SqaleAuditService: audit cleanup by max count fixed for missing ID

Previous version supported only uninterrupted ID sequence, which may
not work after imported audit. Now it really finds the right row from
which to start the delete.

(cherry picked from commit d3fbcf6)

repo/repo-sqale/src/main/java/com/evolveum/midpoint/repo/sqale/audit/SqaleAuditService.java

@@ -479,17 +479,19 @@ private void executeCleanupAuditMaxRecords(int maxRecords) {
         try (JdbcSession jdbcSession = sqlRepoContext.newJdbcSession().startTransaction()) {
             logger.info("Audit cleanup, deleting to leave only {} records.", maxRecords);
             QAuditEventRecord qae = QAuditEventRecordMapping.get().defaultAlias();
-            Long lastId = jdbcSession.newQuery()
-                    .select(qae.id.max())
+            Long deleteFromId = jdbcSession.newQuery()
+                    .select(qae.id)
                     .from(qae)
-                    .fetchOne();
-            if (lastId == null || lastId < maxRecords) {
-                logger.info("Nothing to delete from audit, {} entries allowed, current max ID is {}.", maxRecords, lastId);
+                    .orderBy(qae.id.desc())
+                    .offset(maxRecords)
+                    .fetchFirst();
+            if (deleteFromId == null) {
+                logger.info("Nothing to delete from audit, {} entries allowed.", maxRecords);
                 return;
             }
 
             deletedCount = jdbcSession.newDelete(qae)
-                    .where(qae.id.loe(lastId - maxRecords))
+                    .where(qae.id.loe(deleteFromId))
                     .execute();
             jdbcSession.commit();
         } finally {

repo/repo-sqale/src/test/java/com/evolveum/midpoint/repo/sqale/func/AuditCleanupTest.java

@@ -69,6 +69,7 @@ private void prepareAuditRecords(long startTimestamp, int count, OperationResult
         }
     }
 
+    // These tests rely on uninterrupted ID series, but cleanup works even with holes
     @Test
     public void test100CleanupByCount() throws SchemaException {
         given("audit has 100 records");
@@ -90,6 +91,40 @@ public void test100CleanupByCount() throws SchemaException {
         assertThat(maxId - minId).isEqualTo(recordsToLeave - 1);
     }
 
+    @Test
+    public void test101CleanupByHighCount() throws SchemaException {
+        given("audit has 100 records");
+        OperationResult operationResult = createOperationResult();
+        prepareAuditRecords(System.currentTimeMillis(), 100, operationResult);
+        QAuditEventRecord qae = QAuditEventRecordMapping.get().defaultAlias();
+
+        when("audit cleanup is called to leave 150 records");
+        int recordsToLeave = 150;
+        auditService.cleanupAudit(new CleanupPolicyType()
+                .maxRecords(recordsToLeave), operationResult);
+
+        then("operation is success and nothing is deleted");
+        assertThatOperationResult(operationResult).isSuccess();
+        assertCount(qae, 100); // original count
+    }
+
+    @Test
+    public void test102CleanupByZeroCount() throws SchemaException {
+        given("audit has 100 records");
+        OperationResult operationResult = createOperationResult();
+        prepareAuditRecords(System.currentTimeMillis(), 100, operationResult);
+        QAuditEventRecord qae = QAuditEventRecordMapping.get().defaultAlias();
+
+        when("audit cleanup is called to leave 0 records");
+        int recordsToLeave = 0;
+        auditService.cleanupAudit(new CleanupPolicyType()
+                .maxRecords(recordsToLeave), operationResult);
+
+        then("operation is success and everything is deleted");
+        assertThatOperationResult(operationResult).isSuccess();
+        assertCount(qae, 0);
+    }
+
     @Test
     public void test200CleanupByAge() throws SchemaException {
         given("audit has 100 records across the last 100s");