feat: meaningful comments for internal packages

internal/performance/tracker.go

@@ -1,3 +1,5 @@
+// Package "performance" provides a tracker to observer CPU performance during
+// execution.
 package performance
 
 import (
@@ -6,16 +8,20 @@ import (
 	"runtime/pprof"
 )
 
+// Observes a reduction process, and publishes a CPU performance profile on
+// completion.
 type Tracker struct {
 	File        string
 	filePointer *os.File
 	Error       error
 }
 
+// Create a performance tracker that outputs a profile to "file".
 func Track(file string) *Tracker {
 	return &Tracker{File: file}
 }
 
+// Begin profiling.
 func (t *Tracker) Start() {
 	var absPath string
 
@@ -40,6 +46,7 @@ func (t *Tracker) Start() {
 	}
 }
 
+// Stop profiling.
 func (t *Tracker) End() {
 	pprof.StopCPUProfile()
 	t.filePointer.Close()