Changes made:
* Avoid "encoding/json" for JSON processing, and instead use
"github.com/go-json-experiment/json/jsontext".
Use jsontext.Value.IsValid for validation, which is much faster.
Use jsontext.AppendQuote instead of our own JSON escaping.
* In drainPending, use a different maxLen depending on lowMem.
In lowMem mode, it is better to perform multiple uploads
than it is to construct a large body that OOMs the process.
* In drainPending, if an error is encountered draining,
construct an error message in the logtail JSON format
rather than something that is invalid JSON.
* In appendTextOrJSONLocked, use jsontext.Decoder to check
whether the input is a valid JSON object. This is faster than
the previous approach of unmarshaling into map[string]any and
then re-marshaling that data structure.
This is especially beneficial for network flow logging,
which produces relatively large JSON objects.
* In appendTextOrJSONLocked, enforce maxSize on the input.
If too large, then we may end up in a situation where the logs
can never be uploaded because it exceeds the maximum body size
that the Tailscale logs service accepts.
* Use "tailscale.com/util/truncate" to properly truncate a string
on valid UTF-8 boundaries.
* In general, remove unnecessary spaces in JSON output.
Performance:
name old time/op new time/op delta
WriteText 776ns ± 2% 596ns ± 1% -23.24% (p=0.000 n=10+10)
WriteJSON 110µs ± 0% 9µs ± 0% -91.77% (p=0.000 n=8+8)
name old alloc/op new alloc/op delta
WriteText 448B ± 0% 0B -100.00% (p=0.000 n=10+10)
WriteJSON 37.9kB ± 0% 0.0kB ± 0% -99.87% (p=0.000 n=10+10)
name old allocs/op new allocs/op delta
WriteText 1.00 ± 0% 0.00 -100.00% (p=0.000 n=10+10)
WriteJSON 1.08k ± 0% 0.00k ± 0% -99.91% (p=0.000 n=10+10)
For text payloads, this is 1.30x faster.
For JSON payloads, this is 12.2x faster.
Updates #cleanup
Updates tailscale/corp#18514
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
7a77a2edf1