HashSize is the number of bytes in a hash.
const HashSize = 32
DebugTest is set when GODEBUG=gocachetest=1 is in the environment.
var DebugTest = false
func DefaultDir() string
DefaultDir returns the effective GOCACHE setting. It returns "off" if the cache is disabled.
func FileHash(file string) ([HashSize]byte, error)
FileHash returns the hash of the named file. It caches repeated lookups for a given file, and the cache entry for a file can be initialized using SetFileHash. The hash used by FileHash is not the same as the hash used by NewHash.
func SetFileHash(file string, sum [HashSize]byte)
SetFileHash sets the hash returned by FileHash for file.
An ActionID is a cache action key, the hash of a complete description of a repeatable computation (command line, environment variables, input file contents, executable contents).
type ActionID [HashSize]byte
func Subkey(parent ActionID, desc string) ActionID
Subkey returns an action ID corresponding to mixing a parent action ID with a string description of the subkey.
A Cache is a package cache, backed by a file system directory tree.
type Cache struct {
// contains filtered or unexported fields
}
func Default() *Cache
Default returns the default cache to use. It never returns nil.
func Open(dir string) (*Cache, error)
Open opens and returns the cache in the given directory.
It is safe for multiple processes on a single machine to use the same cache directory in a local file system simultaneously. They will coordinate using operating system file locks and may duplicate effort but will not corrupt the cache.
However, it is NOT safe for multiple processes on different machines to share a cache directory (for example, if the directory were stored in a network file system). File locking is notoriously unreliable in network file systems and may not suffice to protect the cache.
func (c *Cache) FuzzDir() string
FuzzDir returns a subdirectory within the cache for storing fuzzing data. The subdirectory may not exist.
This directory is managed by the internal/fuzz package. Files in this directory aren't removed by the 'go clean -cache' command or by Trim. They may be removed with 'go clean -fuzzcache'.
TODO(#48526): make Trim remove unused files from this directory.
func (c *Cache) Get(id ActionID) (Entry, error)
Get looks up the action ID in the cache, returning the corresponding output ID and file size, if any. Note that finding an output ID does not guarantee that the saved file for that output ID is still available.
func (c *Cache) GetBytes(id ActionID) ([]byte, Entry, error)
GetBytes looks up the action ID in the cache and returns the corresponding output bytes. GetBytes should only be used for data that can be expected to fit in memory.
func (c *Cache) GetFile(id ActionID) (file string, entry Entry, err error)
GetFile looks up the action ID in the cache and returns the name of the corresponding data file.
func (c *Cache) OutputFile(out OutputID) string
OutputFile returns the name of the cache file storing output with the given OutputID.
func (c *Cache) Put(id ActionID, file io.ReadSeeker) (OutputID, int64, error)
Put stores the given output in the cache as the output for the action ID. It may read file twice. The content of file must not change between the two passes.
func (c *Cache) PutBytes(id ActionID, data []byte) error
PutBytes stores the given bytes in the cache as the output for the action ID.
func (c *Cache) PutNoVerify(id ActionID, file io.ReadSeeker) (OutputID, int64, error)
PutNoVerify is like Put but disables the verify check when GODEBUG=goverifycache=1 is set. It is meant for data that is OK to cache but that we expect to vary slightly from run to run, like test output containing times and the like.
func (c *Cache) Trim() error
Trim removes old cache entries that are likely not to be reused.
type Entry struct {
OutputID OutputID
Size int64
Time time.Time
}
A Hash provides access to the canonical hash function used to index the cache. The current implementation uses salted SHA256, but clients must not assume this.
type Hash struct {
// contains filtered or unexported fields
}
func NewHash(name string) *Hash
NewHash returns a new Hash. The caller is expected to Write data to it and then call Sum.
func (h *Hash) Sum() [HashSize]byte
Sum returns the hash of the data written previously.
func (h *Hash) Write(b []byte) (int, error)
Write writes data to the running hash.
An OutputID is a cache output key, the hash of an output of a computation.
type OutputID [HashSize]byte