Add populate_anchor_cache method to bdk

crates/electrum/src/bdk_electrum_client.rs

@@ -7,6 +7,7 @@ use bdk_core::{
     BlockId, CheckPoint, ConfirmationBlockTime, TxUpdate,
 };
 use electrum_client::{ElectrumApi, Error, HeaderNotification};
+use std::convert::TryInto;
 use std::sync::{Arc, Mutex};
 
 /// We include a chain suffix of a certain length for the purpose of robustness.
@@ -37,6 +38,20 @@ impl<E: ElectrumApi> BdkElectrumClient<E> {
         }
     }
 
+    /// Insert anchors into the anchor cache so that they don’t have to be fetched again from
+    /// Electrum. Typically used to pre-populate the cache from an existing `TxGraph`.
+    pub fn populate_anchor_cache(
+        &self,
+        tx_anchors: impl IntoIterator<Item = (Txid, impl IntoIterator<Item = ConfirmationBlockTime>)>,
+    ) {
+        let mut cache = self.anchor_cache.lock().unwrap();
+        for (txid, anchors) in tx_anchors {
+            for anchor in anchors {
+                cache.insert((txid, anchor.block_id.hash), anchor);
+            }
+        }
+    }
+
     /// Inserts transactions into the transaction cache so that the client will not fetch these
     /// transactions.
     pub fn populate_tx_cache(&self, txs: impl IntoIterator<Item = impl Into<Arc<Transaction>>>) {

examples/example_electrum/src/main.rs

@@ -125,7 +125,12 @@ fn main() -> anyhow::Result<()> {
     };
 
     let client = BdkElectrumClient::new(electrum_cmd.electrum_args().client(network)?);
-
+    {
+        // Lock graph mutex - released automatically at scope end
+        // Cache all anchors while holding the lock
+        let graph = graph.lock().unwrap();
+        client.populate_anchor_cache(graph.graph().all_anchors().clone());
+    }
     // Tell the electrum client about the txs we've already got locally so it doesn't re-download
     // them
     client.populate_tx_cache(