64 lines
1.7 KiB
Rust
64 lines
1.7 KiB
Rust
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use crate::Error;
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use std::{
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fs::{create_dir_all, File, OpenOptions},
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io::BufReader,
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path::Path,
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};
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/// Enum to indicate the state of the cache
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pub(crate) enum CacheState {
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/// Current head and cached head are the same
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Current(u64),
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/// Cached head is older than current head
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Old(Cache),
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/// No cache was found
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No,
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}
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impl CacheState {
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pub(crate) fn read_from_file(path: impl AsRef<Path>, head: &str) -> Result<CacheState, Error> {
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if path.as_ref().exists() {
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let cache: Cache = serde_json::from_reader(BufReader::new(File::open(path)?))?;
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if cache.head == head {
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Ok(CacheState::Current(cache.count))
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} else {
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Ok(CacheState::Old(cache))
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}
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} else {
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Ok(CacheState::No)
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}
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}
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pub(crate) fn calculate_new_cache(self, count: u64, head: String) -> Cache {
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match self {
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CacheState::Old(mut cache) => {
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cache.head = head;
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cache.count += count;
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cache
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}
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CacheState::No | CacheState::Current(_) => Cache { head, count },
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}
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}
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}
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#[derive(Serialize, Deserialize)]
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pub(crate) struct Cache {
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pub head: String,
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pub count: u64,
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}
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impl Cache {
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pub(crate) fn write_to_file(&self, path: impl AsRef<Path>) -> Result<(), Error> {
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create_dir_all(path.as_ref().parent().ok_or(Error::Internal)?)?;
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serde_json::to_writer(
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OpenOptions::new()
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.write(true)
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.create(true)
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.truncate(true)
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.open(path)?,
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self,
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)?;
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Ok(())
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}
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}
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