plano/crates/llm_gateway/src/stream_context.rs
2025-07-08 00:33:40 -07:00

663 lines
25 KiB
Rust

use crate::metrics::Metrics;
use common::configuration::{LlmProvider, LlmProviderType, Overrides};
use common::consts::{
ARCH_PROVIDER_HINT_HEADER, ARCH_ROUTING_HEADER, CHAT_COMPLETIONS_PATH, HEALTHZ_PATH,
RATELIMIT_SELECTOR_HEADER_KEY, REQUEST_ID_HEADER, TRACE_PARENT_HEADER,
};
use common::errors::ServerError;
use common::llm_providers::LlmProviders;
use common::ratelimit::Header;
use common::stats::{IncrementingMetric, RecordingMetric};
use common::tracing::{Event, Span, TraceData, Traceparent};
use common::{ratelimit, routing, tokenizer};
use hermesllm::providers::openai::types::{ChatCompletionsRequest, SseChatCompletionIter};
use hermesllm::providers::openai::types::{
ChatCompletionsResponse, ContentType, Message, StreamOptions,
};
use hermesllm::Provider;
use http::StatusCode;
use log::{debug, info, warn};
use proxy_wasm::hostcalls::get_current_time;
use proxy_wasm::traits::*;
use proxy_wasm::types::*;
use std::collections::VecDeque;
use std::num::NonZero;
use std::rc::Rc;
use std::sync::{Arc, Mutex};
use std::time::{Duration, SystemTime, UNIX_EPOCH};
pub struct StreamContext {
context_id: u32,
metrics: Rc<Metrics>,
ratelimit_selector: Option<Header>,
streaming_response: bool,
response_tokens: usize,
is_chat_completions_request: bool,
llm_providers: Rc<LlmProviders>,
llm_provider: Option<Rc<LlmProvider>>,
request_id: Option<String>,
start_time: SystemTime,
ttft_duration: Option<Duration>,
ttft_time: Option<u128>,
traceparent: Option<String>,
request_body_sent_time: Option<u128>,
user_message: Option<Message>,
traces_queue: Arc<Mutex<VecDeque<TraceData>>>,
overrides: Rc<Option<Overrides>>,
}
impl StreamContext {
pub fn new(
context_id: u32,
metrics: Rc<Metrics>,
llm_providers: Rc<LlmProviders>,
traces_queue: Arc<Mutex<VecDeque<TraceData>>>,
overrides: Rc<Option<Overrides>>,
) -> Self {
StreamContext {
context_id,
metrics,
overrides,
ratelimit_selector: None,
streaming_response: false,
response_tokens: 0,
is_chat_completions_request: false,
llm_providers,
llm_provider: None,
request_id: None,
start_time: SystemTime::now(),
ttft_duration: None,
traceparent: None,
ttft_time: None,
user_message: None,
traces_queue,
request_body_sent_time: None,
}
}
fn llm_provider(&self) -> &LlmProvider {
self.llm_provider
.as_ref()
.expect("the provider should be set when asked for it")
}
fn select_llm_provider(&mut self) {
let provider_hint = self
.get_http_request_header(ARCH_PROVIDER_HINT_HEADER)
.map(|llm_name| llm_name.into());
self.llm_provider = Some(routing::get_llm_provider(
&self.llm_providers,
provider_hint,
));
match self.llm_provider.as_ref().unwrap().provider_interface {
LlmProviderType::Groq => {
if let Some(path) = self.get_http_request_header(":path") {
if path.starts_with("/v1/") {
let new_path = format!("/openai{}", path);
self.set_http_request_header(":path", Some(new_path.as_str()));
}
}
}
LlmProviderType::Gemini => {
if let Some(path) = self.get_http_request_header(":path") {
if path == "/v1/chat/completions" {
self.set_http_request_header(
":path",
Some("/v1beta/openai/chat/completions"),
);
}
}
}
_ => {}
}
debug!(
"request received: llm provider hint: {}, selected llm: {}, model: {}",
self.get_http_request_header(ARCH_PROVIDER_HINT_HEADER)
.unwrap_or_default(),
self.llm_provider.as_ref().unwrap().name,
self.llm_provider
.as_ref()
.unwrap()
.model
.as_ref()
.unwrap_or(&String::new())
);
}
fn modify_auth_headers(&mut self) -> Result<(), ServerError> {
let llm_provider_api_key_value =
self.llm_provider()
.access_key
.as_ref()
.ok_or(ServerError::BadRequest {
why: format!(
"No access key configured for selected LLM Provider \"{}\"",
self.llm_provider()
),
})?;
let authorization_header_value = format!("Bearer {}", llm_provider_api_key_value);
self.set_http_request_header("Authorization", Some(&authorization_header_value));
Ok(())
}
fn delete_content_length_header(&mut self) {
// Remove the Content-Length header because further body manipulations in the gateway logic will invalidate it.
// Server's generally throw away requests whose body length do not match the Content-Length header.
// However, a missing Content-Length header is not grounds for bad requests given that intermediary hops could
// manipulate the body in benign ways e.g., compression.
self.set_http_request_header("content-length", None);
}
fn save_ratelimit_header(&mut self) {
self.ratelimit_selector = self
.get_http_request_header(RATELIMIT_SELECTOR_HEADER_KEY)
.and_then(|key| {
self.get_http_request_header(&key)
.map(|value| Header { key, value })
});
}
fn send_server_error(&self, error: ServerError, override_status_code: Option<StatusCode>) {
warn!("server error occurred: {}", error);
self.send_http_response(
override_status_code
.unwrap_or(StatusCode::INTERNAL_SERVER_ERROR)
.as_u16()
.into(),
vec![],
Some(format!("{error}").as_bytes()),
);
}
fn enforce_ratelimits(
&mut self,
model: &str,
json_string: &str,
) -> Result<(), ratelimit::Error> {
// Tokenize and record token count.
let token_count = tokenizer::token_count(model, json_string).unwrap_or(0);
debug!("Recorded input token count: {}", token_count);
// Record the token count to metrics.
self.metrics
.input_sequence_length
.record(token_count as u64);
// Check if rate limiting needs to be applied.
if let Some(selector) = self.ratelimit_selector.take() {
log::debug!("Applying ratelimit for model: {}", model);
ratelimit::ratelimits(None).read().unwrap().check_limit(
model.to_owned(),
selector,
NonZero::new(token_count as u32).unwrap(),
)?;
} else {
debug!("No rate limit applied for model: {}", model);
}
Ok(())
}
}
// HttpContext is the trait that allows the Rust code to interact with HTTP objects.
impl HttpContext for StreamContext {
// Envoy's HTTP model is event driven. The WASM ABI has given implementors events to hook onto
// the lifecycle of the http request and response.
fn on_http_request_headers(&mut self, _num_headers: usize, _end_of_stream: bool) -> Action {
let request_path = self.get_http_request_header(":path").unwrap_or_default();
if request_path == HEALTHZ_PATH {
self.send_http_response(200, vec![], None);
return Action::Continue;
}
self.is_chat_completions_request = CHAT_COMPLETIONS_PATH == request_path;
let use_agent_orchestrator = match self.overrides.as_ref() {
Some(overrides) => overrides.use_agent_orchestrator.unwrap_or_default(),
None => false,
};
let routing_header_value = self.get_http_request_header(ARCH_ROUTING_HEADER);
if routing_header_value.is_some() && !routing_header_value.as_ref().unwrap().is_empty() {
let routing_header_value = routing_header_value.as_ref().unwrap();
info!("routing header already set: {}", routing_header_value);
self.llm_provider = Some(Rc::new(LlmProvider {
name: routing_header_value.to_string(),
provider_interface: LlmProviderType::OpenAI,
..Default::default()
}));
} else {
self.select_llm_provider();
if self.llm_provider().endpoint.is_some() {
self.add_http_request_header(
ARCH_ROUTING_HEADER,
&self.llm_provider().name.to_string(),
);
} else {
self.add_http_request_header(
ARCH_ROUTING_HEADER,
&self.llm_provider().provider_interface.to_string(),
);
}
if let Err(error) = self.modify_auth_headers() {
// ensure that the provider has an endpoint if the access key is missing else return a bad request
if self.llm_provider.as_ref().unwrap().endpoint.is_none()
&& !use_agent_orchestrator
&& self.llm_provider.as_ref().unwrap().provider_interface
!= LlmProviderType::Arch
{
self.send_server_error(error, Some(StatusCode::BAD_REQUEST));
}
}
}
self.delete_content_length_header();
self.save_ratelimit_header();
self.request_id = self.get_http_request_header(REQUEST_ID_HEADER);
self.traceparent = self.get_http_request_header(TRACE_PARENT_HEADER);
Action::Continue
}
fn on_http_request_body(&mut self, body_size: usize, end_of_stream: bool) -> Action {
debug!(
"on_http_request_body [S={}] bytes={} end_stream={}",
self.context_id, body_size, end_of_stream
);
// Let the client send the gateway all the data before sending to the LLM_provider.
// TODO: consider a streaming API.
if self.request_body_sent_time.is_none() {
self.request_body_sent_time = Some(current_time_ns());
}
if !end_of_stream {
return Action::Pause;
}
if body_size == 0 {
return Action::Continue;
}
let body_bytes = match self.get_http_request_body(0, body_size) {
Some(body_bytes) => body_bytes,
None => {
self.send_server_error(
ServerError::LogicError(format!(
"Failed to obtain body bytes even though body_size is {}",
body_size
)),
None,
);
return Action::Pause;
}
};
let mut deserialized_body = match ChatCompletionsRequest::try_from(body_bytes.as_slice()) {
Ok(deserialized) => deserialized,
Err(e) => {
debug!(
"on_http_request_body: request body: {}",
String::from_utf8_lossy(&body_bytes)
);
self.send_server_error(ServerError::OpenAIPError(e), Some(StatusCode::BAD_REQUEST));
return Action::Pause;
}
};
self.user_message = deserialized_body
.messages
.iter()
.filter(|m| m.role == "user")
.last()
.cloned();
let model_name = match self.llm_provider.as_ref() {
Some(llm_provider) => llm_provider.model.as_ref(),
None => None,
};
let use_agent_orchestrator = match self.overrides.as_ref() {
Some(overrides) => overrides.use_agent_orchestrator.unwrap_or_default(),
None => false,
};
let model_requested = deserialized_body.model.clone();
deserialized_body.model = match model_name {
Some(model_name) => model_name.clone(),
None => {
if use_agent_orchestrator {
"agent_orchestrator".to_string()
} else {
self.send_server_error(
ServerError::BadRequest {
why: format!("No model specified in request and couldn't determine model name from arch_config. Model name in req: {}, arch_config, provider: {}, model: {:?}", deserialized_body.model, self.llm_provider().name, self.llm_provider().model).to_string(),
},
Some(StatusCode::BAD_REQUEST),
);
return Action::Continue;
}
}
};
info!(
"on_http_request_body: provider: {}, model requested: {}, model selected: {}",
self.llm_provider().name,
model_requested,
model_name.unwrap_or(&"None".to_string()),
);
if deserialized_body.stream.unwrap_or_default() {
self.streaming_response = true;
}
if deserialized_body.stream.unwrap_or_default()
&& deserialized_body.stream_options.is_none()
{
deserialized_body.stream_options = Some(StreamOptions {
include_usage: true,
});
}
// only use the tokens from the messages, excluding the metadata and json tags
let input_tokens_str = deserialized_body
.messages
.iter()
.fold(String::new(), |acc, m| {
acc + " "
+ m.content
.as_ref()
.unwrap_or(&ContentType::Text(String::new()))
.to_string()
.as_str()
});
// enforce ratelimits on ingress
if let Err(e) = self.enforce_ratelimits(&deserialized_body.model, input_tokens_str.as_str())
{
self.send_server_error(
ServerError::ExceededRatelimit(e),
Some(StatusCode::TOO_MANY_REQUESTS),
);
self.metrics.ratelimited_rq.increment(1);
return Action::Continue;
}
let llm_provider_str = self.llm_provider().provider_interface.to_string();
let hermes_llm_provider = Provider::from(llm_provider_str.as_str());
// convert chat completion request to llm provider specific request
let deserialized_body_bytes = match deserialized_body.to_bytes(hermes_llm_provider) {
Ok(bytes) => bytes,
Err(e) => {
warn!("Failed to serialize request body: {}", e);
self.send_server_error(ServerError::OpenAIPError(e), Some(StatusCode::BAD_REQUEST));
return Action::Pause;
}
};
self.set_http_request_body(0, body_size, &deserialized_body_bytes);
Action::Continue
}
fn on_http_response_headers(&mut self, _num_headers: usize, end_of_stream: bool) -> Action {
debug!(
"on_http_response_headers [S={}] end_stream={}",
self.context_id, end_of_stream
);
self.set_property(
vec!["metadata", "filter_metadata", "llm_filter", "user_prompt"],
Some("hello world from filter".as_bytes()),
);
Action::Continue
}
fn on_http_response_body(&mut self, body_size: usize, end_of_stream: bool) -> Action {
debug!(
"on_http_response_body [S={}] bytes={} end_stream={}",
self.context_id, body_size, end_of_stream
);
if self.request_body_sent_time.is_none() {
debug!("on_http_response_body: request body not sent, not doing any processing in llm filter");
return Action::Continue;
}
if !self.is_chat_completions_request {
info!("on_http_response_body: non-chatcompletion request");
return Action::Continue;
}
let current_time = get_current_time().unwrap();
if end_of_stream && body_size == 0 {
// All streaming responses end with bytes=0 and end_stream=true
// Record the latency for the request
match current_time.duration_since(self.start_time) {
Ok(duration) => {
// Convert the duration to milliseconds
let duration_ms = duration.as_millis();
info!("on_http_response_body: request latency: {}ms", duration_ms);
// Record the latency to the latency histogram
self.metrics.request_latency.record(duration_ms as u64);
if self.response_tokens > 0 {
// Compute the time per output token
let tpot = duration_ms as u64 / self.response_tokens as u64;
// Record the time per output token
self.metrics.time_per_output_token.record(tpot);
debug!(
"time per token: {}ms, tokens per second: {}",
tpot,
1000 / tpot
);
// Record the tokens per second
self.metrics.tokens_per_second.record(1000 / tpot);
}
}
Err(e) => {
warn!("SystemTime error: {:?}", e);
}
}
// Record the output sequence length
self.metrics
.output_sequence_length
.record(self.response_tokens as u64);
if let Some(traceparent) = self.traceparent.as_ref() {
let current_time_ns = current_time_ns();
match Traceparent::try_from(traceparent.to_string()) {
Err(e) => {
warn!("traceparent header is invalid: {}", e);
}
Ok(traceparent) => {
let mut trace_data = common::tracing::TraceData::new();
let mut llm_span = Span::new(
"egress_traffic".to_string(),
Some(traceparent.trace_id),
Some(traceparent.parent_id),
self.request_body_sent_time.unwrap(),
current_time_ns,
);
if let Some(user_message) = self.user_message.as_ref() {
if let Some(prompt) = user_message.content.as_ref() {
llm_span
.add_attribute("user_prompt".to_string(), prompt.to_string());
}
}
llm_span.add_attribute(
"model".to_string(),
self.llm_provider().name.to_string(),
);
if self.ttft_time.is_some() {
llm_span.add_event(Event::new(
"time_to_first_token".to_string(),
self.ttft_time.unwrap(),
));
trace_data.add_span(llm_span);
}
self.traces_queue.lock().unwrap().push_back(trace_data);
}
};
}
return Action::Continue;
}
let body = if self.streaming_response {
let chunk_start = 0;
let chunk_size = body_size;
debug!(
"on_http_response_body: streaming response reading, {}..{}",
chunk_start, chunk_size
);
let streaming_chunk = match self.get_http_response_body(0, chunk_size) {
Some(chunk) => chunk,
None => {
warn!(
"response body empty, chunk_start: {}, chunk_size: {}",
chunk_start, chunk_size
);
return Action::Continue;
}
};
if streaming_chunk.len() != chunk_size {
warn!(
"chunk size mismatch: read: {} != requested: {}",
streaming_chunk.len(),
chunk_size
);
}
streaming_chunk
} else {
if body_size == 0 {
return Action::Continue;
}
debug!("non streaming response bytes read: 0:{}", body_size);
match self.get_http_response_body(0, body_size) {
Some(body) => body,
None => {
warn!("non streaming response body empty");
return Action::Continue;
}
}
};
if log::log_enabled!(log::Level::Debug) {
debug!(
"response data (converted to utf8): {}",
String::from_utf8_lossy(&body)
);
}
let llm_provider_str = self.llm_provider().provider_interface.to_string();
let hermes_llm_provider = Provider::from(llm_provider_str.as_str());
if self.streaming_response {
let chat_completions_chunk_response_events =
match SseChatCompletionIter::try_from((body.as_slice(), &hermes_llm_provider)) {
Ok(events) => events,
Err(e) => {
warn!(
"could not parse response: {}, body str: {}",
e,
String::from_utf8_lossy(&body)
);
return Action::Continue;
}
};
for event in chat_completions_chunk_response_events {
match event {
Ok(event) => {
if let Some(usage) = event.usage.as_ref() {
self.response_tokens += usage.completion_tokens;
}
}
Err(e) => {
warn!("error in response event: {}", e);
continue;
}
}
}
// Compute TTFT if not already recorded
if self.ttft_duration.is_none() {
// if let Some(start_time) = self.start_time {
let current_time = get_current_time().unwrap();
self.ttft_time = Some(current_time_ns());
match current_time.duration_since(self.start_time) {
Ok(duration) => {
let duration_ms = duration.as_millis();
info!(
"on_http_response_body: time to first token: {}ms",
duration_ms
);
self.ttft_duration = Some(duration);
self.metrics.time_to_first_token.record(duration_ms as u64);
}
Err(e) => {
warn!("SystemTime error: {:?}", e);
}
}
}
} else {
debug!("non streaming response");
let chat_completions_response =
match ChatCompletionsResponse::try_from((body.as_slice(), &hermes_llm_provider)) {
Ok(de) => de,
Err(e) => {
warn!(
"could not parse response: {}, body str: {}",
e,
String::from_utf8_lossy(&body)
);
debug!(
"on_http_response_body: S[{}], response body: {}",
self.context_id,
String::from_utf8_lossy(&body)
);
self.send_server_error(
ServerError::OpenAIPError(e),
Some(StatusCode::BAD_REQUEST),
);
return Action::Continue;
}
};
if let Some(usage) = chat_completions_response.usage {
self.response_tokens += usage.completion_tokens;
}
}
debug!(
"recv [S={}] total_tokens={} end_stream={}",
self.context_id, self.response_tokens, end_of_stream
);
Action::Continue
}
}
fn current_time_ns() -> u128 {
SystemTime::now()
.duration_since(UNIX_EPOCH)
.unwrap()
.as_nanos()
}
impl Context for StreamContext {}