feat(UTXO): balance event streaming for Electrum clients

mm2src/coins/tendermint/tendermint_balance_events.rs

@@ -114,6 +114,7 @@ impl EventBehaviour for TendermintCoin {
                         })
                         .collect();
 
+                    let mut balance_updates = vec![];
                     for denom in denoms {
                         if let Some((ticker, decimals)) = self.active_ticker_and_decimals_from_denom(&denom) {
                             let balance_denom = match self.account_balance_for_denom(&self.account_id, denom).await {
@@ -139,17 +140,22 @@ impl EventBehaviour for TendermintCoin {
                             }
 
                             if broadcast {
-                                let payload = json!({
+                                balance_updates.push(json!({
                                     "ticker": ticker,
                                     "balance": { "spendable": balance_decimal, "unspendable": BigDecimal::default() }
-                                });
-
-                                ctx.stream_channel_controller
-                                    .broadcast(Event::new(Self::EVENT_NAME.to_string(), payload.to_string()))
-                                    .await;
+                                }));
                             }
                         }
                     }
+
+                    if !balance_updates.is_empty() {
+                        ctx.stream_channel_controller
+                            .broadcast(Event::new(
+                                Self::EVENT_NAME.to_string(),
+                                json!(balance_updates).to_string(),
+                            ))
+                            .await;
+                    }
                 }
             }
         }

mm2src/coins/utxo.rs

@@ -32,6 +32,7 @@ pub mod rpc_clients;
 pub mod slp;
 pub mod spv;
 pub mod swap_proto_v2_scripts;
+pub mod utxo_balance_events;
 pub mod utxo_block_header_storage;
 pub mod utxo_builder;
 pub mod utxo_common;
@@ -65,7 +66,7 @@ pub use keys::{Address, AddressFormat as UtxoAddressFormat, AddressHashEnum, Key
                Type as ScriptType};
 #[cfg(not(target_arch = "wasm32"))]
 use lightning_invoice::Currency as LightningCurrency;
-use mm2_core::mm_ctx::MmArc;
+use mm2_core::mm_ctx::{MmArc, MmWeak};
 use mm2_err_handle::prelude::*;
 use mm2_metrics::MetricsArc;
 use mm2_number::BigDecimal;
@@ -141,6 +142,9 @@ pub type HistoryUtxoTxMap = HashMap<H256Json, HistoryUtxoTx>;
 pub type MatureUnspentMap = HashMap<Address, MatureUnspentList>;
 pub type RecentlySpentOutPointsGuard<'a> = AsyncMutexGuard<'a, RecentlySpentOutPoints>;
 pub type UtxoHDAddress = HDAddress<Address, Public>;
+pub type ScripthashNotificationSender = Option<Arc<AsyncMutex<AsyncSender<String>>>>;
+
+type ScripthashNotificationReceiver = Option<Arc<AsyncMutex<AsyncReceiver<String>>>>;
 
 #[cfg(windows)]
 #[cfg(not(target_arch = "wasm32"))]
@@ -610,6 +614,11 @@ pub struct UtxoCoinFields {
     /// This abortable system is used to spawn coin's related futures that should be aborted on coin deactivation
     /// and on [`MmArc::stop`].
     pub abortable_system: AbortableQueue,
+    pub(crate) ctx: MmWeak,
+    /// This is used for balance event streaming implementation for UTXOs.
+    /// If balance event streaming isn't enabled, this value will always be `None`; otherwise,
+    /// it will be used for receiving scripthash notifications to re-fetch balances.
+    scripthash_notification_receiver: ScripthashNotificationReceiver,
 }
 
 #[derive(Debug, Display)]