testing: demonstrate expected isolation properties

isolation_test.go

@@ -0,0 +1,322 @@
+// Copyright (c) HashiCorp, Inc.
+// SPDX-License-Identifier: MPL-2.0
+
+package memdb
+
+import (
+	"testing"
+)
+
+func TestMemDB_Isolation(t *testing.T) {
+
+	id1 := "object-one"
+	id2 := "object-two"
+	id3 := "object-three"
+
+	mustNoError := func(t *testing.T, err error) {
+		if err != nil {
+			t.Fatalf("unexpected test error: %v", err)
+		}
+	}
+
+	setup := func(t *testing.T) *MemDB {
+		t.Helper()
+
+		db, err := NewMemDB(testValidSchema())
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+
+		// Add two objects (with a gap between their IDs)
+		obj1a := testObj()
+		obj1a.ID = id1
+		txn := db.Txn(true)
+		mustNoError(t, txn.Insert("main", obj1a))
+
+		obj3 := testObj()
+		obj3.ID = id3
+		mustNoError(t, txn.Insert("main", obj3))
+		txn.Commit()
+		return db
+	}
+
+	t.Run("snapshot dirty read", func(t *testing.T) {
+		db := setup(t)
+		db2 := db.Snapshot()
+
+		// Update an object
+		obj1b := testObj()
+		obj1b.ID = id1
+		txn1 := db.Txn(true)
+		obj1b.Baz = "nope"
+		mustNoError(t, txn1.Insert("main", obj1b))
+
+		// Insert an object
+		obj2 := testObj()
+		obj2.ID = id2
+		mustNoError(t, txn1.Insert("main", obj2))
+
+		txn2 := db2.Txn(false)
+		out, err := txn2.First("main", "id", id1)
+		mustNoError(t, err)
+		if out == nil {
+			t.Fatalf("should exist")
+		}
+		if out.(*TestObject).Baz == "nope" {
+			t.Fatalf("read from snapshot should not observe uncommitted update (dirty read)")
+		}
+
+		out, err = txn2.First("main", "id", id2)
+		mustNoError(t, err)
+		if out != nil {
+			t.Fatalf("read from snapshot should not observe uncommitted insert (dirty read)")
+		}
+
+		// New snapshot should not observe uncommitted writes
+		db3 := db.Snapshot()
+		txn3 := db3.Txn(false)
+		out, err = txn3.First("main", "id", id1)
+		mustNoError(t, err)
+		if out == nil {
+			t.Fatalf("should exist")
+		}
+		if out.(*TestObject).Baz == "nope" {
+			t.Fatalf("read from new snapshot should not observe uncommitted writes")
+		}
+	})
+
+	t.Run("transaction dirty read", func(t *testing.T) {
+		db := setup(t)
+
+		// Update an object
+		obj1b := testObj()
+		obj1b.ID = id1
+		txn1 := db.Txn(true)
+		obj1b.Baz = "nope"
+		mustNoError(t, txn1.Insert("main", obj1b))
+
+		// Insert an object
+		obj2 := testObj()
+		obj2.ID = id2
+		mustNoError(t, txn1.Insert("main", obj2))
+
+		txn2 := db.Txn(false)
+		out, err := txn2.First("main", "id", id1)
+		mustNoError(t, err)
+		if out == nil {
+			t.Fatalf("should exist")
+		}
+		if out.(*TestObject).Baz == "nope" {
+			t.Fatalf("read from transaction should not observe uncommitted update (dirty read)")
+		}
+
+		out, err = txn2.First("main", "id", id2)
+		mustNoError(t, err)
+		if out != nil {
+			t.Fatalf("read from transaction should not observe uncommitted insert (dirty read)")
+		}
+	})
+
+	t.Run("snapshot non-repeatable read", func(t *testing.T) {
+		db := setup(t)
+		db2 := db.Snapshot()
+
+		// Update an object
+		obj1b := testObj()
+		obj1b.ID = id1
+		txn1 := db.Txn(true)
+		obj1b.Baz = "nope"
+		mustNoError(t, txn1.Insert("main", obj1b))
+
+		// Insert an object
+		obj2 := testObj()
+		obj2.ID = id3
+		mustNoError(t, txn1.Insert("main", obj2))
+
+		// Commit
+		txn1.Commit()
+
+		txn2 := db2.Txn(false)
+		out, err := txn2.First("main", "id", id1)
+		mustNoError(t, err)
+		if out == nil {
+			t.Fatalf("should exist")
+		}
+		if out.(*TestObject).Baz == "nope" {
+			t.Fatalf("read from snapshot should not observe committed write from another transaction (non-repeatable read)")
+		}
+
+		out, err = txn2.First("main", "id", id2)
+		mustNoError(t, err)
+		if out != nil {
+			t.Fatalf("read from snapshot should not observe committed write from another transaction (non-repeatable read)")
+		}
+
+	})
+
+	t.Run("transaction non-repeatable read", func(t *testing.T) {
+		db := setup(t)
+
+		// Update an object
+		obj1b := testObj()
+		obj1b.ID = id1
+		txn1 := db.Txn(true)
+		obj1b.Baz = "nope"
+		mustNoError(t, txn1.Insert("main", obj1b))
+
+		// Insert an object
+		obj2 := testObj()
+		obj2.ID = id3
+		mustNoError(t, txn1.Insert("main", obj2))
+
+		txn2 := db.Txn(false)
+
+		// Commit
+		txn1.Commit()
+
+		out, err := txn2.First("main", "id", id1)
+		mustNoError(t, err)
+		if out == nil {
+			t.Fatalf("should exist")
+		}
+		if out.(*TestObject).Baz == "nope" {
+			t.Fatalf("read from transaction should not observe committed write from another transaction (non-repeatable read)")
+		}
+
+		out, err = txn2.First("main", "id", id2)
+		mustNoError(t, err)
+		if out != nil {
+			t.Fatalf("read from transaction should not observe committed write from another transaction (non-repeatable read)")
+		}
+
+	})
+
+	t.Run("snapshot phantom read", func(t *testing.T) {
+		db := setup(t)
+		db2 := db.Snapshot()
+
+		txn2 := db2.Txn(false)
+		iter, err := txn2.Get("main", "id_prefix", "object")
+		mustNoError(t, err)
+		out := iter.Next()
+		if out == nil || out.(*TestObject).ID != id1 {
+			t.Fatal("missing expected object 'object-one'")
+		}
+
+		// Insert an object and commit
+		txn1 := db.Txn(true)
+		obj2 := testObj()
+		obj2.ID = id2
+		mustNoError(t, txn1.Insert("main", obj2))
+		txn1.Commit()
+
+		out = iter.Next()
+		if out == nil {
+			t.Fatal("expected 2 objects")
+		}
+		if out.(*TestObject).ID == id2 {
+			t.Fatalf("read from snapshot should not observe new objects in set (phantom read)")
+		}
+
+		out = iter.Next()
+		if out != nil {
+			t.Fatal("expected only 2 objects: read from snapshot should not observe new objects in set (phantom read)")
+		}
+
+		// Remove an object using an outdated pointer
+		txn1 = db.Txn(true)
+		obj1, err := txn1.First("main", "id", id1)
+		mustNoError(t, err)
+		mustNoError(t, txn1.Delete("main", obj1))
+		txn1.Commit()
+
+		iter, err = txn2.Get("main", "id_prefix", "object")
+		mustNoError(t, err)
+
+		out = iter.Next()
+		if out == nil || out.(*TestObject).ID != id1 {
+			t.Fatal("missing expected object 'object-one': read from snapshot should not observe deletes (phantom read)")
+		}
+		out = iter.Next()
+		if out == nil || out.(*TestObject).ID != id3 {
+			t.Fatal("missing expected object 'object-three': read from snapshot should not observe deletes (phantom read)")
+		}
+
+	})
+
+	t.Run("transaction phantom read", func(t *testing.T) {
+		db := setup(t)
+
+		txn2 := db.Txn(false)
+		iter, err := txn2.Get("main", "id_prefix", "object")
+		mustNoError(t, err)
+		out := iter.Next()
+		if out == nil || out.(*TestObject).ID != id1 {
+			t.Fatal("missing expected object 'object-one'")
+		}
+
+		// Insert an object and commit
+		txn1 := db.Txn(true)
+		obj2 := testObj()
+		obj2.ID = id2
+		mustNoError(t, txn1.Insert("main", obj2))
+		txn1.Commit()
+
+		out = iter.Next()
+		if out == nil {
+			t.Fatal("expected 2 objects")
+		}
+		if out.(*TestObject).ID == id2 {
+			t.Fatalf("read from transaction should not observe new objects in set (phantom read)")
+		}
+
+		out = iter.Next()
+		if out != nil {
+			t.Fatal("expected only 2 objects: read from transaction should not observe new objects in set (phantom read)")
+		}
+
+		// Remove an object using an outdated pointer
+		txn1 = db.Txn(true)
+		obj1, err := txn1.First("main", "id", id1)
+		mustNoError(t, err)
+		mustNoError(t, txn1.Delete("main", obj1))
+		txn1.Commit()
+
+		iter, err = txn2.Get("main", "id_prefix", "object")
+		if err != nil {
+			t.Fatalf("err: %v", err)
+		}
+
+		out = iter.Next()
+		if out == nil || out.(*TestObject).ID != id1 {
+			t.Fatal("missing expected object 'object-one': read from transaction should not observe deletes (phantom read)")
+		}
+		out = iter.Next()
+		if out == nil || out.(*TestObject).ID != id3 {
+			t.Fatal("missing expected object 'object-three': read from transaction should not observe deletes (phantom read)")
+		}
+
+	})
+
+	t.Run("snapshot commits are unobservable", func(t *testing.T) {
+		db := setup(t)
+		db2 := db.Snapshot()
+
+		txn2 := db2.Txn(true)
+		obj1 := testObj()
+		obj1.ID = id1
+		obj1.Baz = "also"
+		mustNoError(t, txn2.Insert("main", obj1))
+		txn2.Commit()
+
+		txn1 := db.Txn(false)
+		out, err := txn1.First("main", "id", id1)
+		mustNoError(t, err)
+		if out == nil {
+			t.Fatalf("should exist")
+		}
+		if out.(*TestObject).Baz == "also" {
+			t.Fatalf("commit from snapshot should never be observed")
+		}
+	})
+}