Trait DataSource 

pub trait DataSource: Send {
    // Required methods
    fn symbols(&self) -> Vec<String>;
    fn subscribe(
        &mut self,
        symbol: String,
        timeframe: Timeframe,
    ) -> Result<(), DataSourceError>;
    fn unsubscribe(&mut self, symbol: String) -> Result<(), DataSourceError>;
    fn poll(&mut self) -> Vec<DataUpdate>;
    fn fetch_historical(
        &mut self,
        request: HistoricalDataRequest,
    ) -> Result<Vec<Bar>, DataSourceError>;
    fn get_timeframe(&self, symbol: &str) -> Option<Timeframe>;

    // Provided methods
    fn supports_historical(&self) -> bool { ... }
    fn is_connected(&self) -> bool { ... }
    fn search_symbols(
        &self,
        _user_input: &str,
        _exchange: &str,
        _symbol_type: &str,
        _max_records: usize,
    ) -> Result<Vec<SymbolSearchResult>, DataSourceError> { ... }
    fn supports_symbol_search(&self) -> bool { ... }
    fn get_marks(
        &self,
        _symbol: &str,
        _from: i64,
        _to: i64,
    ) -> Result<Vec<BarMark>, DataSourceError> { ... }
    fn supports_marks(&self) -> bool { ... }
    fn get_timescale_marks(
        &self,
        _symbol: &str,
        _from: i64,
        _to: i64,
    ) -> Result<Vec<TimescaleMark>, DataSourceError> { ... }
    fn supports_timescale_marks(&self) -> bool { ... }
    fn get_server_time(&self) -> Result<i64, DataSourceError> { ... }
    fn supports_server_time(&self) -> bool { ... }
}

Data source trait – the primary integration point for feeding market data into the chart engine.

Implementors supply OHLCV bars from any source (WebSocket, REST, CSV, etc.). The chart engine calls methods on this trait to subscribe to symbols, poll for live updates, and request historical data when the user scrolls back in time.

Required methods

Method	Purpose
symbols	List available instrument identifiers
subscribe	Begin receiving live data for a symbol
unsubscribe	Stop receiving live data for a symbol
poll	Non-blocking check for new data updates
fetch_historical	Load older bars when the user scrolls left
get_timeframe	Timeframe a symbol was subscribed with

Optional capabilities

Override the supports_* / get_* method pairs to enable:

• Symbol search – typeahead search across instruments
• Bar marks – event annotations on individual bars
• Timescale marks – event annotations on the time axis
• Server time – accurate exchange clock for countdown widget

Thread safety

DataSource requires Send so it can be owned by the chart state which may be passed across threads. If your implementation wraps a connection handle that is not Send, consider using a channel-based architecture.

Required Methods

fn symbols(&self) -> Vec<String>

Returns the list of symbol identifiers available from this data source.

fn subscribe( &mut self, symbol: String, timeframe: Timeframe, ) -> Result<(), DataSourceError>

Subscribe to live updates for symbol at the given timeframe.

After subscribing, subsequent calls to poll should return DataUpdate::NewBars or DataUpdate::FullDataset for this symbol.

fn unsubscribe(&mut self, symbol: String) -> Result<(), DataSourceError>

Unsubscribe from live updates for symbol.

fn poll(&mut self) -> Vec<DataUpdate>

Non-blocking poll for data updates since the last call.

The chart engine calls this on every frame. Return an empty Vec when there is nothing new.

fn fetch_historical( &mut self, request: HistoricalDataRequest, ) -> Result<Vec<Bar>, DataSourceError>

Fetch historical bars older than the data already loaded.

Called when the user scrolls left beyond the currently loaded range. The implementation may block or use internal async machinery – the chart engine will not call this from the UI thread if it would block.

fn get_timeframe(&self, symbol: &str) -> Option<Timeframe>

Returns the timeframe the given symbol was subscribed with, or None if the symbol is not currently subscribed.

Provided Methods

fn supports_historical(&self) -> bool

Whether this data source supports fetch_historical.

Return false (default) if the data source only provides a fixed dataset.

fn is_connected(&self) -> bool

Whether the data source is currently connected and able to deliver data.

Defaults to true. Override to reflect real connection state for WebSocket / network-based sources.

fn search_symbols( &self, _user_input: &str, _exchange: &str, _symbol_type: &str, _max_records: usize, ) -> Result<Vec<SymbolSearchResult>, DataSourceError>

Search for symbols matching _user_input.

Override together with supports_symbol_search to enable the symbol-search dialog in the UI.

fn supports_symbol_search(&self) -> bool

Whether this data source supports the symbol search API.

fn get_marks( &self, _symbol: &str, _from: i64, _to: i64, ) -> Result<Vec<BarMark>, DataSourceError>

Returns event marks attached to bars in the time range [_from, _to] (Unix milliseconds).

fn supports_marks(&self) -> bool

Whether this data source provides bar marks.

fn get_timescale_marks( &self, _symbol: &str, _from: i64, _to: i64, ) -> Result<Vec<TimescaleMark>, DataSourceError>

Returns event marks on the timescale in the range [_from, _to] (Unix milliseconds).

fn supports_timescale_marks(&self) -> bool

Whether this data source provides timescale marks.

fn get_server_time(&self) -> Result<i64, DataSourceError>

Returns the exchange server time as a Unix timestamp (seconds).

Used by the countdown-to-next-bar widget. Defaults to the local system clock.

fn supports_server_time(&self) -> bool

Whether this data source provides authoritative server time.

Implementors