server: Add DatabaseExecutionContext

server/app/com/xsn/explorer/executors/DatabaseExecutionContext.scala

@@ -0,0 +1,15 @@
+package com.xsn.explorer.executors
+
+import javax.inject.{Inject, Singleton}
+
+import akka.actor.ActorSystem
+import play.api.libs.concurrent.CustomExecutionContext
+
+import scala.concurrent.ExecutionContext
+
+trait DatabaseExecutionContext extends ExecutionContext
+
+@Singleton
+class DatabaseAkkaExecutionContext @Inject()(system: ActorSystem)
+    extends CustomExecutionContext(system, "database.dispatcher")
+    with DatabaseExecutionContext

server/app/com/xsn/explorer/modules/ExecutorsModule.scala

@@ -1,11 +1,12 @@
 package com.xsn.explorer.modules
 
 import com.google.inject.AbstractModule
-import com.xsn.explorer.executors.{ExternalServiceAkkaExecutionContext, ExternalServiceExecutionContext}
+import com.xsn.explorer.executors.{DatabaseAkkaExecutionContext, DatabaseExecutionContext, ExternalServiceAkkaExecutionContext, ExternalServiceExecutionContext}
 
 class ExecutorsModule extends AbstractModule {
 
   override def configure(): Unit = {
     bind(classOf[ExternalServiceExecutionContext]).to(classOf[ExternalServiceAkkaExecutionContext])
+    bind(classOf[DatabaseExecutionContext]).to(classOf[DatabaseAkkaExecutionContext])
   }
 }

server/conf/application.conf

@@ -60,6 +60,26 @@ play.evolutions {
   }
 }
 
+# Number of database connections
+# See https://github.com/brettwooldridge/HikariCP/wiki/About-Pool-Sizing
+fixedConnectionPool = 9
+
+play.db {
+  prototype {
+    hikaricp.minimumIdle = ${fixedConnectionPool}
+    hikaricp.maximumPoolSize = ${fixedConnectionPool}
+  }
+}
+
+# Job queue sized to HikariCP connection pool
+database.dispatcher {
+  executor = "thread-pool-executor"
+  throughput = 1
+  thread-pool-executor {
+    fixed-pool-size = ${fixedConnectionPool}
+  }
+}
+
 externalService.dispatcher {
   executor = "thread-pool-executor"
   throughput = 1

server/test/com/xsn/explorer/helpers/Executors.scala

@@ -1,6 +1,6 @@
 package com.xsn.explorer.helpers
 
-import com.xsn.explorer.executors.ExternalServiceExecutionContext
+import com.xsn.explorer.executors.{DatabaseExecutionContext, ExternalServiceExecutionContext}
 
 import scala.concurrent.ExecutionContext
 
@@ -13,4 +13,10 @@ object Executors {
 
     override def reportFailure(cause: Throwable): Unit = globalEC.reportFailure(cause)
   }
+
+  implicit val databaseEC: DatabaseExecutionContext = new DatabaseExecutionContext {
+    override def execute(runnable: Runnable): Unit = globalEC.execute(runnable)
+
+    override def reportFailure(cause: Throwable): Unit = globalEC.reportFailure(cause)
+  }
 }