decisions_total{policy="session_aware",reason="assigned"} 1"#
),
"the first global-preserve request must establish an assignment: {metrics}"
);
assert!(
metrics.contains(
r#"sgl_router_policy_decisions_total{policy="session_aware",reason="session_primary"} 1"#
),
"the second global-preserve request must reuse the assignment: {metrics}"
);
}
#[tokio::test]
async fn cache_winner_uses_target_uncached_work_before_prompt_length_bucket() {
let short = crate::common::mock_worker::MockWorker::start(vec![]).await;
let long = crate::common::mock_worker::MockWorker::start(vec![]).await;
let decode = crate::common::mock_worker::MockWorker::start(vec![]).await;
let mut short_bucket = bucket("p-short", BucketStage::Prefill, 10, "p-short");
short_bucket.max_extend_tokens = Some(8);
let mut long_bucket = bucket("p-long", BucketStage::Prefill, 20, "p-long");
long_bucket.min_extend_tokens = Some(9);
let bucket_config = BucketConfig {
buckets: vec![
short_bucket,
long_bucket,
bucket("d-catch-all", BucketStage::Decode, 30, "d"),
],
ttft_slo_policy: SloBucketPolicy::Disabled,
tps_slo_policy: SloBucketPolicy::Disabled,
};
let index = FakePrefixIndex::matched(short.url.clone());
let prefix_index: Arc<dyn PrefixIndex> = index.clone();
let ctx = build_cache_ctx(
vec![
worker_spec("p-short", short.url.clone(), WorkerMode::Prefill),
worker_spec("p-long", long.url.clone(), WorkerMode::Prefill),
worker_spec("d", decode.url.clone(), WorkerMode::Decode),
],
bucket_config,
prefix_index,
);
let content = "cached-prefix ".repeat(128);
let response = build_router(ctx)
.oneshot(chat_request_with_content(&content, None, Some(8), None))
.await
.unwrap();
assert_eq!(response.status(), StatusCode::OK);
wait_for_prefill(&short).await;
assert!(
long.captured.lock().unwrap().last_body.is_none(),
"a cache winner with small target-specific uncached work must not be replaced by the full-length Bucket"
);
assert_eq!(
index.calls.load(Ordering::Relaxed),
1,
"the async Indexer query must run once at ingress, not once per Bucket"
);
}
#[tokio::test]
async fn unbucketed_global_cache_winner_remains_eligible() {
let best = crate::common::mock_worker::MockWorker::start(vec![]).await;
let lower_ranked = crate::common::mock_worker::MockWorker::start(vec![]).await;
let decode = crate::common::mock_worker::MockWorker::start(vec![]).await;
let mut lower_ranked_bucket = bucket("p-lower", BucketStage::Prefill, 20, "p-lower");
lower_ranked_bucket.min_extend_tokens = Some(32);
let bucket_config = BucketConfig {
buckets: vec![
lower_ranked_bucket,
bucket("d-catch-all", BucketStage::Decode, 30, "d"),
],
ttft_slo_policy: SloBucketPolicy::Disabled,
tps_slo_policy: SloBucketPolicy::Disabled,
};
let index: Arc<dyn PrefixIndex> =
TwoPrefixIndex::new(best.url.clone(), lower_ranked.url.clone());
let ctx = build_cache_ctx_with_affinity(
vec![
worker_spec("p-best", best.url.clone(), WorkerMode::Prefill),
worker_spec("p-lower", lower_ranked.url.clone(), WorkerMode::Prefill),
worker_spec("d", decode.url.clone(), WorkerMode::Decode),
],
bucket_config,
index,
AffinityConfig {
cache_candidate_min_workers: 1,
cache_candidate_ratio: 0.0,
cache_candidate_max_workers: 1,
..AffinityConfig::default()
},
);
let content = "cached bucket candidate ".repeat(256);
let response = build_router(Arc::clone(&ctx))
.oneshot(chat_request_with_content(&content, None, Some(8), None))
.await
.unwrap();
assert_eq!(response.status(), StatusCode::OK);
wait_for_prefill(&best).await;
assert!(
lower_ranked.captured.lock().unwrap().last_body.is_none(),
"an admitted unbucketed cache holder must remain globally eligible"
);
assert!(
ctx.metrics.render().contains(
r#"sgl_router_policy_decisions_total{policy="cache_aware",reason="cache_candidate"} 1"#
),
"the global cache winner must remain a cache candidate"
);
}
#[tokio::test]
async fn cache_candidate_over_context_limit_falls_back_to_compatible_bucket() {
let cached = crate::common::mock_worker::MockWorker::start(vec![]).await;
let fallback = crate::common::mock_worker::MockWorker::start(vec![]).await;
let decode = crate::common::mock_worker::MockWorker::start(vec![]).await;
let mut short_bucket = bucket("p-short", BucketStage::Prefill, 10, "p-cached");
short_bucket.max_context_tokens = Some(32);
let bucket_config = BucketConfig {
buckets: vec![
short_bucket,
bucket("p-long", BucketStage::Prefill, 20, "p-fallback"),
bucket("d-catch-all", BucketStage::Decode, 30, "d"),
],
ttft_slo_policy: SloBucketPolicy::Disabled,
tps_slo_policy: SloBucketPolicy::Disabled,
};
let prefix_index: Arc<dyn PrefixIndex> = FakePrefixIndex::matched(cached.url.clone());
let ctx = build_cache_ctx(
vec![
worker_spec("p-cached", cached.url.clone(), WorkerMode::Prefill),
worker_spec("p-fallback", fallback.url.clone(), WorkerMode::Prefill),
worker_spec("d", decode.url.clone(), WorkerMode::Decode),
],
bucket_config,
prefix_index,
);
let content = "context limit ".repeat(128);
let response = build_router(ctx)
.oneshot(chat_request_with_content(&content, None, Some(8), None))
.await
.unwrap();
assert_eq!(response.status(), StatusCode::OK);
wait_for_prefill(&fallback).await;
assert!(
cached.captured.lock().unwrap().last_body.is_none(),
"a cache holder that cannot serve the full context must not receive the request"
);
}
#[tokio::test]
async fn cache_candidate_outside_slo_first_tier_falls_back_to_eligible_bucket() {
let cached = crate::common::mock_worker::MockWorker::start(vec![]).await;
let fallback = crate::common::mock_worker::MockWorker::start(vec![]).await;
let decode = crate::common::mock_worker::MockWorker::start(vec![]).await;
let mut slow_bucket = bucket("p-slow", BucketStage::Prefill, 10, "p-cached");
slow_bucket.ttft_p95_at_capacity_ms = Some(400);
let mut fast_bucket = bucket("p-fast", BucketStage::Prefill, 20, "p-fallback");
fast_bucket.ttft_p95_at_capacity_ms = Some(100);
let bucket_config = BucketConfig {
buckets: vec![
slow_bucket,
fast_bucket,
bucket("d-catch-all", BucketStage::Decode, 30, "d"),
],
ttft_slo_policy: SloBucketPolicy::SloFirst,
tps_slo_policy: SloBucketPolicy::Disabled,
};
let prefix_index: Arc<dyn PrefixIndex> = FakePrefixIndex::matched(cached.url.clone());
let ctx = build_cache_ctx(
vec![
worker_spec("p-cached", cached.url.clone(), WorkerMode::Prefill),
worker_spec("p-fallback", fallback.url.clone(), WorkerMode::Prefill),
worker_spec("d", decode.url.clone(), WorkerMode::Decode),
],
bucket_config,
prefix_index,
);
let content = "ttft tier ".repeat(128);
let response = build_router(ctx)
.oneshot(chat_request_with_content(
&content,
Some(200),
Some(8),
None,
))
.await
.unwrap();
assert_eq!(response.status(), StatusCode::OK);
wait_for_prefill(&fallback).await;
assert!(
cached.captured.lock().unwrap().last_body.is_none(),
"SloFirst must exclude a cache holder outside the request's TTFT tier"
);
}
#[tokio::test]
async fn cache_candidate_respects_its_bucket_pending_prefill_budget() {
let cached = crate::common::mock_worker::MockWorker::start(vec![]).await;
let fallback = crate::common::mock_worker::MockWorker::start(vec![]).await;
let decode = crate::common::mock_worker::MockWorker::start(vec![]).await;
let mut limited_bucket = bucket("p-limited", BucketStage::Prefill, 10, "p-cached");
limited_bucket.max_pending_prefill_tokens = Some(64);
let bucket_config = BucketConfig {
buckets: vec![
limited_bucket,
bucket("p-fallback", BucketStage::Prefill, 20, "p-fallback"),
bucket("d-catch-all", BucketStage::Decode, 30, "d"),
],
ttft_slo_policy: SloBucketPolicy::Disabled,
tps_slo_policy: SloBucketPolicy::Disabled,
};
let prefix_index: Arc<dyn PrefixIndex> = FakePrefixIndex::matched(cached.url.clone());
let ctx = build_cache_ctx(
vec![
worker_spec("p-cached", cached.url.clone(), WorkerMode::Prefill),
worker_spec("p-fallback", fallback.url.clone(), WorkerMode::Prefill),
worker_spec("d", decode.url.clone(), WorkerMode::Decode),
],
bucket_config,
prefix_index,
);
set_native_load_with_waiting(&ctx, &cached.url, 0, 100_000, 64);
let content = "pending budget ".repeat(128);
let response = build_router(Arc::clone(&ctx))
.oneshot(chat_request_with_content(&content, None, Some(8), None))
.await
.unwrap();
assert_eq!(response.status(), StatusCode::OK);
wait_for_prefill(&fallback).await;
assert!(
cached.captured.lock().unwrap().last_body.is_none(),
"a cache holder beyond its Bucket pending-prefill budget must not receive the request"
);
assert!(ctx
.metrics
.render()
.contains("sgl_router_cache_admission_rejected_total 1"));
}
#[tokio::test]
async fn rejected_global_cache_candidate_falls_back_to_prompt_length_bucket() {
let cached = crate::common::mock_worker::MockWorker::start(vec![]).await;
let fallback = crate::common::mock_worker::MockWorker::start(vec![]).await;
let decode = crate::common::mock_worker::MockWorker::start(vec![]).await;
let mut short_bucket = bucket("p-short", BucketStage::Prefill, 10, "p-cached");
short_bucket.max_extend_tokens = Some(8);
let mut long_bucket = bucket("p-long", BucketStage::Prefill, 20, "p-fallback");
long_bucket.min_extend_tokens = Some(9);
let bucket_config = BucketConfig {
buckets: vec![
short_bucket,
long_bucket,
bucket("d-catch-all", BucketStage::Decode, 30, "d"),
],
ttft_slo_policy: SloBucketPolicy::Disabled,
tps_slo_policy: SloBucketPolicy::Disabled,
};
let prefix_index: Arc<dyn PrefixIndex> = FakePrefixIndex::matched(cached.url.clone());
let ctx = build_cache_ctx(
vec![
worker_spec("p-cached", cached.url.clone(), WorkerMode::Prefill),
worker_spec("p-fallback", fallback.url.clone(), WorkerMode::Prefill),
worker_spec("d", decode.url.clone(), WorkerMode::Decode),
],
bucket_config,
prefix_index,
);
set_native_load(&ctx, &cached.url, 1, 1);
let content = "admission fallback ".repeat(128);
let response = build_router(Arc::clone(&ctx))
.oneshot(chat_request_with_content(&content, None, Some(8), None))
.await
.unwrap();
assert_eq!(response.status(), StatusCode::OK);
wait_for_prefill(&fallback).await;
assert!(
cached.captured.lock().unwrap().last_body.is_none(),
"an admission-rejected cache holder must not receive the request"
);
let metrics = ctx.metrics.render();
assert!(metrics.contains("sgl_router_cache_admission_rejected_total 1"));
assert!(
!metrics.contains(
r#"sgl_router_policy_decisions_total{policy="cache_aware",reason="cache_candidate"} 1"#
),
"Bucket fallback must not be reported as a cache-candidate decision"
);
}
#[tokio::test]
async fn cache_no_signal_restarts_normal_prompt_length_bucket_fallback() {
let short = crate::common::mock_worker::MockWorker::start(vec![]).await;
let long = crate::common::mock_worker::MockWorker::start(vec![]).await;
let decode = crate::common::mock_worker::MockWorker::start(vec![]).await;
let mut short_bucket = bucket("p-short", BucketStage::Prefill, 10, "p-short");
short_bucket.max_extend_tokens = Some(8);
let mut long_bucket = bucket("p-long", BucketStage::Prefill, 20, "p-long");
long_bucket.min_extend_tokens = Some(9);
let bucket_config = BucketConfig {
buckets: vec![
short_bucket,
long_bucket,
bucket("d-catch-all", BucketStage::Decode, 30, "d"),
],
ttft_slo_policy: SloBucketPolicy::Disabled,
tps_slo_policy: SloBucketPolicy::Disabled,
};
let index = FakePrefixIndex::no_signal();
let prefix_index: Arc<dyn PrefixIndex> = index.clone();
let ctx = build_cache_ctx(
vec![
worker_spec("p-short", short.url.clone(), WorkerMode::Prefill),
worker_spec("p-long", long.url.clone(), WorkerMode::Prefill),
worker_spec("d", decode.url.clone(), WorkerMode::Decode),
],
bucket_config,
prefix_index,
);
let content = "uncached-prompt ".repeat(128);
let response = build_router(ctx)
.oneshot(chat_request_with_content(&content, None, Some(8), None))
.await
.unwrap();
assert_eq!(response.status(), StatusCode::OK);
wait_for_prefill(&long).await;
assert!(
short.captured.lock().unwrap().last_body.is_none(),
"without a cache winner the request must restart the normal full-input Bucket path"
);
assert_eq!(index.calls.load(Ordering::Relaxed), 1);
}