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

build_scheduler/go/db/memory.go

Index: build_scheduler/go/db/memory.go
diff --git a/build_scheduler/go/db/memory.go b/build_scheduler/go/db/memory.go
new file mode 100644
index 0000000000000000000000000000000000000000..f0e25cc24fadc2291137706b6039202438de696b
--- /dev/null
+++ b/build_scheduler/go/db/memory.go
@@ -0,0 +1,149 @@
+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
+}