2aa08a5898
This is a more generic version of `keychain::persist::*` structures. Additional changes: * The `Append` trait has a new method `is_empty`. * Introduce `Store` structure for `bdk_file_store`.
101 lines
2.9 KiB
Rust
101 lines
2.9 KiB
Rust
use bincode::Options;
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use std::{
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fs::File,
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io::{self, Seek},
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marker::PhantomData,
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};
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use crate::bincode_options;
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/// Iterator over entries in a file store.
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///
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/// Reads and returns an entry each time [`next`] is called. If an error occurs while reading the
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/// iterator will yield a `Result::Err(_)` instead and then `None` for the next call to `next`.
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///
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/// [`next`]: Self::next
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pub struct EntryIter<'t, T> {
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db_file: Option<&'t mut File>,
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/// The file position for the first read of `db_file`.
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start_pos: Option<u64>,
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types: PhantomData<T>,
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}
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impl<'t, T> EntryIter<'t, T> {
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pub fn new(start_pos: u64, db_file: &'t mut File) -> Self {
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Self {
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db_file: Some(db_file),
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start_pos: Some(start_pos),
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types: PhantomData,
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}
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}
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}
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impl<'t, T> Iterator for EntryIter<'t, T>
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where
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T: serde::de::DeserializeOwned,
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{
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type Item = Result<T, IterError>;
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fn next(&mut self) -> Option<Self::Item> {
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// closure which reads a single entry starting from `self.pos`
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let read_one = |f: &mut File, start_pos: Option<u64>| -> Result<Option<T>, IterError> {
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let pos = match start_pos {
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Some(pos) => f.seek(io::SeekFrom::Start(pos))?,
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None => f.stream_position()?,
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};
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match bincode_options().deserialize_from(&*f) {
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Ok(changeset) => {
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f.stream_position()?;
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Ok(Some(changeset))
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}
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Err(e) => {
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if let bincode::ErrorKind::Io(inner) = &*e {
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if inner.kind() == io::ErrorKind::UnexpectedEof {
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let eof = f.seek(io::SeekFrom::End(0))?;
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if pos == eof {
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return Ok(None);
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}
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}
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}
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f.seek(io::SeekFrom::Start(pos))?;
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Err(IterError::Bincode(*e))
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}
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}
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};
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let result = read_one(self.db_file.as_mut()?, self.start_pos.take());
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if result.is_err() {
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self.db_file = None;
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}
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result.transpose()
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}
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}
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impl From<io::Error> for IterError {
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fn from(value: io::Error) -> Self {
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IterError::Io(value)
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}
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}
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/// Error type for [`EntryIter`].
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#[derive(Debug)]
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pub enum IterError {
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/// Failure to read from the file.
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Io(io::Error),
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/// Failure to decode data from the file.
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Bincode(bincode::ErrorKind),
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}
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impl core::fmt::Display for IterError {
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fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
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match self {
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IterError::Io(e) => write!(f, "io error trying to read entry {}", e),
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IterError::Bincode(e) => write!(f, "bincode error while reading entry {}", e),
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}
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}
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}
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impl std::error::Error for IterError {}
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