Struct DataCache

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pub struct DataCache { /* private fields */ }

Expand description

Data cache with prefetched historical and live data buffers

The cache provides:

Async prefetch of historical data (called before execution)
Sync access to cached data (during execution)
Live data streaming via background tasks

§Thread Safety

The live buffer uses Arc<RwLock<...>> to allow concurrent reads during execution while background tasks write new bars.

Subscriptions use Arc<Mutex<...>> to allow shared ownership across clones.

Implementations§

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impl DataCache

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pub fn new(provider: SharedAsyncProvider, runtime: Handle) -> Self

Create a new data cache

§Arguments

provider - Async data provider for loading data
runtime - Tokio runtime handle for spawning background tasks

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pub async fn prefetch( &self, queries: Vec<DataQuery>, ) -> Result<(), AsyncDataError>

Prefetch historical data for given queries (async)

This loads all queries concurrently and populates the cache. Should be called before execution starts.

§Arguments

queries - List of data queries to prefetch

§Returns

Ok if all queries loaded successfully, error otherwise.

§Example

let queries = vec![
    DataQuery::new("AAPL", Timeframe::d1()).limit(1000),
    DataQuery::new("MSFT", Timeframe::d1()).limit(1000),
];
cache.prefetch(queries).await?;

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pub fn get_row( &self, id: &str, timeframe: &Timeframe, index: usize, ) -> Option<OwnedDataRow>

Get row at index (sync - reads from cache)

This is the hot path - called frequently during execution. Reads are lock-free for historical data, read-locked for live data.

§Arguments

symbol - Symbol to query
timeframe - Timeframe
index - Absolute row index

§Returns

The row if available, None otherwise.

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pub fn get_row_range( &self, id: &str, timeframe: &Timeframe, start: usize, end: usize, ) -> Vec<OwnedDataRow>

Get row range (sync - reads from cache)

§Arguments

symbol - Symbol to query
timeframe - Timeframe
start - Start index (inclusive)
end - End index (exclusive)

§Returns

Vector of rows in the range. May be shorter than requested if data unavailable.

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pub fn subscribe_live( &self, id: &str, timeframe: &Timeframe, ) -> Result<(), AsyncDataError>

Start live data subscription (spawns background task)

This subscribes to live bar updates and spawns a background task that appends new bars to the live buffer as they arrive.

§Arguments

symbol - Symbol to subscribe to
timeframe - Timeframe for bars

§Returns

Ok if subscription started, error otherwise. Returns Ok without action if already subscribed.

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pub fn unsubscribe_live(&self, symbol: &str, timeframe: &Timeframe)

Stop live data subscription

Cancels the background task and unsubscribes from the provider.

§Arguments

symbol - Symbol to unsubscribe from
timeframe - Timeframe

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pub fn row_count(&self, id: &str, timeframe: &Timeframe) -> usize

Get total row count (historical + live)

§Arguments

symbol - Symbol to query
timeframe - Timeframe

§Returns

Total number of rows available (historical + live).

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pub fn has_cached(&self, symbol: &str, timeframe: &Timeframe) -> bool

Check if data is cached

§Arguments

symbol - Symbol to check
timeframe - Timeframe to check

§Returns

true if historical data is cached for this key.

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pub fn cached_keys(&self) -> Vec<(String, Timeframe)>

Get list of cached symbols

§Returns

Vector of (symbol, timeframe) pairs that are cached.

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pub fn clear(&self)

Clear all cached data

Stops all subscriptions and clears all cached data.

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pub fn provider(&self) -> SharedAsyncProvider

Get the async provider

Returns a clone of the SharedAsyncProvider for use in other components.

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pub fn snapshot(&self, store: &SnapshotStore) -> AnyResult<DataCacheSnapshot>

Create a snapshot of the data cache (historical + live buffers).

W17-snapshot-resume surface — see ADR-006 §2.7.4 + §2.7.5.1. The DataFrame (de)serializers were deleted alongside the broader nanboxed-slot snapshot helpers. The kind-threaded replacement lands in the Phase 2c snapshot rebuild session; until then, this method returns a structured anyhow! error rather than panicking via todo!() (the strict improvement over a todo!()-driven process abort).

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