Documentation
¶
Overview ¶
Package scratch provides an abstraction for scratch space.
Index ¶
Constants ¶
const InvalidHandle = Handle(0)
InvalidHandle is the zero value for Handle.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Filesystem ¶
type Filesystem struct {
// contains filtered or unexported fields
}
Filesystem is an implementation of Store that retains data on the filesystem.
Filesystem supports a memory fallback mechanism if writing data fails.
func NewFilesystem ¶
func NewFilesystem(logger log.Logger, path string) (*Filesystem, error)
NewFilesystem returns a new Filesystem store. Stored data is persisted to disk with a random filename and an extension ".lokiscratch".
To avoid leaking scratch files between process iterations, NewFilesystem will remove any existing ".lokiscratch" files in path upon startup.
NewFilesystem creates the path if it does not exist.
func (*Filesystem) Put ¶
func (fs *Filesystem) Put(p []byte) Handle
Put stores the contents of p into scratch space.
Put will be written with a random filename and the extension ".lokiscratch". If writing to the filesystem fails, p will instead be stored in-memory.
func (*Filesystem) Read ¶
func (fs *Filesystem) Read(h Handle) (io.ReadSeekCloser, error)
Read returns a reader for the file identifier by h. Read returns HandleNotFoundError if h doesn't exist either on disk or in-memory.
Callers must close the reader when done to release resources. Reading may fail if the handle is removed while reading data.
func (*Filesystem) Remove ¶
func (fs *Filesystem) Remove(h Handle) error
Remove removes the handle identified by h. If h is stored on disk, its corresponding file will be removed. Remove returns HandleNotFoundError if h doesn't exist on disk or in-memory.
type Handle ¶
type Handle uint64
Handle is a identifier for data placed into scratch space. Handles are unique per store. Handles are immutable once created and can only be read or deleted.
The zero value for handle is invalid.
type HandleNotFoundError ¶
type HandleNotFoundError Handle
HandleNotFoundError is returned when performing an operation on a handle that doesn't exist.
func (HandleNotFoundError) Error ¶
func (e HandleNotFoundError) Error() string
Error returns a string representation of e.
type Memory ¶
type Memory struct {
// contains filtered or unexported fields
}
Memory is an implementation of Store that retains data in memory.
func (*Memory) Read ¶
func (m *Memory) Read(h Handle) (io.ReadSeekCloser, error)
Read returns a reader for h. Read returns HandleNotFoundError if h doesn't exist in memory.
type Metrics ¶
type Metrics struct {
// contains filtered or unexported fields
}
Metrics is a set of metrics for monitoring a Store.
func NewMetrics ¶
func NewMetrics() *Metrics
NewMetrics returns a new Metrics. Returned Metrics must be registered to a registerer using Metrics.Register.
func (*Metrics) Register ¶
func (m *Metrics) Register(reg prometheus.Registerer) error
Register registers metrics to report to reg.
func (*Metrics) Unregister ¶
func (m *Metrics) Unregister(reg prometheus.Registerer)
Unregister unregisters metrics from reg.
type Store ¶
type Store interface {
// Put stores the contents of p into scratch space.
Put(p []byte) Handle
// Read returns a reader for the file identifier by h. Read returns
// [InvalidHandleError] if h doesn't exist in the Store.
//
// Callers must close the reader when done to release resources. Reading may
// fail if the handle is removed while reading data.
Read(h Handle) (io.ReadSeekCloser, error)
// Remove removes the handle identified by h. Remove returns
// [InvalidHandleError] if h doesn't exist in the Store.
Remove(h Handle) error
}
Store is an abstraction for temporarily storing data. Store is ephemeral and starts fresh every time it is created.
Store implementations must be safe for concurrent access.
func ObserveStore ¶
ObserveStore wraps a store and accumulates statistics into the provided Metrics. If metrics is nil, ObserveStore performs no wrapping.
func Open ¶
Open returns the default Store implementation based on whether path is set.
If path is empty, Open returns a Memory store. If path is non-empty, Open returns a Filesystem store.
Open returns an error if the path is non-empty but refers to a non-existent directory.
To observe metrics on the returned store, wrap the result with ObserveStore.
Source Files