Vlad Zolotarov b0f660331a tracing: introduce a span ID and parent span ID ...

This patch makes the tracing framework follow the general idea of Google's
Dapper paper: traces generated in a context of the same query are forming
a single-rooted acyclic tree where in a ScyllaDB case vertexes are spans running
on each involved replica Node and edges are RPCs sent from one Node to another.

   - Each vertex in the tree above has an ID - "span ID".
   - In order to be able to build the tree from the sessions traces we need
     to know the parent "span ID" - the ID of a span that sent an RPC that created
     the current span.
   - Each span of a tracing session is given a 64-bit random span ID.
   - The root span has a span_id::illegal_id value.

This patch adds:
   - The described above parent span ID and a span ID to the one_session_records
     object.
   - The current span ID is passed in the trace_info struct to the remote replica.
   - Add parent_id and span_id columns to system_traces.events table for the parent
     ID and span ID.

Signed-off-by: Vlad Zolotarov <vladz@scylladb.com>

2017-04-25 21:52:23 -04:00

5.3 KiB

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