feat: start logging diff comparing with delta

server/Cargo.toml

@@ -47,6 +47,7 @@ futures = "0.3.31"
 futures-core = "0.3.31"
 iter_tools = "0.24.0"
 itertools = "0.14.0"
+json-structural-diff = "0.2.0"
 lazy_static = "1.5.0"
 num_cpus = "1.16.0"
 opentelemetry = { version = "0.27.1", features = ["trace", "metrics"] }
@@ -94,8 +95,8 @@ tokio-stream = { version = "0.1.17" }
 tracing = { version = "0.1.41", features = ["log"] }
 tracing-subscriber = { version = "0.3.19", features = ["json", "env-filter"] }
 ulid = "1.1.4"
-unleash-types = { version = "0.15.3", features = ["openapi", "hashes"] }
-unleash-yggdrasil = { version = "0.14.5" }
+unleash-types = { version = "0.15.4", features = ["openapi", "hashes"] }
+unleash-yggdrasil = { version = "0.14.6" }
 utoipa = { version = "5.3.1", features = ["actix_extras", "chrono"] }
 utoipa-swagger-ui = { version = "8.1.1", features = ["actix-web"] }
 [dev-dependencies]

server/src/builder.rs

@@ -271,6 +271,7 @@ async fn build_edge(
         refresher_mode,
         client_meta_information,
         args.delta,
+        args.delta_diff
     );
     let feature_refresher = Arc::new(FeatureRefresher::new(
         unleash_client,
@@ -387,6 +388,7 @@ mod tests {
             prometheus_username: None,
             streaming: false,
             delta: false,
+            delta_diff: false,
         };
 
         let result = build_edge(

server/src/cli.rs

@@ -221,6 +221,10 @@ pub struct EdgeArgs {
     #[clap(long, env, default_value_t = false, requires = "strict")]
     pub delta: bool,
 
+    /// If set to true, it compares features payload with delta payload and logs diff. This is experimental feature and might change. Requires strict mode
+    #[clap(long, env, default_value_t = false, requires = "strict")]
+    pub delta_diff: bool,
+
     /// Sets a remote write url for prometheus metrics, if this is set, prometheus metrics will be written upstream
     #[clap(long, env)]
     pub prometheus_remote_write_url: Option<String>,

server/src/client_api.rs

@@ -1024,6 +1024,7 @@ mod tests {
             streaming: false,
             client_meta_information: ClientMetaInformation::test_config(),
             delta: false,
+            delta_diff: false,
         });
         let token_validator = Arc::new(TokenValidator {
             unleash_client: unleash_client.clone(),

server/src/http/refresher/delta_refresher.rs

@@ -47,14 +47,14 @@ impl FeatureRefresher {
     }
 
     pub async fn refresh_single_delta(&self, refresh: TokenRefresh) {
-        let features_result = self
+        let delta_result = self
             .unleash_client
             .get_client_features_delta(ClientFeaturesRequest {
                 api_key: refresh.token.token.clone(),
                 etag: refresh.etag,
             })
             .await;
-        match features_result {
+        match delta_result {
             Ok(delta_response) => match delta_response {
                 ClientFeaturesDeltaResponse::NoUpdate(tag) => {
                     debug!("No update needed. Will update last check time with {tag}");
@@ -154,7 +154,8 @@ mod tests {
             strict: false,
             streaming: false,
             delta: true,
-            client_meta_information:ClientMetaInformation::test_config(),
+            delta_diff : false,
+            client_meta_information: ClientMetaInformation::test_config(),
         });
         let features = ClientFeatures {
             version: 2,

server/src/http/refresher/feature_refresher.rs

@@ -6,6 +6,7 @@ use chrono::Utc;
 use dashmap::DashMap;
 use eventsource_client::Client;
 use futures::TryStreamExt;
+use json_structural_diff::JsonDiff;
 use reqwest::StatusCode;
 use tracing::{debug, info, warn};
 use unleash_types::client_features::{ClientFeatures};
@@ -18,9 +19,7 @@ use crate::filters::{filter_client_features, FeatureFilterSet};
 use crate::http::headers::{
     UNLEASH_APPNAME_HEADER, UNLEASH_CLIENT_SPEC_HEADER, UNLEASH_INSTANCE_ID_HEADER,
 };
-use crate::types::{
-    build, EdgeResult, TokenType, TokenValidationStatus,
-};
+use crate::types::{build, ClientFeaturesDeltaResponse, EdgeResult, TokenType, TokenValidationStatus};
 use crate::{
     persistence::EdgePersistence,
     tokens::{cache_key, simplify},
@@ -52,6 +51,7 @@ pub struct FeatureRefresher {
     pub streaming: bool,
     pub client_meta_information: ClientMetaInformation,
     pub delta: bool,
+    pub delta_diff: bool,
 }
 
 impl Default for FeatureRefresher {
@@ -67,6 +67,7 @@ impl Default for FeatureRefresher {
             streaming: false,
             client_meta_information: Default::default(),
             delta: false,
+            delta_diff: false,
         }
     }
 }
@@ -105,6 +106,7 @@ pub struct FeatureRefreshConfig {
     mode: FeatureRefresherMode,
     client_meta_information: ClientMetaInformation,
     delta: bool,
+    delta_diff: bool,
 }
 
 impl FeatureRefreshConfig {
@@ -113,12 +115,14 @@ impl FeatureRefreshConfig {
         mode: FeatureRefresherMode,
         client_meta_information: ClientMetaInformation,
         delta: bool,
+        delta_diff: bool,
     ) -> Self {
         Self {
             features_refresh_interval,
             mode,
             client_meta_information,
             delta,
+            delta_diff
         }
     }
 }
@@ -142,6 +146,7 @@ impl FeatureRefresher {
             streaming: config.mode == FeatureRefresherMode::Streaming,
             client_meta_information: config.client_meta_information,
             delta: config.delta,
+            delta_diff: config.delta_diff,
         }
     }
 
@@ -393,6 +398,40 @@ impl FeatureRefresher {
         Ok(())
     }
 
+    async fn compare_delta_cache(&self, refresh: &TokenRefresh) {
+        let delta_result = self
+            .unleash_client
+            .get_client_features_delta(ClientFeaturesRequest {
+                api_key: refresh.token.token.clone(),
+                etag: refresh.etag.clone(),
+            })
+            .await;
+
+        let key = cache_key(&refresh.token);
+        if let Some(client_features) = self.features_cache.get(&key).as_ref() {
+            if let Ok(ClientFeaturesDeltaResponse::Updated(delta_features, _etag)) = delta_result {
+                let c_features = &client_features.features;
+                let d_features = delta_features.updated;
+
+                let delta_json = serde_json::to_value(d_features).unwrap();
+                let client_json = serde_json::to_value(c_features).unwrap();
+
+                let delta_json_len = delta_json.to_string().len();
+                let client_json_len = client_json.to_string().len();
+
+                if delta_json_len == client_json_len {
+                    info!("The JSON structure lengths are identical.");
+                } else {
+                    info!("Structural differences found:");
+                    info!("Length of delta_json: {}", delta_json_len);
+                    info!("Length of old_json: {}", client_json_len);
+                    let diff = JsonDiff::diff(&delta_json, &client_json, false);
+                    debug!("{:?}", diff.diff.unwrap());
+                }
+            }
+        }
+    }
+
     pub async fn start_refresh_features_background_task(&self) {
         if self.streaming {
             loop {
@@ -470,7 +509,7 @@ impl FeatureRefresher {
             .unleash_client
             .get_client_features(ClientFeaturesRequest {
                 api_key: refresh.token.token.clone(),
-                etag: refresh.etag,
+                etag: refresh.etag.clone(),
             })
             .await;
 
@@ -482,7 +521,10 @@ impl FeatureRefresher {
                 }
                 ClientFeaturesResponse::Updated(features, etag) => {
                     self.handle_client_features_updated(&refresh.token, features, etag)
-                        .await
+                        .await;
+                    if cfg!(feature = "delta") && self.delta_diff {
+                        self.compare_delta_cache(&refresh).await;
+                    }
                 }
             },
             Err(e) => {

server/tests/streaming_test.rs

@@ -212,6 +212,7 @@ mod streaming_test {
                 strict: true,
                 dynamic: false,
                 delta: false,
+                delta_diff:false,
                 prometheus_remote_write_url: None,
                 prometheus_push_interval: 60,
                 prometheus_username: None,