chore: Del and NUMINCRBY use json::Path (#2655)

* chore: Del and NUMINCRBY use json::Path

Also, fix various protocol bugs when we sent simple string
instead of sending bulk strings.

Fixed a typo in path.cc that lead to a data race bug.

Finally, flip the flag in regression tests to start covering json::Path code
and added test coverage for the data race bug

---------

Signed-off-by: Roman Gershman <[email protected]>

src/core/json/path.cc

@@ -365,8 +365,9 @@ auto Dfs::MutateStep(const PathSegment& segment, const MutateCallback& cb, JsonT
       if (segment.index() >= node->size()) {
         return make_unexpected(OUT_OF_BOUNDS);
       }
-      if (Mutate(cb, nullopt, &node[segment.index()])) {
-        node->erase(node->array_range().begin() + segment.index());
+      auto it = node->array_range().begin() + segment.index();
+      if (Mutate(cb, nullopt, &*it)) {
+        node->erase(it);
       }
     } break;
 
@@ -475,10 +476,12 @@ nonstd::expected<json::Path, string> ParsePath(string_view path) {
   return driver.TakePath();
 }
 
-void MutatePath(const Path& path, MutateCallback callback, JsonType* json) {
+unsigned MutatePath(const Path& path, MutateCallback callback, JsonType* json) {
   if (path.empty())
-    return;
-  Dfs().Mutate(path, callback, json);
+    return 0;
+  Dfs dfs;
+  dfs.Mutate(path, callback, json);
+  return dfs.matches();
 }
 
 }  // namespace dfly::json

src/core/json/path.h

@@ -95,7 +95,9 @@ using PathCallback = absl::FunctionRef<void(std::optional<std::string_view>, con
 using MutateCallback = absl::FunctionRef<bool(std::optional<std::string_view>, JsonType*)>;
 
 void EvaluatePath(const Path& path, const JsonType& json, PathCallback callback);
-void MutatePath(const Path& path, MutateCallback callback, JsonType* json);
+
+// returns number of matches found with the given path.
+unsigned MutatePath(const Path& path, MutateCallback callback, JsonType* json);
 nonstd::expected<Path, std::string> ParsePath(std::string_view path);
 
 }  // namespace dfly::json