This adds support for having every viewer type implement
jsonv2.MarshalerTo and jsonv2.UnmarshalerFrom.
This provides a significant boost in performance
as the json package no longer needs to validate
the entirety of the JSON value outputted by MarshalJSON,
nor does it need to identify the boundaries of a JSON value
in order to call UnmarshalJSON.
For deeply nested and recursive MarshalJSON or UnmarshalJSON calls,
this can improve runtime from O(N²) to O(N).
This still references "github.com/go-json-experiment/json"
instead of the experimental "encoding/json/v2" package
now available in Go 1.25 under goexperiment.jsonv2
so that code still builds without the experiment tag.
Of note, the "github.com/go-json-experiment/json" package
aliases the standard library under the right build conditions.
Updates tailscale/corp#791
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Joe Tsai
fbb91758ac