From b8c9569f04a640712da5d2d945c29c03eb53ff09 Mon Sep 17 00:00:00 2001
From: Krasimir Angelov <kr.angelov@gmail.com>
Date: Thu, 2 Mar 2023 09:08:14 +0100
Subject: [PATCH] fix transaction accounting in pgf_boot_ngf &
 pgf_checkout_revision

---
 src/runtime/c/pgf/pgf.cxx | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/src/runtime/c/pgf/pgf.cxx b/src/runtime/c/pgf/pgf.cxx
index 9a74adf95..f9136b03b 100644
--- a/src/runtime/c/pgf/pgf.cxx
+++ b/src/runtime/c/pgf/pgf.cxx
@@ -153,12 +153,15 @@ PgfDB *pgf_read_ngf(const char *fpath,
         db = new PgfDB(fpath, O_RDWR, 0, 0);
 
         {
-            DB_scope scope(db, WRITER_SCOPE);
+            DB_scope scope(db, READER_SCOPE);
             ref<PgfPGF> pgf = db->get_active_revision();
-            *revision = db->register_revision(pgf.tagged(), PgfDB::get_txn_id());
+            *revision = 0;
+            if (pgf != 0) {
+                *revision = db->register_revision(pgf.tagged(), PgfDB::get_txn_id()-1);
+                db->ref_count++;
+            }
         }
 
-        db->ref_count++;
         return db;
     } PGF_API_END
 
@@ -1245,11 +1248,11 @@ PGF_API
 PgfRevision pgf_checkout_revision(PgfDB *db, PgfExn *err)
 {
     PGF_API_BEGIN {
-        DB_scope scope(db, WRITER_SCOPE);
+        DB_scope scope(db, READER_SCOPE);
         ref<PgfPGF> pgf = db->get_active_revision();
         object rev = 0;
         if (pgf != 0) {
-            rev = db->register_revision(pgf.tagged(), PgfDB::get_txn_id());
+            rev = db->register_revision(pgf.tagged(), PgfDB::get_txn_id()-1);
             db->ref_count++;
         }
         return rev;