WIP

tools/analysis/trace-tools/src/lib/parquet.rs

@@ -565,7 +565,13 @@ enum ReadStateVariant<'scope> {
         fmt_fmt: FieldFmt,
         buf_fmt: FieldFmt,
         generic: TableState<'scope>,
+        // We have a table indexed by the address of the format string since that is what we get
+        // from the bprint event.
         meta_events_by_addr: BTreeMap<Address, MetaEventEntry<'scope>>,
+        // However, we don't want to accidentally create 2 identical meta events if 2 or more
+        // independent format strings have the exact same format (e.g. the user copy-pasted some
+        // calls to trace_printk() in various places). For this purpose, we also maintain a map
+        // indexed by the format string content, which is used to populate the by-address map.
         meta_events_by_fmt: BTreeMap<PrintFmtStr, MetaEventEntry<'scope>>,
     },
 }
@@ -764,10 +770,10 @@ where
                                 // Find an already-created meta event that would have the same
                                 // print format string, therefore the same schema.
                                 match meta_events_by_fmt.entry(print_fmt) {
-                                    Entry::Occupied(entry) => entry.get().clone(),
+                                    Entry::Occupied(entry) => Rc::clone(entry.get()),
                                     Entry::Vacant(entry) => {
                                         let new = Rc::new(make_schema(entry.key().clone()));
-                                        entry.insert(new.clone());
+                                        entry.insert(Rc::clone(&new));
                                         new
                                     },
                                 }