diskv: github.com/peterbourgon/diskv Index | Files

package diskv

import "github.com/peterbourgon/diskv"

Index

Package Files

compression.go diskv.go index.go

type AdvancedTransformFunction Uses

type AdvancedTransformFunction func(s string) *PathKey

AdvancedTransformFunction transforms a key into a PathKey.

A PathKey contains a slice of strings, where each element in the slice represents a directory in the file path where the key's entry will eventually be stored, as well as the filename.

For example, if AdvancedTransformFunc transforms "abcdef/file.txt" to the PathKey {Path: ["ab", "cde", "f"], FileName: "file.txt"}, the final location of the data file will be <basedir>/ab/cde/f/file.txt.

You must provide an InverseTransformFunction if you use an AdvancedTransformFunction.

type BTreeIndex Uses

type BTreeIndex struct {
    sync.RWMutex
    LessFunction
    *btree.BTree
}

BTreeIndex is an implementation of the Index interface using google/btree.

func (*BTreeIndex) Delete Uses

func (i *BTreeIndex) Delete(key string)

Delete removes the given key (only) from the BTree tree.

func (*BTreeIndex) Initialize Uses

func (i *BTreeIndex) Initialize(less LessFunction, keys <-chan string)

Initialize populates the BTree tree with data from the keys channel, according to the passed less function. It's destructive to the BTreeIndex.

func (*BTreeIndex) Insert Uses

func (i *BTreeIndex) Insert(key string)

Insert inserts the given key (only) into the BTree tree.

func (*BTreeIndex) Keys Uses

func (i *BTreeIndex) Keys(from string, n int) []string

Keys yields a maximum of n keys in order. If the passed 'from' key is empty, Keys will return the first n keys. If the passed 'from' key is non-empty, the first key in the returned slice will be the key that immediately follows the passed key, in key order.

type Compression Uses

type Compression interface {
    Writer(dst io.Writer) (io.WriteCloser, error)
    Reader(src io.Reader) (io.ReadCloser, error)
}

Compression is an interface that Diskv uses to implement compression of data. Writer takes a destination io.Writer and returns a WriteCloser that compresses all data written through it. Reader takes a source io.Reader and returns a ReadCloser that decompresses all data read through it. You may define these methods on your own type, or use one of the NewCompression helpers.

func NewGzipCompression Uses

func NewGzipCompression() Compression

NewGzipCompression returns a Gzip-based Compression.

func NewGzipCompressionLevel Uses

func NewGzipCompressionLevel(level int) Compression

NewGzipCompressionLevel returns a Gzip-based Compression with the given level.

func NewZlibCompression Uses

func NewZlibCompression() Compression

NewZlibCompression returns a Zlib-based Compression.

func NewZlibCompressionLevel Uses

func NewZlibCompressionLevel(level int) Compression

NewZlibCompressionLevel returns a Zlib-based Compression with the given level.

func NewZlibCompressionLevelDict Uses

func NewZlibCompressionLevelDict(level int, dict []byte) Compression

NewZlibCompressionLevelDict returns a Zlib-based Compression with the given level, based on the given dictionary.

type Diskv Uses

type Diskv struct {
    Options
    // contains filtered or unexported fields
}

Diskv implements the Diskv interface. You shouldn't construct Diskv structures directly; instead, use the New constructor.

func New Uses

func New(o Options) *Diskv

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 (*Diskv) Erase Uses

func (d *Diskv) Erase(key string) error

Erase synchronously erases the given key from the disk and the cache.

func (*Diskv) EraseAll Uses

func (d *Diskv) EraseAll() error

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 (*Diskv) Has Uses

func (d *Diskv) Has(key string) bool

Has returns true if the given key exists.

func (*Diskv) Import Uses

func (d *Diskv) Import(srcFilename, dstKey string, move bool) (err error)

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 (*Diskv) Keys Uses

func (d *Diskv) Keys(cancel <-chan struct{}) <-chan string

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 (*Diskv) KeysPrefix Uses

func (d *Diskv) KeysPrefix(prefix string, cancel <-chan struct{}) <-chan string

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 (*Diskv) Read Uses

func (d *Diskv) Read(key string) ([]byte, error)

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 (*Diskv) ReadStream Uses

func (d *Diskv) ReadStream(key string, direct bool) (io.ReadCloser, error)

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 (*Diskv) ReadString Uses

func (d *Diskv) ReadString(key string) string

ReadString reads the key and returns a string value In case of error, an empty string is returned

func (*Diskv) Write Uses

func (d *Diskv) Write(key string, val []byte) error

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 (*Diskv) WriteStream Uses

func (d *Diskv) WriteStream(key string, r io.Reader, sync bool) error

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 (*Diskv) WriteString Uses

func (d *Diskv) WriteString(key string, val string) error

WriteString writes a string key-value pair to disk

type Index Uses

type Index interface {
    Initialize(less LessFunction, keys <-chan string)
    Insert(key string)
    Delete(key string)
    Keys(from string, n int) []string
}

Index is a generic interface for things that can provide an ordered list of keys.

type InverseTransformFunction Uses

type InverseTransformFunction func(pathKey *PathKey) string

InverseTransformFunction takes a PathKey and converts it back to a Diskv key. In effect, it's the opposite of an AdvancedTransformFunction.

type LessFunction Uses

type LessFunction func(string, string) bool

LessFunction is used to initialize an Index of keys in a specific order.

type Options Uses

type Options struct {
    BasePath          string
    Transform         TransformFunction
    AdvancedTransform AdvancedTransformFunction
    InverseTransform  InverseTransformFunction
    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
}

Options define a set of properties that dictate Diskv behavior. All values are optional.

type PathKey Uses

type PathKey struct {
    Path     []string
    FileName string
    // contains filtered or unexported fields
}

PathKey represents a string key that has been transformed to a directory and file name where the content will eventually be stored

type TransformFunction Uses

type TransformFunction func(s string) []string

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

Package diskv imports 14 packages (graph) and is imported by 119 packages. Updated 2019-06-28. Refresh now. Tools for package owners.