kvs

README

kvs

kvs is a small library that provides an interface to key-value storage. There are two implementations here - inmem and Redis based.

Documentation

Index

• type Record
  • func (r Record) Copy() Record
• type Storage

Types

type Record

type Record struct {
	// Key is a key for the record
	Key string
	// Value is a value for the record
	Value []byte

	// A version that identifies the record. It is managed by the Storage, and
	// it is ignored in Create and update operations
	Version string

	// ExpiresAt indicate the record expiration time. If it is not provided
	// the record doesn't have the expiration time
	ExpiresAt *time.Time
}

A record that can be stored in a storage

func (Record) Copy

func (r Record) Copy() Record

Copy returns copy of the record r

type Storage

type Storage interface {
	// Create adds a new record into the storage. It returns existing record with
	// ErrExist error if it already exists in the storage.
	// Create returns version of the new record with error=nil
	Create(ctx context.Context, record Record) (string, error)

	// Get retrieves the record by its key. ErrNotExist is returned if the key
	// is not found in the storage
	Get(ctx context.Context, key string) (Record, error)

	// GetMany retrieves many records at a time. It will return only the records it
	// finds, and skip that one, which doesn't exist
	GetMany(ctx context.Context, keys ...string) ([]*Record, error)

	// Put replaces the record if it exists and write the new one if it doesn't
	// The record version will be updated automatically
	Put(ctx context.Context, record Record) (Record, error)

	// PutMany allows to update multiple records in one call
	PutMany(ctx context.Context, records []Record) error

	// CasByVersion compares-and-sets the record Value if the record stored
	// version is same as in the provided record. The record version will be updated,
	// and it be returned as first parameter in the result.
	//
	// The error will contain the reason if the operation was not successful, or
	// the new version will be returned otherwise
	//   ErrConflict - indicates that the version is different than one is expected
	//   ErrNotExist - indicates that the record does not exist
	CasByVersion(ctx context.Context, record Record) (Record, error)

	// Delete removes the record from the storage by its key. It returns
	// an error if the operation was not successful:
	//   ErrNotExist - indicates that the record does not exist
	Delete(ctx context.Context, key string) error

	// WaitForVersionChange blocks the call until the ctx is closed or the key's version
	// becomes different from the ver.
	//
	// The function may return the following results:
	// nil: the key exists, and it's version is different from the ver
	// ctx.Err(): if the context is closed
	// ErrNotExist: the key is not found or was deleted being in the function
	WaitForVersionChange(ctx context.Context, key, ver string) error

	// ListKeys allows to read the keys by the pattern provided. The pattern is a glob-alike
	// matcher (not a regexp). For the pattern matching please refer to the
	// Glob library doc https://github.com/gobwas/glob
	ListKeys(ctx context.Context, pattern string) (iterable.Iterator[string], error)
}

Storage interface defines some operations over the record storage. The record storage allows to keep key-value pairs, and supports a set of operations that allow to implement some distributed (if supported) primitives