feat: cache sent media file ids for instant repeat sends

This commit is contained in:
2026-08-05 02:06:30 +08:00
parent ab2306002a
commit 51b40cdb42
9 changed files with 726 additions and 92 deletions
+230
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//! Persistent cache of successfully sent posts.
//!
//! After a media send succeeds, the raw render data plus the Telegram
//! `file_id`s of the sent items are stored keyed by [`crate::site` cache
//! key]. A repeated link is then answered entirely from local state — no
//! re-fetch of the source site, no re-upload — and no media file is stored
//! on disk (the file ids point at Telegram's servers). Entries expire after
//! [`Config::link_cache_ttl`]; a stale entry is dropped lazily on read and
//! by the periodic prune in `main`.
use rusqlite::{params, Connection};
use serde::{Deserialize, Serialize};
use std::time::Duration;
#[derive(Serialize, Deserialize, Clone, Debug, PartialEq)]
#[serde(rename_all = "snake_case")]
pub enum CachedMediaKind {
Photo,
Video,
Animation,
}
#[derive(Serialize, Deserialize, Clone, Debug)]
pub struct CachedMedia {
pub kind: CachedMediaKind,
pub file_id: String,
}
/// Everything needed to re-send a post without touching the source site:
/// the canonical URL, pre-escaped caption fields, and the file ids produced
/// by the original successful send.
#[derive(Serialize, Deserialize, Clone, Debug)]
pub struct CachedPost {
pub url: String,
/// The site's built-in caption (used when the chat has no format
/// override).
pub caption: String,
pub title: String,
pub author: String,
pub author_url: String,
pub tags: String,
pub sensitive: bool,
pub media: Vec<CachedMedia>,
}
/// SQLite-backed cache sharing `data/task_queue.db` with the queue and chat
/// state (same `open_db` pattern: busy timeout, `spawn_blocking` I/O).
pub struct LinkCache {
db_path: String,
}
fn open_db(path: &str) -> rusqlite::Result<Connection> {
let conn = Connection::open(path)?;
conn.busy_timeout(Duration::from_secs(5))?;
Ok(conn)
}
impl LinkCache {
pub fn open(db_path: &str) -> Self {
if let Ok(conn) = Connection::open(db_path)
&& let Err(e) = conn.execute_batch(
"CREATE TABLE IF NOT EXISTS link_cache (url TEXT PRIMARY KEY, \
payload TEXT NOT NULL, created_at REAL NOT NULL);",
)
{
log::error!("failed to initialize link cache schema: {e}");
}
Self {
db_path: db_path.to_string(),
}
}
/// Returns the cached post if present and not expired; a stale entry is
/// removed on the spot.
pub async fn get(&self, key: &str, ttl: Duration) -> Option<CachedPost> {
let db_path = self.db_path.clone();
let key = key.to_string();
let ttl = ttl.as_secs_f64();
tokio::task::spawn_blocking(move || -> rusqlite::Result<Option<CachedPost>> {
let conn = open_db(&db_path)?;
let mut stmt =
conn.prepare("SELECT payload, created_at FROM link_cache WHERE url = ?1")?;
let mut rows = stmt.query(params![key])?;
let Some(row) = rows.next()? else {
return Ok(None);
};
let payload: String = row.get(0)?;
let created_at: f64 = row.get(1)?;
if now_f64() - created_at > ttl {
conn.execute("DELETE FROM link_cache WHERE url = ?1", params![key])?;
return Ok(None);
}
serde_json::from_str(&payload).map(Some).map_err(|e| {
rusqlite::Error::ToSqlConversionFailure(Box::new(e))
})
})
.await
.expect("link cache read worker panicked")
.unwrap_or_else(|e| {
log::error!("link cache read failed: {e}");
None
})
}
pub async fn put(&self, key: &str, post: &CachedPost) {
let db_path = self.db_path.clone();
let key = key.to_string();
let payload = serde_json::to_string(post).expect("cached post serializes");
tokio::task::spawn_blocking(move || -> rusqlite::Result<()> {
let conn = open_db(&db_path)?;
conn.execute(
"INSERT OR REPLACE INTO link_cache (url, payload, created_at) VALUES (?1, ?2, ?3)",
params![key, payload, now_f64()],
)?;
Ok(())
})
.await
.expect("link cache write worker panicked")
.unwrap_or_else(|e| log::error!("link cache write failed: {e}"));
}
/// Drops an entry (e.g. a cached file id that turned out invalid).
pub async fn remove(&self, key: &str) {
let db_path = self.db_path.clone();
let key = key.to_string();
tokio::task::spawn_blocking(move || -> rusqlite::Result<()> {
let conn = open_db(&db_path)?;
conn.execute("DELETE FROM link_cache WHERE url = ?1", params![key])?;
Ok(())
})
.await
.expect("link cache delete worker panicked")
.unwrap_or_else(|e| log::error!("link cache delete failed: {e}"));
}
/// Removes expired entries; returns how many were deleted.
pub async fn prune(&self, ttl: Duration) -> usize {
let db_path = self.db_path.clone();
let cutoff = now_f64() - ttl.as_secs_f64();
tokio::task::spawn_blocking(move || -> rusqlite::Result<usize> {
let conn = open_db(&db_path)?;
conn.execute(
"DELETE FROM link_cache WHERE created_at < ?1",
params![cutoff],
)
})
.await
.expect("link cache prune worker panicked")
.unwrap_or_else(|e| {
log::error!("link cache prune failed: {e}");
0
})
}
}
fn now_f64() -> f64 {
std::time::SystemTime::now()
.duration_since(std::time::UNIX_EPOCH)
.map(|d| d.as_secs_f64())
.unwrap_or(0.0)
}
#[cfg(test)]
mod tests {
use super::*;
fn entry() -> CachedPost {
CachedPost {
url: "https://x.com/u/status/1".into(),
caption: "cap".into(),
title: "t".into(),
author: "a".into(),
author_url: "au".into(),
tags: "".into(),
sensitive: true,
media: vec![CachedMedia {
kind: CachedMediaKind::Photo,
file_id: "AgAC...".into(),
}],
}
}
#[tokio::test]
async fn put_get_roundtrip() {
let dir = tempfile::tempdir().unwrap();
let cache = LinkCache::open(dir.path().join("c.db").to_str().unwrap());
cache.put("twitter:1", &entry()).await;
let got = cache.get("twitter:1", Duration::from_secs(3600)).await;
assert!(got.is_some());
let got = got.unwrap();
assert_eq!(got.url, "https://x.com/u/status/1");
assert_eq!(got.media[0].file_id, "AgAC...");
}
#[tokio::test]
async fn expired_entry_removed_on_read() {
let dir = tempfile::tempdir().unwrap();
let cache = LinkCache::open(dir.path().join("c.db").to_str().unwrap());
cache.put("twitter:1", &entry()).await;
// Force the row into the past so a 1s TTL expires it.
{
let conn = Connection::open(dir.path().join("c.db")).unwrap();
conn.execute(
"UPDATE link_cache SET created_at = created_at - 100",
[],
)
.unwrap();
}
assert!(cache.get("twitter:1", Duration::from_secs(1)).await.is_none());
assert!(cache.get("twitter:1", Duration::from_secs(3600)).await.is_none());
}
#[tokio::test]
async fn remove_and_prune() {
let dir = tempfile::tempdir().unwrap();
let cache = LinkCache::open(dir.path().join("c.db").to_str().unwrap());
cache.put("twitter:1", &entry()).await;
cache.put("pixiv:2", &entry()).await;
cache.remove("twitter:1").await;
assert!(cache.get("twitter:1", Duration::from_secs(3600)).await.is_none());
assert!(cache.get("pixiv:2", Duration::from_secs(3600)).await.is_some());
{
let conn = Connection::open(dir.path().join("c.db")).unwrap();
conn.execute("UPDATE link_cache SET created_at = created_at - 100", [])
.unwrap();
}
assert_eq!(cache.prune(Duration::from_secs(1)).await, 1);
assert!(cache.get("pixiv:2", Duration::from_secs(3600)).await.is_none());
}
}