Documentation
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Overview ¶
Command gen-clientcodec generates the browser runtime's protobuf codec.
The client encodes and decodes the same gotthlive.v1.Frame the server does, but it cannot afford a general protobuf runtime: the entire client budget is 12,288 bytes gzipped, and a general runtime would consume most of it on its own. So the codec is generated for this one fixed schema — a tag table and generic encode and decode paths that interpret it, plus skipping unknown tags by wire type so a newer server cannot break an older client.
It is generated rather than hand-written because the bugs this code attracts are a wrong field number, a wrong wire type, or a field somebody forgot. This command reads the same FileDescriptorSet that drives the Go refinement generator, so the two sides cannot disagree about the wire.
Alongside the codec it emits client/predicates.manifest.txt, which lists every predicate in the schema and states whether the client enforces it. Length bounds are enforced there, because the decoder already reads a length prefix and the check costs two comparisons; numeric ranges and regular expressions are not, because a regexp engine is not in the budget. That asymmetry is a generated artifact a reviewer can read rather than an unwritten assumption, and CI fails if it drifts from the descriptors.
It also emits client/test/golden.json: frames encoded by the Go protobuf runtime, each with the value it must decode to. The JavaScript suite decodes them and re-encodes them, which is the only check that the two independent codecs agree about actual bytes rather than about intentions.
This command is contributor tooling. Its output is committed, so consumers of this module never run it.
Usage:
gen-clientcodec -descriptor_set <path> -out <dir>
Source Files