don't require db lock on connect / cache.get

Author: phiresky

exampledir/exif.png

@@ -1,6 +1,6 @@
 use std::{future::Future, pin::Pin};
 
-use anyhow::Result;
+use anyhow::{Context, Result};
 use async_compression::tokio::write::ZstdEncoder;
 use async_stream::stream;
 
@@ -64,7 +64,7 @@ pub fn async_read_and_write_to_cache<'a>(
         };
 
         // EOF, finish!
-        on_finish(finish).await
+        on_finish(finish).await.context("write_to_cache on_finish")
             .map_err(to_io_err)?;
 
     };

src/caching_writer.rs

@@ -151,7 +151,7 @@ async fn adapt_caching(
     let mut cache = cache.context("No cache?")?;
     let cache_key = CacheKey::new(&ai.filepath_hint, adapter.as_ref(), &active_adapters)?;
     // let dbg_ctx = format!("adapter {}", &adapter.metadata().name);
-    let cached = cache.get(&cache_key).await?;
+    let cached = cache.get(&cache_key).await.context("cache.get")?;
     match cached {
         Some(cached) => Ok(Box::pin(ZstdDecoder::new(Cursor::new(cached)))),
         None => {

src/preproc.rs

@@ -49,7 +49,7 @@ pub trait PreprocCache {
     async fn set(&mut self, key: &CacheKey, value: Vec<u8>) -> Result<()>;
 }
 
-async fn pragmas(db: &Connection) -> Result<()> {
+async fn connect_pragmas(db: &Connection) -> Result<()> {
     // https://phiresky.github.io/blog/2020/sqlite-performance-tuning/
     //let want_page_size = 32768;
     //db.execute(&format!("pragma page_size = {};", want_page_size))
@@ -63,9 +63,6 @@ async fn pragmas(db: &Connection) -> Result<()> {
     pragma synchronous = off; -- integrity isn't very important here
     pragma mmap_size = 30000000000;
 
-    pragma application_id = 924716026;
-    pragma user_version = 2; -- todo: on upgrade clear db if version is unexpected
-
     create table if not exists preproc_cache (
         adapter text not null,
         adapter_version integer not null,
@@ -80,23 +77,36 @@ async fn pragmas(db: &Connection) -> Result<()> {
     ",
         )
     })
-    .await?;
-    /*let jm: String = db
-        .call(|db| db.pragma_query_value(None, "journal_mode", |r| r.get(0))?)
+    .await.context("connect_pragmas")?;
+    let jm: i64 = db
+        .call(|db| db.pragma_query_value(None, "application_id", |r| r.get(0)))
         .await?;
-    if &jm != "wal" {
-        anyhow::bail!("journal mode is not wal");
-    }*/
+    if jm != 924716026 {
+        // (probably) newly created db
+        create_pragmas(db).await.context("create_pragmas")?;
+    }
     Ok(())
 }
 
+async fn create_pragmas(db: &Connection) -> Result<()> {
+    db.call(|db| {
+        db.execute_batch(
+            "
+        pragma application_id = 924716026;
+        pragma user_version = 2; -- todo: on upgrade clear db if version is unexpected
+        ",
+        )
+    })
+    .await?;
+    Ok(())
+}
 struct SqliteCache {
     db: Connection,
 }
 impl SqliteCache {
     async fn new(path: &Path) -> Result<SqliteCache> {
         let db = Connection::open(path.join("cache.sqlite3")).await?;
-        pragmas(&db).await?;
+        connect_pragmas(&db).await?;
 
         Ok(SqliteCache { db })
     }