Add tracer_guard to restore database tracer

2 files changed, 13 insertions, 2 deletions

diff --git a/bpkg/database b/bpkg/database
index c4ace56..05ffb04 100644
--- a/bpkg/database
+++ b/bpkg/database
@@ -17,6 +17,17 @@ namespace bpkg
 
   database
   open (const dir_path& configuration, tracer&, bool create = false);
+
+  struct tracer_guard
+  {
+    tracer_guard (database& db, tracer& t)
+        : db_ (db), t_ (db.tracer ()) {db.tracer (t);}
+    ~tracer_guard () {db_.tracer (*t_);}
+
+  private:
+    database& db_;
+    odb::tracer* t_;
+  };
 }
 
 #endif // BPKG_DATABASE
diff --git a/bpkg/pkg-unpack.cxx b/bpkg/pkg-unpack.cxx
index 6979842..463531f 100644
--- a/bpkg/pkg-unpack.cxx
+++ b/bpkg/pkg-unpack.cxx
@@ -28,7 +28,7 @@ namespace bpkg
   pkg_unpack (database& db, const dir_path& c, const dir_path& d, bool purge)
   {
     tracer trace ("pkg_unpack(dir)");
-    db.tracer (trace); // "Tail" call, never restored.
+    tracer_guard tg (db, trace);
 
     if (!exists (d))
       fail << "package directory " << d << " does not exist";
@@ -82,7 +82,7 @@ namespace bpkg
   pkg_unpack (database& db, const dir_path& c, const string& name)
   {
     tracer trace ("pkg_unpack(pkg)");
-    db.tracer (trace); // "Tail" call, never restored.
+    tracer_guard tg (db, trace);
 
     transaction t (db.begin ());
     shared_ptr<package> p (db.find<package> (name));