Refactor update checker to use AppState (#17387)

We have the `AppState` module now, it can store app related data easily. We do not need to create separate tables for each feature.

So the update checker can use `AppState` instead of a one-row dedicate table.

And the code of update checker is moved from `models` to `modules`.

4 files changed, 20 insertions, 133 deletions

diff --git a/models/migrations/migrations.go b/models/migrations/migrations.go
index b1c91beef6..2686dfb3cf 100644
--- a/models/migrations/migrations.go
+++ b/models/migrations/migrations.go
@@ -351,9 +351,11 @@ var migrations = []Migration{
 	// v198 -> v199
 	NewMigration("Add issue content history table", addTableIssueContentHistory),
 	// v199 -> v200
-	NewMigration("Add remote version table", addRemoteVersionTable),
+	NewMigration("No-op (remote version is using AppState now)", addRemoteVersionTableNoop),
 	// v200 -> v201
 	NewMigration("Add table app_state", addTableAppState),
+	// v201 -> v202
+	NewMigration("Drop table remote_version (if exists)", dropTableRemoteVersion),
 }
 
 // GetCurrentDBVersion returns the current db version
diff --git a/models/migrations/v199.go b/models/migrations/v199.go
index 64b21172c1..4351ba4fa8 100644
--- a/models/migrations/v199.go
+++ b/models/migrations/v199.go
@@ -5,19 +5,10 @@
 package migrations
 
 import (
-	"fmt"
-
 	"xorm.io/xorm"
 )
 
-func addRemoteVersionTable(x *xorm.Engine) error {
-	type RemoteVersion struct {
-		ID      int64  `xorm:"pk autoincr"`
-		Version string `xorm:"VARCHAR(50)"`
-	}
-
-	if err := x.Sync2(new(RemoteVersion)); err != nil {
-		return fmt.Errorf("Sync2: %v", err)
-	}
+func addRemoteVersionTableNoop(x *xorm.Engine) error {
+	// we used to use a table `remote_version` to store information for updater, now we use `AppState`, so this migration task is a no-op now.
 	return nil
 }
diff --git a/models/migrations/v201.go b/models/migrations/v201.go
new file mode 100644
index 0000000000..637c30617c
--- /dev/null
+++ b/models/migrations/v201.go
@@ -0,0 +1,15 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package migrations
+
+import (
+	"xorm.io/xorm"
+)
+
+func dropTableRemoteVersion(x *xorm.Engine) error {
+	// drop the orphaned table introduced in `v199`, now the update checker also uses AppState, do not need this table
+	_ = x.DropTables("remote_version")
+	return nil
+}
diff --git a/models/update_checker.go b/models/update_checker.go
deleted file mode 100644
index 5b4fce69ec..0000000000
--- a/models/update_checker.go
+++ /dev/null
@@ -1,121 +0,0 @@
-// Copyright 2021 The Gitea Authors. All rights reserved.
-// Use of this source code is governed by a MIT-style
-// license that can be found in the LICENSE file.
-
-package models
-
-import (
-	"encoding/json"
-	"fmt"
-	"io/ioutil"
-	"net/http"
-
-	"code.gitea.io/gitea/models/db"
-	"code.gitea.io/gitea/modules/proxy"
-	"code.gitea.io/gitea/modules/setting"
-
-	"github.com/hashicorp/go-version"
-)
-
-// RemoteVersion stores the remote version from the JSON endpoint
-type RemoteVersion struct {
-	ID      int64  `xorm:"pk autoincr"`
-	Version string `xorm:"VARCHAR(50)"`
-}
-
-func init() {
-	db.RegisterModel(new(RemoteVersion))
-}
-
-// GiteaUpdateChecker returns error when new version of Gitea is available
-func GiteaUpdateChecker(httpEndpoint string) error {
-	httpClient := &http.Client{
-		Transport: &http.Transport{
-			Proxy: proxy.Proxy(),
-		},
-	}
-
-	req, err := http.NewRequest("GET", httpEndpoint, nil)
-	if err != nil {
-		return err
-	}
-	resp, err := httpClient.Do(req)
-	if err != nil {
-		return err
-	}
-	defer resp.Body.Close()
-	body, err := ioutil.ReadAll(resp.Body)
-	if err != nil {
-		return err
-	}
-
-	type v struct {
-		Latest struct {
-			Version string `json:"version"`
-		} `json:"latest"`
-	}
-	ver := v{}
-	err = json.Unmarshal(body, &ver)
-	if err != nil {
-		return err
-	}
-
-	return UpdateRemoteVersion(ver.Latest.Version)
-
-}
-
-// UpdateRemoteVersion updates the latest available version of Gitea
-func UpdateRemoteVersion(version string) (err error) {
-	sess := db.NewSession(db.DefaultContext)
-	defer sess.Close()
-	if err = sess.Begin(); err != nil {
-		return err
-	}
-
-	currentVersion := &RemoteVersion{ID: 1}
-	has, err := sess.Get(currentVersion)
-	if err != nil {
-		return fmt.Errorf("get: %v", err)
-	} else if !has {
-		currentVersion.ID = 1
-		currentVersion.Version = version
-
-		if _, err = sess.InsertOne(currentVersion); err != nil {
-			return fmt.Errorf("insert: %v", err)
-		}
-		return nil
-	}
-
-	if _, err = sess.Update(&RemoteVersion{ID: 1, Version: version}); err != nil {
-		return err
-	}
-
-	return sess.Commit()
-}
-
-// GetRemoteVersion returns the current remote version (or currently installed verson if fail to fetch from DB)
-func GetRemoteVersion() string {
-	e := db.GetEngine(db.DefaultContext)
-	v := &RemoteVersion{ID: 1}
-	_, err := e.Get(&v)
-	if err != nil {
-		// return current version if fail to fetch from DB
-		return setting.AppVer
-	}
-	return v.Version
-}
-
-// GetNeedUpdate returns true whether a newer version of Gitea is available
-func GetNeedUpdate() bool {
-	curVer, err := version.NewVersion(setting.AppVer)
-	if err != nil {
-		// return false to fail silently
-		return false
-	}
-	remoteVer, err := version.NewVersion(GetRemoteVersion())
-	if err != nil {
-		// return false to fail silently
-		return false
-	}
-	return curVer.LessThan(remoteVer)
-}