[milo] Refactor all html knowledge out of backends.

milo/buildsource/buildbot/builder.go

 // Copyright 2016 The LUCI Authors.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //      http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
 package buildbot
 
 import (
         "crypto/sha1"
         "encoding/base64"
-        "errors"
         "fmt"
         "sort"
         "strings"
         "time"
 
         "github.com/luci/gae/service/datastore"
         "github.com/luci/gae/service/memcache"
 
         "github.com/luci/luci-go/common/clock"
+        "github.com/luci/luci-go/common/errors"
         "github.com/luci/luci-go/common/logging"
         "github.com/luci/luci-go/milo/api/resp"
+        "github.com/luci/luci-go/milo/common"
         "golang.org/x/net/context"
 )
 
 // builderRef is used for keying specific builds in a master json.
 type builderRef struct {
         builder  string
         buildNum int
 }
 
 // buildMap contains all of the current build within a master json.  We use this
@@ skipping 46 matching lines @@
                 },
                 Text:     mergeText(b.Text),
                 Blame:    blame(b),
                 Revision: b.Sourcestamp.Revision,
         }
 }
 
 // getBuilds fetches all of the recent builds from the .  Note that
 // getBuilds() does not perform ACL checks.
 func getBuilds(
-        c context.Context, masterName, builderName string, finished bool, limit int, cursor *datastore.Cursor) (
-        []*resp.BuildSummary, *datastore.Cursor, error) {
+        c context.Context, masterName, builderName string, finished bool, limit int, cursor datastore.Cursor) (
+        []*resp.BuildSummary, datastore.Cursor, error) {
 
         // TODO(hinoka): Builder specific structs.
         result := []*resp.BuildSummary{}
         q := datastore.NewQuery("buildbotBuild")
         q = q.Eq("finished", finished)
         q = q.Eq("master", masterName)
         q = q.Eq("builder", builderName)
         q = q.Order("-number")
         if cursor != nil {
-                q = q.Start(*cursor)
+                q = q.Start(cursor)
         }
         buildbots, nextCursor, err := runBuildsQuery(c, q, int32(limit))
         if err != nil {
                 return nil, nil, err
         }
         for _, b := range buildbots {
                 result = append(result, getBuildSummary(b))
         }
         return result, nextCursor, nil
 }
 
 // maybeSetGetCursor is a cheesy way to implement bidirectional paging with forward-only
 // datastore cursor by creating a mapping of nextCursor -> thisCursor
 // in memcache.  maybeSetGetCursor stores the future mapping, then returns prevCursor
 // in the mapping for thisCursor -> prevCursor, if available.
-func maybeSetGetCursor(c context.Context, thisCursor, nextCursor *datastore.Cursor, limit int) (*datastore.Cursor, bool) {
+func maybeSetGetCursor(c context.Context, thisCursor, nextCursor datastore.Cursor, limit int) (datastore.Cursor, bool) {
         key := func(c datastore.Cursor) string {
                 // Memcache key limit is 250 bytes, hash our cursor to get under this limit.
                 blob := sha1.Sum([]byte(c.String()))
                 return fmt.Sprintf("v2:cursors:buildbot_builders:%d:%s", limit, base64.StdEncoding.EncodeToString(blob[:]))
         }
         // Set the next cursor to this cursor mapping, if available.
         if nextCursor != nil {
-                item := memcache.NewItem(c, key(*nextCursor))
+                item := memcache.NewItem(c, key(nextCursor))
                 if thisCursor == nil {
                         // Make sure we know it exists, just empty
                         item.SetValue([]byte{})
                 } else {
-                        item.SetValue([]byte((*thisCursor).String()))
+                        item.SetValue([]byte(thisCursor.String()))
                 }
                 item.SetExpiration(24 * time.Hour)
                 memcache.Set(c, item)
         }
         // Try to get the last cursor, if valid and available.
         if thisCursor == nil {
                 return nil, false
         }
-        if item, err := memcache.GetKey(c, key(*thisCursor)); err == nil {
+        if item, err := memcache.GetKey(c, key(thisCursor)); err == nil {
                 if len(item.Value()) == 0 {
                         return nil, true
                 }
                 if prevCursor, err := datastore.DecodeCursor(c, string(item.Value())); err == nil {
-                        return &prevCursor, true
+                        return prevCursor, true
                 }
         }
         return nil, false
 }
 
-var errMasterNotFound = errors.New(
-        "Either the request resource was not found or you have insufficient permissions")
-var errNotAuth = errors.New("You are not authenticated, try logging in")
-
-type errBuilderNotFound struct {
-        master    string
-        builder   string
-        available []string
-}
-
-func (e errBuilderNotFound) Error() string {
-        avail := strings.Join(e.available, "\n")
-        return fmt.Sprintf("Cannot find builder %q in master %q.\nAvailable builders: \n%s",
-                e.builder, e.master, avail)
-}
-
 func summarizeSlavePool(
         baseURL string, slaves []string, slaveMap map[string]*buildbotSlave) *resp.MachinePool {
 
         mp := &resp.MachinePool{
                 Total: len(slaves),
                 Bots:  make([]resp.Bot, 0, len(slaves)),
         }
         for _, slaveName := range slaves {
                 slave, ok := slaveMap[slaveName]
                 bot := resp.Bot{
@@ skipping 13 matching lines @@
                         mp.Busy++
                 default:
                         bot.Status = resp.Idle
                         mp.Idle++
                 }
                 mp.Bots = append(mp.Bots, bot)
         }
         return mp
 }
 
-// builderImpl is the implementation for getting a milo builder page from buildbot.
+// GetBuilder is the implementation for getting a milo builder page from
+// buildbot.
+//
 // This gets:
-// * Current Builds from querying the master json from the datastore.
-// * Recent Builds from a cron job that backfills the recent builds.
-func builderImpl(
-        c context.Context, masterName, builderName string, limit int, cursor string) (
-        *resp.Builder, error) {
-
-        var thisCursor *datastore.Cursor
-        if cursor != "" {
-                tmpCur, err := datastore.DecodeCursor(c, cursor)
-                if err != nil {
-                        return nil, fmt.Errorf("bad cursor: %s", err)
-                }
-                thisCursor = &tmpCur
-        }
-
+//   * Current Builds from querying the master json from the datastore.
+//   * Recent Builds from a cron job that backfills the recent builds.
+func GetBuilder(c context.Context, masterName, builderName string, limit int, cursor datastore.Cursor) (*resp.Builder, error) {
         result := &resp.Builder{
                 Name: builderName,
         }
         master, internal, t, err := getMasterJSON(c, masterName)
         if err != nil {
                 return nil, err
         }
         if clock.Now(c).Sub(t) > 2*time.Minute {
                 warning := fmt.Sprintf(
                         "WARNING: Master data is stale (last updated %s)", t)
                 logging.Warningf(c, warning)
                 result.Warning = warning
         }
 
         p, ok := master.Builders[builderName]
         if !ok {
                 // This long block is just to return a good error message when an invalid
                 // buildbot builder is specified.
                 keys := make([]string, 0, len(master.Builders))
                 for k := range master.Builders {
                         keys = append(keys, k)
                 }
                 sort.Strings(keys)
-                return nil, errBuilderNotFound{masterName, builderName, keys}
+                // TODO(iannucci): add error-info-helper tags to give the error page enough
+                // information to render link-to-master and link-to-builder.
+                builders := strings.Join(keys, "\n")
+                return nil, errors.Reason(
+                        "Cannot find builder %q in master %q.\nAvailable builders: \n%s",
+                        builderName, masterName, builders,
+                ).Tag(common.CodeNotFound).Err()
         }
         // Extract pending builds out of the master json.
         result.PendingBuilds = make([]*resp.BuildSummary, len(p.PendingBuildStates))
         logging.Debugf(c, "Number of pending builds: %d", len(p.PendingBuildStates))
         for i, pb := range p.PendingBuildStates {
                 start := time.Unix(int64(pb.SubmittedAt), 0).UTC()
                 result.PendingBuilds[i] = &resp.BuildSummary{
                         PendingTime: resp.Interval{
                                 Started:  start,
                                 Duration: clock.Now(c).UTC().Sub(start),
                         },
                 }
                 result.PendingBuilds[i].Blame = make([]*resp.Commit, len(pb.Source.Changes))
                 for j, cm := range pb.Source.Changes {
                         result.PendingBuilds[i].Blame[j] = &resp.Commit{
                                 AuthorEmail: cm.Who,
                                 CommitURL:   cm.Revlink,
                         }
                 }
         }
 
         baseURL := "https://build.chromium.org/p/"
         if internal {
                 baseURL = "https://uberchromegw.corp.google.com/i/"
         }
         result.MachinePool = summarizeSlavePool(baseURL+master.Name, p.Slaves, master.Slaves)
 
         // This is CPU bound anyways, so there's no need to do this in parallel.
-        finishedBuilds, nextCursor, err := getBuilds(c, masterName, builderName, true, limit, thisCursor)
+        finishedBuilds, nextCursor, err := getBuilds(c, masterName, builderName, true, limit, cursor)
         if err != nil {
                 return nil, err
         }
-        if prevCursor, ok := maybeSetGetCursor(c, thisCursor, nextCursor, limit); ok {
+        if prevCursor, ok := maybeSetGetCursor(c, cursor, nextCursor, limit); ok {
                 if prevCursor == nil {
                         // Magic string to signal display prev without cursor
                         result.PrevCursor = "EMPTY"
                 } else {
-                        result.PrevCursor = (*prevCursor).String()
+                        result.PrevCursor = prevCursor.String()
                 }
         }
         if nextCursor != nil {
-                result.NextCursor = (*nextCursor).String()
+                result.NextCursor = nextCursor.String()
         }
         // Cursor is not needed for current builds.
         currentBuilds, _, err := getBuilds(c, masterName, builderName, false, 0, nil)
         if err != nil {
                 return nil, err
         }
         // currentBuilds is presented in reversed order, so flip it
         for i, j := 0, len(currentBuilds)-1; i < j; i, j = i+1, j-1 {
                 currentBuilds[i], currentBuilds[j] = currentBuilds[j], currentBuilds[i]
         }
         result.CurrentBuilds = currentBuilds
 
         for _, fb := range finishedBuilds {
                 if fb != nil {
                         result.FinishedBuilds = append(result.FinishedBuilds, fb)
                 }
         }
         return result, nil
 }