gotools/internal/modindex/modindex.go

// Create always creates a new index for the go module cache that is in cachedir.
func Create(cachedir string) error { … }

// Update the index for the go module cache that is in cachedir,
// If there is no existing index it will build one.
// If there are changed directories since the last index, it will
// write a new one and return true. Otherwise it returns false.
func Update(cachedir string) (bool, error) { … }

// indexModCache writes an index current as of when it is called.
// If clear is true the index is constructed from all of GOMODCACHE
// otherwise the index is constructed from the last previous index
// and the updates to the cache. It returns true if it wrote an index,
// false otherwise.
func indexModCache(cachedir string, clear bool) (bool, error) { … }

// modindexTimed writes an index current as of onlyBefore.
// If clear is true the index is constructed from all of GOMODCACHE
// otherwise the index is constructed from the last previous index
// and all the updates to the cache before onlyBefore.
// It returns true if it wrote a new index, false if it wrote nothing.
func modindexTimed(onlyBefore time.Time, cachedir Abspath, clear bool) (bool, error) { … }

type work …

func (w *work) buildIndex() error { … }

func (w *work) writeIndex() error { … }