openethereum/dapps/src/apps/cache.rs

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// Copyright 2015-2017 Parity Technologies (UK) Ltd.
// This file is part of Parity.
// Parity is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Parity is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Parity. If not, see <http://www.gnu.org/licenses/>.
//! Fetchable Dapps support.
use std::fs;
use linked_hash_map::LinkedHashMap;
use page::local;
use handlers::FetchControl;
pub enum ContentStatus {
Fetching(FetchControl),
Ready(local::Dapp),
}
#[derive(Default)]
pub struct ContentCache {
cache: LinkedHashMap<String, ContentStatus>,
}
impl ContentCache {
pub fn insert(&mut self, content_id: String, status: ContentStatus) -> Option<ContentStatus> {
self.cache.insert(content_id, status)
}
pub fn remove(&mut self, content_id: &str) -> Option<ContentStatus> {
self.cache.remove(content_id)
}
pub fn get(&mut self, content_id: &str) -> Option<&mut ContentStatus> {
self.cache.get_refresh(content_id)
}
pub fn clear_garbage(&mut self, expected_size: usize) -> Vec<(String, ContentStatus)> {
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let len = self.cache.len();
if len <= expected_size {
return Vec::new();
}
let mut removed = Vec::with_capacity(len - expected_size);
while self.cache.len() > expected_size {
let entry = self.cache.pop_front().expect("expected_size bounded at 0, len is greater; qed");
match entry.1 {
ContentStatus::Fetching(ref fetch) => {
trace!(target: "dapps", "Aborting {} because of limit.", entry.0);
// Mark as aborted
fetch.abort()
},
ContentStatus::Ready(ref endpoint) => {
trace!(target: "dapps", "Removing {} because of limit.", entry.0);
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// Remove path (dir or file)
let res = fs::remove_dir_all(&endpoint.path()).or_else(|_| fs::remove_file(&endpoint.path()));
if let Err(e) = res {
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warn!(target: "dapps", "Unable to remove dapp/content from cache: {:?}", e);
}
}
}
removed.push(entry);
}
removed
}
#[cfg(test)]
pub fn len(&self) -> usize {
self.cache.len()
}
}
#[cfg(test)]
mod tests {
use super::*;
fn only_keys(data: Vec<(String, ContentStatus)>) -> Vec<String> {
data.into_iter().map(|x| x.0).collect()
}
#[test]
fn should_remove_least_recently_used() {
// given
let mut cache = ContentCache::default();
cache.insert("a".into(), ContentStatus::Fetching(Default::default()));
cache.insert("b".into(), ContentStatus::Fetching(Default::default()));
cache.insert("c".into(), ContentStatus::Fetching(Default::default()));
// when
let res = cache.clear_garbage(2);
// then
assert_eq!(cache.len(), 2);
assert_eq!(only_keys(res), vec!["a"]);
}
#[test]
fn should_update_lru_if_accessed() {
// given
let mut cache = ContentCache::default();
cache.insert("a".into(), ContentStatus::Fetching(Default::default()));
cache.insert("b".into(), ContentStatus::Fetching(Default::default()));
cache.insert("c".into(), ContentStatus::Fetching(Default::default()));
// when
cache.get("a");
let res = cache.clear_garbage(2);
// then
assert_eq!(cache.len(), 2);
assert_eq!(only_keys(res), vec!["b"]);
}
}