[errors] de-specialize Transient in favor of Tags.

scheduler/appengine/frontend/handler.go

 // Copyright 2015 The LUCI Authors. All rights reserved.
 // Use of this source code is governed under the Apache License, Version 2.0
 // that can be found in the LICENSE file.
 
 // Package frontend implements GAE web server for luci-scheduler service.
 //
 // Due to the way classic GAE imports work, this package can not have
 // subpackages (or at least subpackages referenced via absolute import path).
 // We can't use relative imports because luci-go will then become unbuildable
 // by regular (non GAE) toolset.
@@ skipping 17 matching lines @@
         tq "github.com/luci/gae/service/taskqueue"
 
         "github.com/luci/luci-go/grpc/discovery"
         "github.com/luci/luci-go/grpc/grpcmon"
         "github.com/luci/luci-go/grpc/prpc"
         "github.com/luci/luci-go/server/router"
 
         "github.com/luci/luci-go/appengine/gaemiddleware"
 
         "github.com/luci/luci-go/common/data/rand/mathrand"
-        "github.com/luci/luci-go/common/errors"
         "github.com/luci/luci-go/common/logging"
+        "github.com/luci/luci-go/common/retry/transient"
 
         "github.com/luci/luci-go/scheduler/api/scheduler/v1"
 
         "github.com/luci/luci-go/scheduler/appengine/apiservers"
         "github.com/luci/luci-go/scheduler/appengine/catalog"
         "github.com/luci/luci-go/scheduler/appengine/engine"
         "github.com/luci/luci-go/scheduler/appengine/task"
         "github.com/luci/luci-go/scheduler/appengine/task/buildbucket"
         "github.com/luci/luci-go/scheduler/appengine/task/gitiles"
         "github.com/luci/luci-go/scheduler/appengine/task/noop"
@@ skipping 28 matching lines @@
         body := fmt.Sprintf(msg, args...)
         logging.Errorf(c.Context, "HTTP %d: %s", code, body)
         http.Error(c.Writer, body, code)
 }
 
 // err sets status to 500 on transient errors or 202 on fatal ones. Returning
 // status code in range [200–299] is the only way to tell Task Queues to stop
 // retrying the task.
 func (c *requestContext) err(e error, msg string, args ...interface{}) {
         code := 500
-        if !errors.IsTransient(e) {
+        if !transient.Tag.In(e) {
                 code = 202
         }
         args = append(args, e)
         c.fail(code, msg+" - %s", args...)
 }
 
 // ok sets status to 200 and puts "OK" in response.
 func (c *requestContext) ok() {
         c.Writer.Header().Set("Content-Type", "text/plain; charset=utf-8")
         c.Writer.WriteHeader(200)
@@ skipping 147 matching lines @@
 
         // Handle each project in its own task to avoid "bad" projects (e.g. ones with
         // lots of jobs) to slow down "good" ones.
         tasks := make([]*tq.Task, 0, len(projectsToVisit))
         for projectID := range projectsToVisit {
                 tasks = append(tasks, &tq.Task{
                         Path: "/internal/tasks/read-project-config?projectID=" + url.QueryEscape(projectID),
                 })
         }
         if err = tq.Add(rc.Context, "read-project-config", tasks...); err != nil {
-                rc.err(errors.WrapTransient(err), "Failed to add tasks to task queue")
+                rc.err(transient.Tag.Apply(err), "Failed to add tasks to task queue")
         } else {
                 rc.ok()
         }
 }
 
 // readProjectConfigTask grabs a list of jobs in a project from catalog, updates
 // all changed jobs, adds new ones, disables old ones.
 func readProjectConfigTask(c *router.Context) {
         rc := requestContext(*c)
         projectID := rc.Request.URL.Query().Get("projectID")
@@ skipping 25 matching lines @@
                 return
         }
         count, _ := strconv.Atoi(rc.Request.Header.Get("X-AppEngine-TaskExecutionCount"))
         err = globalEngine.ExecuteSerializedAction(rc.Context, body, count)
         if err != nil {
                 rc.err(err, "Error when executing the action")
                 return
         }
         rc.ok()
 }