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|
// -*- coding: utf-8 -*-
//
// Simple CMS
//
// Copyright (C) 2011-2024 Michael Büsch <m@bues.ch>
//
// Licensed under the Apache License version 2.0
// or the MIT license, at your option.
// SPDX-License-Identifier: Apache-2.0 OR MIT
use crate::db_fsintf::{DbFsIntf, PageInfo};
use cms_ident::{CheckedIdent, CheckedIdentElem, Ident};
use inotify::{Inotify, Watches};
use lru::LruCache;
use tokio::sync::Mutex;
#[derive(Clone, PartialEq, Eq, Hash, Debug)]
enum CacheKey {
Page(Ident),
PageRedirect(Ident),
PageTitle(Ident),
PageStamp(Ident),
Subpages(Ident),
Macro(Ident, Ident),
String(Ident),
Image(Ident),
Headers(Ident),
}
#[derive(Debug)]
enum CacheValue {
Blob(Vec<u8>),
PageInfoList(Vec<PageInfo>),
U64(u64),
}
pub struct DbCache {
fs_intf: DbFsIntf,
inotify: Mutex<Inotify>,
inotify_watches: Watches,
cache: Option<Mutex<LruCache<CacheKey, CacheValue>>>,
}
macro_rules! get_cached {
(
$self:ident,
$key:ident,
$value_type:ident,
$getter:ident ( $( $getter_args:ident ),* )
) => {
{
let unpack = |data: &CacheValue| {
if let CacheValue::$value_type(data) = data {
data.clone()
} else {
panic!("CacheValue: Not a valid type.");
}
};
// Query the cache.
if let Some(cache) = &$self.cache {
let mut cache = cache.lock().await;
if let Some(data) = cache.get(&$key) {
return unpack(data);
}
// The cache does not contain the value.
}
let data = {
// Get an inotify handle for adding watches.
let mut watches = $self.inotify_watches.clone();
// Access the DB without holding any lock.
$self.fs_intf.$getter( $( $getter_args ),* , &mut watches ).await
};
// Insert it into the cache.
if let Some(cache) = &$self.cache {
let mut cache = cache.lock().await;
unpack(cache.try_get_or_insert::<_, ()>(
$key,
|| Ok(CacheValue::$value_type(data))
).unwrap())
} else {
data
}
}
}
}
impl DbCache {
pub fn new(fs_intf: DbFsIntf, cache_size: usize) -> Self {
let cache = if cache_size == 0 {
None
} else {
let cache_size = cache_size.try_into().unwrap();
Some(Mutex::new(LruCache::new(cache_size)))
};
let inotify = Inotify::init().expect("Inotify initialization failed");
let watches = inotify.watches();
Self {
fs_intf,
inotify: Mutex::new(inotify),
inotify_watches: watches,
cache,
}
}
pub async fn clear(&self) {
if let Some(cache) = &self.cache {
let mut cache = cache.lock().await;
if !cache.is_empty() {
cache.clear();
println!("DB cache cleared.");
}
}
}
pub async fn check_inotify(&self) {
let mut inotify = self.inotify.lock().await;
let mut buffer = [0; 4096];
loop {
match inotify.read_events(&mut buffer) {
Ok(events) => {
if events.count() > 0 {
self.clear().await;
} else {
return;
}
}
Err(_) => {
return;
}
}
}
}
pub async fn get_page(&self, page: &CheckedIdent) -> Vec<u8> {
let key = CacheKey::Page(page.downgrade_clone());
get_cached!(self, key, Blob, get_page(page))
}
pub async fn get_page_redirect(&self, page: &CheckedIdent) -> Vec<u8> {
let key = CacheKey::PageRedirect(page.downgrade_clone());
get_cached!(self, key, Blob, get_page_redirect(page))
}
pub async fn get_page_title(&self, page: &CheckedIdent) -> Vec<u8> {
let key = CacheKey::PageTitle(page.downgrade_clone());
get_cached!(self, key, Blob, get_page_title(page))
}
pub async fn get_page_stamp(&self, page: &CheckedIdent) -> u64 {
let key = CacheKey::PageStamp(page.downgrade_clone());
get_cached!(self, key, U64, get_page_stamp(page))
}
pub async fn get_subpages(&self, page: &CheckedIdent) -> Vec<PageInfo> {
let key = CacheKey::Subpages(page.downgrade_clone());
get_cached!(self, key, PageInfoList, get_subpages(page))
}
pub async fn get_macro(&self, page: &CheckedIdent, name: &CheckedIdentElem) -> Vec<u8> {
let key = CacheKey::Macro(page.downgrade_clone(), name.downgrade_clone());
get_cached!(self, key, Blob, get_macro(page, name))
}
pub async fn get_string(&self, name: &CheckedIdentElem) -> Vec<u8> {
let key = CacheKey::String(name.downgrade_clone());
get_cached!(self, key, Blob, get_string(name))
}
pub async fn get_image(&self, name: &CheckedIdentElem) -> Vec<u8> {
let key = CacheKey::Image(name.downgrade_clone());
get_cached!(self, key, Blob, get_image(name))
}
pub async fn get_headers(&self, page: &CheckedIdent) -> Vec<u8> {
let key = CacheKey::Headers(page.downgrade_clone());
get_cached!(self, key, Blob, get_headers(page))
}
}
// vim: ts=4 sw=4 expandtab
|
