mirror of
https://github.com/hasura/graphql-engine.git
synced 2024-12-15 09:22:43 +03:00
bb8f6a76cc
[PLAT-438](https://hasurahq.atlassian.net/browse/PLAT-438) After this change the top level trace is is annotated with `request_id` and `parameterized_query_hash`. It looks like this, in jeager:  bulk queries should output a separate `parameterized_query_hash` for each query span ...after the last two commits, things look like this (remove pointless spans, more attributes):  [PLAT-438]: https://hasurahq.atlassian.net/browse/PLAT-438?atlOrigin=eyJpIjoiNWRkNTljNzYxNjVmNDY3MDlhMDU5Y2ZhYzA5YTRkZjUiLCJwIjoiZ2l0aHViLWNvbS1KU1cifQ PR-URL: https://github.com/hasura/graphql-engine-mono/pull/8824 GitOrigin-RevId: 0fd105c879161587d41b729b9bac968e92efae95
84 lines
3.0 KiB
Haskell
84 lines
3.0 KiB
Haskell
module Hasura.Tracing (module Tracing) where
|
|
|
|
import Hasura.Tracing.Class as Tracing
|
|
import Hasura.Tracing.Context as Tracing
|
|
import Hasura.Tracing.Monad as Tracing
|
|
import Hasura.Tracing.Reporter as Tracing
|
|
import Hasura.Tracing.Sampling as Tracing
|
|
import Hasura.Tracing.TraceId as Tracing
|
|
import Hasura.Tracing.Utils as Tracing
|
|
|
|
{- Note [Tracing]
|
|
|
|
\## Usage
|
|
|
|
The Tracing library allows us to trace arbitrary pieces of our code, providing
|
|
that the current monad implements 'MonadTrace'.
|
|
|
|
newTrace "request" do
|
|
userInfo <- newSpan "authentication" retrieveUserInfo
|
|
parsedQuery <- newSpan "parsing" $ parseQuery q
|
|
result <- newSpan "execution" $ runQuery parsedQuery userInfo
|
|
pure result
|
|
|
|
\## Trace and span
|
|
|
|
Each _trace_ is distinct, and is composed of one or more _spans_. Spans are
|
|
organized as a tree: the root span covers the entire trace, and each sub span
|
|
keeps track of its parent.
|
|
|
|
We report each span individually, and to each of them we associate a
|
|
'TraceContext', that contains:
|
|
- a trace id, common to all the spans of that trace
|
|
- a unique span id, generated randomly
|
|
- the span id of the parent span, if any
|
|
- whether that trace was sampled (see "Sampling").
|
|
|
|
All of this can be retrieved for the current span with 'currentContext'.
|
|
|
|
Starting a new trace masks the previous one; in the following example, "span2"
|
|
is associated to "trace2" and "span1" is associated to "trace1"; the two trees
|
|
are distinct:
|
|
|
|
newTrace "trace1" $
|
|
newSpan "span1" $
|
|
newTrace "trace2" $
|
|
newSpan "span2"
|
|
|
|
Lastly, a span that is started outside of a root trace is, for now, silently
|
|
ignored, as it has no trace id to attach to. This is a design decision we may
|
|
revisit.
|
|
|
|
\## Metadata
|
|
|
|
Metadata can be attached to the current span with 'attachMetadata', as a list
|
|
of pair of text key and text values.
|
|
|
|
\## Reporters
|
|
|
|
'TraceT' is the de-facto implementation of 'MonadTrace'; but, in practice, it
|
|
only does half the job: once a span finishes, 'TraceT' delegates the job of
|
|
actually reporting / exporting all relevant information to a 'Reporter'. Said
|
|
reporter must be provided to 'runTraceT', and is a wrapper around a function in
|
|
IO that processes the span.
|
|
|
|
In practice, 'TraceT' is only a reader that keeps track of the reporter, the
|
|
default sampling policy, and the current trace.
|
|
|
|
\## Sampling
|
|
|
|
To run 'TraceT', you must also provide a 'SamplingPolicy': an IO action that,
|
|
when evaluated, will decide whether an arbitrary trace should be reporter or
|
|
not. This decision is only made once per trace: every span within a trace will
|
|
use the same result: they're either all reporter, or none of them are.
|
|
|
|
When starting a trace, the default sampling policy can be overriden. You can for
|
|
instance run 'TraceT' with an action that, by default, only reports one out of
|
|
every ten traces, but use 'newTraceWithPolicy sampleAlways' when sending
|
|
critical requests to your authentication service.
|
|
|
|
Note that sampling and reporting are distinct: using 'sampleAlways' simply
|
|
guarantees that the 'Reporter' you provided will be called.
|
|
|
|
-}
|