Performance optimization of STL loading

CHANGELOG.md

@@ -42,6 +42,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * Fixed typo in name `Rhino.Geometry.MeshingParameters` in `compas_rhino.geometry.RhinoBrep.to_meshes()`.
 * Fixed `TypeErrorException` when serializing a `Mesh` which has been converted from Rhino.
 * Fixed color conversions in `compas_rhion.conversions.mesh_to_compas`.
+* Fixed double downloading of STL files caused by binary/ascii detection.
+* Improved download speed of STL files when running in IronPython by switching to a .NET-based downloadd.
 
 ### Removed
 

src/compas/_iotools.py

@@ -1,11 +1,42 @@
 """For the time being, these functions are only for internal use."""
-from contextlib import contextmanager
+from __future__ import print_function
+
 import io
+import platform
+from contextlib import contextmanager
+
+if "ironpython" == platform.python_implementation().lower():
+    from System import Array
+    from System import Byte
+    from System.IO import MemoryStream
+    from System.Net import SecurityProtocolType
+    from System.Net import ServicePointManager
+    from System.Net import WebRequest
+
+    def download_url_as_bytes(url):
+        ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12
+
+        request = WebRequest.Create(url)
 
-try:
+        response = request.GetResponse()
+        responseStream = response.GetResponseStream()
+
+        memoryStream = MemoryStream()
+        buffer = Array.CreateInstance(Byte, 8192)
+        bytesRead = responseStream.Read(buffer, 0, buffer.Length)
+
+        while bytesRead > 0:
+            memoryStream.Write(buffer, 0, bytesRead)
+            bytesRead = responseStream.Read(buffer, 0, buffer.Length)
+
+        return memoryStream.ToArray()
+
+else:
     from urllib.request import urlopen
-except ImportError:
-    from urllib2 import urlopen
+
+    def download_url_as_bytes(url):
+        response = urlopen(url)
+        return response.read()
 
 
 @contextmanager
@@ -45,8 +76,7 @@ def open_file(file_or_filename, mode="r"):
             # support all read modes (r, r+, rb, etc)
             if not mode.startswith("r"):
                 raise ValueError("URLs can only be opened in read mode.")
-            response = urlopen(file)
-            file = io.BytesIO(response.read())
+            file = io.BytesIO(download_url_as_bytes(file))
         else:
             file = open(file, mode=mode)
             close_source = True

src/compas/files/stl.py

@@ -114,24 +114,26 @@ def read(self):
 
         """
         is_binary = False
-        with _iotools.open_file(self.filepath, "rb") as file:
-            line = file.readline().strip()
+
+        with _iotools.open_file(self.filepath, "rb") as self.file:
+            line = self.file.readline().strip()
             if b"solid" in line:
                 is_binary = False
             else:
                 is_binary = True
-        try:
-            if not is_binary:
-                self._read_ascii()
-            else:
+            try:
+                if not is_binary:
+                    with _iotools.open_file(self.filepath, "r") as self.file:
+                        self._read_ascii()
+                else:
+                    self._read_binary()
+            except Exception:
+                # raise if it was already detected as binary, but failed anyway
+                if is_binary:
+                    raise
+                # else, ascii parsing failed, try binary
+                is_binary = True
                 self._read_binary()
-        except Exception:
-            # raise if it was already detected as binary, but failed anyway
-            if is_binary:
-                raise
-            # else, ascii parsing failed, try binary
-            is_binary = True
-            self._read_binary()
 
     # ==========================================================================
     # ascii
@@ -151,10 +153,8 @@ def read(self):
     # ==========================================================================
 
     def _read_ascii(self):
-        with _iotools.open_file(self.filepath, "r") as file:
-            self.file = file
-            self.file.seek(0)
-            self.facets = self._read_solids_ascii()
+        self.file.seek(0)
+        self.facets = self._read_solids_ascii()
 
     def _read_solids_ascii(self):
         if not self.file:
@@ -233,11 +233,9 @@ def _read_uint32(self):
         return struct.unpack("<I", bytes_)[0]
 
     def _read_binary(self):
-        with _iotools.open_file(self.filepath, "rb") as file:
-            self.file = file
-            self.file.seek(0)
-            self.header = self._read_header_binary()
-            self.facets = self._read_facets_binary()
+        self.file.seek(0)
+        self.header = self._read_header_binary()
+        self.facets = self._read_facets_binary()
 
     def _read_header_binary(self):
         bytes_ = self.file.read(80)