better monitor PMs sent

app/controllers/Clas.scala

@@ -178,8 +178,14 @@ final class Clas(
                 Reasonable(clas, students, "notify") {
                   val url  = routes.Clas.show(clas.id.value).url
                   val full = if (text contains url) text else s"$text\n\n${env.net.baseUrl}$url"
-                  env.msg.api.multiPost(me, Source(students.map(_.user.id)), full) inject
-                    Redirect(routes.Clas.show(clas.id.value)).flashSuccess
+                  env.msg.api
+                    .multiPost(me, Source(students.map(_.user.id)), full)
+                    .addEffect { nb =>
+                      lila.mon.msg.clasBulk(clas.id.value).record(nb).unit
+                    }
+                    .inject {
+                      Redirect(routes.Clas.show(clas.id.value)).flashSuccess
+                    }
                 }
               }
           )

app/controllers/Team.scala

@@ -516,7 +516,7 @@ You received this because you are subscribed to messages of the team $url."""
               env.msg.api
                 .multiPost(me, env.team.memberStream.subscribedIds(team, MaxPerSecond(50)), full)
                 .addEffect { nb =>
-                  lila.mon.team.massPm(team.id).record(nb).unit
+                  lila.mon.msg.teamBulk(team.id).record(nb).unit
                 }
               funit // we don't wait for the stream to complete, it would make lichess time out
             }(funit)

modules/common/src/main/mon.scala

@@ -420,8 +420,12 @@ object mon {
     }
     def reaction(r: String) = counter("forum.reaction").withTag("reaction", r)
   }
-  object team {
-    def massPm(teamId: String) = histogram("team.mass-pm").withTag("from", teamId)
+  object msg {
+    def post(verdict: String, isNew: Boolean, multi: Boolean) = counter("msg.post").withTags(
+      Map("verdict" -> verdict, "isNew" -> isNew, "multi" -> multi)
+    )
+    def teamBulk(teamId: String) = histogram("msg.bulk.team").withTag("id", teamId)
+    def clasBulk(clasId: String) = histogram("msg.bulk.clas").withTag("id", clasId)
   }
   object puzzle {
     object selector {

modules/msg/src/main/MsgApi.scala

@@ -86,6 +86,7 @@ final class MsgApi(
         contacts <- userRepo.contacts(orig, dest) orFail s"Missing convo contact user $orig->$dest"
         isNew    <- !colls.thread.exists($id(threadId))
         verdict  <- security.can.post(contacts, msgPre.text, isNew, unlimited = multi)
+        _ = lila.mon.msg.post(verdict.toString, isNew = isNew, multi = multi).increment()
         res <- verdict match {
           case MsgSecurity.Limit     => fuccess(PostResult.Limited)
           case _: MsgSecurity.Reject => fuccess(PostResult.Bounced)