Merge pull request #284 from writeas/high-load-error-page

Show 503 page on blogs under high load
5 years ago · dbd7eff7ea
parent 8ad04c5187 07debec8d5
commit dbd7eff7ea
7 changed files with 45 additions and 1 deletions
--- a/database-lib.go
+++ b/database-lib.go
@ -22,3 +22,7 @@ func (db *datastore) isDuplicateKeyErr(err error) bool {
 func (db *datastore) isIgnorableError(err error) bool {
 	return false
 }
+
+func (db *datastore) isHighLoadError(err error) bool {
+	return false
+}
--- a/database-no-sqlite.go
+++ b/database-no-sqlite.go
@ -40,3 +40,13 @@ func (db *datastore) isIgnorableError(err error) bool {

 	return false
 }
+
+func (db *datastore) isHighLoadError(err error) bool {
+	if db.driverName == driverMySQL {
+		if mysqlErr, ok := err.(*mysql.MySQLError); ok {
+			return mysqlErr.Number == mySQLErrMaxUserConns || mysqlErr.Number == mySQLErrTooManyConns
+		}
+	}
+
+	return false
+}
--- a/database-sqlite.go
+++ b/database-sqlite.go
@ -1,7 +1,7 @@
 // +build sqlite,!wflib

 /*
- * Copyright © 2019 A Bunch Tell LLC.
+ * Copyright © 2019-2020 A Bunch Tell LLC.
 *
 * This file is part of WriteFreely.
 *
@ -60,3 +60,13 @@ func (db *datastore) isIgnorableError(err error) bool {

 	return false
 }
+
+func (db *datastore) isHighLoadError(err error) bool {
+	if db.driverName == driverMySQL {
+		if mysqlErr, ok := err.(*mysql.MySQLError); ok {
+			return mysqlErr.Number == mySQLErrMaxUserConns || mysqlErr.Number == mySQLErrTooManyConns
+		}
+	}
+
+	return false
+}
--- a/database.go
+++ b/database.go
@ -39,6 +39,8 @@ import (
 const (
 	mySQLErrDuplicateKey = 1062
 	mySQLErrCollationMix = 1267
+	mySQLErrTooManyConns = 1040
+	mySQLErrMaxUserConns = 1203

 	driverMySQL  = "mysql"
 	driverSQLite = "sqlite3"
@ -795,6 +797,8 @@ func (db *datastore) GetCollectionBy(condition string, value interface{}) (*Coll
 	switch {
 	case err == sql.ErrNoRows:
 		return nil, impart.HTTPError{http.StatusNotFound, "Collection doesn't exist."}
+	case db.isHighLoadError(err):
+		return nil, ErrUnavailable
 	case err != nil:
 		log.Error("Failed selecting from collections: %v", err)
 		return nil, err
--- a/errors.go
+++ b/errors.go
@ -37,6 +37,8 @@ var (
 	ErrInternalGeneral       = impart.HTTPError{http.StatusInternalServerError, "The humans messed something up. They've been notified."}
 	ErrInternalCookieSession = impart.HTTPError{http.StatusInternalServerError, "Could not get cookie session."}

+	ErrUnavailable = impart.HTTPError{http.StatusServiceUnavailable, "Service temporarily unavailable due to high load."}
+
 	ErrCollectionNotFound     = impart.HTTPError{http.StatusNotFound, "Collection doesn't exist."}
 	ErrCollectionGone         = impart.HTTPError{http.StatusGone, "This blog was unpublished."}
 	ErrCollectionPageNotFound = impart.HTTPError{http.StatusNotFound, "Collection page doesn't exist."}
--- a/handle.go
+++ b/handle.go
@ -83,6 +83,7 @@ type ErrorPages struct {
 	NotFound            *template.Template
 	Gone                *template.Template
 	InternalServerError *template.Template
+	UnavailableError    *template.Template
 	Blank               *template.Template
 }

@ -94,6 +95,7 @@ func NewHandler(apper Apper) *Handler {
 			NotFound:            template.Must(template.New("").Parse("{{define \"base\"}}<html><head><title>404</title></head><body><p>Not found.</p></body></html>{{end}}")),
 			Gone:                template.Must(template.New("").Parse("{{define \"base\"}}<html><head><title>410</title></head><body><p>Gone.</p></body></html>{{end}}")),
 			InternalServerError: template.Must(template.New("").Parse("{{define \"base\"}}<html><head><title>500</title></head><body><p>Internal server error.</p></body></html>{{end}}")),
+			UnavailableError:    template.Must(template.New("").Parse("{{define \"base\"}}<html><head><title>503</title></head><body><p>Service is temporarily unavailable.</p></body></html>{{end}}")),
 			Blank:               template.Must(template.New("").Parse("{{define \"base\"}}<html><head><title>{{.Title}}</title></head><body><p>{{.Content}}</p></body></html>{{end}}")),
 		},
 		sessionStore: apper.App().SessionStore(),
@ -111,6 +113,7 @@ func NewWFHandler(apper Apper) *Handler {
 		NotFound:            pages["404-general.tmpl"],
 		Gone:                pages["410.tmpl"],
 		InternalServerError: pages["500.tmpl"],
+		UnavailableError:    pages["503.tmpl"],
 		Blank:               pages["blank.tmpl"],
 	})
 	return h
@ -763,6 +766,10 @@ func (h *Handler) handleHTTPError(w http.ResponseWriter, r *http.Request, err er
 			log.Info("handleHTTPErorr internal error render")
 			h.errors.InternalServerError.ExecuteTemplate(w, "base", pageForReq(h.app.App(), r))
 			return
+		} else if err.Status == http.StatusServiceUnavailable {
+			w.WriteHeader(err.Status)
+			h.errors.UnavailableError.ExecuteTemplate(w, "base", pageForReq(h.app.App(), r))
+			return
 		} else if err.Status == http.StatusAccepted {
 			impart.WriteSuccess(w, "", err.Status)
 			return
--- a/pages/503.tmpl
+++ b/pages/503.tmpl
@ -0,0 +1,7 @@
+{{define "head"}}<title>Temporarily Unavailable &mdash; {{.SiteMetaName}}</title>{{end}}
+{{define "content"}}
+		<div class="error-page">
+			<p class="msg">The words aren't coming to me. &#x1F5C5;</p>
+			<p>We couldn't serve this page due to high server load. This should only be temporary.</p>
+		</div>
+{{end}}