From 211ac0501f0f048d160d3dbd2df88733a41d4467 Mon Sep 17 00:00:00 2001
From: Andrey Smirnov <smirnov.andrey@gmail.com>
Date: Wed, 5 Jul 2017 00:17:48 +0300
Subject: [PATCH 1/2] Rework the way database is open/re-open in aptly

Allow database to be initialized without opening, unify all the
open paths to retry on failure.

In API router make sure open requests are matched with acks in explicit
way.

This also enables re-open attempts in all the aptly commands, so it
should make running aptly CLI much easier now hopefully.

Fix up system tests for oldoldstable ;)
---
 api/api.go                                    | 51 ++++++++++---------
 api/router.go                                 | 26 +++++-----
 cmd/cmd.go                                    |  1 +
 context/context.go                            | 49 ++++++++++--------
 database/leveldb.go                           | 20 +++++---
 database/leveldb_test.go                      |  6 +--
 deb/checksum_collection_test.go               |  2 +-
 deb/local_test.go                             |  4 +-
 deb/package_collection_test.go                |  2 +-
 deb/publish_test.go                           |  6 +--
 deb/reflist_test.go                           |  6 +--
 deb/remote_test.go                            |  4 +-
 deb/snapshot_test.go                          |  2 +-
 main.go                                       |  4 ++
 man/aptly.1                                   |  6 ++-
 system/t03_help/MainHelpTest_gold             |  1 +
 system/t03_help/MainTest_gold                 |  1 +
 system/t03_help/MirrorCreateHelpTest_gold     |  1 +
 system/t03_help/MirrorCreateTest_gold         |  1 +
 system/t03_help/MirrorHelpTest_gold           |  1 +
 system/t03_help/MirrorTest_gold               |  1 +
 system/t03_help/WrongFlagTest_gold            |  1 +
 .../t04_mirror/CreateMirror11Test_mirror_show |  4 +-
 .../t04_mirror/CreateMirror13Test_mirror_show |  4 +-
 .../t04_mirror/CreateMirror17Test_mirror_show |  4 +-
 .../t04_mirror/CreateMirror19Test_mirror_show |  2 +-
 .../t04_mirror/CreateMirror1Test_mirror_show  |  4 +-
 .../t04_mirror/CreateMirror22Test_mirror_show |  2 +-
 .../t04_mirror/CreateMirror25Test_mirror_show |  4 +-
 .../t04_mirror/CreateMirror2Test_mirror_show  |  4 +-
 .../t04_mirror/CreateMirror3Test_mirror_show  |  4 +-
 .../t04_mirror/CreateMirror7Test_mirror_show  |  4 +-
 system/t04_mirror/EditMirror5Test_mirror_show |  2 +-
 system/t04_mirror/EditMirror6Test_mirror_show |  4 +-
 system/t04_mirror/ShowMirror1Test_gold        |  4 +-
 system/t04_mirror/ShowMirror4Test_gold        |  2 +-
 36 files changed, 138 insertions(+), 106 deletions(-)

diff --git a/api/api.go b/api/api.go
index c15e8ec0..d9820e01 100644
--- a/api/api.go
+++ b/api/api.go
@@ -23,11 +23,18 @@ func apiVersion(c *gin.Context) {
 	c.JSON(200, gin.H{"Version": aptly.Version})
 }
 
+type dbRequestKind int
+
 const (
-	acquiredb = iota
+	acquiredb dbRequestKind = iota
 	releasedb
 )
 
+type dbRequest struct {
+	kind dbRequestKind
+	err  chan<- error
+}
+
 // Flushes all collections which cache in-memory objects
 func flushColections() {
 	// lock everything to eliminate in-progress calls
@@ -52,50 +59,48 @@ func flushColections() {
 }
 
 // Periodically flushes CollectionFactory to free up memory used by
-// collections, flushing caches. If the two channels are provided,
-// they are used to acquire and release the database.
+// collections, flushing caches.
 //
 // Should be run in goroutine!
-func cacheFlusher(requests chan int, acks chan error) {
+func cacheFlusher() {
 	ticker := time.Tick(15 * time.Minute)
 
 	for {
 		<-ticker
 
-		// if aptly API runs in -no-lock mode,
-		// caches are flushed when DB is closed anyway, no need
-		// to flush them here
-		if requests == nil {
-			flushColections()
-		}
+		flushColections()
 	}
 }
 
-// Acquire database lock and release it when not needed anymore. Two
-// channels must be provided. The first one is to receive requests to
-// acquire/release the database and the second one is to send acks.
+// Acquire database lock and release it when not needed anymore.
 //
 // Should be run in a goroutine!
-func acquireDatabase(requests chan int, acks chan error) {
+func acquireDatabase(requests <-chan dbRequest) {
 	clients := 0
-	for {
-		request := <-requests
-		switch request {
+	for request := range requests {
+		var err error
+
+		switch request.kind {
 		case acquiredb:
 			if clients == 0 {
-				acks <- context.ReOpenDatabase()
-			} else {
-				acks <- nil
+				err = context.ReOpenDatabase()
+			}
+
+			request.err <- err
+
+			if err == nil {
+				clients++
 			}
-			clients++
 		case releasedb:
 			clients--
 			if clients == 0 {
 				flushColections()
-				acks <- context.CloseDatabase()
+				err = context.CloseDatabase()
 			} else {
-				acks <- nil
+				err = nil
 			}
+
+			request.err <- err
 		}
 	}
 }
diff --git a/api/router.go b/api/router.go
index 6adca87f..cdbf0c13 100644
--- a/api/router.go
+++ b/api/router.go
@@ -20,35 +20,35 @@ func Router(c *ctx.AptlyContext) http.Handler {
 		// We use a goroutine to count the number of
 		// concurrent requests. When no more requests are
 		// running, we close the database to free the lock.
-		requests := make(chan int)
-		acks := make(chan error)
+		requests := make(chan dbRequest)
 
-		go acquireDatabase(requests, acks)
-		go cacheFlusher(requests, acks)
+		go acquireDatabase(requests)
 
 		router.Use(func(c *gin.Context) {
 			var err error
 
-			requests <- acquiredb
+			errCh := make(chan error)
+			requests <- dbRequest{acquiredb, errCh}
+
+			err = <-errCh
+			if err != nil {
+				c.Fail(500, err)
+				return
+			}
 
 			defer func() {
-				requests <- releasedb
-				err = <-acks
+				requests <- dbRequest{releasedb, errCh}
+				err = <-errCh
 				if err != nil {
 					c.Fail(500, err)
 				}
 			}()
 
-			err = <-acks
-			if err != nil {
-				c.Fail(500, err)
-				return
-			}
 			c.Next()
 		})
 
 	} else {
-		go cacheFlusher(nil, nil)
+		go cacheFlusher()
 	}
 
 	root := router.Group("/api")
diff --git a/cmd/cmd.go b/cmd/cmd.go
index 8ce39df8..1d360787 100644
--- a/cmd/cmd.go
+++ b/cmd/cmd.go
@@ -111,6 +111,7 @@ package environment to new version.`,
 		},
 	}
 
+	cmd.Flag.Int("db-open-attempts", 10, "number of attempts to open DB if it's locked by other instance")
 	cmd.Flag.Bool("dep-follow-suggests", false, "when processing dependencies, follow Suggests")
 	cmd.Flag.Bool("dep-follow-source", false, "when processing dependencies, follow from binary to Source packages")
 	cmd.Flag.Bool("dep-follow-recommends", false, "when processing dependencies, follow Recommends")
diff --git a/context/context.go b/context/context.go
index 955416c2..c1b13d29 100644
--- a/context/context.go
+++ b/context/context.go
@@ -3,6 +3,7 @@ package context
 
 import (
 	"fmt"
+	"math/rand"
 	"os"
 	"path/filepath"
 	"runtime"
@@ -238,13 +239,34 @@ func (context *AptlyContext) _database() (database.Storage, error) {
 	if context.database == nil {
 		var err error
 
-		context.database, err = database.OpenDB(context.dbPath())
+		context.database, err = database.NewDB(context.dbPath())
 		if err != nil {
-			return nil, fmt.Errorf("can't open database: %s", err)
+			return nil, fmt.Errorf("can't instanciate database: %s", err)
 		}
 	}
 
-	return context.database, nil
+	tries := context.flags.Lookup("db-open-attempts").Value.Get().(int)
+	const BaseDelay = 10 * time.Second
+	const Jitter = 1 * time.Second
+
+	for ; tries >= 0; tries-- {
+		err := context.database.Open()
+		if err == nil || !strings.Contains(err.Error(), "resource temporarily unavailable") {
+			return context.database, err
+		}
+
+		if tries > 0 {
+			delay := time.Duration(rand.NormFloat64()*float64(Jitter) + float64(BaseDelay))
+			if delay < 0 {
+				delay = time.Second
+			}
+
+			context._progress().Printf("Unable to open database, sleeping %s, attempts left %d...\n", delay, tries)
+			time.Sleep(delay)
+		}
+	}
+
+	return nil, fmt.Errorf("unable to reopen the DB, maximum number of retries reached")
 }
 
 // CloseDatabase closes the db temporarily
@@ -261,26 +283,9 @@ func (context *AptlyContext) CloseDatabase() error {
 
 // ReOpenDatabase reopens the db after close
 func (context *AptlyContext) ReOpenDatabase() error {
-	context.Lock()
-	defer context.Unlock()
+	_, err := context.Database()
 
-	if context.database == nil {
-		return nil
-	}
-
-	const MaxTries = 10
-	const Delay = 10 * time.Second
-
-	for try := 0; try < MaxTries; try++ {
-		err := context.database.ReOpen()
-		if err == nil || !strings.Contains(err.Error(), "resource temporarily unavailable") {
-			return err
-		}
-		context._progress().Printf("Unable to reopen database, sleeping %s\n", Delay)
-		<-time.After(Delay)
-	}
-
-	return fmt.Errorf("unable to reopen the DB, maximum number of retries reached")
+	return err
 }
 
 // CollectionFactory builds factory producing all kinds of collections
diff --git a/database/leveldb.go b/database/leveldb.go
index 8b065725..bea1c84f 100644
--- a/database/leveldb.go
+++ b/database/leveldb.go
@@ -32,8 +32,8 @@ type Storage interface {
 	ProcessByPrefix(prefix []byte, proc StorageProcessor) error
 	KeysByPrefix(prefix []byte) [][]byte
 	FetchByPrefix(prefix []byte) [][]byte
+	Open() error
 	Close() error
-	ReOpen() error
 	StartBatch()
 	FinishBatch() error
 	CompactDB() error
@@ -66,13 +66,19 @@ func internalOpen(path string, throttleCompaction bool) (*leveldb.DB, error) {
 	return leveldb.OpenFile(path, o)
 }
 
-// OpenDB opens (creates) LevelDB database
-func OpenDB(path string) (Storage, error) {
-	db, err := internalOpen(path, false)
+// NewDB creates new instance of DB, but doesn't open it (yet)
+func NewDB(path string) (Storage, error) {
+	return &levelDB{path: path}, nil
+}
+
+// NewOpenDB creates new instance of DB and opens it
+func NewOpenDB(path string) (Storage, error) {
+	db, err := NewDB(path)
 	if err != nil {
 		return nil, err
 	}
-	return &levelDB{db: db, path: path}, nil
+
+	return db, db.Open()
 }
 
 // RecoverDB recovers LevelDB database from corruption
@@ -215,8 +221,8 @@ func (l *levelDB) Close() error {
 	return err
 }
 
-// Reopen tries to re-open the database
-func (l *levelDB) ReOpen() error {
+// Reopen tries to open (re-open) the database
+func (l *levelDB) Open() error {
 	if l.db != nil {
 		return nil
 	}
diff --git a/database/leveldb_test.go b/database/leveldb_test.go
index 155a3120..21f43a24 100644
--- a/database/leveldb_test.go
+++ b/database/leveldb_test.go
@@ -22,7 +22,7 @@ func (s *LevelDBSuite) SetUpTest(c *C) {
 	var err error
 
 	s.path = c.MkDir()
-	s.db, err = OpenDB(s.path)
+	s.db, err = NewOpenDB(s.path)
 	c.Assert(err, IsNil)
 }
 
@@ -46,7 +46,7 @@ func (s *LevelDBSuite) TestRecoverDB(c *C) {
 	err = RecoverDB(s.path)
 	c.Check(err, IsNil)
 
-	s.db, err = OpenDB(s.path)
+	s.db, err = NewOpenDB(s.path)
 	c.Check(err, IsNil)
 
 	result, err := s.db.Get(key)
@@ -223,7 +223,7 @@ func (s *LevelDBSuite) TestReOpen(c *C) {
 	err = s.db.Close()
 	c.Assert(err, IsNil)
 
-	err = s.db.ReOpen()
+	err = s.db.Open()
 	c.Assert(err, IsNil)
 
 	result, err := s.db.Get(key)
diff --git a/deb/checksum_collection_test.go b/deb/checksum_collection_test.go
index a93e6d26..cf64e2d0 100644
--- a/deb/checksum_collection_test.go
+++ b/deb/checksum_collection_test.go
@@ -22,7 +22,7 @@ func (s *ChecksumCollectionSuite) SetUpTest(c *C) {
 		SHA1:   "da39a3ee5e6b4b0d3255bfef95601890afd80709",
 		SHA256: "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
 	}
-	s.db, _ = database.OpenDB(c.MkDir())
+	s.db, _ = database.NewOpenDB(c.MkDir())
 	s.collection = NewChecksumCollection(s.db)
 }
 
diff --git a/deb/local_test.go b/deb/local_test.go
index 98a99bf8..76455ad6 100644
--- a/deb/local_test.go
+++ b/deb/local_test.go
@@ -18,7 +18,7 @@ type LocalRepoSuite struct {
 var _ = Suite(&LocalRepoSuite{})
 
 func (s *LocalRepoSuite) SetUpTest(c *C) {
-	s.db, _ = database.OpenDB(c.MkDir())
+	s.db, _ = database.NewOpenDB(c.MkDir())
 	s.list = NewPackageList()
 	s.list.Add(&Package{Name: "lib", Version: "1.7", Architecture: "i386"})
 	s.list.Add(&Package{Name: "app", Version: "1.9", Architecture: "amd64"})
@@ -83,7 +83,7 @@ type LocalRepoCollectionSuite struct {
 var _ = Suite(&LocalRepoCollectionSuite{})
 
 func (s *LocalRepoCollectionSuite) SetUpTest(c *C) {
-	s.db, _ = database.OpenDB(c.MkDir())
+	s.db, _ = database.NewOpenDB(c.MkDir())
 	s.collection = NewLocalRepoCollection(s.db)
 
 	s.list = NewPackageList()
diff --git a/deb/package_collection_test.go b/deb/package_collection_test.go
index 89e364a1..b11e3f21 100644
--- a/deb/package_collection_test.go
+++ b/deb/package_collection_test.go
@@ -17,7 +17,7 @@ var _ = Suite(&PackageCollectionSuite{})
 
 func (s *PackageCollectionSuite) SetUpTest(c *C) {
 	s.p = NewPackageFromControlFile(packageStanza.Copy())
-	s.db, _ = database.OpenDB(c.MkDir())
+	s.db, _ = database.NewOpenDB(c.MkDir())
 	s.collection = NewPackageCollection(s.db)
 }
 
diff --git a/deb/publish_test.go b/deb/publish_test.go
index ace1bce8..eb0ff55b 100644
--- a/deb/publish_test.go
+++ b/deb/publish_test.go
@@ -87,7 +87,7 @@ var _ = Suite(&PublishedRepoSuite{})
 func (s *PublishedRepoSuite) SetUpTest(c *C) {
 	s.SetUpPackages()
 
-	s.db, _ = database.OpenDB(c.MkDir())
+	s.db, _ = database.NewOpenDB(c.MkDir())
 	s.factory = NewCollectionFactory(s.db)
 
 	s.root = c.MkDir()
@@ -449,7 +449,7 @@ type PublishedRepoCollectionSuite struct {
 var _ = Suite(&PublishedRepoCollectionSuite{})
 
 func (s *PublishedRepoCollectionSuite) SetUpTest(c *C) {
-	s.db, _ = database.OpenDB(c.MkDir())
+	s.db, _ = database.NewOpenDB(c.MkDir())
 	s.factory = NewCollectionFactory(s.db)
 
 	s.snapshotCollection = s.factory.SnapshotCollection()
@@ -640,7 +640,7 @@ type PublishedRepoRemoveSuite struct {
 var _ = Suite(&PublishedRepoRemoveSuite{})
 
 func (s *PublishedRepoRemoveSuite) SetUpTest(c *C) {
-	s.db, _ = database.OpenDB(c.MkDir())
+	s.db, _ = database.NewOpenDB(c.MkDir())
 	s.factory = NewCollectionFactory(s.db)
 
 	s.snapshotCollection = s.factory.SnapshotCollection()
diff --git a/deb/reflist_test.go b/deb/reflist_test.go
index da224177..d1824762 100644
--- a/deb/reflist_test.go
+++ b/deb/reflist_test.go
@@ -44,7 +44,7 @@ func (s *PackageRefListSuite) SetUpTest(c *C) {
 }
 
 func (s *PackageRefListSuite) TestNewPackageListFromRefList(c *C) {
-	db, _ := database.OpenDB(c.MkDir())
+	db, _ := database.NewOpenDB(c.MkDir())
 	coll := NewPackageCollection(db)
 	coll.Update(s.p1)
 	coll.Update(s.p3)
@@ -166,7 +166,7 @@ func (s *PackageRefListSuite) TestSubstract(c *C) {
 }
 
 func (s *PackageRefListSuite) TestDiff(c *C) {
-	db, _ := database.OpenDB(c.MkDir())
+	db, _ := database.NewOpenDB(c.MkDir())
 	coll := NewPackageCollection(db)
 
 	packages := []*Package{
@@ -238,7 +238,7 @@ func (s *PackageRefListSuite) TestDiff(c *C) {
 }
 
 func (s *PackageRefListSuite) TestMerge(c *C) {
-	db, _ := database.OpenDB(c.MkDir())
+	db, _ := database.NewOpenDB(c.MkDir())
 	coll := NewPackageCollection(db)
 
 	packages := []*Package{
diff --git a/deb/remote_test.go b/deb/remote_test.go
index 22321525..9bb9301f 100644
--- a/deb/remote_test.go
+++ b/deb/remote_test.go
@@ -92,7 +92,7 @@ func (s *RemoteRepoSuite) SetUpTest(c *C) {
 	s.flat, _ = NewRemoteRepo("exp42", "http://repos.express42.com/virool/precise/", "./", []string{}, []string{}, false, false)
 	s.downloader = http.NewFakeDownloader().ExpectResponse("http://mirror.yandex.ru/debian/dists/squeeze/Release", exampleReleaseFile)
 	s.progress = console.NewProgress()
-	s.db, _ = database.OpenDB(c.MkDir())
+	s.db, _ = database.NewOpenDB(c.MkDir())
 	s.collectionFactory = NewCollectionFactory(s.db)
 	s.packagePool = files.NewPackagePool(c.MkDir(), false)
 	s.cs = files.NewMockChecksumStorage()
@@ -615,7 +615,7 @@ type RemoteRepoCollectionSuite struct {
 var _ = Suite(&RemoteRepoCollectionSuite{})
 
 func (s *RemoteRepoCollectionSuite) SetUpTest(c *C) {
-	s.db, _ = database.OpenDB(c.MkDir())
+	s.db, _ = database.NewOpenDB(c.MkDir())
 	s.collection = NewRemoteRepoCollection(s.db)
 	s.SetUpPackages()
 }
diff --git a/deb/snapshot_test.go b/deb/snapshot_test.go
index 63890dcd..ba1bb247 100644
--- a/deb/snapshot_test.go
+++ b/deb/snapshot_test.go
@@ -112,7 +112,7 @@ type SnapshotCollectionSuite struct {
 var _ = Suite(&SnapshotCollectionSuite{})
 
 func (s *SnapshotCollectionSuite) SetUpTest(c *C) {
-	s.db, _ = database.OpenDB(c.MkDir())
+	s.db, _ = database.NewOpenDB(c.MkDir())
 	s.collection = NewSnapshotCollection(s.db)
 	s.SetUpPackages()
 
diff --git a/main.go b/main.go
index edb2c30b..e192a86e 100644
--- a/main.go
+++ b/main.go
@@ -1,7 +1,9 @@
 package main
 
 import (
+	"math/rand"
 	"os"
+	"time"
 
 	"github.com/smira/aptly/aptly"
 	"github.com/smira/aptly/cmd"
@@ -17,5 +19,7 @@ func main() {
 
 	aptly.Version = Version
 
+	rand.Seed(time.Now().UnixNano())
+
 	os.Exit(cmd.Run(cmd.RootCommand(), os.Args[1:], true))
 }
diff --git a/man/aptly.1 b/man/aptly.1
index cd94e78f..e3f893b4 100644
--- a/man/aptly.1
+++ b/man/aptly.1
@@ -1,7 +1,7 @@
 .\" generated with Ronn/v0.7.3
 .\" http://github.com/rtomayko/ronn/tree/0.7.3
 .
-.TH "APTLY" "1" "April 2017" "" ""
+.TH "APTLY" "1" "July 2017" "" ""
 .
 .SH "NAME"
 \fBaptly\fR \- Debian repository management tool
@@ -392,6 +392,10 @@ list of architectures to consider during (comma\-separated), default to all avai
 location of configuration file (default locations are /etc/aptly\.conf, ~/\.aptly\.conf)
 .
 .TP
+\-\fBdb\-open\-attempts\fR=10
+number of attempts to open DB if it\(cqs locked by other instance
+.
+.TP
 \-\fBdep\-follow\-all\-variants\fR=false
 when processing dependencies, follow a & b if dependency is \(cqa|b\(cq
 .
diff --git a/system/t03_help/MainHelpTest_gold b/system/t03_help/MainHelpTest_gold
index aca7b6cf..2d97b08b 100644
--- a/system/t03_help/MainHelpTest_gold
+++ b/system/t03_help/MainHelpTest_gold
@@ -13,6 +13,7 @@ package environment to new version.
 Options:
   -architectures="": list of architectures to consider during (comma-separated), default to all available
   -config="": location of configuration file (default locations are /etc/aptly.conf, ~/.aptly.conf)
+  -db-open-attempts=10: number of attempts to open DB if it's locked by other instance
   -dep-follow-all-variants=false: when processing dependencies, follow a & b if dependency is 'a|b'
   -dep-follow-recommends=false: when processing dependencies, follow Recommends
   -dep-follow-source=false: when processing dependencies, follow from binary to Source packages
diff --git a/system/t03_help/MainTest_gold b/system/t03_help/MainTest_gold
index 603f3d59..94d476bc 100644
--- a/system/t03_help/MainTest_gold
+++ b/system/t03_help/MainTest_gold
@@ -21,6 +21,7 @@ Use "aptly help <command>" for more information about a command.
 Options:
   -architectures="": list of architectures to consider during (comma-separated), default to all available
   -config="": location of configuration file (default locations are /etc/aptly.conf, ~/.aptly.conf)
+  -db-open-attempts=10: number of attempts to open DB if it's locked by other instance
   -dep-follow-all-variants=false: when processing dependencies, follow a & b if dependency is 'a|b'
   -dep-follow-recommends=false: when processing dependencies, follow Recommends
   -dep-follow-source=false: when processing dependencies, follow from binary to Source packages
diff --git a/system/t03_help/MirrorCreateHelpTest_gold b/system/t03_help/MirrorCreateHelpTest_gold
index c38b22d3..9889dadb 100644
--- a/system/t03_help/MirrorCreateHelpTest_gold
+++ b/system/t03_help/MirrorCreateHelpTest_gold
@@ -15,6 +15,7 @@ Example:
 Options:
   -architectures="": list of architectures to consider during (comma-separated), default to all available
   -config="": location of configuration file (default locations are /etc/aptly.conf, ~/.aptly.conf)
+  -db-open-attempts=10: number of attempts to open DB if it's locked by other instance
   -dep-follow-all-variants=false: when processing dependencies, follow a & b if dependency is 'a|b'
   -dep-follow-recommends=false: when processing dependencies, follow Recommends
   -dep-follow-source=false: when processing dependencies, follow from binary to Source packages
diff --git a/system/t03_help/MirrorCreateTest_gold b/system/t03_help/MirrorCreateTest_gold
index a0f93be5..8ecef76e 100644
--- a/system/t03_help/MirrorCreateTest_gold
+++ b/system/t03_help/MirrorCreateTest_gold
@@ -6,6 +6,7 @@ aptly mirror create - create new mirror
 Options:
   -architectures="": list of architectures to consider during (comma-separated), default to all available
   -config="": location of configuration file (default locations are /etc/aptly.conf, ~/.aptly.conf)
+  -db-open-attempts=10: number of attempts to open DB if it's locked by other instance
   -dep-follow-all-variants=false: when processing dependencies, follow a & b if dependency is 'a|b'
   -dep-follow-recommends=false: when processing dependencies, follow Recommends
   -dep-follow-source=false: when processing dependencies, follow from binary to Source packages
diff --git a/system/t03_help/MirrorHelpTest_gold b/system/t03_help/MirrorHelpTest_gold
index e72eb6fc..dabffe60 100644
--- a/system/t03_help/MirrorHelpTest_gold
+++ b/system/t03_help/MirrorHelpTest_gold
@@ -17,6 +17,7 @@ Use "mirror help <command>" for more information about a command.
 Options:
   -architectures="": list of architectures to consider during (comma-separated), default to all available
   -config="": location of configuration file (default locations are /etc/aptly.conf, ~/.aptly.conf)
+  -db-open-attempts=10: number of attempts to open DB if it's locked by other instance
   -dep-follow-all-variants=false: when processing dependencies, follow a & b if dependency is 'a|b'
   -dep-follow-recommends=false: when processing dependencies, follow Recommends
   -dep-follow-source=false: when processing dependencies, follow from binary to Source packages
diff --git a/system/t03_help/MirrorTest_gold b/system/t03_help/MirrorTest_gold
index a685ca02..a0806da5 100644
--- a/system/t03_help/MirrorTest_gold
+++ b/system/t03_help/MirrorTest_gold
@@ -17,6 +17,7 @@ Use "mirror help <command>" for more information about a command.
 Options:
   -architectures="": list of architectures to consider during (comma-separated), default to all available
   -config="": location of configuration file (default locations are /etc/aptly.conf, ~/.aptly.conf)
+  -db-open-attempts=10: number of attempts to open DB if it's locked by other instance
   -dep-follow-all-variants=false: when processing dependencies, follow a & b if dependency is 'a|b'
   -dep-follow-recommends=false: when processing dependencies, follow Recommends
   -dep-follow-source=false: when processing dependencies, follow from binary to Source packages
diff --git a/system/t03_help/WrongFlagTest_gold b/system/t03_help/WrongFlagTest_gold
index 17cda4c2..449977bc 100644
--- a/system/t03_help/WrongFlagTest_gold
+++ b/system/t03_help/WrongFlagTest_gold
@@ -7,6 +7,7 @@ aptly mirror create - create new mirror
 Options:
   -architectures="": list of architectures to consider during (comma-separated), default to all available
   -config="": location of configuration file (default locations are /etc/aptly.conf, ~/.aptly.conf)
+  -db-open-attempts=10: number of attempts to open DB if it's locked by other instance
   -dep-follow-all-variants=false: when processing dependencies, follow a & b if dependency is 'a|b'
   -dep-follow-recommends=false: when processing dependencies, follow Recommends
   -dep-follow-source=false: when processing dependencies, follow from binary to Source packages
diff --git a/system/t04_mirror/CreateMirror11Test_mirror_show b/system/t04_mirror/CreateMirror11Test_mirror_show
index 2369a407..c8081bad 100644
--- a/system/t04_mirror/CreateMirror11Test_mirror_show
+++ b/system/t04_mirror/CreateMirror11Test_mirror_show
@@ -11,10 +11,10 @@ Information from release file:
 Architectures: amd64 armel armhf i386 ia64 kfreebsd-amd64 kfreebsd-i386 mips mipsel powerpc s390 s390x sparc
 Codename: wheezy
 Components: main contrib non-free
-Date: Sat, 04 Jun 2016 11:47:54 UTC
+Date: Sat, 17 Jun 2017 08:55:32 UTC
 Description:  Debian 7.11 Released 04 June 2016
 
 Label: Debian
 Origin: Debian
-Suite: oldstable
+Suite: oldoldstable
 Version: 7.11
diff --git a/system/t04_mirror/CreateMirror13Test_mirror_show b/system/t04_mirror/CreateMirror13Test_mirror_show
index 4716d755..d91e9a7a 100644
--- a/system/t04_mirror/CreateMirror13Test_mirror_show
+++ b/system/t04_mirror/CreateMirror13Test_mirror_show
@@ -11,10 +11,10 @@ Information from release file:
 Architectures: amd64 armel armhf i386 ia64 kfreebsd-amd64 kfreebsd-i386 mips mipsel powerpc s390 s390x sparc
 Codename: wheezy
 Components: main contrib non-free
-Date: Sat, 04 Jun 2016 11:47:54 UTC
+Date: Sat, 17 Jun 2017 08:55:32 UTC
 Description:  Debian 7.11 Released 04 June 2016
 
 Label: Debian
 Origin: Debian
-Suite: oldstable
+Suite: oldoldstable
 Version: 7.11
diff --git a/system/t04_mirror/CreateMirror17Test_mirror_show b/system/t04_mirror/CreateMirror17Test_mirror_show
index f7aaf047..f1d42987 100644
--- a/system/t04_mirror/CreateMirror17Test_mirror_show
+++ b/system/t04_mirror/CreateMirror17Test_mirror_show
@@ -11,10 +11,10 @@ Information from release file:
 Architectures: amd64 armel armhf i386 ia64 kfreebsd-amd64 kfreebsd-i386 mips mipsel powerpc s390 s390x sparc
 Codename: wheezy
 Components: main contrib non-free
-Date: Sat, 04 Jun 2016 11:47:54 UTC
+Date: Sat, 17 Jun 2017 08:55:32 UTC
 Description:  Debian 7.11 Released 04 June 2016
 
 Label: Debian
 Origin: Debian
-Suite: oldstable
+Suite: oldoldstable
 Version: 7.11
diff --git a/system/t04_mirror/CreateMirror19Test_mirror_show b/system/t04_mirror/CreateMirror19Test_mirror_show
index 1e3ae991..1f30d822 100644
--- a/system/t04_mirror/CreateMirror19Test_mirror_show
+++ b/system/t04_mirror/CreateMirror19Test_mirror_show
@@ -15,5 +15,5 @@ Description:  Long Term Support for Debian 7
 
 Label: Debian-Security
 Origin: Debian
-Suite: oldstable
+Suite: oldoldstable
 Version: 7.0
diff --git a/system/t04_mirror/CreateMirror1Test_mirror_show b/system/t04_mirror/CreateMirror1Test_mirror_show
index d085a10f..9234b079 100644
--- a/system/t04_mirror/CreateMirror1Test_mirror_show
+++ b/system/t04_mirror/CreateMirror1Test_mirror_show
@@ -11,10 +11,10 @@ Information from release file:
 Architectures: amd64 armel armhf i386 ia64 kfreebsd-amd64 kfreebsd-i386 mips mipsel powerpc s390 s390x sparc
 Codename: wheezy
 Components: main contrib non-free
-Date: Sat, 04 Jun 2016 11:47:54 UTC
+Date: Sat, 17 Jun 2017 08:55:32 UTC
 Description:  Debian 7.11 Released 04 June 2016
 
 Label: Debian
 Origin: Debian
-Suite: oldstable
+Suite: oldoldstable
 Version: 7.11
diff --git a/system/t04_mirror/CreateMirror22Test_mirror_show b/system/t04_mirror/CreateMirror22Test_mirror_show
index 378ad062..cade92ff 100644
--- a/system/t04_mirror/CreateMirror22Test_mirror_show
+++ b/system/t04_mirror/CreateMirror22Test_mirror_show
@@ -17,5 +17,5 @@ Description:  Long Term Support for Debian 7
 
 Label: Debian-Security
 Origin: Debian
-Suite: oldstable
+Suite: oldoldstable
 Version: 7.0
diff --git a/system/t04_mirror/CreateMirror25Test_mirror_show b/system/t04_mirror/CreateMirror25Test_mirror_show
index 193d91b2..bece2370 100644
--- a/system/t04_mirror/CreateMirror25Test_mirror_show
+++ b/system/t04_mirror/CreateMirror25Test_mirror_show
@@ -11,10 +11,10 @@ Information from release file:
 Architectures: amd64 armel armhf i386 ia64 kfreebsd-amd64 kfreebsd-i386 mips mipsel powerpc s390 s390x sparc
 Codename: wheezy
 Components: main contrib non-free
-Date: Sat, 04 Jun 2016 11:47:54 UTC
+Date: Sat, 17 Jun 2017 08:55:32 UTC
 Description:  Debian 7.11 Released 04 June 2016
 
 Label: Debian
 Origin: Debian
-Suite: oldstable
+Suite: oldoldstable
 Version: 7.11
diff --git a/system/t04_mirror/CreateMirror2Test_mirror_show b/system/t04_mirror/CreateMirror2Test_mirror_show
index 6f512cb6..1db78329 100644
--- a/system/t04_mirror/CreateMirror2Test_mirror_show
+++ b/system/t04_mirror/CreateMirror2Test_mirror_show
@@ -11,10 +11,10 @@ Information from release file:
 Architectures: amd64 armel armhf i386 ia64 kfreebsd-amd64 kfreebsd-i386 mips mipsel powerpc s390 s390x sparc
 Codename: wheezy
 Components: main contrib non-free
-Date: Sat, 04 Jun 2016 11:47:54 UTC
+Date: Sat, 17 Jun 2017 08:55:32 UTC
 Description:  Debian 7.11 Released 04 June 2016
 
 Label: Debian
 Origin: Debian
-Suite: oldstable
+Suite: oldoldstable
 Version: 7.11
diff --git a/system/t04_mirror/CreateMirror3Test_mirror_show b/system/t04_mirror/CreateMirror3Test_mirror_show
index 6407d429..4af9bd7c 100644
--- a/system/t04_mirror/CreateMirror3Test_mirror_show
+++ b/system/t04_mirror/CreateMirror3Test_mirror_show
@@ -11,10 +11,10 @@ Information from release file:
 Architectures: amd64 armel armhf i386 ia64 kfreebsd-amd64 kfreebsd-i386 mips mipsel powerpc s390 s390x sparc
 Codename: wheezy
 Components: main contrib non-free
-Date: Sat, 04 Jun 2016 11:47:54 UTC
+Date: Sat, 17 Jun 2017 08:55:32 UTC
 Description:  Debian 7.11 Released 04 June 2016
 
 Label: Debian
 Origin: Debian
-Suite: oldstable
+Suite: oldoldstable
 Version: 7.11
diff --git a/system/t04_mirror/CreateMirror7Test_mirror_show b/system/t04_mirror/CreateMirror7Test_mirror_show
index 6c748350..d2b2014c 100644
--- a/system/t04_mirror/CreateMirror7Test_mirror_show
+++ b/system/t04_mirror/CreateMirror7Test_mirror_show
@@ -11,10 +11,10 @@ Information from release file:
 Architectures: amd64 armel armhf i386 ia64 kfreebsd-amd64 kfreebsd-i386 mips mipsel powerpc s390 s390x sparc
 Codename: wheezy
 Components: main contrib non-free
-Date: Sat, 04 Jun 2016 11:47:54 UTC
+Date: Sat, 17 Jun 2017 08:55:32 UTC
 Description:  Debian 7.11 Released 04 June 2016
 
 Label: Debian
 Origin: Debian
-Suite: oldstable
+Suite: oldoldstable
 Version: 7.11
diff --git a/system/t04_mirror/EditMirror5Test_mirror_show b/system/t04_mirror/EditMirror5Test_mirror_show
index 8f583817..c952ee3e 100644
--- a/system/t04_mirror/EditMirror5Test_mirror_show
+++ b/system/t04_mirror/EditMirror5Test_mirror_show
@@ -15,5 +15,5 @@ Description:  Long Term Support for Debian 7
 
 Label: Debian-Security
 Origin: Debian
-Suite: oldstable
+Suite: oldoldstable
 Version: 7.0
diff --git a/system/t04_mirror/EditMirror6Test_mirror_show b/system/t04_mirror/EditMirror6Test_mirror_show
index 08627cc6..a325dfe1 100644
--- a/system/t04_mirror/EditMirror6Test_mirror_show
+++ b/system/t04_mirror/EditMirror6Test_mirror_show
@@ -11,10 +11,10 @@ Information from release file:
 Architectures: amd64 armel armhf i386 ia64 kfreebsd-amd64 kfreebsd-i386 mips mipsel powerpc s390 s390x sparc
 Codename: wheezy
 Components: main contrib non-free
-Date: Sat, 04 Jun 2016 11:47:54 UTC
+Date: Sat, 17 Jun 2017 08:55:32 UTC
 Description:  Debian 7.11 Released 04 June 2016
 
 Label: Debian
 Origin: Debian
-Suite: oldstable
+Suite: oldoldstable
 Version: 7.11
diff --git a/system/t04_mirror/ShowMirror1Test_gold b/system/t04_mirror/ShowMirror1Test_gold
index d085a10f..9234b079 100644
--- a/system/t04_mirror/ShowMirror1Test_gold
+++ b/system/t04_mirror/ShowMirror1Test_gold
@@ -11,10 +11,10 @@ Information from release file:
 Architectures: amd64 armel armhf i386 ia64 kfreebsd-amd64 kfreebsd-i386 mips mipsel powerpc s390 s390x sparc
 Codename: wheezy
 Components: main contrib non-free
-Date: Sat, 04 Jun 2016 11:47:54 UTC
+Date: Sat, 17 Jun 2017 08:55:32 UTC
 Description:  Debian 7.11 Released 04 June 2016
 
 Label: Debian
 Origin: Debian
-Suite: oldstable
+Suite: oldoldstable
 Version: 7.11
diff --git a/system/t04_mirror/ShowMirror4Test_gold b/system/t04_mirror/ShowMirror4Test_gold
index a3ce5404..e8b14605 100644
--- a/system/t04_mirror/ShowMirror4Test_gold
+++ b/system/t04_mirror/ShowMirror4Test_gold
@@ -17,5 +17,5 @@ Description:  Long Term Support for Debian 7
 
 Label: Debian-Security
 Origin: Debian
-Suite: oldstable
+Suite: oldoldstable
 Version: 7.0

From c13eb9992544ad956b701eee1e7952b27147b645 Mon Sep 17 00:00:00 2001
From: Andrey Smirnov <smirnov.andrey@gmail.com>
Date: Wed, 5 Jul 2017 00:36:48 +0300
Subject: [PATCH 2/2] Style fixups

---
 deb/reflist.go    |  2 --
 deb/remote.go     |  2 +-
 query/lex_test.go | 12 ++++--------
 3 files changed, 5 insertions(+), 11 deletions(-)

diff --git a/deb/reflist.go b/deb/reflist.go
index 1c8a4255..187475dd 100644
--- a/deb/reflist.go
+++ b/deb/reflist.go
@@ -395,6 +395,4 @@ func (l *PackageRefList) FilterLatestRefs() {
 
 		lastArch, lastName, lastVer = arch, name, ver
 	}
-
-	return
 }
diff --git a/deb/remote.go b/deb/remote.go
index dcc419d9..b0f25fc1 100644
--- a/deb/remote.go
+++ b/deb/remote.go
@@ -198,7 +198,7 @@ func (repo *RemoteRepo) IndexesRootURL() *url.URL {
 	if !repo.IsFlat() {
 		path = &url.URL{Path: fmt.Sprintf("dists/%s/", repo.Distribution)}
 	} else {
-		path = &url.URL{Path: fmt.Sprintf("%s", repo.Distribution)}
+		path = &url.URL{Path: repo.Distribution}
 	}
 
 	return repo.archiveRootURL.ResolveReference(path)
diff --git a/query/lex_test.go b/query/lex_test.go
index 27d8b04b..607712c3 100644
--- a/query/lex_test.go
+++ b/query/lex_test.go
@@ -1,10 +1,6 @@
 package query
 
-import (
-	"fmt"
-
-	. "gopkg.in/check.v1"
-)
+import . "gopkg.in/check.v1"
 
 type LexerSuite struct {
 }
@@ -46,13 +42,13 @@ func (s *LexerSuite) TestConsume(c *C) {
 func (s *LexerSuite) TestString(c *C) {
 	l, _ := lex("query", "package (<< 1.3)")
 
-	c.Check(fmt.Sprintf("%s", l.Current()), Equals, "\"package\"")
+	c.Check(l.Current().String(), Equals, "\"package\"")
 	l.Consume()
-	c.Check(fmt.Sprintf("%s", l.Current()), Equals, "(")
+	c.Check(l.Current().String(), Equals, "(")
 }
 
 func (s *LexerSuite) TestError(c *C) {
 	l, _ := lex("query", "'package")
 
-	c.Check(fmt.Sprintf("%s", l.Current()), Equals, "error: unexpected eof in quoted string")
+	c.Check(l.Current().String(), Equals, "error: unexpected eof in quoted string")
 }