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Refactor make trace conversion more explicit
And move them to the telemetry package as an extension trait
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,88 @@ | ||
| use std::collections::HashMap; | ||
|
|
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| pub trait TxTraceExt { | ||
| fn into_trace_id(self) -> opentelemetry::trace::TraceId; | ||
| fn into_trace_context(self) -> opentelemetry::Context; | ||
| fn as_traceparent(&self) -> String; | ||
| } | ||
|
|
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| impl TxTraceExt for crate::TxId { | ||
| // in order to convert a TxId (a 48 bytes cuid) into a TraceId (16 bytes), we remove the first byte, | ||
| // (always 'c') and get the next 16 bytes, which are random enough to be used as a trace id. | ||
| // this is a typical cuid: "c-lct0q6ma-0004-rb04-h6en1roa" | ||
| // | ||
| // - first letter is always the same | ||
| // - next 7-8 byte are random a timestamp. There's more entropy in the least significative bytes | ||
| // - next 4 bytes are a counter since the server started | ||
| // - next 4 bytes are a system fingerprint, invariant for the same server instance | ||
| // - least significative 8 bytes. Totally random. | ||
| // | ||
| // We want the most entropic slice of 16 bytes that's deterministicly determined | ||
| fn into_trace_id(self) -> opentelemetry::trace::TraceId { | ||
| let mut buffer = [0; 16]; | ||
| let str = self.to_string(); | ||
| let tx_id_bytes = str.as_bytes(); | ||
| let len = tx_id_bytes.len(); | ||
|
|
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| // bytes [len-20 to len-12): least significative 4 bytes of the timestamp + 4 bytes counter | ||
| for (i, source_idx) in (len - 20..len - 12).enumerate() { | ||
| buffer[i] = tx_id_bytes[source_idx]; | ||
| } | ||
| // bytes [len-8 to len): the random blocks | ||
| for (i, source_idx) in (len - 8..len).enumerate() { | ||
| buffer[i + 8] = tx_id_bytes[source_idx]; | ||
| } | ||
|
|
||
| opentelemetry::trace::TraceId::from_bytes(buffer) | ||
| } | ||
| // This is a bit of a hack, but it's the only way to have a default trace span for a whole | ||
| // transaction when no traceparent is propagated from the client. | ||
| // | ||
| // This is done so we can capture traces happening accross the different queries in a | ||
| // transaction. Otherwise, if a traceparent is not propagated from the client, each query in | ||
| // the transaction will run within a span that has already been generated at the begining of the | ||
| // transaction, and held active in the actor in charge of running the queries. Thus, making | ||
| // impossible to capture traces happening in the individual queries, as they won't be aware of | ||
| // the transaction they are part of. | ||
| // | ||
| // By generating this "fake" traceparent based on the transaction id, we can have a common | ||
| // trace_id for all transaction operations. | ||
| fn into_trace_context(self) -> opentelemetry::Context { | ||
| let extractor: HashMap<String, String> = | ||
| HashMap::from_iter(vec![("traceparent".to_string(), self.as_traceparent())]); | ||
| opentelemetry::global::get_text_map_propagator(|propagator| propagator.extract(&extractor)) | ||
| } | ||
|
|
||
| fn as_traceparent(&self) -> String { | ||
| let trace_id = self.clone().into_trace_id(); | ||
| format!("00-{}-0000000000000001-01", trace_id) | ||
| } | ||
| } | ||
|
|
||
| // tests for txid into traits | ||
| #[cfg(test)] | ||
| mod test { | ||
| use super::*; | ||
| use crate::TxId; | ||
|
|
||
| #[test] | ||
| fn test_txid_into_traceid() { | ||
| let fixture = vec![ | ||
| ("clct0q6ma0000rb04768tiqbj", "71366d6130303030373638746971626a"), | ||
| // counter changed, trace id changed: | ||
| ("clct0q6ma0002rb04cpa6zkmx", "71366d6130303032637061367a6b6d78"), | ||
| // fingerprint changed, trace id did not change, as that chunk is ignored: | ||
| ("clct0q6ma00020000cpa6zkmx", "71366d6130303032637061367a6b6d78"), | ||
| // first 5 bytes changed, trace id did not change, as that chunk is ignored: | ||
| ("00000q6ma00020000cpa6zkmx", "71366d6130303032637061367a6b6d78"), | ||
| // 6 th byte changed, trace id changed, as that chunk is part of the lsb of the timestamp | ||
| ("0000006ma00020000cpa6zkmx", "30366d6130303032637061367a6b6d78"), | ||
| ]; | ||
|
|
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| for (txid, expected_trace_id) in fixture { | ||
| let txid: TxId = txid.into(); | ||
| let trace_id: opentelemetry::trace::TraceId = txid.into_trace_id(); | ||
| assert_eq!(trace_id.to_string(), expected_trace_id); | ||
| } | ||
| } | ||
| } |
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