diff options
| -rw-r--r-- | src/bootstrap/metrics.rs | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/src/bootstrap/metrics.rs b/src/bootstrap/metrics.rs index 405a88d7568..5990f33b9bc 100644 --- a/src/bootstrap/metrics.rs +++ b/src/bootstrap/metrics.rs @@ -16,9 +16,21 @@ use sysinfo::{CpuExt, System, SystemExt}; // Update this number whenever a breaking change is made to the build metrics. // -// Versions: -// 0: initial version -// 1: replaced JsonNode::Test with JsonNode::TestSuite +// The output format is versioned for two reasons: +// +// - The metadata is intended to be consumed by external tooling, and exposing a format version +// helps the tools determine whether they're compatible with a metrics file. +// +// - If a developer enables build metrics in their local checkout, making a breaking change to the +// metrics format would result in a hard-to-diagnose error message when an existing metrics file +// is not compatible with the new changes. With a format version number, bootstrap can discard +// incompatible metrics files instead of appending metrics to them. +// +// Version changelog: +// +// - v0: initial version +// - v1: replaced JsonNode::Test with JsonNode::TestSuite +// const CURRENT_FORMAT_VERSION: usize = 1; pub(crate) struct BuildMetrics { |