Add two STATIC_ settings. Fix #1982

STATIC_CREATE_LINKS = False

Create links instead of copying files. If the content and output
directories are on the same device, then create hard links. Falls
back to symbolic links if the output directory is on a different
filesystem. If symlinks are created, don’t forget to add the -L or
--copy-links option to rsync when uploading your site.

STATIC_CHECK_IF_MODIFIED = False

If set to True, and STATIC_CREATE_LINKS is False, compare mtimes of
content and output files, and only copy content files that are newer
than existing output files.

pelican/generators.py

@@ -2,6 +2,7 @@
 from __future__ import print_function, unicode_literals
 
 import calendar
+import errno
 import fnmatch
 import logging
 import os
@@ -20,9 +21,8 @@ from pelican import signals
 from pelican.cache import FileStampDataCacher
 from pelican.contents import Article, Draft, Page, Static, is_valid_content
 from pelican.readers import Readers
-from pelican.utils import (DateFormatter, copy, copy_file_metadata, mkdir_p,
-                           posixize_path, process_translations,
-                           python_2_unicode_compatible)
+from pelican.utils import (DateFormatter, copy, mkdir_p, posixize_path,
+                           process_translations, python_2_unicode_compatible)
 
 
 logger = logging.getLogger(__name__)
@@ -682,21 +682,9 @@ class StaticGenerator(Generator):
 
     def __init__(self, *args, **kwargs):
         super(StaticGenerator, self).__init__(*args, **kwargs)
+        self.fallback_to_symlinks = False
         signals.static_generator_init.send(self)
 
-    def _copy_paths(self, paths, source, destination, output_path,
-                    final_path=None):
-        """Copy all the paths from source to destination"""
-        for path in paths:
-            if final_path:
-                copy(os.path.join(source, path),
-                     os.path.join(output_path, destination, final_path),
-                     self.settings['IGNORE_FILES'])
-            else:
-                copy(os.path.join(source, path),
-                     os.path.join(output_path, destination, path),
-                     self.settings['IGNORE_FILES'])
-
     def generate_context(self):
         self.staticfiles = []
         for f in self.get_files(self.settings['STATIC_PATHS'],
@@ -724,13 +712,88 @@ class StaticGenerator(Generator):
         self._copy_paths(self.settings['THEME_STATIC_PATHS'], self.theme,
                          self.settings['THEME_STATIC_DIR'], self.output_path,
                          os.curdir)
-        # copy all Static files
         for sc in self.context['staticfiles']:
-            source_path = os.path.join(self.path, sc.source_path)
-            save_as = os.path.join(self.output_path, sc.save_as)
-            mkdir_p(os.path.dirname(save_as))
-            logger.info('Copying %s to %s', sc.source_path, sc.save_as)
-            copy_file_metadata(source_path, save_as)
+            if self._file_update_required(sc):
+                self._link_or_copy_staticfile(sc)
+            else:
+                logger.debug('%s is up to date, not copying', sc.source_path)
+
+    def _copy_paths(self, paths, source, destination, output_path,
+                    final_path=None):
+        """Copy all the paths from source to destination"""
+        for path in paths:
+            if final_path:
+                copy(os.path.join(source, path),
+                     os.path.join(output_path, destination, final_path),
+                     self.settings['IGNORE_FILES'])
+            else:
+                copy(os.path.join(source, path),
+                     os.path.join(output_path, destination, path),
+                     self.settings['IGNORE_FILES'])
+
+    def _file_update_required(self, staticfile):
+        source_path = os.path.join(self.path, staticfile.source_path)
+        save_as = os.path.join(self.output_path, staticfile.save_as)
+        if not os.path.exists(save_as):
+            return True
+        elif (self.settings['STATIC_CREATE_LINKS'] and
+              os.path.samefile(source_path, save_as)):
+            return False
+        elif (self.settings['STATIC_CREATE_LINKS'] and
+              os.path.realpath(save_as) == source_path):
+            return False
+        elif not self.settings['STATIC_CHECK_IF_MODIFIED']:
+            return True
+        else:
+            return self._source_is_newer(staticfile)
+
+    def _source_is_newer(self, staticfile):
+        source_path = os.path.join(self.path, staticfile.source_path)
+        save_as = os.path.join(self.output_path, staticfile.save_as)
+        s_mtime = os.path.getmtime(source_path)
+        d_mtime = os.path.getmtime(save_as)
+        return s_mtime > d_mtime
+
+    def _link_or_copy_staticfile(self, sc):
+        if self.settings['STATIC_CREATE_LINKS']:
+            self._link_staticfile(sc)
+        else:
+            self._copy_staticfile(sc)
+
+    def _copy_staticfile(self, sc):
+        source_path = os.path.join(self.path, sc.source_path)
+        save_as = os.path.join(self.output_path, sc.save_as)
+        self._mkdir(os.path.dirname(save_as))
+        copy(source_path, save_as)
+        logger.info('Copying %s to %s', sc.source_path, sc.save_as)
+
+    def _link_staticfile(self, sc):
+        source_path = os.path.join(self.path, sc.source_path)
+        save_as = os.path.join(self.output_path, sc.save_as)
+        self._mkdir(os.path.dirname(save_as))
+        try:
+            if os.path.lexists(save_as):
+                os.unlink(save_as)
+            logger.info('Linking %s and %s', sc.source_path, sc.save_as)
+            if self.fallback_to_symlinks:
+                os.symlink(source_path, save_as)
+            else:
+                os.link(source_path, save_as)
+        except OSError as err:
+            if err.errno == errno.EXDEV:  # 18: Invalid cross-device link
+                logger.debug(
+                    "Cross-device links not valid. "
+                    "Creating symbolic links instead."
+                    )
+                self.fallback_to_symlinks = True
+                self._link_staticfile(sc)
+            else:
+                raise err
+
+    def _mkdir(self, path):
+        if os.path.lexists(path) and not os.path.isdir(path):
+            os.unlink(path)
+        mkdir_p(path)
 
 
 class SourceFileGenerator(Generator):