Cache message-lookup result longer if a message was found

Author: rtyley

app/controllers/Api.scala

@@ -9,16 +9,26 @@ import play.api.cache.Cached
 import play.api.libs.json.Json._
 import play.api.mvc._
 
+import scala.Function.unlift
 import scala.concurrent.ExecutionContext.Implicits.global
-import scala.concurrent.Future
+import scala.concurrent.duration._
+import scala.language.postfixOps
 
 class Api @Inject() (cached: Cached) extends Controller {
 
-  def messageLookup(repoId: RepoId, query: String) = cached(s"$repoId $query") {
-    Action.async {
-      for {
-        messagesOpt <- Project.byRepoId(repoId).mailingList.lookupMessage(query)
-      } yield Ok(toJson(messagesOpt: Seq[MessageSummary]))
+  val MessageFoundHeader = "X-submitGit-MessageFound"
+  
+  val CacheForLongerIfMessageFound = unlift[ResponseHeader, Duration](_.headers.get(MessageFoundHeader).map(_ => 100 days))
+  
+  def messageLookup(repoId: RepoId, query: String) = {
+    cached.apply((_ => s"$repoId $query"): (RequestHeader => String), CacheForLongerIfMessageFound).default(3 seconds) {
+      Action.async {
+        for {
+          messagesOpt <- Project.byRepoId(repoId).mailingList.lookupMessage(query)
+        } yield {
+          Ok(toJson(messagesOpt: Seq[MessageSummary])).withHeaders(messagesOpt.map(_ => MessageFoundHeader -> "true") : _*)
+        }
+      }
     }
   }