python: connection resume and MSVC support (#1535)

gpt4all-bindings/python/gpt4all/gpt4all.py

@@ -11,7 +11,9 @@ from pathlib import Path
 from typing import Any, Dict, Iterable, List, Optional, Union
 
 import requests
+from requests.exceptions import ChunkedEncodingError
 from tqdm import tqdm
+from urllib3.exceptions import IncompleteRead, ProtocolError
 
 from . import pyllmodel
 
@@ -217,35 +219,61 @@ class GPT4All:
         download_path = os.path.join(model_path, model_filename).replace("\\", "\\\\")
         download_url = get_download_url(model_filename)
 
-        response = requests.get(download_url, stream=True)
-        if response.status_code != 200:
-            raise ValueError(f'Request failed: HTTP {response.status_code} {response.reason}')
+        def make_request(offset=None):
+            headers = {}
+            if offset:
+                print(f"\nDownload interrupted, resuming from byte position {offset}", file=sys.stderr)
+                headers['Range'] = f'bytes={offset}-'  # resume incomplete response
+            response = requests.get(download_url, stream=True, headers=headers)
+            if response.status_code not in (200, 206):
+                raise ValueError(f'Request failed: HTTP {response.status_code} {response.reason}')
+            if offset and (response.status_code != 206 or str(offset) not in response.headers.get('Content-Range', '')):
+                raise ValueError('Connection was interrupted and server does not support range requests')
+            return response
+
+        response = make_request()
 
         total_size_in_bytes = int(response.headers.get("content-length", 0))
         block_size = 2**20  # 1 MB
 
-        with tqdm(total=total_size_in_bytes, unit="iB", unit_scale=True) as progress_bar:
+        with open(download_path, "wb") as file, \
+                tqdm(total=total_size_in_bytes, unit="iB", unit_scale=True) as progress_bar:
             try:
-                with open(download_path, "wb") as file:
-                    for data in response.iter_content(block_size):
-                        progress_bar.update(len(data))
-                        file.write(data)
+                while True:
+                    last_progress = progress_bar.n
+                    try:
+                        for data in response.iter_content(block_size):
+                            file.write(data)
+                            progress_bar.update(len(data))
+                    except ChunkedEncodingError as cee:
+                        if cee.args and isinstance(pe := cee.args[0], ProtocolError):
+                            if len(pe.args) >= 2 and isinstance(ir := pe.args[1], IncompleteRead):
+                                assert progress_bar.n <= ir.partial  # urllib3 may be ahead of us but never behind
+                                # the socket was closed during a read - retry
+                                response = make_request(progress_bar.n)
+                                continue
+                        raise
+                    if total_size_in_bytes != 0 and progress_bar.n < total_size_in_bytes:
+                        if progress_bar.n == last_progress:
+                            raise RuntimeError('Download not making progress, aborting.')
+                        # server closed connection prematurely - retry
+                        response = make_request(progress_bar.n)
+                        continue
+                    break
             except Exception:
-                if os.path.exists(download_path):
-                    if verbose:
-                        print("Cleaning up the interrupted download...")
+                if verbose:
+                    print("Cleaning up the interrupted download...", file=sys.stderr)
+                try:
                     os.remove(download_path)
+                except OSError:
+                    pass
                 raise
 
-        # Validate download was successful
-        if total_size_in_bytes != 0 and progress_bar.n != total_size_in_bytes:
-            raise RuntimeError("An error occurred during download. Downloaded file may not work.")
-
-        # Sleep for a little bit so OS can remove file lock
-        time.sleep(2)
+        if os.name == 'nt':
+            time.sleep(2)  # Sleep for a little bit so Windows can remove file lock
 
         if verbose:
-            print("Model downloaded at: ", download_path)
+            print("Model downloaded at:", download_path, file=sys.stderr)
         return download_path
 
     def generate(

gpt4all-bindings/python/gpt4all/pyllmodel.py

@@ -23,28 +23,20 @@ MODEL_LIB_PATH = file_manager.enter_context(importlib.resources.as_file(
     importlib.resources.files("gpt4all") / "llmodel_DO_NOT_MODIFY" / "build",
 ))
 
+
 def load_llmodel_library():
-    system = platform.system()
+    ext = {"Darwin": "dylib", "Linux": "so", "Windows": "dll"}[platform.system()]
 
-    def get_c_shared_lib_extension():
-        if system == "Darwin":
-            return "dylib"
-        elif system == "Linux":
-            return "so"
-        elif system == "Windows":
-            return "dll"
-        else:
-            raise Exception("Operating System not supported")
+    try:
+        # Linux, Windows, MinGW
+        lib = ctypes.CDLL(str(MODEL_LIB_PATH / f"libllmodel.{ext}"))
+    except FileNotFoundError:
+        if ext != 'dll':
+            raise
+        # MSVC
+        lib = ctypes.CDLL(str(MODEL_LIB_PATH / "llmodel.dll"))
 
-    c_lib_ext = get_c_shared_lib_extension()
-
-    llmodel_file = "libllmodel" + "." + c_lib_ext
-
-    llmodel_dir = str(MODEL_LIB_PATH / llmodel_file).replace("\\", r"\\")
-
-    llmodel_lib = ctypes.CDLL(llmodel_dir)
-
-    return llmodel_lib
+    return lib
 
 
 llmodel = load_llmodel_library()