AddHeaders parse headers like "a: b" and add them to exist header.

CollectLog collects logs.

DirSize returns the total file size of a dir.

FlatMap iterate all map element with the given tagPath, return a slice contain all visited elements.

MustCmpDuration return 0, -1, 1; 0 left == right, 1 left > right, -1 left < right Only use this method in gengine.

MustCmpReadableSize return 0, -1, 1; 0 left == right, 1 left > right, -1 left < right Only use this method in gengine.

NewTokenLimiter creates a TokenLimiter with count tokens.

ParseReadableDuration is copied from prometheus ParseDuration function.

ParseTime converts a string to time.Time, ported from Prometheus: web/api/v1/api.go.

TrimLeftSpace trim all left space.

ValueToString return the parsed string value for other type.

Token is used as a permission to keep on running.

TokenLimiter is used to limit the number of concurrent tasks.