Module history

Expand description

Collecting history of request executions - retries, speculative, etc.

Structs§

AttemptHistory
AttemptId: Id of a single attempt within a request run - a single request sent on some connection.
FiberHistory
HistoryCollector: HistoryCollector can be used as HistoryListener to collect all the request history events. Each event is marked with an UTC timestamp.
HistoryCollectorData
RequestHistory
RequestId: Id of a single request, i.e. a single call to Session::{query,execute}_{unpaged,single_page}/etc.
SpeculativeId: Id of a speculative execution fiber. When speculative execution is enabled the driver will start multiple speculative threads, each of them performing sequential attempts.
StructuredHistory: Structured representation of requests history.
HistoryCollector collects raw events which later can be converted to this pretty representation.
It has a Display impl which can be used for printing pretty request history.

HistoryListener: Any type implementing this trait can be passed to Session to collect execution history of specific requests.
In order to use it call set_history_listener on Query, PreparedStatement, etc…
The listener has to generate unique IDs for new requests, attempts and speculative fibers. These ids are then used by the caller to identify them.
It’s important to note that even after a request is finished there still might come events related to it. These events come from speculative futures that didn’t notice the request is done already.