Fix add_spk API

bdk_chain/src/keychain/keychain_txout_index.rs

@@ -202,7 +202,8 @@ impl<K: Clone + Ord + Debug> KeychainTxOutIndex<K> {
                 .derived_descriptor(&secp)
                 .expect("the descritpor cannot need hardened derivation")
                 .script_pubkey();
-            self.inner.add_spk((keychain.clone(), index), spk);
+            self.inner
+                .insert_script_pubkey((keychain.clone(), index), spk);
         }
 
         true
@@ -231,7 +232,7 @@ impl<K: Clone + Ord + Debug> KeychainTxOutIndex<K> {
             .script_pubkey();
 
         let index = (keychain.clone(), next_derivation_index);
-        self.inner.add_spk(index.clone(), new_spk);
+        self.inner.insert_script_pubkey(index.clone(), new_spk);
         let new_spk = self
             .inner
             .script_pubkeys()

bdk_chain/src/lib.rs

@@ -37,13 +37,15 @@ pub mod collections {
     #![allow(dead_code)]
     pub type HashSet<K> = alloc::collections::BTreeSet<K>;
     pub type HashMap<K, V> = alloc::collections::BTreeMap<K, V>;
+    pub use alloc::collections::btree_map as hash_map;
     pub use alloc::collections::*;
 }
 
 // When we have std use `std`'s all collections
 #[cfg(all(feature = "std", not(feature = "hashbrown")))]
 #[doc(hidden)]
 pub mod collections {
+    pub use std::collections::hash_map;
     pub use std::collections::*;
 }
 
@@ -55,4 +57,5 @@ pub mod collections {
     pub type HashSet<K> = hashbrown::HashSet<K>;
     pub type HashMap<K, V> = hashbrown::HashMap<K, V>;
     pub use alloc::collections::*;
+    pub use hashbrown::hash_map;
 }

bdk_chain/src/spk_txout_index.rs

@@ -1,7 +1,7 @@
 use core::ops::RangeBounds;
 
 use crate::{
-    collections::{BTreeMap, BTreeSet, HashMap},
+    collections::{hash_map::Entry, BTreeMap, BTreeSet, HashMap},
     ForEachTxout,
 };
 use bitcoin::{self, OutPoint, Script, Transaction, TxOut, Txid};
@@ -22,7 +22,7 @@ use bitcoin::{self, OutPoint, Script, Transaction, TxOut, Txid};
 /// chain or unspent etc you must use other sources of information like a [`SparseChain`].
 ///
 /// [`TxOut`]: bitcoin::TxOut
-/// [`add_spk`]: Self::add_spk
+/// [`add_spk`]: Self::insert_script_pubkey
 /// [`Ord`]: core::cmp::Ord
 /// [`scan`]: Self::scan
 /// [`SparseChain`]: crate::sparse_chain::SparseChain
@@ -149,13 +149,19 @@ impl<I: Clone + Ord> SpkTxOutIndex<I> {
         &self.script_pubkeys
     }
 
-    /// Adds a script pubkey to scan for.
+    /// Adds a script pubkey to scan for. Returns `false` and does nothing if spk already exists in the map
     ///
     /// the index will look for outputs spending to whenever it scans new data.
-    pub fn add_spk(&mut self, index: I, spk: Script) {
-        self.spk_indexes.insert(spk.clone(), index.clone());
-        self.script_pubkeys.insert(index.clone(), spk);
-        self.unused.insert(index);
+    pub fn insert_script_pubkey(&mut self, index: I, spk: Script) -> bool {
+        match self.spk_indexes.entry(spk.clone()) {
+            Entry::Vacant(value) => {
+                value.insert(index.clone());
+                self.script_pubkeys.insert(index.clone(), spk);
+                self.unused.insert(index);
+                true
+            }
+            Entry::Occupied(_) => false,
+        }
     }
 
     /// Iterates over a unused script pubkeys in a index range.

bdk_chain/tests/test_spk_txout_index.rs

@@ -7,8 +7,8 @@ fn spk_txout_sent_and_received() {
     let spk2 = Script::from_hex("00142b57404ae14f08c3a0c903feb2af7830605eb00f").unwrap();
 
     let mut index = SpkTxOutIndex::default();
-    index.add_spk(0, spk1.clone());
-    index.add_spk(1, spk2.clone());
+    index.insert_script_pubkey(0, spk1.clone());
+    index.insert_script_pubkey(1, spk2.clone());
 
     let tx1 = Transaction {
         version: 0x02,