Expose hooks to load ET pybindings with your own data loader

CMakeLists.txt

@@ -997,6 +997,18 @@ if(EXECUTORCH_BUILD_PYBIND)
     EXPORT ExecuTorchTargets
     LIBRARY DESTINATION executorch/extension/pybindings
   )
+
+  # pybind data_loader module - provides PyDataLoader type for external
+  # pybinding extensions to create custom data loaders
+  pybind11_add_module(
+    data_loader SHARED extension/pybindings/pybindings_data_loader.cpp
+  )
+  target_include_directories(data_loader PRIVATE ${_common_include_directories})
+  target_compile_options(data_loader PUBLIC ${_pybind_compile_options})
+  target_link_libraries(data_loader PRIVATE executorch)
+  install(TARGETS data_loader
+          LIBRARY DESTINATION executorch/extension/pybindings
+  )
 endif()
 
 if(EXECUTORCH_BUILD_WASM)

extension/pybindings/BUCK

@@ -1,4 +1,6 @@
 load("@fbcode_macros//build_defs:build_file_migration.bzl", "fbcode_target", "non_fbcode_target")
+load("@fbcode_macros//build_defs:cpp_library.bzl", "cpp_library")
+load("@fbcode_macros//build_defs:cpp_python_extension.bzl", "cpp_python_extension")
 # Any targets that should be shared between fbcode and xplat must be defined in
 # targets.bzl. This file can contain fbcode-only targets.
 
@@ -72,3 +74,33 @@ fbcode_target(_kind = runtime.python_library,
         "//executorch/exir:_warnings",
     ],
 )
+
+# Header-only library that provides PyDataLoader for external pybinding extensions.
+# This allows external libraries (like PTEZ) to create custom data loaders that can
+# be passed to _load_for_executorch_from_data_loader().
+fbcode_target(
+    _kind = cpp_library,
+    name = "data_loader_types",
+    headers = ["pybindings_data_loader.h"],
+    exported_deps = [
+        "//executorch/runtime/core:core",
+    ],
+    visibility = ["PUBLIC"],
+)
+
+# Python extension that registers the PyDataLoader type.
+# This allows external libraries to create PyDataLoader instances without
+# importing the full core pybindings.
+fbcode_target(
+    _kind = cpp_python_extension,
+    name = "data_loader",
+    srcs = ["pybindings_data_loader.cpp"],
+    base_module = "executorch.extension.pybindings",
+    deps = [
+        ":data_loader_types",
+    ],
+    external_deps = [
+        "pybind11",
+    ],
+    visibility = ["PUBLIC"],
+)

extension/pybindings/data_loader.pyi

@@ -0,0 +1,12 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+# pyre-strict
+
+class PyDataLoader:
+    """Pybind11 wrapper for DataLoader."""
+
+    ...

extension/pybindings/pybindings.cpp

@@ -24,6 +24,7 @@
 #include <executorch/extension/memory_allocator/malloc_memory_allocator.h>
 #include <executorch/extension/module/bundled_module.h>
 #include <executorch/extension/module/module.h>
+#include <executorch/extension/pybindings/pybindings_data_loader.h>
 #include <executorch/extension/tensor/tensor_ptr.h>
 #include <executorch/extension/tensor/tensor_ptr_maker.h>
 #include <executorch/extension/threadpool/threadpool.h>
@@ -85,6 +86,8 @@ using ::executorch::extension::BufferDataLoader;
 using ::executorch::extension::MallocMemoryAllocator;
 using ::executorch::extension::MmapDataLoader;
 using ::executorch::extension::ET_BUNDLED_MODULE_NAMESPACE::BundledModule;
+using ::executorch::extension::pybindings::PyDataLoader;
+using ::executorch::extension::pybindings::SharedPtrDataLoader;
 using ::executorch::runtime::ArrayRef;
 using ::executorch::runtime::DataLoader;
 using ::executorch::runtime::Error;
@@ -246,6 +249,29 @@ inline std::unique_ptr<Module> load_module_from_buffer_with_data_file(
       std::move(data_loader));
 }
 
+inline std::unique_ptr<Module> load_module_from_data_loader(
+    std::shared_ptr<PyDataLoader> loader,
+    std::optional<const std::string> data_map_path,
+    std::unique_ptr<runtime::EventTracer> event_tracer) {
+  EXECUTORCH_SCOPE_PROF("load_module_from_data_loader");
+
+  if (data_map_path.has_value()) {
+    auto data_map_loader = loader_from_file(data_map_path.value());
+    return std::make_unique<Module>(
+        loader->make_delegating_loader(),
+        nullptr, // memory_allocator
+        nullptr, // temp_allocator
+        std::move(event_tracer), // event_tracer
+        std::move(data_map_loader)); // data_map_loader
+  }
+  return std::make_unique<Module>(
+      loader->make_delegating_loader(),
+      nullptr, // memory_allocator
+      nullptr, // temp_allocator
+      std::move(event_tracer), // event_tracer
+      nullptr); // data_map_loader
+}
+
 inline py::list get_outputs_as_py_list(
     const std::vector<EValue>& outputs,
     bool clone_outputs = true) {
@@ -601,6 +627,17 @@ struct PyModule final {
             setup_event_tracer(enable_etdump, debug_buffer_size),
             program_verification)) {}
 
+  explicit PyModule(
+      std::shared_ptr<PyDataLoader> loader,
+      std::optional<const std::string> data_path,
+      bool enable_etdump,
+      size_t debug_buffer_size = 0)
+      : debug_buffer_size_(debug_buffer_size),
+        module_(load_module_from_data_loader(
+            std::move(loader),
+            data_path,
+            setup_event_tracer(enable_etdump, debug_buffer_size))) {}
+
   PyModule(const PyModule&) = delete;
   PyModule& operator=(const PyModule&) = delete;
   PyModule(PyModule&&) = default;
@@ -676,6 +713,17 @@ struct PyModule final {
         Program::Verification::InternalConsistency);
   }
 
+  // Load from an external data loader.
+  // This allows external libraries (like PTEZ) to provide custom data loaders.
+  static std::unique_ptr<PyModule> load_from_data_loader(
+      std::shared_ptr<PyDataLoader> loader,
+      std::optional<const std::string> data_path,
+      bool enable_etdump,
+      size_t debug_buffer_size = 0) {
+    return std::make_unique<PyModule>(
+        std::move(loader), data_path, enable_etdump, debug_buffer_size);
+  }
+
   py::list run_method(
       const std::string& method_name,
       const py::sequence& inputs,
@@ -1529,6 +1577,20 @@ PYBIND11_MODULE(EXECUTORCH_PYTHON_MODULE_NAME, m) {
       py::arg("buffer"),
       py::arg("non_const_pool_size") = kDEFAULT_BUNDLED_INPUT_POOL_SIZE,
       call_guard);
+
+  // Import the PyDataLoader type from the shared module.
+  // This ensures the type is registered once and shared across all modules.
+  py::module_::import("executorch.extension.pybindings.data_loader");
+
+  m.def(
+      "_load_for_executorch_from_data_loader",
+      &PyModule::load_from_data_loader,
+      py::arg("loader"),
+      py::arg("data_path") = py::none(),
+      py::arg("enable_etdump") = false,
+      py::arg("debug_buffer_size") = 0,
+      call_guard);
+
   m.def(
       "_dump_profile_results",
       []() {

extension/pybindings/pybindings.pyi

@@ -154,6 +154,9 @@ class MethodMeta:
 
     def __repr__(self) -> str: ...
 
+# Re-export PyDataLoader from the shared module for backward compatibility.
+from executorch.extension.pybindings.data_loader import PyDataLoader as PyDataLoader
+
 @experimental("This API is experimental and subject to change without notice.")
 def _load_for_executorch(
     program_path: str,
@@ -215,6 +218,33 @@ def _load_for_executorch_from_bundled_program(
     """
     ...
 
+@experimental("This API is experimental and subject to change without notice.")
+def _load_for_executorch_from_data_loader(
+    loader: PyDataLoader,
+    data_path: Optional[str] = None,
+    enable_etdump: bool = False,
+    debug_buffer_size: int = 0,
+) -> ExecuTorchModule:
+    """Load an ExecuTorch Program from a PyDataLoader.
+
+    This function allows external libraries to provide custom data loaders
+    (e.g., for compressed files) and load programs using them.
+
+    .. warning::
+
+        This API is experimental and subject to change without notice.
+
+    Args:
+        loader: A PyDataLoader wrapping a custom DataLoader implementation.
+        data_path: Optional path to a data file (e.g., for external weights).
+        enable_etdump: If true, enables an ETDump which can store profiling information.
+        debug_buffer_size: If non-zero, enables a debug buffer for intermediate results.
+
+    Returns:
+        An ExecuTorchModule ready for execution.
+    """
+    ...
+
 @experimental("This API is experimental and subject to change without notice.")
 def _load_bundled_program_from_buffer(
     buffer: bytes, non_const_pool_size: int = ...

extension/pybindings/pybindings_data_loader.cpp

@@ -0,0 +1,19 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#include <pybind11/pybind11.h>
+
+#include <executorch/extension/pybindings/pybindings_data_loader.h>
+
+namespace py = pybind11;
+
+using ::executorch::extension::pybindings::PyDataLoader;
+
+PYBIND11_MODULE(data_loader, m) {
+  py::class_<PyDataLoader, std::shared_ptr<PyDataLoader>>(m, "PyDataLoader");
+}

extension/pybindings/pybindings_data_loader.h

@@ -0,0 +1,77 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#pragma once
+
+#include <memory>
+
+#include <executorch/runtime/core/data_loader.h>
+#include <executorch/runtime/core/freeable_buffer.h>
+#include <executorch/runtime/core/result.h>
+#include <executorch/runtime/platform/compiler.h>
+
+namespace executorch {
+namespace extension {
+namespace pybindings {
+
+/// DataLoader wrapper holding a shared_ptr, allowing sharing between Python
+/// and C++ while Module takes ownership via unique_ptr.
+class SharedPtrDataLoader final : public runtime::DataLoader {
+ public:
+  explicit SharedPtrDataLoader(std::shared_ptr<runtime::DataLoader> loader)
+      : loader_(std::move(loader)) {}
+
+  ET_NODISCARD runtime::Result<runtime::FreeableBuffer> load(
+      size_t offset,
+      size_t size,
+      const SegmentInfo& segment_info) const override {
+    return loader_->load(offset, size, segment_info);
+  }
+
+  ET_NODISCARD runtime::Result<size_t> size() const override {
+    return loader_->size();
+  }
+
+  ET_NODISCARD runtime::Error load_into(
+      size_t offset,
+      size_t size,
+      const SegmentInfo& segment_info,
+      void* buffer) const override {
+    return loader_->load_into(offset, size, segment_info, buffer);
+  }
+
+ private:
+  std::shared_ptr<runtime::DataLoader> loader_;
+};
+
+/// Pybind11 wrapper for DataLoader. Use shared_ptr holder type in pybind11.
+struct PyDataLoader {
+  explicit PyDataLoader(std::shared_ptr<runtime::DataLoader> loader)
+      : loader_(std::move(loader)) {}
+
+  PyDataLoader(const PyDataLoader&) = delete;
+  PyDataLoader& operator=(const PyDataLoader&) = delete;
+  PyDataLoader(PyDataLoader&&) = default;
+  PyDataLoader& operator=(PyDataLoader&&) = default;
+
+  std::shared_ptr<runtime::DataLoader> get() const {
+    return loader_;
+  }
+
+  /// Creates a unique_ptr DataLoader that delegates to the shared loader.
+  std::unique_ptr<runtime::DataLoader> make_delegating_loader() const {
+    return std::make_unique<SharedPtrDataLoader>(loader_);
+  }
+
+ private:
+  std::shared_ptr<runtime::DataLoader> loader_;
+};
+
+} // namespace pybindings
+} // namespace extension
+} // namespace executorch

setup.py

@@ -805,6 +805,13 @@ def run(self):  # noqa C901
             modpath="executorch.extension.pybindings._portable_lib",
             dependent_cmake_flags=["EXECUTORCH_BUILD_PYBIND"],
         ),
+        # Install the data_loader pybindings extension which provides the
+        # PyDataLoader type for external pybinding extensions.
+        BuiltExtension(
+            src="data_loader.cp*" if _is_windows() else "data_loader.*",
+            modpath="executorch.extension.pybindings.data_loader",
+            dependent_cmake_flags=["EXECUTORCH_BUILD_PYBIND"],
+        ),
         BuiltExtension(
             src="extension/training/_training_lib.*",  # @lint-ignore https://github.com/pytorch/executorch/blob/cb3eba0d7f630bc8cec0a9cc1df8ae2f17af3f7a/scripts/lint_xrefs.sh
             modpath="executorch.extension.training.pybindings._training_lib",

shim_et/xplat/executorch/extension/pybindings/pybindings.bzl

@@ -61,6 +61,7 @@ def executorch_pybindings(python_module_name, srcs = [], cppdeps = [], visibilit
         deps = [
             "//executorch/runtime/core:core",
             "//executorch/extension/threadpool:threadpool",
+            "//executorch/extension/pybindings:data_loader_types",
         ] + cppdeps,
         external_deps = [
             "pybind11",