Experimental session count (#3786)

* WIP

* Allow `experimetnal_session_count` request serialization

* Extend `Plausible.Stats.Query` with `experimental_session_count` flag

* Add `FunWithFlags` actor implementation for `Site`

* Change the way sessions are retrieved

* Remove redundant test

* Format

* Update the test

---------

Co-authored-by: Uku Taht <uku.taht@gmail.com>

assets/js/dashboard/api.js

@@ -1,4 +1,4 @@
-import {formatISO} from './util/date'
+import { formatISO } from './util/date'
 
 let abortController = new AbortController()
 let SHARED_LINK_AUTH = null
@@ -36,14 +36,15 @@ function serializeFilters(filters) {
   return JSON.stringify(cleaned)
 }
 
-export function serializeQuery(query, extraQuery=[]) {
+export function serializeQuery(query, extraQuery = []) {
   const queryObj = {}
-  if (query.period)  { queryObj.period = query.period  }
-  if (query.date)    { queryObj.date = formatISO(query.date)  }
-  if (query.from)    { queryObj.from = formatISO(query.from)  }
-  if (query.to)      { queryObj.to = formatISO(query.to)  }
-  if (query.filters) { queryObj.filters = serializeFilters(query.filters)  }
-  if (query.with_imported) { queryObj.with_imported = query.with_imported  }
+  if (query.period) { queryObj.period = query.period }
+  if (query.date) { queryObj.date = formatISO(query.date) }
+  if (query.from) { queryObj.from = formatISO(query.from) }
+  if (query.to) { queryObj.to = formatISO(query.to) }
+  if (query.filters) { queryObj.filters = serializeFilters(query.filters) }
+  if (query.experimental_session_count) { queryObj.experimental_session_count = query.experimental_session_count }
+  if (query.with_imported) { queryObj.with_imported = query.with_imported }
   if (SHARED_LINK_AUTH) { queryObj.auth = SHARED_LINK_AUTH }
 
   if (query.comparison) {
@@ -58,11 +59,11 @@ export function serializeQuery(query, extraQuery=[]) {
   return '?' + serialize(queryObj)
 }
 
-export function get(url, query={}, ...extraQuery) {
-  const headers = SHARED_LINK_AUTH ? {'X-Shared-Link-Auth': SHARED_LINK_AUTH} : {}
+export function get(url, query = {}, ...extraQuery) {
+  const headers = SHARED_LINK_AUTH ? { 'X-Shared-Link-Auth': SHARED_LINK_AUTH } : {}
   url = url + serializeQuery(query, extraQuery)
-  return fetch(url, {signal: abortController.signal, headers: headers})
-    .then( response => {
+  return fetch(url, { signal: abortController.signal, headers: headers })
+    .then(response => {
       if (!response.ok) {
         return response.json().then((msg) => {
           throw new ApiError(msg.error, msg)

assets/js/dashboard/query.js

@@ -39,6 +39,7 @@ export function parseQuery(querystring, site) {
     to: q.get('to') ? dayjs.utc(q.get('to')) : undefined,
     match_day_of_week: matchDayOfWeek == 'true',
     with_imported: q.get('with_imported') ? q.get('with_imported') === 'true' : true,
+    experimental_session_count: q.get('experimental_session_count'),
     filters: {
       'goal': q.get('goal'),
       'props': JSON.parse(q.get('props')),

lib/plausible/site.ex

@@ -242,3 +242,9 @@ defmodule Plausible.Site do
     end
   end
 end
+
+defimpl FunWithFlags.Actor, for: Plausible.Site do
+  def id(%{domain: domain}) do
+    "site:#{domain}"
+  end
+end

lib/plausible/stats/base.ex

@@ -132,14 +132,18 @@ defmodule Plausible.Stats.Base do
   }
 
   def query_sessions(site, query) do
-    {first_datetime, last_datetime} = utc_boundaries(query, site)
+    {first_datetime, last_datetime} =
+      utc_boundaries(query, site)
+
+    q = from(s in "sessions_v2", where: s.site_id == ^site.id)
 
     sessions_q =
-      from(
-        s in "sessions_v2",
-        where: s.site_id == ^site.id,
-        where: s.start >= ^first_datetime and s.start < ^last_datetime
-      )
+      if FunWithFlags.enabled?(:experimental_session_count, for: site) or
+           query.experimental_session_count? do
+        from s in q, where: s.timestamp >= ^first_datetime and s.start < ^last_datetime
+      else
+        from s in q, where: s.start >= ^first_datetime and s.start < ^last_datetime
+      end
 
     on_full_build do
       sessions_q = Plausible.Stats.Sampling.add_query_hint(sessions_q, query)

lib/plausible/stats/query.ex

@@ -8,7 +8,8 @@ defmodule Plausible.Stats.Query do
             sample_threshold: 20_000_000,
             imported_data_requested: false,
             include_imported: false,
-            now: nil
+            now: nil,
+            experimental_session_count?: false
 
   require OpenTelemetry.Tracer, as: Tracer
   alias Plausible.Stats.{Filters, Interval}
@@ -21,6 +22,7 @@ defmodule Plausible.Stats.Query do
     query =
       __MODULE__
       |> struct!(now: now)
+      |> put_experimental_session_count(params)
       |> put_period(site, params)
       |> put_interval(params)
       |> put_parsed_filters(params)
@@ -34,6 +36,14 @@ defmodule Plausible.Stats.Query do
     query
   end
 
+  defp put_experimental_session_count(query, params) do
+    if Map.get(params, "experimental_session_count") == "true" do
+      struct!(query, experimental_session_count?: true)
+    else
+      query
+    end
+  end
+
   defp put_period(query, site, %{"period" => "realtime"}) do
     date = today(site.timezone)
 

test/plausible_web/controllers/api/stats_controller/top_stats_test.exs

@@ -40,19 +40,32 @@ defmodule PlausibleWeb.Api.StatsController.TopStatsTest do
              } in res["top_stats"]
     end
 
-    test "counts total visits", %{conn: conn, site: site} do
+    test "experimental session count", %{conn: conn, site: site} do
       populate_stats(site, [
-        build(:pageview, user_id: @user_id, timestamp: ~N[2021-01-01 00:00:00]),
+        build(:pageview, user_id: 3421, timestamp: ~N[2020-12-31 23:30:00]),
+        build(:pageview, user_id: @user_id, timestamp: ~N[2020-12-31 23:59:00]),
         build(:pageview, user_id: @user_id, timestamp: ~N[2021-01-01 00:01:00]),
-        build(:pageview, user_id: @user_id, timestamp: ~N[2021-01-01 10:00:00]),
-        build(:pageview, timestamp: ~N[2021-01-01 15:00:00])
+        build(:pageview, user_id: 2, timestamp: ~N[2020-12-31 23:59:00]),
+        build(:pageview, user_id: 2, timestamp: ~N[2021-01-01 00:01:00]),
+        build(:pageview, user_id: 617_235, timestamp: ~N[2021-01-03 00:00:00])
       ])
 
-      conn = get(conn, "/api/stats/#{site.domain}/top-stats?period=day&date=2021-01-01")
+      conn =
+        get(
+          conn,
+          "/api/stats/#{site.domain}/top-stats?period=day&date=2021-01-01&experimental_session_count=true"
+        )
 
       res = json_response(conn, 200)
 
-      assert %{"name" => "Total visits", "value" => 3} in res["top_stats"]
+      assert res["top_stats"] == [
+               %{"name" => "Unique visitors", "value" => 2},
+               %{"name" => "Total visits", "value" => 2},
+               %{"name" => "Total pageviews", "value" => 2},
+               %{"name" => "Views per visit", "value" => 2.0},
+               %{"name" => "Bounce rate", "value" => 0},
+               %{"name" => "Visit duration", "value" => 120}
+             ]
     end
 
     test "counts pages per visit", %{conn: conn, site: site} do