deal with deadlocks while fetching contracts in json-api Oracle (#11391)

* clean up some imports

* test case trying to find deadlock situation

* add deadlocks to causes of ContractsFetch retry for Oracle

* Revert "test case trying to find deadlock situation"

This reverts commit 9b19046.

* no changelog

CHANGELOG_BEGIN
CHANGELOG_END

ledger-service/http-json/src/itlib/scala/http/AbstractDatabaseIntegrationTest.scala

@@ -187,11 +187,10 @@ abstract class AbstractDatabaseIntegrationTest extends AsyncFreeSpecLike with Be
   }.unsafeToFuture()
 
   "SurrogateTemplateIdCache" - {
+    import dao.logHandler, dao.jdbcDriver.q.queries
+
     "should be used on template insertion and reads" in {
-      import dao.jdbcDriver.q.queries
-      def getOrElseInsertTemplate(tpid: TemplateId[String])(implicit
-          logHandler: LogHandler = dao.logHandler
-      ) = instanceUUIDLogCtx(implicit lc =>
+      def getOrElseInsertTemplate(tpid: TemplateId[String]) = instanceUUIDLogCtx(implicit lc =>
         dao.transact(
           queries
             .surrogateTemplateId(tpid.packageId, tpid.moduleName, tpid.entityName)
@@ -212,7 +211,6 @@ abstract class AbstractDatabaseIntegrationTest extends AsyncFreeSpecLike with Be
     "doesn't cache uncommitted template IDs" in {
       import dbbackend.Queries.DBContract, spray.json.{JsObject, JsNull, JsValue},
       spray.json.DefaultJsonProtocol._
-      import dao.logHandler, dao.jdbcDriver.q.queries
 
       val tpId = TemplateId("pkg", "mod", "UncomCollision")
 

ledger-service/http-json/src/main/scala/com/digitalasset/http/dbbackend/SupportedJdbcDriver.scala

@@ -88,7 +88,10 @@ object SupportedJdbcDriver {
       // all oracle class 23 errors yield 23000; if we want to check for *unique*
       // violation specifically we'll have to look at something other than the SQLState.
       // All other class 23 errors indicate a bug, which should exhaust the retry loop anyway
-      retrySqlStates = Set("23000", ContractDao.StaleOffsetException.SqlState),
+      // likewise, class 61 covers a swath of errors for which one transaction was aborted
+      // in favor of continuing another [conflicting] transaction, for which retrying
+      // seems appropriate as well
+      retrySqlStates = Set("23000", "61000", ContractDao.StaleOffsetException.SqlState),
     )
   }
 }