From 2af7e4ef2669f5f263b7f7a8423746302a25ca8c Mon Sep 17 00:00:00 2001
From: Egon Elbre <egonelbre@gmail.com>
Date: Fri, 7 May 2021 12:05:51 +0300
Subject: [PATCH] satellite/metabase/metaloop: use database time

The system and database time may drift. We should use database time for
absolute "as of system time" to ensure that it's not newer than the
current database time. When the "as of system time" is in the future,
then the query will fail.

Change-Id: I5423f6aaad966ca03a76b5ff805bfba932e44a51
---
 satellite/metabase/db.go                              |  8 ++++++++
 satellite/metabase/{db_migrate_test.go => db_test.go} | 10 ++++++++++
 satellite/metabase/metaloop/service.go                |  7 ++++++-
 satellite/metainfo/config.go                          |  3 +++
 4 files changed, 27 insertions(+), 1 deletion(-)
 rename satellite/metabase/{db_migrate_test.go => db_test.go} (92%)

diff --git a/satellite/metabase/db.go b/satellite/metabase/db.go
index 34c0b47fd..3f09fee7f 100644
--- a/satellite/metabase/db.go
+++ b/satellite/metabase/db.go
@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"sort"
 	"strconv"
+	"time"
 
 	_ "github.com/jackc/pgx/v4"        // registers pgx as a tagsql driver.
 	_ "github.com/jackc/pgx/v4/stdlib" // registers pgx as a tagsql driver.
@@ -415,3 +416,10 @@ func (pq postgresRebind) Rebind(sql string) string {
 
 	return string(out)
 }
+
+// Now returns time on the database.
+func (db *DB) Now(ctx context.Context) (time.Time, error) {
+	var t time.Time
+	err := db.db.QueryRowContext(ctx, `SELECT now()`).Scan(&t)
+	return t, Error.Wrap(err)
+}
diff --git a/satellite/metabase/db_migrate_test.go b/satellite/metabase/db_test.go
similarity index 92%
rename from satellite/metabase/db_migrate_test.go
rename to satellite/metabase/db_test.go
index 430c23653..c43ed1cd3 100644
--- a/satellite/metabase/db_migrate_test.go
+++ b/satellite/metabase/db_test.go
@@ -6,6 +6,7 @@ package metabase_test
 import (
 	"sort"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/require"
 	"go.uber.org/zap/zaptest"
@@ -116,3 +117,12 @@ func TestMigrateToAliases(t *testing.T) {
 		})
 	}
 }
+
+func TestNow(t *testing.T) {
+	metabasetest.Run(t, func(ctx *testcontext.Context, t *testing.T, db *metabase.DB) {
+		sysnow := time.Now()
+		now, err := db.Now(ctx)
+		require.NoError(t, err)
+		require.WithinDuration(t, sysnow, now, 5*time.Second)
+	})
+}
diff --git a/satellite/metabase/metaloop/service.go b/satellite/metabase/metaloop/service.go
index 1ec9df04d..07ea53ca7 100644
--- a/satellite/metabase/metaloop/service.go
+++ b/satellite/metabase/metaloop/service.go
@@ -167,6 +167,8 @@ type Config struct {
 
 // MetabaseDB contains iterators for the metabase data.
 type MetabaseDB interface {
+	// Now returns the time on the database.
+	Now(ctx context.Context) (time.Time, error)
 	// IterateLoopObjects iterates through all objects in metabase for metainfo loop purpose.
 	IterateLoopObjects(ctx context.Context, opts metabase.IterateLoopObjects, fn func(context.Context, metabase.LoopObjectsIterator) error) (err error)
 	// IterateLoopStreams iterates through all streams passed in as arguments.
@@ -372,7 +374,10 @@ func iterateObjects(ctx context.Context, metabaseDB MetabaseDB, observers []*obs
 		limit = batchsizeLimit
 	}
 
-	startingTime := time.Now()
+	startingTime, err := metabaseDB.Now(ctx)
+	if err != nil {
+		return observers, Error.Wrap(err)
+	}
 
 	noObserversErr := errs.New("no observers")
 
diff --git a/satellite/metainfo/config.go b/satellite/metainfo/config.go
index f1a3eb0b9..0aa8fc977 100644
--- a/satellite/metainfo/config.go
+++ b/satellite/metainfo/config.go
@@ -131,6 +131,9 @@ type Config struct {
 type MetabaseDB interface {
 	io.Closer
 
+	// Now returns time on the database.
+	Now(ctx context.Context) (time.Time, error)
+
 	// MigrateToLatest migrates to latest schema version.
 	MigrateToLatest(ctx context.Context) error
 	// CheckVersion checks the database is the correct version