refactor(store)!: change Store's method and error names

The changes in this commit were motivated due to a bug in the
`StoreFile` which caused old data to be lost if the file was `open`
instead of created and new data was appended. The bugfix later motivated
a general name cleanup in StoreFile's methods and errors and some minor
changes in their signatures. FileError was renamed to StoreError, which
now includes the IterError variants, allowing the remplacement of the
former form. The new StoreFile methods are:
- create: create file in write only mode or fail if file exists.
- load: open existing file, check integrity of content and retrieve
  Store.
- append: add new changesets to Store. Do nothing if changeset is empty.
- dump: aggregate and retrieve all stored changesets in store.
- load_or_create: load if file exists, create if not, and retrieve
  Store.

Author: nymius

README.md

@@ -42,7 +42,7 @@ The project is split up into several crates in the `/crates` directory:
 - [`wallet`](./crates/wallet): Contains the central high level `Wallet` type that is built from the low-level mechanisms provided by the other components
 - [`chain`](./crates/chain): Tools for storing and indexing chain data
 - [`persist`](./crates/persist): Types that define data persistence of a BDK wallet
-- [`file_store`](./crates/file_store): A (experimental) persistence backend for storing chain data in a single file.
+- [`file_store`](./crates/file_store): Persistence backend for storing chain data in a single file. Intended for testing and development purposes, not for production.
 - [`esplora`](./crates/esplora): Extends the [`esplora-client`] crate with methods to fetch chain data from an esplora HTTP server in the form that [`bdk_chain`] and `Wallet` can consume.
 - [`electrum`](./crates/electrum): Extends the [`electrum-client`] crate with methods to fetch chain data from an electrum server in the form that [`bdk_chain`] and `Wallet` can consume.
 

crates/file_store/src/entry_iter.rs

@@ -1,3 +1,4 @@
+use crate::StoreError;
 use bincode::Options;
 use std::{
     fs::File,
@@ -37,7 +38,7 @@ impl<T> Iterator for EntryIter<'_, T>
 where
     T: serde::de::DeserializeOwned,
 {
-    type Item = Result<T, IterError>;
+    type Item = Result<T, StoreError>;
 
     fn next(&mut self) -> Option<Self::Item> {
         if self.finished {
@@ -63,7 +64,7 @@ where
                         }
                     }
                     self.db_file.seek(io::SeekFrom::Start(pos_before_read))?;
-                    Err(IterError::Bincode(*e))
+                    Err(StoreError::Bincode(*e))
                 }
             }
         })()
@@ -80,29 +81,3 @@ impl<T> Drop for EntryIter<'_, T> {
         }
     }
 }
-
-/// Error type for [`EntryIter`].
-#[derive(Debug)]
-pub enum IterError {
-    /// Failure to read from the file.
-    Io(io::Error),
-    /// Failure to decode data from the file.
-    Bincode(bincode::ErrorKind),
-}
-
-impl core::fmt::Display for IterError {
-    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
-        match self {
-            IterError::Io(e) => write!(f, "io error trying to read entry {}", e),
-            IterError::Bincode(e) => write!(f, "bincode error while reading entry {}", e),
-        }
-    }
-}
-
-impl From<io::Error> for IterError {
-    fn from(value: io::Error) -> Self {
-        IterError::Io(value)
-    }
-}
-
-impl std::error::Error for IterError {}

crates/file_store/src/lib.rs

@@ -13,7 +13,7 @@ pub(crate) fn bincode_options() -> impl bincode::Options {
 
 /// Error that occurs due to problems encountered with the file.
 #[derive(Debug)]
-pub enum FileError {
+pub enum StoreError {
     /// IO error, this may mean that the file is too short.
     Io(io::Error),
     /// Magic bytes do not match what is expected.
@@ -22,7 +22,7 @@ pub enum FileError {
     Bincode(bincode::ErrorKind),
 }
 
-impl core::fmt::Display for FileError {
+impl core::fmt::Display for StoreError {
     fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
         match self {
             Self::Io(e) => write!(f, "io error trying to read file: {}", e),
@@ -36,10 +36,10 @@ impl core::fmt::Display for FileError {
     }
 }
 
-impl From<io::Error> for FileError {
+impl From<io::Error> for StoreError {
     fn from(value: io::Error) -> Self {
         Self::Io(value)
     }
 }
 
-impl std::error::Error for FileError {}
+impl std::error::Error for StoreError {}