immediately fetch TX from mempool after broadcast

src/daemon.rs

@@ -220,6 +220,12 @@ impl Daemon {
             .context("failed to get mempool txids")
     }
 
+    pub(crate) fn get_mempool_entry(&self, txid: &Txid) -> Result<json::GetMempoolEntryResult> {
+        self.rpc
+            .get_mempool_entry(txid)
+            .context("failed to get mempool entry")
+    }
+
     pub(crate) fn get_mempool_entries(
         &self,
         txids: &[Txid],

src/electrum.rs

@@ -19,7 +19,7 @@ use crate::{
     cache::Cache,
     config::{Config, ELECTRS_VERSION},
     daemon::{self, extract_bitcoind_error, Daemon},
-    mempool::MempoolSyncUpdate,
+    mempool::{self, MempoolSyncUpdate},
     merkle::Proof,
     metrics::{self, Histogram, Metrics},
     signals::Signal,
@@ -49,6 +49,20 @@ struct Request {
     params: Value,
 }
 
+struct CallResult {
+    response: Value,
+    mempool_update: MempoolSyncUpdate,
+}
+
+impl CallResult {
+    fn new<T: serde::Serialize>(response: T) -> CallResult {
+        CallResult {
+            response: json!(response),
+            mempool_update: MempoolSyncUpdate::default(),
+        }
+    }
+}
+
 #[derive(Deserialize)]
 #[serde(untagged)]
 enum Requests {
@@ -372,11 +386,20 @@ impl Rpc {
         Ok(status)
     }
 
-    fn transaction_broadcast(&self, (tx_hex,): &(String,)) -> Result<Value> {
+    fn transaction_broadcast(&self, (tx_hex,): &(String,)) -> Result<(Value, MempoolSyncUpdate)> {
         let tx_bytes = Vec::from_hex(tx_hex).context("non-hex transaction")?;
         let tx = deserialize(&tx_bytes).context("invalid transaction")?;
         let txid = self.daemon.broadcast(&tx)?;
-        Ok(json!(txid))
+
+        // Try to fetch the mempool entry immediately, so we can return an update
+        // to be applied to the mempool.
+        let mut mempool_update = MempoolSyncUpdate::default();
+        if let Ok(rpc_entry) = self.daemon.get_mempool_entry(&txid) {
+            let entry = mempool::Entry::new(txid, tx, rpc_entry);
+            mempool_update.new_entries.push(entry);
+        }
+
+        Ok((json!(txid), mempool_update))
     }
 
     fn transaction_get(&self, args: &TxGetArgs) -> Result<Value> {
@@ -475,7 +498,7 @@ impl Rpc {
         }))
     }
 
-    pub fn handle_requests(&self, client: &mut Client, lines: &[String]) -> Vec<String> {
+    pub fn handle_requests(&mut self, client: &mut Client, lines: &[String]) -> Vec<String> {
         lines
             .iter()
             .map(|line| {
@@ -487,7 +510,7 @@ impl Rpc {
             .collect()
     }
 
-    fn handle_calls(&self, client: &mut Client, calls: Result<Calls, Value>) -> Value {
+    fn handle_calls(&mut self, client: &mut Client, calls: Result<Calls, Value>) -> Value {
         let calls: Calls = match calls {
             Ok(calls) => calls,
             Err(response) => return response, // JSON parsing failed - the response does not contain request id
@@ -498,12 +521,33 @@ impl Rpc {
                 if let Some(result) = self.try_multi_call(client, &batch) {
                     return json!(result);
                 }
-                json!(batch
+                let responses = batch
                     .into_iter()
-                    .map(|result| self.single_call(client, result))
-                    .collect::<Vec<Value>>())
+                    .map(|call| {
+                        let CallResult {
+                            response,
+                            mempool_update,
+                        } = self.single_call(client, call);
+
+                        // Apply the mempool update immediately, so that the next
+                        // response will reflect the updated mempool state.
+                        self.mempool_apply(mempool_update);
+
+                        response
+                    })
+                    .collect::<Vec<Value>>();
+                json!(responses)
+            }
+
+            Calls::Single(call) => {
+                let CallResult {
+                    response,
+                    mempool_update,
+                } = self.single_call(client, call);
+
+                self.mempool_apply(mempool_update);
+                response
             }
-            Calls::Single(result) => self.single_call(client, result),
         }
     }
 
@@ -538,10 +582,10 @@ impl Rpc {
         )
     }
 
-    fn single_call(&self, client: &mut Client, call: Result<Call, Value>) -> Value {
+    fn single_call(&self, client: &mut Client, call: Result<Call, Value>) -> CallResult {
         let call = match call {
             Ok(call) => call,
-            Err(response) => return response, // params parsing may fail - the response contains request id
+            Err(response) => return CallResult::new(response), // params parsing may fail - the response contains request id
         };
         self.rpc_duration.observe_duration(&call.method, || {
             if self.tracker.status().is_err() {
@@ -551,9 +595,11 @@ impl Rpc {
                     | Params::BlockHeaders(_)
                     | Params::HeadersSubscribe
                     | Params::Version(_) => (),
-                    _ => return error_msg(&call.id, RpcError::UnavailableIndex),
+                    _ => return CallResult::new(error_msg(&call.id, RpcError::UnavailableIndex)),
                 };
             }
+
+            let mut mempool_update = MempoolSyncUpdate::default();
             let result = match &call.params {
                 Params::Banner => Ok(json!(self.banner)),
                 Params::BlockHeader(args) => self.block_header(*args),
@@ -571,13 +617,23 @@ impl Rpc {
                 Params::ScriptHashListUnspent(args) => self.scripthash_list_unspent(client, args),
                 Params::ScriptHashSubscribe(args) => self.scripthash_subscribe(client, args),
                 Params::ScriptHashUnsubscribe(args) => self.scripthash_unsubscribe(client, args),
-                Params::TransactionBroadcast(args) => self.transaction_broadcast(args),
+                Params::TransactionBroadcast(args) => {
+                    self.transaction_broadcast(args)
+                        .map(|(result, sync_update)| {
+                            mempool_update = sync_update; // extract the mempool sync update
+                            result
+                        })
+                }
                 Params::TransactionGet(args) => self.transaction_get(args),
                 Params::TransactionGetMerkle(args) => self.transaction_get_merkle(args),
                 Params::TransactionFromPosition(args) => self.transaction_from_pos(*args),
                 Params::Version(args) => self.version(args),
             };
-            call.response(result)
+
+            CallResult {
+                response: call.response(result),
+                mempool_update,
+            }
         })
     }
 }

src/mempool.rs

@@ -24,6 +24,22 @@ pub(crate) struct Entry {
     pub has_unconfirmed_inputs: bool,
 }
 
+impl Entry {
+    pub fn new(
+        txid: Txid,
+        tx: Transaction,
+        rpc_entry: bitcoincore_rpc::json::GetMempoolEntryResult,
+    ) -> Entry {
+        Entry {
+            txid,
+            tx,
+            vsize: rpc_entry.vsize,
+            fee: rpc_entry.fees.base,
+            has_unconfirmed_inputs: !rpc_entry.depends.is_empty(),
+        }
+    }
+}
+
 /// Mempool current state
 pub(crate) struct Mempool {
     entries: HashMap<Txid, Entry>,
@@ -38,8 +54,9 @@ pub(crate) struct Mempool {
 /// An update to [`Mempool`]'s internal state. This can be fetched
 /// asynchronously using [`MempoolSyncUpdate::poll`], and applied
 /// using [`Mempool::apply_sync_update`].
+#[derive(Default)]
 pub(crate) struct MempoolSyncUpdate {
-    new_entries: Vec<Entry>,
+    pub(crate) new_entries: Vec<Entry>,
     removed_entries: HashSet<Txid>,
 }
 
@@ -174,6 +191,11 @@ impl Mempool {
         let removed = update.removed_entries.len();
         let added = update.new_entries.len();
 
+        // Return early to avoid spurious logs.
+        if added == 0 && removed == 0 {
+            return;
+        }
+
         for txid_to_remove in update.removed_entries {
             self.remove_entry(txid_to_remove);
         }

src/server.rs

@@ -164,7 +164,7 @@ fn serve() -> Result<()> {
                     let rest = server_rx.iter().take(server_rx.len());
                     let events: Vec<Event> = first.chain(rest).collect();
                     server_batch_size.observe("recv", events.len() as f64);
-                    duration.observe_duration("handle", || handle_events(&rpc, &mut peers, events));
+                    duration.observe_duration("handle", || handle_events(&mut rpc, &mut peers, events));
                 },
                 default(config.wait_duration) => (), // sync and update
             };
@@ -206,7 +206,7 @@ enum Message {
     Done,
 }
 
-fn handle_events(rpc: &Rpc, peers: &mut HashMap<usize, Peer>, events: Vec<Event>) {
+fn handle_events(rpc: &mut Rpc, peers: &mut HashMap<usize, Peer>, events: Vec<Event>) {
     let mut events_by_peer = HashMap::<usize, Vec<Message>>::new();
     events
         .into_iter()
@@ -217,7 +217,7 @@ fn handle_events(rpc: &Rpc, peers: &mut HashMap<usize, Peer>, events: Vec<Event>
 }
 
 fn handle_peer_events(
-    rpc: &Rpc,
+    rpc: &mut Rpc,
     peers: &mut HashMap<usize, Peer>,
     peer_id: usize,
     messages: Vec<Message>,