Merge pull request #6028 from babbageclunk/update-mgo

Update mgo dependency

This version includes the fixes for the duplicate key error on upsert, which means we don't need the patch any more.

[go-mgo/mgo#291](go-mgo/mgo#291)
[go-mgo/mgo#316](go-mgo/mgo#316)

Add a readme to keep the patches directory alive and explain its use. mgz has made a change to apply_patches.py to ignore any files with a different extension.

(Review request: http://reviews.vapour.ws/r/5477/)

dependencies.tsv

@@ -81,7 +81,7 @@ gopkg.in/juju/jujusvg.v2	git	d82160011935ef79fc7aca84aba2c6f74700fe75	2016-06-09
 gopkg.in/juju/names.v2	git	fa4c1959bef64b8f18569dc83a85b25d15204503	2016-08-16T07:05:44Z
 gopkg.in/macaroon-bakery.v1	git	469b44e6f1f9479e115c8ae879ef80695be624d5	2016-06-22T12:14:21Z
 gopkg.in/macaroon.v1	git	ab3940c6c16510a850e1c2dd628b919f0f3f1464	2015-01-21T11:42:31Z
-gopkg.in/mgo.v2	git	29cc868a5ca65f401ff318143f9408d02f4799cc	2016-06-09T18:00:28Z
+gopkg.in/mgo.v2	git	f2b6f6c918c452ad107eec89615f074e3bd80e33	2016-08-18T01:52:18Z
 gopkg.in/natefinch/lumberjack.v2	git	514cbda263a734ae8caac038dadf05f8f3f9f738	2016-01-25T11:17:49Z
 gopkg.in/natefinch/npipe.v2	git	c1b8fa8bdccecb0b8db834ee0b92fdbcfa606dd6	2016-06-21T03:49:01Z
 gopkg.in/tomb.v1	git	dd632973f1e7218eb1089048e0798ec9ae7dceb8	2014-10-24T13:56:13Z

patches/001-mgo.v2-issue-277-fix.diff

@@ -1,106 +0,0 @@
-diff --git a/session.go b/session.go
-index a8ad115..75cb838 100644
-
-This applies the minimal changes to fix the mgo duplicate key error,
-see https://github.com/go-mgo/mgo/pull/291 and https://github.com/go-mgo/mgo/pull/302
-
-It also includes logging so we can see that the patch is applied.
-
-Diff on github: https://github.com/go-mgo/mgo/compare/v2...babbageclunk:fix-277-v2-minimal?expand=1
-Generated with "git diff v2..fix-277-v2-minimal"
-
-Apply from $GOPATH/src with: patch -p1 < github.com/juju/juju/patches/001-mgo.v2-issue-277-fix.diff
-
---- a/gopkg.in/mgo.v2/session.go
-+++ b/gopkg.in/mgo.v2/session.go
-@@ -41,6 +41,7 @@ import (
- 	"sync"
- 	"time"
- 
-+	"github.com/juju/loggo"
- 	"gopkg.in/mgo.v2/bson"
- )
- 
-@@ -144,9 +145,18 @@ type Iter struct {
- var (
- 	ErrNotFound = errors.New("not found")
- 	ErrCursor   = errors.New("invalid cursor")
-+
-+	logPatchedOnce sync.Once
-+	logger         = loggo.GetLogger("mgo")
- )
- 
--const defaultPrefetch = 0.25
-+const (
-+	defaultPrefetch = 0.25
-+
-+	// How many times we will retry an upsert if it produces duplicate
-+	// key errors.
-+	maxUpsertRetries = 5
-+)
- 
- // Dial establishes a new session to the cluster identified by the given seed
- // server(s). The session will enable communication with all of the servers in
-@@ -410,6 +420,16 @@ func (addr *ServerAddr) TCPAddr() *net.TCPAddr {
- 
- // DialWithInfo establishes a new session to the cluster identified by info.
- func DialWithInfo(info *DialInfo) (*Session, error) {
-+	// This is using loggo because that can be done here in a
-+	// localised patch, while using mgo's logging would need a change
-+	// in Juju to call mgo.SetLogger. It's in this short-lived patch
-+	// as a stop-gap because it's proving difficult to tell if the
-+	// patch is applied in a running system. If you see it in
-+	// committed code then something has gone very awry - please
-+	// complain loudly! (babbageclunk)
-+	logPatchedOnce.Do(func() {
-+		logger.Debugf("duplicate key error patch applied")
-+	})
- 	addrs := make([]string, len(info.Addrs))
- 	for i, addr := range info.Addrs {
- 		p := strings.LastIndexAny(addr, "]:")
-@@ -2478,7 +2498,16 @@ func (c *Collection) Upsert(selector interface{}, update interface{}) (info *Cha
- 		Flags:      1,
- 		Upsert:     true,
- 	}
--	lerr, err := c.writeOp(&op, true)
-+	var lerr *LastError
-+	// <= to allow for the first attempt (not a retry).
-+	for i := 0; i <= maxUpsertRetries; i++ {
-+		lerr, err = c.writeOp(&op, true)
-+		// Retry duplicate key errors on upserts.
-+		// https://docs.mongodb.com/v3.2/reference/method/db.collection.update/#use-unique-indexes
-+		if !IsDup(err) {
-+			break
-+		}
-+	}
- 	if err == nil && lerr != nil {
- 		info = &ChangeInfo{}
- 		if lerr.UpdatedExisting {
-@@ -4208,13 +4237,22 @@ func (q *Query) Apply(change Change, result interface{}) (info *ChangeInfo, err
- 	session.SetMode(Strong, false)
- 
- 	var doc valueResult
--	err = session.DB(dbname).Run(&cmd, &doc)
--	if err != nil {
--		if qerr, ok := err.(*QueryError); ok && qerr.Message == "No matching object found" {
--			return nil, ErrNotFound
-+	for retries := 0; ; retries++ {
-+		err = session.DB(dbname).Run(&cmd, &doc)
-+		if err != nil {
-+			if qerr, ok := err.(*QueryError); ok && qerr.Message == "No matching object found" {
-+				return nil, ErrNotFound
-+			}
-+			if change.Upsert && IsDup(err) && retries < maxUpsertRetries {
-+				// Retry duplicate key errors on upserts.
-+				// https://docs.mongodb.com/v3.2/reference/method/db.collection.update/#use-unique-indexes
-+				continue
-+			}
-+			return nil, err
- 		}
--		return nil, err
-+		break // No error, so don't retry.
- 	}
-+
- 	if doc.LastError.N == 0 {
- 		return nil, ErrNotFound
- 	}

patches/README.md

@@ -0,0 +1,13 @@
+Emergency patches for dependencies
+==================================
+
+Files in this directory named `*.patch` or `*.diff` will be applied to
+the source tree before building Juju for release. The expectation is
+that these should be changes that will be accepted upstream, but that
+we need to apply sooner.
+
+They're applied with `$GOPATH/src` as the current directory, and with
+`-p1` to strip one component off the start of the file path.
+
+For more details, see `lp:juju-release-tools/apply_patches.py` or ask
+babbageclunk or mgz in IRC.