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use std::time::SystemTime;
use recloser::Recloser;
use reqwest::header::{HeaderValue, IF_NONE_MATCH};
use reqwest_retry::{RetryDecision, RetryPolicy};
use retry_policies::policies::ExponentialBackoff;
use tokio::sync::RwLock;
use crate::supergraph_fetcher::{
builder::SupergraphFetcherBuilder, SupergraphFetcher, SupergraphFetcherError,
};
#[derive(Debug)]
pub struct SupergraphFetcherSyncState {
endpoints_with_circuit_breakers: Vec<(String, Recloser)>,
reqwest_client: reqwest::blocking::Client,
retry_policy: ExponentialBackoff,
}
impl SupergraphFetcher<SupergraphFetcherSyncState> {
pub fn fetch_supergraph(&self) -> Result<Option<String>, SupergraphFetcherError> {
let mut last_error: Option<SupergraphFetcherError> = None;
let mut last_resp = None;
for (endpoint, circuit_breaker) in &self.state.endpoints_with_circuit_breakers {
let resp = {
circuit_breaker
.call(|| {
let request_start_time = SystemTime::now();
// Implementing retry logic for sync client
let mut n_past_retries = 0;
loop {
let mut req = self.state.reqwest_client.get(endpoint);
let etag = self.get_latest_etag()?;
if let Some(etag) = etag {
req = req.header(IF_NONE_MATCH, etag);
}
let mut response = req.send().map_err(|err| {
SupergraphFetcherError::Network(reqwest_middleware::Error::Reqwest(
err,
))
});
// Server errors (5xx) are considered retryable
if let Ok(ok_res) = response {
response = if ok_res.status().is_server_error() {
Err(SupergraphFetcherError::Network(
reqwest_middleware::Error::Middleware(anyhow::anyhow!(
"Server error: {}",
ok_res.status()
)),
))
} else if ok_res.status().is_client_error() {
return Err(SupergraphFetcherError::Network(
reqwest_middleware::Error::Middleware(anyhow::anyhow!(
"Client error: {}",
ok_res.status()
)),
));
} else {
Ok(ok_res)
}
}
match response {
Ok(resp) => break Ok(resp),
Err(e) => {
match self
.state
.retry_policy
.should_retry(request_start_time, n_past_retries)
{
RetryDecision::DoNotRetry => {
return Err(e);
}
RetryDecision::Retry { execute_after } => {
n_past_retries += 1;
match execute_after.elapsed() {
Ok(duration) => {
std::thread::sleep(duration);
}
Err(err) => {
tracing::error!(
"Error determining sleep duration for retry: {}",
err
);
// If elapsed time cannot be determined, do not wait
return Err(e);
}
}
}
}
}
}
}
})
// Map recloser errors to SupergraphFetcherError
.map_err(|e| match e {
recloser::Error::Inner(e) => e,
recloser::Error::Rejected => {
SupergraphFetcherError::RejectedByCircuitBreaker
}
})
};
match resp {
Err(e) => {
last_error = Some(e);
continue;
}
Ok(resp) => {
last_resp = Some(resp);
break;
}
}
}
if let Some(last_resp) = last_resp {
if last_resp.status().as_u16() == 304 {
return Ok(None);
}
self.update_latest_etag(last_resp.headers().get("etag"))?;
let text = last_resp
.text()
.map_err(SupergraphFetcherError::ResponseParse)?;
Ok(Some(text))
} else if let Some(error) = last_error {
Err(error)
} else {
Ok(None)
}
}
fn get_latest_etag(&self) -> Result<Option<HeaderValue>, SupergraphFetcherError> {
let guard = self
.etag
.try_read()
.map_err(SupergraphFetcherError::ETagRead)?;
Ok(guard.clone())
}
fn update_latest_etag(&self, etag: Option<&HeaderValue>) -> Result<(), SupergraphFetcherError> {
let mut guard = self
.etag
.try_write()
.map_err(SupergraphFetcherError::ETagWrite)?;
if let Some(etag_value) = etag {
*guard = Some(etag_value.clone());
} else {
*guard = None;
}
Ok(())
}
}
impl SupergraphFetcherBuilder {
/// Builds a synchronous SupergraphFetcher
pub fn build_sync(
self,
) -> Result<SupergraphFetcher<SupergraphFetcherSyncState>, SupergraphFetcherError> {
self.validate_endpoints()?;
let headers = self.prepare_headers()?;
let mut reqwest_client = reqwest::blocking::Client::builder()
.danger_accept_invalid_certs(self.accept_invalid_certs)
.connect_timeout(self.connect_timeout)
.timeout(self.request_timeout)
.default_headers(headers);
if let Some(user_agent) = &self.user_agent {
reqwest_client = reqwest_client.user_agent(user_agent);
}
let reqwest_client = reqwest_client
.build()
.map_err(SupergraphFetcherError::HTTPClientCreation)?;
let fetcher = SupergraphFetcher {
state: SupergraphFetcherSyncState {
reqwest_client,
retry_policy: self.retry_policy,
endpoints_with_circuit_breakers: self
.endpoints
.into_iter()
.map(|endpoint| {
let circuit_breaker = self
.circuit_breaker
.clone()
.unwrap_or_default()
.build_sync()
.map_err(SupergraphFetcherError::CircuitBreakerCreation);
circuit_breaker.map(|cb| (endpoint, cb))
})
.collect::<Result<Vec<_>, _>>()?,
},
etag: RwLock::new(None),
};
Ok(fetcher)
}
}