groupcache/example_test.go

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package groupcache_test
import (
"context"
"fmt"
"log"
"time"
"github.com/mailgun/groupcache/v2"
)
func ExampleUsage() {
/*
// Keep track of peers in our cluster and add our instance to the pool `http://localhost:8080`
pool := groupcache.NewHTTPPoolOpts("http://localhost:8080", &groupcache.HTTPPoolOptions{})
// Add more peers to the cluster
//pool.Set("http://peer1:8080", "http://peer2:8080")
server := http.Server{
Addr: "localhost:8080",
Handler: pool,
}
// Start a HTTP server to listen for peer requests from the groupcache
go func() {
log.Printf("Serving....\n")
if err := server.ListenAndServe(); err != nil {
log.Fatal(err)
}
}()
defer server.Shutdown(context.Background())
*/
// Create a new group cache with a max cache size of 3MB
group := groupcache.NewGroup("users", 3000000, groupcache.GetterFunc(
func(ctx context.Context, id string, dest groupcache.Sink) error {
// In a real scenario we might fetch the value from a database.
/*if user, err := fetchUserFromMongo(ctx, id); err != nil {
return err
}*/
user := User{
Id: "12345",
Name: "John Doe",
Age: 40,
IsSuper: true,
}
// Set the user in the groupcache to expire after 5 minutes
if err := dest.SetProto(&user, time.Now().Add(time.Minute*5)); err != nil {
return err
}
return nil
},
))
var user User
ctx, cancel := context.WithTimeout(context.Background(), time.Second)
defer cancel()
if err := group.Get(ctx, "12345", groupcache.ProtoSink(&user)); err != nil {
log.Fatal(err)
}
fmt.Printf("-- User --\n")
fmt.Printf("Id: %s\n", user.Id)
fmt.Printf("Name: %s\n", user.Name)
fmt.Printf("Age: %d\n", user.Age)
fmt.Printf("IsSuper: %t\n", user.IsSuper)
/*
// Remove the key from the groupcache
if err := group.Remove(ctx, "12345"); err != nil {
fmt.Printf("Remove Err: %s\n", err)
log.Fatal(err)
}
*/
// Output: -- User --
// Id: 12345
// Name: John Doe
// Age: 40
// IsSuper: true
}