A transparent cache for datastore, backed by memcache.

filter/dscache/dscache_test.go

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package dscache
+
+import (
+        "fmt"
+        "math/rand"
+        "testing"
+        "time"
+
+        "github.com/luci/gae/impl/memory"
+        "github.com/luci/gae/service/datastore"
+        "github.com/luci/gae/service/memcache"
+        "github.com/luci/luci-go/common/clock"
+        "github.com/luci/luci-go/common/clock/testclock"
+        "github.com/luci/luci-go/common/mathrand"
+        . "github.com/smartystreets/goconvey/convey"
+        "golang.org/x/net/context"
+)
+
+type object struct {
+        ID int64 `gae:"$id"`
+
+        Value string
+}
+
+func TestDSCache(t *testing.T) {
+        t.Parallel()
+
+        zeroTime, err := time.Parse("2006-01-02T15:04:05.999999999Z", "2006-01-02T15:04:05.999999999Z")
+        if err != nil {
+                panic(err)
+        }
+
+        Convey("Test dscache", t, func() {
+                c := mathrand.Set(context.Background(), rand.New(rand.NewSource(1)))
+                clk := testclock.New(zeroTime)
+                c = clock.Set(c, clk)
+                c = memory.Use(c)
+                dsUnder := datastore.Get(c)
+                ds := datastore.Get(FilterRDS(c))
+                mc := memcache.Get(c)
+
+                itmFor := func(i int, k datastore.Key) memcache.Item {
+                        return mc.NewItem(fmt.Sprintf(KeyFormat, i, mkKeySuffix(k)))
+                }
+
+                So(dsUnder, ShouldNotBeNil)
+                So(ds, ShouldNotBeNil)
+                So(mc, ShouldNotBeNil)
+
+                Convey("basically works", func() {
+                        o := object{ID: 1, Value: "hi"}
+                        So(ds.Put(&o), ShouldBeNil)
+
+                        o = object{ID: 1}
+                        So(dsUnder.Get(&o), ShouldBeNil)
+                        So(o.Value, ShouldEqual, "hi")
+
+                        itm := itmFor(0, ds.KeyForObj(&o))
+                        So(mc.Get(itm), ShouldEqual, memcache.ErrCacheMiss)
+
+                        o = object{ID: 1}
+                        So(ds.Get(&o), ShouldBeNil)
+                        So(o.Value, ShouldEqual, "hi")
+                        So(mc.Get(itm), ShouldBeNil)
+                        So(itm.Value(), ShouldResemble,
+                                []byte("\x00\x80\x80W1[\x8fW(\x80\x80\x06i5@"))
+
+                        Convey("now we don't need the datastore!", func() {
+                                o := object{ID: 1}
+
+                                // delete it, bypassing the cache filter. Don't do this in production
+                                // unless you want a crappy cache.
+                                So(dsUnder.Delete(ds.KeyForObj(&o)), ShouldBeNil)
+
+                                itm := itmFor(0, ds.KeyForObj(&o))
+                                So(mc.Get(itm), ShouldBeNil)
+                                So(itm.Value(), ShouldResemble,
+                                        []byte("\x00\x80\x80W1[\x8fW(\x80\x80\x06i5@"))

[iannucci, 2015/08/04 05:26:17]

for reference, the equivalent gob encoding is 57 bytes :P

+
+                                So(ds.Get(&o), ShouldBeNil)
+                                So(o.Value, ShouldEqual, "hi")
+                        })
+
+                        Convey("deleting it properly records that", func() {
+                                o := object{ID: 1}
+                                So(ds.Delete(ds.KeyForObj(&o)), ShouldBeNil)
+
+                                itm := itmFor(0, ds.KeyForObj(&o))
+                                So(mc.Get(itm), ShouldEqual, memcache.ErrCacheMiss)
+                                So(ds.Get(&o), ShouldEqual, datastore.ErrNoSuchEntity)
+
+                                So(mc.Get(itm), ShouldBeNil)
+                                So(itm.Value(), ShouldResemble, []byte{})
+
+                                // this one hits memcache
+                                So(ds.Get(&o), ShouldEqual, datastore.ErrNoSuchEntity)
+                        })
+                })
+        })
+}