feat: Default endpoints and gateway accessors are cached between requests

crates/lib/Cargo.toml

@@ -16,6 +16,7 @@ tracing-config = ["tracing", "qcs-api-client-common/tracing-config", "qcs-api-cl
 otel-tracing = ["tracing-config", "qcs-api-client-grpc/otel-tracing", "qcs-api-client-openapi/otel-tracing"]
 
 [dependencies]
+cached = "0.44.0"
 dirs = "5.0.0"
 enum-as-inner = "0.5.1"
 futures = "0.3.24"
@@ -43,8 +44,6 @@ uuid = { version = "1.2.1", features = ["v4"] }
 tonic = { version = "0.9.2", features = ["tls", "tls-roots"] }
 zmq = { version = "0.10.0" }
 itertools = "0.11.0"
-rstest = "0.17.0"
-insta = "1.29.0"
 derive_builder = "0.12.0"
 
 [dev-dependencies]
@@ -60,6 +59,8 @@ warp = { version = "0.3.3", default-features = false }
 regex = "1.7.0"
 test-case = "3.1.0"
 tracing-subscriber = "0.3.17"
+rstest = "0.17.0"
+insta = "1.29.0"
 
 [build-dependencies]
 built = "0.6.1"

crates/lib/src/qpu/api.rs

@@ -3,6 +3,7 @@
 
 use std::{fmt, time::Duration};
 
+use cached::proc_macro::cached;
 use derive_builder::Builder;
 use qcs_api_client_common::{configuration::RefreshError, ClientConfiguration};
 pub use qcs_api_client_grpc::channel::Error as GrpcError;
@@ -22,7 +23,8 @@ use qcs_api_client_grpc::{
 pub use qcs_api_client_openapi::apis::Error as OpenApiError;
 use qcs_api_client_openapi::apis::{
     endpoints_api::{
-        get_default_endpoint, get_endpoint, GetDefaultEndpointError, GetEndpointError,
+        get_default_endpoint as api_get_default_endpoint, get_endpoint, GetDefaultEndpointError,
+        GetEndpointError,
     },
     quantum_processors_api::{
         list_quantum_processor_accessors, ListQuantumProcessorAccessorsError,
@@ -307,55 +309,100 @@ impl ExecutionOptions {
         quantum_processor_id: &str,
         client: &Qcs,
     ) -> Result<String, QpuApiError> {
-        let mut min = None;
-        let mut next_page_token = None;
-        loop {
-            let accessors = list_quantum_processor_accessors(
-                &client.get_openapi_client(),
-                quantum_processor_id,
-                Some(100),
-                next_page_token.as_deref(),
-            )
-            .await?;
-
-            let accessor = accessors
-                .accessors
-                .into_iter()
-                .filter(|acc| {
-                    acc.live
-                    // `as_deref` needed to work around the `Option<Box<_>>` type.
-                    && acc.access_type.as_deref() == Some(&QuantumProcessorAccessorType::GatewayV1)
-                })
-                .min_by_key(|acc| acc.rank.unwrap_or(i64::MAX));
-
-            min = std::cmp::min_by_key(min, accessor, |acc| {
-                acc.as_ref().and_then(|acc| acc.rank).unwrap_or(i64::MAX)
-            });
-
-            next_page_token = accessors.next_page_token.clone();
-            if next_page_token.is_none() {
-                break;
-            }
-        }
-        min.map(|accessor| accessor.url)
-            .ok_or_else(|| QpuApiError::GatewayNotFound(quantum_processor_id.to_string()))
+        get_accessor_with_cache(quantum_processor_id, client).await
     }
 
     async fn get_default_endpoint_address(
         &self,
         quantum_processor_id: &str,
         client: &Qcs,
     ) -> Result<String, QpuApiError> {
-        let default_endpoint =
-            get_default_endpoint(&client.get_openapi_client(), quantum_processor_id).await?;
-        let addresses = default_endpoint.addresses.as_ref();
-        let grpc_address = addresses.grpc.as_ref();
-        grpc_address
-            .ok_or_else(|| QpuApiError::QpuEndpointNotFound(quantum_processor_id.into()))
-            .cloned()
+        get_default_endpoint_with_cache(quantum_processor_id, client).await
     }
 }
 
+#[cached(
+    result = true,
+    time = 60,
+    time_refresh = true,
+    sync_writes = true,
+    key = "String",
+    convert = r"{ String::from(quantum_processor_id)}"
+)]
+async fn get_accessor_with_cache(
+    quantum_processor_id: &str,
+    client: &Qcs,
+) -> Result<String, QpuApiError> {
+    #[cfg(feature = "tracing")]
+    tracing::info!(quantum_processor_id=%quantum_processor_id, "get_accessor cache miss");
+    get_accessor(quantum_processor_id, client).await
+}
+
+async fn get_accessor(quantum_processor_id: &str, client: &Qcs) -> Result<String, QpuApiError> {
+    let mut min = None;
+    let mut next_page_token = None;
+    loop {
+        let accessors = list_quantum_processor_accessors(
+            &client.get_openapi_client(),
+            quantum_processor_id,
+            Some(100),
+            next_page_token.as_deref(),
+        )
+        .await?;
+
+        let accessor = accessors
+            .accessors
+            .into_iter()
+            .filter(|acc| {
+                acc.live
+                // `as_deref` needed to work around the `Option<Box<_>>` type.
+                && acc.access_type.as_deref() == Some(&QuantumProcessorAccessorType::GatewayV1)
+            })
+            .min_by_key(|acc| acc.rank.unwrap_or(i64::MAX));
+
+        min = std::cmp::min_by_key(min, accessor, |acc| {
+            acc.as_ref().and_then(|acc| acc.rank).unwrap_or(i64::MAX)
+        });
+
+        next_page_token = accessors.next_page_token.clone();
+        if next_page_token.is_none() {
+            break;
+        }
+    }
+    min.map(|accessor| accessor.url)
+        .ok_or_else(|| QpuApiError::GatewayNotFound(quantum_processor_id.to_string()))
+}
+
+#[cached(
+    result = true,
+    time = 60,
+    time_refresh = true,
+    sync_writes = true,
+    key = "String",
+    convert = r"{ String::from(quantum_processor_id)}"
+)]
+async fn get_default_endpoint_with_cache(
+    quantum_processor_id: &str,
+    client: &Qcs,
+) -> Result<String, QpuApiError> {
+    #[cfg(feature = "tracing")]
+    tracing::info!(quantum_processor_id=%quantum_processor_id, "get_default_endpoint cache miss");
+    get_default_endpoint(quantum_processor_id, client).await
+}
+
+async fn get_default_endpoint(
+    quantum_processor_id: &str,
+    client: &Qcs,
+) -> Result<String, QpuApiError> {
+    let default_endpoint =
+        api_get_default_endpoint(&client.get_openapi_client(), quantum_processor_id).await?;
+    let addresses = default_endpoint.addresses.as_ref();
+    let grpc_address = addresses.grpc.as_ref();
+    grpc_address
+        .ok_or_else(|| QpuApiError::QpuEndpointNotFound(quantum_processor_id.into()))
+        .cloned()
+}
+
 /// Errors that can occur while attempting to establish a connection to the QPU.
 #[derive(Debug, thiserror::Error)]
 pub enum QpuApiError {