Add build scheduler DB interface, dumb in-memory impl, cache

build_scheduler/go/db/memory.go

+package db
+
+import (
+        "sort"
+        "sync"
+        "time"
+
+        "github.com/satori/go.uuid"
+        "github.com/skia-dev/glog"
+)
+
+type BuildSlice []*Build
+
+func (s BuildSlice) Len() int { return len(s) }
+
+func (s BuildSlice) Less(i, j int) bool {
+        ts1, err := s[i].Created()
+        if err != nil {
+                glog.Errorf("Failed to parse CreatedTimestamp: %v", s[i])
+        }
+        ts2, err := s[j].Created()
+        if err != nil {
+                glog.Errorf("Failed to parse CreatedTimestamp: %v", s[j])
+        }
+        return ts1.Before(ts2)
+}
+
+func (s BuildSlice) Swap(i, j int) {
+        s[i], s[j] = s[j], s[i]
+}
+
+type inMemoryDB struct {
+        builds    map[string]*Build
+        buildsMtx sync.RWMutex
+        modBuilds map[string]map[string]*Build
+        modExpire map[string]time.Time
+        modMtx    sync.RWMutex
+}
+
+// See docs for DB interface.
+func (db *inMemoryDB) Close() error {
+        return nil
+}
+
+// See docs for DB interface.
+func (db *inMemoryDB) GetBuildsFromDateRange(start, end time.Time) ([]*Build, error) {
+        db.buildsMtx.RLock()
+        defer db.buildsMtx.RUnlock()
+
+        rv := []*Build{}
+        // TODO(borenet): Binary search.
+        for _, b := range db.builds {
+                created, err := b.Created()
+                if err != nil {
+                        return nil, err
+                }
+                if created.After(start) && created.Before(end) {
+                        rv = append(rv, b)

[dogben, 2016/08/08 19:22:38]

nit: Probably want to copy.

(Or change the docs on the interface to say the caller can't modify the returned
builds, but that seems error-prone.)

[borenet, 2016/08/08 19:51:18]

Done.

+                }
+        }
+        sort.Sort(BuildSlice(rv))
+        return rv, nil
+}
+
+// See docs for DB interface.
+func (db *inMemoryDB) GetModifiedBuilds(id string) ([]*Build, error) {
+        db.modMtx.Lock()
+        defer db.modMtx.Unlock()
+        modifiedBuilds, ok := db.modBuilds[id]
+        if !ok {
+                return nil, ErrUnknownId
+        }
+        rv := make([]*Build, 0, len(modifiedBuilds))
+        for _, b := range modifiedBuilds {
+                rv = append(rv, b)

[dogben, 2016/08/08 19:22:39]

nit: Probably want to copy.

[borenet, 2016/08/08 19:51:18]

Done.

+        }
+        db.modExpire[id] = time.Now().Add(MODIFIED_BUILDS_TIMEOUT)
+        db.modBuilds[id] = map[string]*Build{}
+        sort.Sort(BuildSlice(rv))
+        return rv, nil
+}
+
+func (db *inMemoryDB) clearExpiredModifiedUsers() {
+        db.modMtx.Lock()
+        defer db.modMtx.Unlock()
+        for id, t := range db.modExpire {
+                if time.Now().After(t) {
+                        delete(db.modBuilds, id)
+                        delete(db.modExpire, id)
+                }
+        }
+}
+
+func (db *inMemoryDB) modify(b *Build) {
+        db.modMtx.Lock()
+        defer db.modMtx.Unlock()
+        for _, modBuilds := range db.modBuilds {
+                modBuilds[b.Id] = b.Copy()
+        }
+}
+
+// See docs for DB interface.
+func (db *inMemoryDB) PutBuild(build *Build) error {
+        db.buildsMtx.Lock()
+        defer db.buildsMtx.Unlock()
+
+        // TODO(borenet): Keep builds in a sorted slice.
+        db.builds[build.Id] = build
+        db.modify(build)
+        return nil
+}
+
+// See docs for DB interface.
+func (db *inMemoryDB) PutBuilds(builds []*Build) error {
+        for _, b := range builds {
+                if err := db.PutBuild(b); err != nil {
+                        return err
+                }
+        }
+        return nil
+}
+
+// See docs for DB interface.
+func (db *inMemoryDB) StartTrackingModifiedBuilds() (string, error) {
+        db.modMtx.Lock()
+        defer db.modMtx.Unlock()
+        if len(db.modBuilds) >= MAX_MODIFIED_BUILDS_USERS {
+                return "", ErrTooManyUsers
+        }
+        id := uuid.NewV5(uuid.NewV1(), uuid.NewV4().String()).String()
+        db.modBuilds[id] = map[string]*Build{}
+        db.modExpire[id] = time.Now().Add(MODIFIED_BUILDS_TIMEOUT)
+        return id, nil
+}
+
+// NewInMemoryDB returns an extremely simple, inefficient, in-memory DB implementation.
+func NewInMemoryDB() DB {
+        db := &inMemoryDB{
+                builds:    map[string]*Build{},
+                modBuilds: map[string]map[string]*Build{},
+                modExpire: map[string]time.Time{},
+        }
+        go func() {
+                for _ = range time.Tick(time.Minute) {
+                        db.clearExpiredModifiedUsers()
+                }
+        }()
+        return db
+}