chore: Revert to only using 1 timezone support for template DAUs (#7721)

* chore: Revert to only using 1 timezone support for template DAUs

Keeping the logic to support more in case we optimize later

coderd/metricscache/metricscache.go

@@ -21,14 +21,23 @@ import (
 	"github.com/coder/retry"
 )
 
-// timezoneOffsets are the timezones that are cached and supported.
+// deploymentTimezoneOffsets are the timezones that are cached and supported.
 // Any non-listed timezone offsets will need to use the closest supported one.
-var timezoneOffsets = []int{
+var deploymentTimezoneOffsets = []int{
 	0, // UTC - is listed first intentionally.
 	-12, -11, -10, -9, -8, -7, -6, -5, -4, -3, -2, -1,
 	1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
 }
 
+// templateTimezoneOffsets are the timezones each template will use for it's DAU
+// calculations. This is expensive as each template needs to do each timezone, so keep this list
+// very small.
+var templateTimezoneOffsets = []int{
+	// Only do one for now. If people request more accurate template DAU, we can
+	// fix this. But it adds too much cost, so optimization is needed first.
+	0, // UTC - is listed first intentionally.
+}
+
 // Cache holds the template metrics.
 // The aggregation queries responsible for these values can take up to a minute
 // on large deployments. Even in small deployments, aggregation queries can
@@ -166,7 +175,7 @@ func (c *Cache) refreshDeploymentDAUs(ctx context.Context) error {
 	ctx = dbauthz.AsSystemRestricted(ctx)
 
 	deploymentDAUs := make(map[int]codersdk.DAUsResponse)
-	for _, tzOffset := range timezoneOffsets {
+	for _, tzOffset := range deploymentTimezoneOffsets {
 		rows, err := c.database.GetDeploymentDAUs(ctx, int32(tzOffset))
 		if err != nil {
 			return err
@@ -199,7 +208,7 @@ func (c *Cache) refreshTemplateDAUs(ctx context.Context) error {
 	}
 
 	for _, template := range templates {
-		for _, tzOffset := range timezoneOffsets {
+		for _, tzOffset := range templateTimezoneOffsets {
 			rows, err := c.database.GetTemplateDAUs(ctx, database.GetTemplateDAUsParams{
 				TemplateID: template.ID,
 				TzOffset:   int32(tzOffset),

coderd/metricscache/metricscache_test.go

@@ -48,12 +48,14 @@ func TestCache_TemplateUsers(t *testing.T) {
 		uniqueUsers int
 	}
 	tests := []struct {
-		name     string
-		args     args
-		want     want
+		name    string
+		args    args
+		tplWant want
+		// dauWant is optional
+		dauWant  []codersdk.DAUEntry
 		tzOffset int
 	}{
-		{name: "empty", args: args{}, want: want{nil, 0}},
+		{name: "empty", args: args{}, tplWant: want{nil, 0}},
 		{
 			name: "one hole",
 			args: args{
@@ -62,7 +64,7 @@ func TestCache_TemplateUsers(t *testing.T) {
 					statRow(zebra, dateH(2022, 8, 30, 0)),
 				},
 			},
-			want: want{[]codersdk.DAUEntry{
+			tplWant: want{[]codersdk.DAUEntry{
 				{
 					Date:   date(2022, 8, 27),
 					Amount: 1,
@@ -90,7 +92,7 @@ func TestCache_TemplateUsers(t *testing.T) {
 					statRow(zebra, dateH(2022, 8, 29, 0)),
 				},
 			},
-			want: want{[]codersdk.DAUEntry{
+			tplWant: want{[]codersdk.DAUEntry{
 				{
 					Date:   date(2022, 8, 27),
 					Amount: 1,
@@ -116,7 +118,7 @@ func TestCache_TemplateUsers(t *testing.T) {
 					statRow(tiger, dateH(2022, 1, 7, 0)),
 				},
 			},
-			want: want{[]codersdk.DAUEntry{
+			tplWant: want{[]codersdk.DAUEntry{
 				{
 					Date:   date(2022, 1, 1),
 					Amount: 2,
@@ -159,7 +161,13 @@ func TestCache_TemplateUsers(t *testing.T) {
 					statRow(tiger, dateH(2022, 1, 2, 0)),
 				},
 			},
-			want: want{[]codersdk.DAUEntry{
+			tplWant: want{[]codersdk.DAUEntry{
+				{
+					Date:   date(2022, 1, 2),
+					Amount: 2,
+				},
+			}, 2},
+			dauWant: []codersdk.DAUEntry{
 				{
 					Date:   date(2022, 1, 1),
 					Amount: 2,
@@ -168,7 +176,7 @@ func TestCache_TemplateUsers(t *testing.T) {
 					Date:   date(2022, 1, 2),
 					Amount: 2,
 				},
-			}, 2},
+			},
 		},
 		{
 			name:     "tzOffsetPreviousDay",
@@ -181,11 +189,17 @@ func TestCache_TemplateUsers(t *testing.T) {
 					statRow(tiger, dateH(2022, 1, 2, 0)),
 				},
 			},
-			want: want{[]codersdk.DAUEntry{
+			dauWant: []codersdk.DAUEntry{
 				{
 					Date:   date(2022, 1, 1),
 					Amount: 2,
 				},
+			},
+			tplWant: want{[]codersdk.DAUEntry{
+				{
+					Date:   date(2022, 1, 2),
+					Amount: 2,
+				},
 			}, 2},
 		},
 	}
@@ -223,11 +237,18 @@ func TestCache_TemplateUsers(t *testing.T) {
 			gotUniqueUsers, ok := cache.TemplateUniqueUsers(template.ID)
 			require.True(t, ok)
 
+			if tt.dauWant != nil {
+				_, dauResponse, ok := cache.DeploymentDAUs(tt.tzOffset)
+				require.True(t, ok)
+				require.Equal(t, tt.dauWant, dauResponse.Entries)
+			}
+
 			offset, gotEntries, ok := cache.TemplateDAUs(template.ID, tt.tzOffset)
 			require.True(t, ok)
-			require.Equal(t, offset, tt.tzOffset)
-			require.Equal(t, tt.want.entries, gotEntries.Entries)
-			require.Equal(t, tt.want.uniqueUsers, gotUniqueUsers)
+			// Template only supports 0 offset.
+			require.Equal(t, 0, offset)
+			require.Equal(t, tt.tplWant.entries, gotEntries.Entries)
+			require.Equal(t, tt.tplWant.uniqueUsers, gotUniqueUsers)
 		})
 	}
 }