read_through_cache does not cache data for list/select by query operations

[blono]

I wrote the following code to test if it can be cached with read_through_cache and read from cache with read_cached_only.

pub async fn init_db_cache(db: &FirestoreDb, cache_name: &str, collection_path: &str, parent_path: ParentPathBuilder, listener_target: u32, max_capacity: u64) -> Result<FirestoreCache<FirestoreMemoryCacheBackend, FirestoreMemListenStateStorage>, FirestoreError> {
    let conf = FirestoreCacheCollectionConfiguration::new(
        collection_path,
        FirestoreListenerTarget::new(listener_target),
        FirestoreCacheCollectionLoadMode::PreloadNone,
    ).with_parent(parent_path);

    let mut cache = FirestoreCache::new(
        cache_name.into(),
        db,
        FirestoreMemoryCacheBackend::with_max_capacity(
            FirestoreCacheConfiguration::new().add_collection_config(&db, conf),
            max_capacity
        )?,
        FirestoreMemListenStateStorage::new(),
    ).await?;

    cache.load().await?;

    Ok(cache)
}

async fn main() -> Result<()> {
    let db = FirestoreDb::new(&config_env_var("PROJECT_ID")?).await?;
    let parent_path = db.parent_path("p", "c").unwrap();
    let cache = init_db_cache(&db, "mem-cache", "mydoc", parent_path, 1000, 32 * 1024 * 1024);

    let _ = db.read_through_cache(&cache)
        .fluent()
        .list()
        .from("mydoc")
        .parent(&parent_path)
        .order_by([
            (path!(MyDoc::last_update_millis), FirestoreQueryDirection::Descending),
        ])
        .obj()
        .stream_all_with_errors()
        .await?
        .try_collect::<Vec<MyDoc>>()
        .await;

    let list = db.read_cached_only(&cache) // Should be able to get list.
        .fluent()
        .list()
        .from("mydoc")
        .parent(&parent_path)
        .order_by([
            (path!(MyDoc::last_update_millis), FirestoreQueryDirection::Descending),
        ])
        .obj()
        .stream_all_with_errors()
        .await?
        .try_collect::<Vec<MyDoc>>()
        .await;
}

I expected to be able to retrieve the list in the subsequent read_cached_only because it is cached in read_through_cache, but I could not retrieve it.

I also tested PreloadAllDocs with a different code, and it worked fine!

[abdolence]

Hey,

This is not related to parent per see, more like the cache update supports only 3 sources right now:

Described here:
https://github.com/abdolence/firestore-rs#how-a-cache-is-updated

• Reading using get by IDs
• Listener updates
• Preload

So, the results from list actually is not cached at least right now, mostly because they might be incomplete, etc. This is not implemented at least yet.
I'll think about it.

PS. Also, I recommend avoid using list for big collections, since for some reason Google doesn't like the idea with big page sizes, and this operation is slower than just select.

[abdolence]

Currently I recommend using PreloadAll if you want to work with querying/listing ready-to-use caches.

[blono]

I see and understand!
I guess I was mistaken!

[abdolence]

Let's leave the issue opened, to make it more visible and remind me about this limitation :)