Implementation:Google deepmind Mujoco Platform Model Holder

Knowledge Sources	Google_deepmind_Mujoco
Domains	Model Management, Resource Ownership
Last Updated	2026-02-15 04:00 GMT

Overview

Provides a RAII container that owns an mjModel, mjData, mjSpec, and mjVFS, with factory methods for loading models from specs, files, or memory buffers.

Description

model_holder.h declares the ModelHolder class which manages the lifecycle of MuJoCo model resources. It provides three static factory methods: FromSpec (takes ownership of an existing mjSpec), FromFile (parses a model file), and FromBuffer (decodes from a memory buffer with a content type). The class stores an mjVFS for virtual file system state, an mjSpec for the model specification, and the compiled mjModel and mjData pair. The ok() method checks for successful loading, and error() returns any load error message. The class is non-copyable.

Usage

Used by Studio's App class and other applications as the primary mechanism for loading and owning MuJoCo models. The holder ensures proper cleanup of all MuJoCo resources (spec deletion, model/data freeing) on destruction.

Code Reference

Source Location

• Repository: Google_deepmind_Mujoco
• File: src/experimental/platform/model_holder.h
• Lines: 1-77

Key Functions

class ModelHolder {
  static std::unique_ptr<ModelHolder> FromSpec(mjSpec* spec);
  static std::unique_ptr<ModelHolder> FromFile(std::string_view filepath);
  static std::unique_ptr<ModelHolder> FromBuffer(std::span<const std::byte> buffer, std::string_view content_type, std::string_view filename);
  mjVFS* vfs();  mjSpec* spec();  mjData* data();  mjModel* model();
  bool ok() const;
  std::string_view error() const;
};

Import

#include "experimental/platform/model_holder.h"

I/O Contract

Inputs

Name	Type	Required	Description
spec	mjSpec*	No	Existing spec (FromSpec takes ownership)
filepath	std::string_view	No	Path to .xml, .mjb, or .mjz file (FromFile)
buffer	std::span<const std::byte>	No	In-memory model data (FromBuffer)
content_type	std::string_view	No	MIME type of buffer contents (FromBuffer)

Outputs

Name	Type	Description
ModelHolder	std::unique_ptr<ModelHolder>	Owned container with mjModel, mjData, mjSpec, mjVFS
error	std::string_view	Error message if loading failed

Related Pages

• Environment:Google_deepmind_Mujoco_C_Build_Environment