Files
postgrest/src/PostgREST/Response/Performance.hs
T
steve-chavez 4d35eb02e7 fix: inaccurate Server-Timing durations
The transaction duration was notably off, doing:

```
curl localhost:3000/rpc/sleep?seconds=5 -i
```

Shows `46.1` for the `transaction;dur`, with this fix we obtain
`5007.3`.

Fixes https://github.com/PostgREST/postgrest/issues/4522

This also fixes inaccurate "schema cache queried" logs,
see https://github.com/PostgREST/postgrest/issues/4551.

(cherry picked from commit 013f078bc4)
2025-12-18 18:18:09 -05:00

39 lines
1.3 KiB
Haskell

module PostgREST.Response.Performance
( ServerTiming (..)
, serverTimingHeader
)
where
import qualified Data.ByteString.Char8 as BS
import qualified Network.HTTP.Types as HTTP
import Numeric (showFFloat)
import Protolude
-- | ServerTiming represents the timing data for a request, in seconds.
data ServerTiming =
ServerTiming
{ jwt :: Maybe Double
, parse :: Maybe Double
, plan :: Maybe Double
, transaction :: Maybe Double
, response :: Maybe Double
}
deriving (Show)
-- | Render the Server-Timing header from a ServerTimingData
-- The duration precision is milliseconds, per the docs
--
-- >>> serverTimingHeader ServerTiming { plan=Just 0.1, transaction=Just 0.2, response=Just 0.3, jwt=Just 0.4, parse=Just 0.5}
-- ("Server-Timing","jwt;dur=0.4, parse;dur=0.5, plan;dur=0.1, transaction;dur=0.2, response;dur=0.3")
serverTimingHeader :: ServerTiming -> HTTP.Header
serverTimingHeader timing =
("Server-Timing", renderTiming)
where
renderMetric metric = maybe "" (\dur -> BS.concat [metric, BS.pack $ ";dur=" <> showFFloat (Just 1) dur ""])
renderTiming = BS.intercalate ", " $ (\(k, v) -> renderMetric k (v timing)) <$>
[ ("jwt", jwt)
, ("parse", parse)
, ("plan", plan)
, ("transaction", transaction)
, ("response", response)
]