Add the ability to download the current perfetto trace in Spinner.

spinner/lib/src/main/assets/partials/prefix.hbs

@@ -9,6 +9,12 @@
   {{/each}}
 </table>
 
+<div>
+  Download Trace: <a href="/trace">Link</a>
+</div>
+
+<br />
+
 <div>
   Database:
   <select id="database-selector">

spinner/lib/src/main/java/org/signal/spinner/SpinnerServer.kt

@@ -12,7 +12,9 @@ import org.signal.core.util.ExceptionUtil
 import org.signal.core.util.ForeignKeyConstraint
 import org.signal.core.util.getForeignKeys
 import org.signal.core.util.logging.Log
+import org.signal.core.util.tracing.Tracer
 import org.signal.spinner.Spinner.DatabaseConfig
+import java.io.ByteArrayInputStream
 import java.lang.IllegalArgumentException
 import java.security.NoSuchAlgorithmException
 import java.text.SimpleDateFormat
@@ -71,6 +73,7 @@ internal class SpinnerServer(
         session.method == Method.GET && session.uri == "/query" -> getQuery(dbParam)
         session.method == Method.POST && session.uri == "/query" -> postQuery(dbParam, dbConfig, session)
         session.method == Method.GET && session.uri == "/recent" -> getRecent(dbParam)
+        session.method == Method.GET && session.uri == "/trace" -> getTrace()
         session.method == Method.GET && session.uri == "/logs" -> getLogs(dbParam)
         isWebsocketRequested(session) && session.uri == "/logs/websocket" -> getLogWebSocket(session)
         else -> {
@@ -217,6 +220,14 @@ internal class SpinnerServer(
     )
   }
 
+  private fun getTrace(): Response {
+    return newChunkedResponse(
+      Response.Status.OK,
+      "application/octet-stream",
+      ByteArrayInputStream(Tracer.getInstance().serialize())
+    )
+  }
+
   private fun getLogs(dbName: String): Response {
     return renderTemplate(
       "logs",