go/src/runtime/metrics/sample.go

type Sample …

// Implemented in the runtime.
func runtime_readMetrics(unsafe.Pointer, int, int)

// Read populates each [Value] field in the given slice of metric samples.
//
// Desired metrics should be present in the slice with the appropriate name.
// The user of this API is encouraged to re-use the same slice between calls for
// efficiency, but is not required to do so.
//
// Note that re-use has some caveats. Notably, Values should not be read or
// manipulated while a Read with that value is outstanding; that is a data race.
// This property includes pointer-typed Values (for example, [Float64Histogram])
// whose underlying storage will be reused by Read when possible. To safely use
// such values in a concurrent setting, all data must be deep-copied.
//
// It is safe to execute multiple Read calls concurrently, but their arguments
// must share no underlying memory. When in doubt, create a new []Sample from
// scratch, which is always safe, though may be inefficient.
//
// Sample values with names not appearing in [All] will have their Value populated
// as KindBad to indicate that the name is unknown.
func Read(m []Sample) { … }