remove Database::flush and implicitly call it in keyvalue::Databaes impl functions

Author: kafaichoi

CHANGELOG.md

@@ -25,6 +25,8 @@ To decouple the `Wallet` from the `Blockchain` we've made major changes:
 - Stop making a request for the block height when calling `Wallet:new`.
 - Added `SyncOptions` to capture extra (future) arguments to `Wallet::sync`.
 - Removed `max_addresses` sync parameter which determined how many addresses to cache before syncing since this can just be done with `ensure_addresses_cached`.
+- remove `flush` method from the `Database` trait and implicitly call it in keyvalue::Database
+
 
 ## [v0.16.1] - [v0.16.0]
 
@@ -437,4 +439,4 @@ final transaction is created by calling `finish` on the builder.
 [v0.16.0]: https://github.com/bitcoindevkit/bdk/compare/v0.15.0...v0.16.0
 [v0.16.1]: https://github.com/bitcoindevkit/bdk/compare/v0.16.0...v0.16.1
 [v0.17.0]: https://github.com/bitcoindevkit/bdk/compare/v0.16.1...v0.17.0
-[unreleased]: https://github.com/bitcoindevkit/bdk/compare/v0.17.0...HEAD
+[unreleased]: https://github.com/bitcoindevkit/bdk/compare/v0.17.0...HEAD

src/database/any.rs

@@ -254,10 +254,6 @@ impl Database for AnyDatabase {
     fn increment_last_index(&mut self, keychain: KeychainKind) -> Result<u32, Error> {
         impl_inner_method!(AnyDatabase, self, increment_last_index, keychain)
     }
-
-    fn flush(&mut self) -> Result<(), Error> {
-        impl_inner_method!(AnyDatabase, self, flush)
-    }
 }
 
 impl BatchOperations for AnyBatch {

src/database/keyvalue.rs

@@ -207,6 +207,8 @@ impl BatchOperations for Batch {
     impl_batch_operations!({}, process_delete_batch);
 }
 
+/// Implementation of Database using [`sled::Tree`]. All write operations will be
+/// auto-flushed.
 impl Database for Tree {
     fn check_descriptor_checksum<B: AsRef<[u8]>>(
         &mut self,
@@ -224,6 +226,7 @@ impl Database for Tree {
             }
         } else {
             self.insert(&key, bytes.as_ref())?;
+            Tree::flush(self)?;
             Ok(())
         }
     }
@@ -380,31 +383,31 @@ impl Database for Tree {
     // inserts 0 if not present
     fn increment_last_index(&mut self, keychain: KeychainKind) -> Result<u32, Error> {
         let key = MapKey::LastIndex(keychain).as_map_key();
-        self.update_and_fetch(key, |prev| {
-            let new = match prev {
-                Some(b) => {
-                    let array: [u8; 4] = b.try_into().unwrap_or([0; 4]);
-                    let val = u32::from_be_bytes(array);
-
-                    val + 1
-                }
-                None => 0,
-            };
-
-            Some(new.to_be_bytes().to_vec())
-        })?
-        .map_or(Ok(0), |b| -> Result<_, Error> {
-            let array: [u8; 4] = b
-                .as_ref()
-                .try_into()
-                .map_err(|_| Error::InvalidU32Bytes(b.to_vec()))?;
-            let val = u32::from_be_bytes(array);
-            Ok(val)
-        })
-    }
+        let last_index = self
+            .update_and_fetch(key, |prev| {
+                let new = match prev {
+                    Some(b) => {
+                        let array: [u8; 4] = b.try_into().unwrap_or([0; 4]);
+                        let val = u32::from_be_bytes(array);
+
+                        val + 1
+                    }
+                    None => 0,
+                };
+
+                Some(new.to_be_bytes().to_vec())
+            })?
+            .map_or(Ok(0), |b| -> Result<_, Error> {
+                let array: [u8; 4] = b
+                    .as_ref()
+                    .try_into()
+                    .map_err(|_| Error::InvalidU32Bytes(b.to_vec()))?;
+                let val = u32::from_be_bytes(array);
+                Ok(val)
+            })?;
 
-    fn flush(&mut self) -> Result<(), Error> {
-        Ok(Tree::flush(self).map(|_| ())?)
+        Tree::flush(self).map(|_| ())?;
+        Ok(last_index)
     }
 }
 

src/database/memory.rs

@@ -449,10 +449,6 @@ impl Database for MemoryDatabase {
 
         Ok(*value)
     }
-
-    fn flush(&mut self) -> Result<(), Error> {
-        Ok(())
-    }
 }
 
 impl BatchDatabase for MemoryDatabase {

src/database/mod.rs

@@ -158,9 +158,6 @@ pub trait Database: BatchOperations {
     ///
     /// It should insert and return `0` if not present in the database
     fn increment_last_index(&mut self, keychain: KeychainKind) -> Result<u32, Error>;
-
-    /// Force changes to be written to disk
-    fn flush(&mut self) -> Result<(), Error>;
 }
 
 /// Trait for a database that supports batch operations