From 1b09e7293f579a2c3be439ad78905387a17bd910 Mon Sep 17 00:00:00 2001
From: krangelov <kr.angelov@gmail.com>
Date: Fri, 10 Sep 2021 11:39:54 +0200
Subject: [PATCH] implemented pgf_free_revision

---
 src/runtime/c/pgf/db.cxx  | 25 +++++++++++++++++++------
 src/runtime/c/pgf/db.h    |  2 +-
 src/runtime/c/pgf/pgf.cxx | 17 ++++++++++++++++-
 3 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/src/runtime/c/pgf/db.cxx b/src/runtime/c/pgf/db.cxx
index 6a26b602a..44bc78a04 100644
--- a/src/runtime/c/pgf/db.cxx
+++ b/src/runtime/c/pgf/db.cxx
@@ -312,14 +312,23 @@ PgfDB::PgfDB(const char* filepath, int flags, int mode) {
     if (ms == MAP_FAILED)
         throw pgf_systemerror(errno, filepath);
 
-    if (is_new) {
-        init_state(file_size);
-    }
-
     int res = pthread_rwlock_init(&rwlock, NULL);
     if (res != 0) {
         throw pgf_systemerror(errno);
     }
+
+    if (is_new) {
+        init_state(file_size);
+    } else {
+        // We must make sure that left-over transient revisions are
+        // released. This may happen if a client process was killed
+        // or if the garbadge collector has not managed to run
+        // pgf_release_revision() before the process ended.
+
+        while (ms->transient_revisions != 0) {
+            pgf_free_revision(this, ms->transient_revisions.as_object());
+        }
+    }
 }
 
 PGF_INTERNAL
@@ -994,14 +1003,18 @@ void PgfDB::link_transient_revision(ref<PgfPGF> pgf)
 }
 
 PGF_INTERNAL
-void PgfDB::unlink_transient_revision(ref<PgfPGF> pgf)
+bool PgfDB::unlink_transient_revision(ref<PgfPGF> pgf)
 {
     if (pgf->next != 0)
         pgf->next->prev = pgf->prev;
     if (pgf->prev != 0)
         pgf->prev->next = pgf->next;
-    else
+    else if (current_db->ms->transient_revisions == pgf)
         current_db->ms->transient_revisions = pgf->next;
+    else
+        return false;
+
+    return true;
 }
 
 DB_scope::DB_scope(PgfDB *db, DB_scope_mode tp)
diff --git a/src/runtime/c/pgf/db.h b/src/runtime/c/pgf/db.h
index 810510e80..ac8e0558b 100644
--- a/src/runtime/c/pgf/db.h
+++ b/src/runtime/c/pgf/db.h
@@ -82,7 +82,7 @@ public:
     static PGF_INTERNAL_DECL void set_revision(ref<PgfPGF> pgf);
     static PGF_INTERNAL_DECL ref<PgfPGF> revision2pgf(PgfRevision revision);
     static PGF_INTERNAL_DECL void link_transient_revision(ref<PgfPGF> pgf);
-    static PGF_INTERNAL_DECL void unlink_transient_revision(ref<PgfPGF> pgf);
+    static PGF_INTERNAL_DECL bool unlink_transient_revision(ref<PgfPGF> pgf);
 
     PGF_INTERNAL_DECL static void sync();
 
diff --git a/src/runtime/c/pgf/pgf.cxx b/src/runtime/c/pgf/pgf.cxx
index b6737c4b4..21ae51a7e 100644
--- a/src/runtime/c/pgf/pgf.cxx
+++ b/src/runtime/c/pgf/pgf.cxx
@@ -156,8 +156,23 @@ void pgf_free(PgfDB *db)
 }
 
 PGF_API_DECL
-void pgf_free_revision(PgfDB *pgf, PgfRevision revision)
+void pgf_free_revision(PgfDB *db, PgfRevision revision)
 {
+    try {
+        DB_scope scope(db, READER_SCOPE);
+        ref<PgfPGF> pgf = PgfDB::revision2pgf(revision);
+
+        if (PgfDB::unlink_transient_revision(pgf)) {
+            namespace_release(pgf->gflags);
+            PgfDB::free(pgf->abstract.name);
+            namespace_release(pgf->abstract.aflags);
+            namespace_release(pgf->abstract.funs);
+            namespace_release(pgf->abstract.cats);
+            PgfDB::free(pgf);
+        }
+    } catch (std::runtime_error& e) {
+        // silently ignore and hope for the best
+    }
 }
 
 PGF_API