[Backport releases/v0.2] fix: remove racy endpoint PENDING_ACCEPTED_ITEMS_ENDPOINT for SESSION_STATUS_ENDPOINT

fedimint-core/src/endpoint_constants.rs

@@ -11,7 +11,7 @@ pub const SERVER_CONFIG_CONSENSUS_HASH_ENDPOINT: &str = "server_config_consensus
 pub const SESSION_COUNT_ENDPOINT: &str = "session_count";
 pub const AWAIT_SESSION_OUTCOME_ENDPOINT: &str = "await_session_outcome";
 pub const AWAIT_SIGNED_SESSION_OUTCOME_ENDPOINT: &str = "await_signed_session_outcome";
-pub const PENDING_ACCEPTED_ITEMS_ENDPOINT: &str = "pending_accepted_items";
+pub const SESSION_STATUS_ENDPOINT: &str = "session_status";
 pub const CONFIG_GEN_PEERS_ENDPOINT: &str = "config_gen_peers";
 pub const CONSENSUS_CONFIG_GEN_PARAMS_ENDPOINT: &str = "consensus_config_gen_params";
 pub const DEFAULT_CONFIG_GEN_PARAMS_ENDPOINT: &str = "default_config_gen_params";

fedimint-core/src/session_outcome.rs

@@ -60,6 +60,13 @@ pub struct SignedSessionOutcome {
     pub signatures: std::collections::BTreeMap<PeerId, SchnorrSignature>,
 }
 
+#[derive(Debug, Clone, Eq, PartialEq, Encodable, Decodable)]
+pub enum SessionStatus {
+    Initial,
+    Pending(Vec<AcceptedItem>),
+    Complete(SessionOutcome),
+}
+
 // TODO: remove this as soon as we bump bitcoin_hashes in fedimint_core to
 // 0.12.0
 pub fn consensus_hash_sha256<E: Encodable>(encodable: &E) -> sha256::Hash {

fedimint-server/src/config/mod.rs

@@ -211,7 +211,7 @@ impl ServerConfig {
     pub fn supported_api_versions() -> SupportedCoreApiVersions {
         SupportedCoreApiVersions {
             core_consensus: CORE_CONSENSUS_VERSION,
-            api: MultiApiVersion::try_from_iter([ApiVersion { major: 0, minor: 0 }])
+            api: MultiApiVersion::try_from_iter([ApiVersion { major: 0, minor: 1 }])
                 .expect("not version conflicts"),
         }
     }

fedimint-server/src/net/api.rs

@@ -1,4 +1,5 @@
 //! Implements the client API through which users interact with the federation
+use std::cmp::Ordering;
 use std::collections::{BTreeMap, HashMap};
 use std::fmt::{Debug, Formatter};
 use std::sync::Arc;
@@ -20,10 +21,9 @@ use fedimint_core::db::{
 use fedimint_core::endpoint_constants::{
     AUDIT_ENDPOINT, AUTH_ENDPOINT, AWAIT_OUTPUT_OUTCOME_ENDPOINT, AWAIT_SESSION_OUTCOME_ENDPOINT,
     AWAIT_SIGNED_SESSION_OUTCOME_ENDPOINT, AWAIT_TRANSACTION_ENDPOINT, BACKUP_ENDPOINT,
-    CLIENT_CONFIG_ENDPOINT, INVITE_CODE_ENDPOINT, MODULES_CONFIG_JSON_ENDPOINT,
-    PENDING_ACCEPTED_ITEMS_ENDPOINT, RECOVER_ENDPOINT, SERVER_CONFIG_CONSENSUS_HASH_ENDPOINT,
-    SESSION_COUNT_ENDPOINT, STATUS_ENDPOINT, SUBMIT_TRANSACTION_ENDPOINT,
-    VERIFY_CONFIG_HASH_ENDPOINT, VERSION_ENDPOINT,
+    CLIENT_CONFIG_ENDPOINT, INVITE_CODE_ENDPOINT, MODULES_CONFIG_JSON_ENDPOINT, RECOVER_ENDPOINT,
+    SERVER_CONFIG_CONSENSUS_HASH_ENDPOINT, SESSION_COUNT_ENDPOINT, SESSION_STATUS_ENDPOINT,
+    STATUS_ENDPOINT, SUBMIT_TRANSACTION_ENDPOINT, VERIFY_CONFIG_HASH_ENDPOINT, VERSION_ENDPOINT,
 };
 use fedimint_core::epoch::ConsensusItem;
 use fedimint_core::module::audit::{Audit, AuditSummary};
@@ -33,7 +33,7 @@ use fedimint_core::module::{
     SupportedApiVersionsSummary,
 };
 use fedimint_core::server::DynServerModule;
-use fedimint_core::session_outcome::{AcceptedItem, SessionOutcome, SignedSessionOutcome};
+use fedimint_core::session_outcome::{SessionOutcome, SessionStatus, SignedSessionOutcome};
 use fedimint_core::transaction::{SerdeTransaction, Transaction, TransactionError};
 use fedimint_core::{OutPoint, PeerId, TransactionId};
 use fedimint_logging::LOG_NET_API;
@@ -177,15 +177,25 @@ impl ConsensusApi {
             .0
     }
 
-    pub async fn pending_accepted_items(&self) -> Vec<AcceptedItem> {
-        self.db
-            .begin_transaction_nc()
-            .await
-            .find_by_prefix(&AcceptedItemPrefix)
-            .await
-            .map(|entry| entry.1)
-            .collect()
-            .await
+    pub async fn session_status(&self, session_index: u64) -> SessionStatus {
+        let mut dbtx = self.db.begin_transaction_nc().await;
+
+        match session_index.cmp(&get_finished_session_count_static(&mut dbtx).await) {
+            Ordering::Greater => SessionStatus::Initial,
+            Ordering::Equal => SessionStatus::Pending(
+                dbtx.find_by_prefix(&AcceptedItemPrefix)
+                    .await
+                    .map(|entry| entry.1)
+                    .collect()
+                    .await,
+            ),
+            Ordering::Less => SessionStatus::Complete(
+                dbtx.get_value(&SignedSessionOutcomeKey(session_index))
+                    .await
+                    .expect("There are no gaps in session outcomes")
+                    .session_outcome,
+            ),
+        }
     }
 
     pub async fn get_federation_status(&self) -> ApiResult<FederationStatus> {
@@ -439,9 +449,9 @@ pub fn server_endpoints() -> Vec<ApiEndpoint<ConsensusApi>> {
             }
         },
         api_endpoint! {
-            PENDING_ACCEPTED_ITEMS_ENDPOINT,
-            async |fedimint: &ConsensusApi, _context, _v: ()| -> SerdeModuleEncoding<Vec<AcceptedItem>> {
-                Ok((&fedimint.pending_accepted_items().await).into())
+            SESSION_STATUS_ENDPOINT,
+            async |fedimint: &ConsensusApi, _context, index: u64| -> SerdeModuleEncoding<SessionStatus> {
+                Ok((&fedimint.session_status(index).await).into())
             }
         },
         api_endpoint! {