Dependencies for the affinity router and the
affinity routing daemon.
Change-Id: Icda72c3594ef7f8f0bc0c33dc03087a4c25529ca
diff --git a/vendor/github.com/peterbourgon/diskv/diskv.go b/vendor/github.com/peterbourgon/diskv/diskv.go
new file mode 100644
index 0000000..524dc0a
--- /dev/null
+++ b/vendor/github.com/peterbourgon/diskv/diskv.go
@@ -0,0 +1,624 @@
+// Diskv (disk-vee) is a simple, persistent, key-value store.
+// It stores all data flatly on the filesystem.
+
+package diskv
+
+import (
+ "bytes"
+ "errors"
+ "fmt"
+ "io"
+ "io/ioutil"
+ "os"
+ "path/filepath"
+ "strings"
+ "sync"
+ "syscall"
+)
+
+const (
+ defaultBasePath = "diskv"
+ defaultFilePerm os.FileMode = 0666
+ defaultPathPerm os.FileMode = 0777
+)
+
+var (
+ defaultTransform = func(s string) []string { return []string{} }
+ errCanceled = errors.New("canceled")
+ errEmptyKey = errors.New("empty key")
+ errBadKey = errors.New("bad key")
+ errImportDirectory = errors.New("can't import a directory")
+)
+
+// TransformFunction transforms a key into a slice of strings, with each
+// element in the slice representing a directory in the file path where the
+// key's entry will eventually be stored.
+//
+// For example, if TransformFunc transforms "abcdef" to ["ab", "cde", "f"],
+// the final location of the data file will be <basedir>/ab/cde/f/abcdef
+type TransformFunction func(s string) []string
+
+// Options define a set of properties that dictate Diskv behavior.
+// All values are optional.
+type Options struct {
+ BasePath string
+ Transform TransformFunction
+ CacheSizeMax uint64 // bytes
+ PathPerm os.FileMode
+ FilePerm os.FileMode
+ // If TempDir is set, it will enable filesystem atomic writes by
+ // writing temporary files to that location before being moved
+ // to BasePath.
+ // Note that TempDir MUST be on the same device/partition as
+ // BasePath.
+ TempDir string
+
+ Index Index
+ IndexLess LessFunction
+
+ Compression Compression
+}
+
+// Diskv implements the Diskv interface. You shouldn't construct Diskv
+// structures directly; instead, use the New constructor.
+type Diskv struct {
+ Options
+ mu sync.RWMutex
+ cache map[string][]byte
+ cacheSize uint64
+}
+
+// New returns an initialized Diskv structure, ready to use.
+// If the path identified by baseDir already contains data,
+// it will be accessible, but not yet cached.
+func New(o Options) *Diskv {
+ if o.BasePath == "" {
+ o.BasePath = defaultBasePath
+ }
+ if o.Transform == nil {
+ o.Transform = defaultTransform
+ }
+ if o.PathPerm == 0 {
+ o.PathPerm = defaultPathPerm
+ }
+ if o.FilePerm == 0 {
+ o.FilePerm = defaultFilePerm
+ }
+
+ d := &Diskv{
+ Options: o,
+ cache: map[string][]byte{},
+ cacheSize: 0,
+ }
+
+ if d.Index != nil && d.IndexLess != nil {
+ d.Index.Initialize(d.IndexLess, d.Keys(nil))
+ }
+
+ return d
+}
+
+// Write synchronously writes the key-value pair to disk, making it immediately
+// available for reads. Write relies on the filesystem to perform an eventual
+// sync to physical media. If you need stronger guarantees, see WriteStream.
+func (d *Diskv) Write(key string, val []byte) error {
+ return d.WriteStream(key, bytes.NewBuffer(val), false)
+}
+
+// WriteStream writes the data represented by the io.Reader to the disk, under
+// the provided key. If sync is true, WriteStream performs an explicit sync on
+// the file as soon as it's written.
+//
+// bytes.Buffer provides io.Reader semantics for basic data types.
+func (d *Diskv) WriteStream(key string, r io.Reader, sync bool) error {
+ if len(key) <= 0 {
+ return errEmptyKey
+ }
+
+ d.mu.Lock()
+ defer d.mu.Unlock()
+
+ return d.writeStreamWithLock(key, r, sync)
+}
+
+// createKeyFileWithLock either creates the key file directly, or
+// creates a temporary file in TempDir if it is set.
+func (d *Diskv) createKeyFileWithLock(key string) (*os.File, error) {
+ if d.TempDir != "" {
+ if err := os.MkdirAll(d.TempDir, d.PathPerm); err != nil {
+ return nil, fmt.Errorf("temp mkdir: %s", err)
+ }
+ f, err := ioutil.TempFile(d.TempDir, "")
+ if err != nil {
+ return nil, fmt.Errorf("temp file: %s", err)
+ }
+
+ if err := f.Chmod(d.FilePerm); err != nil {
+ f.Close() // error deliberately ignored
+ os.Remove(f.Name()) // error deliberately ignored
+ return nil, fmt.Errorf("chmod: %s", err)
+ }
+ return f, nil
+ }
+
+ mode := os.O_WRONLY | os.O_CREATE | os.O_TRUNC // overwrite if exists
+ f, err := os.OpenFile(d.completeFilename(key), mode, d.FilePerm)
+ if err != nil {
+ return nil, fmt.Errorf("open file: %s", err)
+ }
+ return f, nil
+}
+
+// writeStream does no input validation checking.
+func (d *Diskv) writeStreamWithLock(key string, r io.Reader, sync bool) error {
+ if err := d.ensurePathWithLock(key); err != nil {
+ return fmt.Errorf("ensure path: %s", err)
+ }
+
+ f, err := d.createKeyFileWithLock(key)
+ if err != nil {
+ return fmt.Errorf("create key file: %s", err)
+ }
+
+ wc := io.WriteCloser(&nopWriteCloser{f})
+ if d.Compression != nil {
+ wc, err = d.Compression.Writer(f)
+ if err != nil {
+ f.Close() // error deliberately ignored
+ os.Remove(f.Name()) // error deliberately ignored
+ return fmt.Errorf("compression writer: %s", err)
+ }
+ }
+
+ if _, err := io.Copy(wc, r); err != nil {
+ f.Close() // error deliberately ignored
+ os.Remove(f.Name()) // error deliberately ignored
+ return fmt.Errorf("i/o copy: %s", err)
+ }
+
+ if err := wc.Close(); err != nil {
+ f.Close() // error deliberately ignored
+ os.Remove(f.Name()) // error deliberately ignored
+ return fmt.Errorf("compression close: %s", err)
+ }
+
+ if sync {
+ if err := f.Sync(); err != nil {
+ f.Close() // error deliberately ignored
+ os.Remove(f.Name()) // error deliberately ignored
+ return fmt.Errorf("file sync: %s", err)
+ }
+ }
+
+ if err := f.Close(); err != nil {
+ return fmt.Errorf("file close: %s", err)
+ }
+
+ if f.Name() != d.completeFilename(key) {
+ if err := os.Rename(f.Name(), d.completeFilename(key)); err != nil {
+ os.Remove(f.Name()) // error deliberately ignored
+ return fmt.Errorf("rename: %s", err)
+ }
+ }
+
+ if d.Index != nil {
+ d.Index.Insert(key)
+ }
+
+ d.bustCacheWithLock(key) // cache only on read
+
+ return nil
+}
+
+// Import imports the source file into diskv under the destination key. If the
+// destination key already exists, it's overwritten. If move is true, the
+// source file is removed after a successful import.
+func (d *Diskv) Import(srcFilename, dstKey string, move bool) (err error) {
+ if dstKey == "" {
+ return errEmptyKey
+ }
+
+ if fi, err := os.Stat(srcFilename); err != nil {
+ return err
+ } else if fi.IsDir() {
+ return errImportDirectory
+ }
+
+ d.mu.Lock()
+ defer d.mu.Unlock()
+
+ if err := d.ensurePathWithLock(dstKey); err != nil {
+ return fmt.Errorf("ensure path: %s", err)
+ }
+
+ if move {
+ if err := syscall.Rename(srcFilename, d.completeFilename(dstKey)); err == nil {
+ d.bustCacheWithLock(dstKey)
+ return nil
+ } else if err != syscall.EXDEV {
+ // If it failed due to being on a different device, fall back to copying
+ return err
+ }
+ }
+
+ f, err := os.Open(srcFilename)
+ if err != nil {
+ return err
+ }
+ defer f.Close()
+ err = d.writeStreamWithLock(dstKey, f, false)
+ if err == nil && move {
+ err = os.Remove(srcFilename)
+ }
+ return err
+}
+
+// Read reads the key and returns the value.
+// If the key is available in the cache, Read won't touch the disk.
+// If the key is not in the cache, Read will have the side-effect of
+// lazily caching the value.
+func (d *Diskv) Read(key string) ([]byte, error) {
+ rc, err := d.ReadStream(key, false)
+ if err != nil {
+ return []byte{}, err
+ }
+ defer rc.Close()
+ return ioutil.ReadAll(rc)
+}
+
+// ReadStream reads the key and returns the value (data) as an io.ReadCloser.
+// If the value is cached from a previous read, and direct is false,
+// ReadStream will use the cached value. Otherwise, it will return a handle to
+// the file on disk, and cache the data on read.
+//
+// If direct is true, ReadStream will lazily delete any cached value for the
+// key, and return a direct handle to the file on disk.
+//
+// If compression is enabled, ReadStream taps into the io.Reader stream prior
+// to decompression, and caches the compressed data.
+func (d *Diskv) ReadStream(key string, direct bool) (io.ReadCloser, error) {
+ d.mu.RLock()
+ defer d.mu.RUnlock()
+
+ if val, ok := d.cache[key]; ok {
+ if !direct {
+ buf := bytes.NewBuffer(val)
+ if d.Compression != nil {
+ return d.Compression.Reader(buf)
+ }
+ return ioutil.NopCloser(buf), nil
+ }
+
+ go func() {
+ d.mu.Lock()
+ defer d.mu.Unlock()
+ d.uncacheWithLock(key, uint64(len(val)))
+ }()
+ }
+
+ return d.readWithRLock(key)
+}
+
+// read ignores the cache, and returns an io.ReadCloser representing the
+// decompressed data for the given key, streamed from the disk. Clients should
+// acquire a read lock on the Diskv and check the cache themselves before
+// calling read.
+func (d *Diskv) readWithRLock(key string) (io.ReadCloser, error) {
+ filename := d.completeFilename(key)
+
+ fi, err := os.Stat(filename)
+ if err != nil {
+ return nil, err
+ }
+ if fi.IsDir() {
+ return nil, os.ErrNotExist
+ }
+
+ f, err := os.Open(filename)
+ if err != nil {
+ return nil, err
+ }
+
+ var r io.Reader
+ if d.CacheSizeMax > 0 {
+ r = newSiphon(f, d, key)
+ } else {
+ r = &closingReader{f}
+ }
+
+ var rc = io.ReadCloser(ioutil.NopCloser(r))
+ if d.Compression != nil {
+ rc, err = d.Compression.Reader(r)
+ if err != nil {
+ return nil, err
+ }
+ }
+
+ return rc, nil
+}
+
+// closingReader provides a Reader that automatically closes the
+// embedded ReadCloser when it reaches EOF
+type closingReader struct {
+ rc io.ReadCloser
+}
+
+func (cr closingReader) Read(p []byte) (int, error) {
+ n, err := cr.rc.Read(p)
+ if err == io.EOF {
+ if closeErr := cr.rc.Close(); closeErr != nil {
+ return n, closeErr // close must succeed for Read to succeed
+ }
+ }
+ return n, err
+}
+
+// siphon is like a TeeReader: it copies all data read through it to an
+// internal buffer, and moves that buffer to the cache at EOF.
+type siphon struct {
+ f *os.File
+ d *Diskv
+ key string
+ buf *bytes.Buffer
+}
+
+// newSiphon constructs a siphoning reader that represents the passed file.
+// When a successful series of reads ends in an EOF, the siphon will write
+// the buffered data to Diskv's cache under the given key.
+func newSiphon(f *os.File, d *Diskv, key string) io.Reader {
+ return &siphon{
+ f: f,
+ d: d,
+ key: key,
+ buf: &bytes.Buffer{},
+ }
+}
+
+// Read implements the io.Reader interface for siphon.
+func (s *siphon) Read(p []byte) (int, error) {
+ n, err := s.f.Read(p)
+
+ if err == nil {
+ return s.buf.Write(p[0:n]) // Write must succeed for Read to succeed
+ }
+
+ if err == io.EOF {
+ s.d.cacheWithoutLock(s.key, s.buf.Bytes()) // cache may fail
+ if closeErr := s.f.Close(); closeErr != nil {
+ return n, closeErr // close must succeed for Read to succeed
+ }
+ return n, err
+ }
+
+ return n, err
+}
+
+// Erase synchronously erases the given key from the disk and the cache.
+func (d *Diskv) Erase(key string) error {
+ d.mu.Lock()
+ defer d.mu.Unlock()
+
+ d.bustCacheWithLock(key)
+
+ // erase from index
+ if d.Index != nil {
+ d.Index.Delete(key)
+ }
+
+ // erase from disk
+ filename := d.completeFilename(key)
+ if s, err := os.Stat(filename); err == nil {
+ if s.IsDir() {
+ return errBadKey
+ }
+ if err = os.Remove(filename); err != nil {
+ return err
+ }
+ } else {
+ // Return err as-is so caller can do os.IsNotExist(err).
+ return err
+ }
+
+ // clean up and return
+ d.pruneDirsWithLock(key)
+ return nil
+}
+
+// EraseAll will delete all of the data from the store, both in the cache and on
+// the disk. Note that EraseAll doesn't distinguish diskv-related data from non-
+// diskv-related data. Care should be taken to always specify a diskv base
+// directory that is exclusively for diskv data.
+func (d *Diskv) EraseAll() error {
+ d.mu.Lock()
+ defer d.mu.Unlock()
+ d.cache = make(map[string][]byte)
+ d.cacheSize = 0
+ if d.TempDir != "" {
+ os.RemoveAll(d.TempDir) // errors ignored
+ }
+ return os.RemoveAll(d.BasePath)
+}
+
+// Has returns true if the given key exists.
+func (d *Diskv) Has(key string) bool {
+ d.mu.Lock()
+ defer d.mu.Unlock()
+
+ if _, ok := d.cache[key]; ok {
+ return true
+ }
+
+ filename := d.completeFilename(key)
+ s, err := os.Stat(filename)
+ if err != nil {
+ return false
+ }
+ if s.IsDir() {
+ return false
+ }
+
+ return true
+}
+
+// Keys returns a channel that will yield every key accessible by the store,
+// in undefined order. If a cancel channel is provided, closing it will
+// terminate and close the keys channel.
+func (d *Diskv) Keys(cancel <-chan struct{}) <-chan string {
+ return d.KeysPrefix("", cancel)
+}
+
+// KeysPrefix returns a channel that will yield every key accessible by the
+// store with the given prefix, in undefined order. If a cancel channel is
+// provided, closing it will terminate and close the keys channel. If the
+// provided prefix is the empty string, all keys will be yielded.
+func (d *Diskv) KeysPrefix(prefix string, cancel <-chan struct{}) <-chan string {
+ var prepath string
+ if prefix == "" {
+ prepath = d.BasePath
+ } else {
+ prepath = d.pathFor(prefix)
+ }
+ c := make(chan string)
+ go func() {
+ filepath.Walk(prepath, walker(c, prefix, cancel))
+ close(c)
+ }()
+ return c
+}
+
+// walker returns a function which satisfies the filepath.WalkFunc interface.
+// It sends every non-directory file entry down the channel c.
+func walker(c chan<- string, prefix string, cancel <-chan struct{}) filepath.WalkFunc {
+ return func(path string, info os.FileInfo, err error) error {
+ if err != nil {
+ return err
+ }
+
+ if info.IsDir() || !strings.HasPrefix(info.Name(), prefix) {
+ return nil // "pass"
+ }
+
+ select {
+ case c <- info.Name():
+ case <-cancel:
+ return errCanceled
+ }
+
+ return nil
+ }
+}
+
+// pathFor returns the absolute path for location on the filesystem where the
+// data for the given key will be stored.
+func (d *Diskv) pathFor(key string) string {
+ return filepath.Join(d.BasePath, filepath.Join(d.Transform(key)...))
+}
+
+// ensurePathWithLock is a helper function that generates all necessary
+// directories on the filesystem for the given key.
+func (d *Diskv) ensurePathWithLock(key string) error {
+ return os.MkdirAll(d.pathFor(key), d.PathPerm)
+}
+
+// completeFilename returns the absolute path to the file for the given key.
+func (d *Diskv) completeFilename(key string) string {
+ return filepath.Join(d.pathFor(key), key)
+}
+
+// cacheWithLock attempts to cache the given key-value pair in the store's
+// cache. It can fail if the value is larger than the cache's maximum size.
+func (d *Diskv) cacheWithLock(key string, val []byte) error {
+ valueSize := uint64(len(val))
+ if err := d.ensureCacheSpaceWithLock(valueSize); err != nil {
+ return fmt.Errorf("%s; not caching", err)
+ }
+
+ // be very strict about memory guarantees
+ if (d.cacheSize + valueSize) > d.CacheSizeMax {
+ panic(fmt.Sprintf("failed to make room for value (%d/%d)", valueSize, d.CacheSizeMax))
+ }
+
+ d.cache[key] = val
+ d.cacheSize += valueSize
+ return nil
+}
+
+// cacheWithoutLock acquires the store's (write) mutex and calls cacheWithLock.
+func (d *Diskv) cacheWithoutLock(key string, val []byte) error {
+ d.mu.Lock()
+ defer d.mu.Unlock()
+ return d.cacheWithLock(key, val)
+}
+
+func (d *Diskv) bustCacheWithLock(key string) {
+ if val, ok := d.cache[key]; ok {
+ d.uncacheWithLock(key, uint64(len(val)))
+ }
+}
+
+func (d *Diskv) uncacheWithLock(key string, sz uint64) {
+ d.cacheSize -= sz
+ delete(d.cache, key)
+}
+
+// pruneDirsWithLock deletes empty directories in the path walk leading to the
+// key k. Typically this function is called after an Erase is made.
+func (d *Diskv) pruneDirsWithLock(key string) error {
+ pathlist := d.Transform(key)
+ for i := range pathlist {
+ dir := filepath.Join(d.BasePath, filepath.Join(pathlist[:len(pathlist)-i]...))
+
+ // thanks to Steven Blenkinsop for this snippet
+ switch fi, err := os.Stat(dir); true {
+ case err != nil:
+ return err
+ case !fi.IsDir():
+ panic(fmt.Sprintf("corrupt dirstate at %s", dir))
+ }
+
+ nlinks, err := filepath.Glob(filepath.Join(dir, "*"))
+ if err != nil {
+ return err
+ } else if len(nlinks) > 0 {
+ return nil // has subdirs -- do not prune
+ }
+ if err = os.Remove(dir); err != nil {
+ return err
+ }
+ }
+
+ return nil
+}
+
+// ensureCacheSpaceWithLock deletes entries from the cache in arbitrary order
+// until the cache has at least valueSize bytes available.
+func (d *Diskv) ensureCacheSpaceWithLock(valueSize uint64) error {
+ if valueSize > d.CacheSizeMax {
+ return fmt.Errorf("value size (%d bytes) too large for cache (%d bytes)", valueSize, d.CacheSizeMax)
+ }
+
+ safe := func() bool { return (d.cacheSize + valueSize) <= d.CacheSizeMax }
+
+ for key, val := range d.cache {
+ if safe() {
+ break
+ }
+
+ d.uncacheWithLock(key, uint64(len(val)))
+ }
+
+ if !safe() {
+ panic(fmt.Sprintf("%d bytes still won't fit in the cache! (max %d bytes)", valueSize, d.CacheSizeMax))
+ }
+
+ return nil
+}
+
+// nopWriteCloser wraps an io.Writer and provides a no-op Close method to
+// satisfy the io.WriteCloser interface.
+type nopWriteCloser struct {
+ io.Writer
+}
+
+func (wc *nopWriteCloser) Write(p []byte) (int, error) { return wc.Writer.Write(p) }
+func (wc *nopWriteCloser) Close() error { return nil }