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

build_scheduler/go/db/cache_test.go

+package db
+
+import (
+        "testing"
+        "time"
+
+        assert "github.com/stretchr/testify/require"
+        "go.skia.org/infra/go/testutils"
+)
+
+func testGetBuildsForCommits(t *testing.T, c *BuildCache, b *Build) {

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

Is there any reason to test GetBuildsForCommits for multiple input commits or
multiple builds at the same commit?

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

If ingestion is done correctly, we should never have two builds for the same
builder with the same commit in the blamelist.  I don't know if it makes sense
to test that here yet, although I guess I could add some kind of check at
insertion time to enforce that?  Seems slow though.

[dogben, 2016/08/08 20:16:07]

Sorry, I meant two builds for the same commit but different builders.

[borenet, 2016/08/09 11:22:55]

Oh! Done.

+        for _, commit := range b.Commits {
+                builds, err := c.GetBuildsForCommits([]string{commit})
+                assert.NoError(t, err)
+                testutils.AssertDeepEqual(t, map[string]map[string]*Build{
+                        commit: map[string]*Build{
+                                b.Id: b,
+                        },
+                }, builds)
+        }
+}
+
+func TestDBCache(t *testing.T) {
+        db := NewInMemoryDB()
+        defer testutils.AssertCloses(t, db)
+
+        // Pre-load a build into the DB.
+        startTime := time.Now().Add(-30 * time.Minute) // Arbitrary starting point.
+        b1 := makeBuild("build1", startTime, []string{"a", "b", "c", "d"})
+        assert.NoError(t, db.PutBuild(b1))
+
+        // Create the cache. Ensure that the existing build is present.
+        c, err := NewBuildCache(db, time.Hour)
+        assert.NoError(t, err)
+        testGetBuildsForCommits(t, c, b1)
+
+        // Bisect the first build.
+        b2 := makeBuild("build2", startTime.Add(time.Minute), []string{"c", "d"})
+        b1.Commits = []string{"a", "b"}
+        assert.NoError(t, db.PutBuilds([]*Build{b2, b1}))
+        assert.NoError(t, c.Update())
+
+        // Ensure that b2 (and not b1) shows up for commits "c" and "d".
+        testGetBuildsForCommits(t, c, b1)
+        testGetBuildsForCommits(t, c, b2)
+}