memstore

README

memstore

An in-memory session store for SCS.

Because memstore uses in-memory storage only, all session data will be lost when your application is stopped or restarted. Therefore it should only be used in applications where data loss is an acceptable trade off for fast performance, or for prototyping and testing purposes.

Example

package main

import (
	"io"
	"net/http"

	"github.com/alexedwards/scs/v2"
	"github.com/alexedwards/scs/v2/memstore"
)

var sessionManager *scs.SessionManager

func main() {
	// Initialize a new session manager and configure it to use memstore as
	// the session store.
	sessionManager = scs.New()
	sessionManager.Store = memstore.New()

	mux := http.NewServeMux()
	mux.HandleFunc("/put", putHandler)
	mux.HandleFunc("/get", getHandler)

	http.ListenAndServe(":4000", sessionManager.LoadAndSave(mux))
}

func putHandler(w http.ResponseWriter, r *http.Request) {
	sessionManager.Put(r.Context(), "message", "Hello from a session!")
}

func getHandler(w http.ResponseWriter, r *http.Request) {
	msg := sessionManager.GetString(r.Context(), "message")
	io.WriteString(w, msg)
}

Expired Session Cleanup

This package provides a background 'cleanup' goroutine to delete expired session data. This stops the database table from holding on to invalid sessions indefinitely and growing unnecessarily large. By default the cleanup runs once every minute. You can change this by using the NewWithCleanupInterval() function to initialize your session store. For example:

// Run a cleanup every 30 seconds.
memstore.NewWithCleanupInterval(db, 30*time.Second)

// Disable the cleanup goroutine by setting the cleanup interval to zero.
memstore.NewWithCleanupInterval(db, 0)

Terminating the Cleanup Goroutine

It's rare that the cleanup goroutine needs to be terminated --- it is generally intended to be long-lived and run for the lifetime of your application.

However, there may be occasions when your use of a session store instance is transient. A common example would be using it in a short-lived test function. In this scenario, the cleanup goroutine (which will run forever) will prevent the session store instance from being garbage collected even after the test function has finished. You can prevent this by either disabling the cleanup goroutine altogether (as described above) or by stopping it using the StopCleanup() method. For example:

func TestExample(t *testing.T) {
	store := memstore.New()
	defer store.StopCleanup()

	sessionManager = scs.New()
	sessionManager.Store = store

	// Run test...
}

Documentation

Index

• type MemStore
  • func New() *MemStore
  • func NewWithCleanupInterval(cleanupInterval time.Duration) *MemStore
  • func (m *MemStore) All() (map[string][]byte, error)
  • func (m *MemStore) Commit(token string, b []byte, expiry time.Time) error
  • func (m *MemStore) Delete(token string) error
  • func (m *MemStore) Find(token string) ([]byte, bool, error)
  • func (m *MemStore) StopCleanup()

Types

type MemStore

type MemStore struct {
	// contains filtered or unexported fields
}

MemStore represents the session store.

func New

func New() *MemStore

New returns a new MemStore instance, with a background cleanup goroutine that runs every minute to remove expired session data.

func NewWithCleanupInterval

func NewWithCleanupInterval(cleanupInterval time.Duration) *MemStore

NewWithCleanupInterval returns a new MemStore instance. The cleanupInterval parameter controls how frequently expired session data is removed by the background cleanup goroutine. Setting it to 0 prevents the cleanup goroutine from running (i.e. expired sessions will not be removed).

func (*MemStore) All

func (m *MemStore) All() (map[string][]byte, error)

All returns a map containing the token and data for all active (i.e. not expired) sessions.

func (*MemStore) Commit

func (m *MemStore) Commit(token string, b []byte, expiry time.Time) error

Commit adds a session token and data to the MemStore instance with the given expiry time. If the session token already exists, then the data and expiry time are updated.

func (*MemStore) Delete

func (m *MemStore) Delete(token string) error

Delete removes a session token and corresponding data from the MemStore instance.

func (*MemStore) Find

func (m *MemStore) Find(token string) ([]byte, bool, error)

Find returns the data for a given session token from the MemStore instance. If the session token is not found or is expired, the returned exists flag will be set to false.

func (*MemStore) StopCleanup

func (m *MemStore) StopCleanup()

StopCleanup terminates the background cleanup goroutine for the MemStore instance. It's rare to terminate this; generally MemStore instances and their cleanup goroutines are intended to be long-lived and run for the lifetime of your application.

There may be occasions though when your use of the MemStore is transient. An example is creating a new MemStore instance in a test function. In this scenario, the cleanup goroutine (which will run forever) will prevent the MemStore object from being garbage collected even after the test function has finished. You can prevent this by manually calling StopCleanup.