roverlay/overlay/pkgdir: SymlinkDistroot/dir

A SymlinkDistroot manages zero or more per-package SymlinkDistdirs that
contain symlinks to the R package files.
Used for Manifest file creation.

3 files changed, 286 insertions, 0 deletions

diff --git a/roverlay/overlay/pkgdir/symlink/__init__.py b/roverlay/overlay/pkgdir/symlink/__init__.py
new file mode 100644
index 0000000..a7f7e7d
--- /dev/null
+++ b/roverlay/overlay/pkgdir/symlink/__init__.py
@@ -0,0 +1,5 @@
+# R overlay -- overlay package, symlink directories
+# -*- coding: utf-8 -*-
+# Copyright (C) 2013 André Erdmann <dywi@mailerd.de>
+# Distributed under the terms of the GNU General Public License;
+# either version 2 of the License, or (at your option) any later version.
diff --git a/roverlay/overlay/pkgdir/symlink/distdir.py b/roverlay/overlay/pkgdir/symlink/distdir.py
new file mode 100644
index 0000000..cca9b31
--- /dev/null
+++ b/roverlay/overlay/pkgdir/symlink/distdir.py
@@ -0,0 +1,47 @@
+# R overlay -- overlay package, symlink distdir
+# -*- coding: utf-8 -*-
+# Copyright (C) 2013 André Erdmann <dywi@mailerd.de>
+# Distributed under the terms of the GNU General Public License;
+# either version 2 of the License, or (at your option) any later version.
+
+import os
+
+__all__ = [ 'SymlinkDistdir', ]
+
+class SymlinkDistdir ( object ):
+
+	def __init__ ( self, root ):
+		"""Initializes a symlink DISTDIR.
+
+		arguments:
+		* root -- directory where symlinks will be created
+		"""
+		self.root = root
+		if not os.path.isdir ( self.root ):
+			os.mkdir ( self.root )
+	# --- end of __init__ (...) ---
+
+	def add ( self, fpath, fname=None ):
+		"""Adds a symlink to a file to this dir.
+
+		arguments:
+		* fpath -- path to the file for which a symlink will be created
+		* fname -- name of the symlink, defaults to os.path.basename ( fpath )
+		"""
+		symlink = self.root + os.sep + ( fname or os.path.basename ( fpath ) )
+
+		if os.path.lexists ( symlink ):
+			os.unlink ( symlink )
+
+		if not os.path.exists ( symlink ):
+			os.symlink ( fpath, symlink )
+			return symlink
+		else:
+			raise OSError ( "cannot set up symlink {!r}!".format ( symlink ) )
+	# --- end of add (...) ---
+
+	def __str__ ( self ):
+		return self.root
+	# --- end of __str__ (...) ---
+
+# --- end of SymlinkDistdir ---
diff --git a/roverlay/overlay/pkgdir/symlink/distroot.py b/roverlay/overlay/pkgdir/symlink/distroot.py
new file mode 100644
index 0000000..7345d98
--- /dev/null
+++ b/roverlay/overlay/pkgdir/symlink/distroot.py
@@ -0,0 +1,234 @@
+# R overlay -- overlay package, symlink distroot
+# -*- coding: utf-8 -*-
+# Copyright (C) 2013 André Erdmann <dywi@mailerd.de>
+# Distributed under the terms of the GNU General Public License;
+# either version 2 of the License, or (at your option) any later version.
+
+__all__ = [ 'SymlinkDistroot', 'ThreadsafeSymlinkDistroot' ]
+
+import os
+import atexit
+import shutil
+import tempfile
+import threading
+import logging
+
+import roverlay.config
+
+import roverlay.overlay.pkgdir.symlink.distdir
+
+class _SymlinkDistrootBase ( object ):
+
+	_instance_lock = threading.Lock()
+	__instance     = None
+
+	@classmethod
+	def get_configured ( cls ):
+		"""Returns the static SymlinkDistroot instance."""
+		if cls.__instance is None:
+			with cls._instance_lock:
+				if cls.__instance is None:
+					cls.__instance = cls (
+						root = roverlay.config.get (
+							'OVERLAY.SYMLINK_DISTROOT.root', ""
+						),
+						is_tmpdir = roverlay.config.get_or_fail (
+							'OVERLAY.SYMLINK_DISTROOT.tmp'
+						),
+					)
+		return cls.__instance
+	# --- end of get_configured (...) ---
+
+	def __repr__ ( self ):
+		return "{}<root={}, tmpdir={}>".format (
+			self.__class__.__name__, self._root, self._is_tmpdir
+		)
+	# --- end of __repr__ (...) ---
+
+	def __str__ ( self ):
+		return str ( self._root )
+	# --- end of __str__ (...) ---
+
+	def __init__ ( self, root, is_tmpdir ):
+		"""Initializes a _SymlinkDistrootBase instance.
+
+		arguments:
+		* root      -- root directory where per-package SymlinkDistdirs will
+		               be created. An empty value is only valid if is_tmpdir
+		               evaluates to True.
+		* is_tmpdir -- whether this SymlinkDistroot is a temporary directory
+		               or not. A temporary directory will be wiped at exit,
+		               while a non-temporary one will only be cleaned up.
+
+		tempfile.mktempd() will be used as directory if root is empty
+		and is_tmpdir is true.
+
+		Raises: ConfigError if root is not set and is_tmpdir evaluates to False.
+		"""
+		super ( _SymlinkDistrootBase, self ).__init__()
+
+		self._root      = root
+		self._is_tmpdir = bool ( is_tmpdir )
+
+		if not self._root:
+			if self._is_tmpdir:
+				self._root = tempfile.mkdtemp ( prefix='tmp_roverlay_sym' )
+			else:
+				raise roverlay.config.ConfigError (
+					"OVERLAY.symlink_distroot: invalid value."
+				)
+		elif not os.path.isdir ( self._root ):
+			os.makedirs ( self._root, 0o755 )
+
+		self._prepare()
+
+		atexit.register ( self._destroy if self._is_tmpdir else self._cleanup )
+	# --- end of __init__ (...) ---
+
+	def _cleanup ( self ):
+		"""Cleans up a SymlinkDistroot."""
+		# derived classes can implement this to define actions for non-temporary
+		# SymlinkDistroots  that will be performed at ext.
+		pass
+	# --- end of _cleanup (...) ---
+
+	def _destroy ( self, force=False ):
+		"""Destroys a SymlinkDistroot.
+
+		arguments:
+		* force -- force destruction even if this distroot is not temporary
+		"""
+		if force or self._is_tmpdir:
+			shutil.rmtree ( self._root )
+	# --- end of _destroy (...) ---
+
+	def _get ( self, package_name ):
+		"""Returns a new SymlinkDistdir instance for given package.
+
+		arguments:
+		* package_name -- will be used as subdirectory name and must not
+		                  contain any os.sep chars (typically "/")
+		"""
+		assert os.sep not in package_name
+		return roverlay.overlay.pkgdir.symlink.distdir.SymlinkDistdir (
+			self._root + os.sep + package_name
+		)
+	# --- end of get (...) ---
+
+	def _prepare ( self ):
+		"""Prepares the SymlinkDistroot. Called for both temporary and
+		persistent distroots.
+
+		The default actions is to remove broken symlinks.
+		"""
+		if not self._is_tmpdir:
+			self.remove_broken_symlinks ( unsafe_assumptions=True )
+	# --- end of _prepare (...) ---
+
+	def get ( self, package_name ):
+		"""Returns a SymlinkDistdir for the given package.
+
+		arguments:
+		* package_name
+
+		Has to be implemented by derived classes.
+		"""
+		raise NotImplementedError()
+	# --- end of get (...) ---
+
+	def remove_broken_symlinks ( self, unsafe_assumptions=False ):
+		"""Recursively remove broken/dead symlinks.
+
+		arguments:
+		* unsafe_assumptions -- use (potentially) faster but less safe code
+		"""
+		def recursive_remove ( root, rmdir ):
+			for item in os.listdir ( root ):
+				fpath = root + os.sep + item
+
+				if not os.path.exists ( fpath ):
+					os.unlink ( fpath )
+
+				elif os.path.isdir ( fpath ):
+					recursive_remove ( fpath, True )
+					if rmdir:
+						try:
+							os.rmdir ( fpath )
+						except OSError:
+							pass
+		# --- end of recursive_remove (...) ---
+
+		if unsafe_assumptions:
+			# completely "unroll" the recursion using the following assumptions:
+			# * self._root contains directories only
+			# * maximum recursion depth is 1 (no nested subdir structure)
+
+			for d_item in os.listdir ( self._root ):
+				d_path = self._root + os.sep + d_item
+
+				for l_item in os.listdir ( d_path ):
+					l_path = self._root + os.sep + l_item
+					if not os.path.exists ( l_path ):
+						os.unlink ( l_path )
+
+				try:
+					os.rmdir ( dpath )
+				except OSError:
+					pass
+		else:
+			recursive_remove ( self._root, False )
+
+	# --- end of remove_broken_symlinks (...) ---
+
+# --- end of _SymlinkDistrootBase ---
+
+class SymlinkDistroot ( _SymlinkDistrootBase ):
+	"""A symlink distroot that uses a dict to remember
+	per-package SymlinkDistdirs.
+	"""
+
+	# _not_ threadsafe, but get() is expected to be called
+	#  within a (per-package_name) threadsafe context
+
+	def __init__ ( self, *args, **kwargs ):
+		"""see _SymlinkDistrootBase.__init__()"""
+		super ( SymlinkDistroot, self ).__init__ ( *args, **kwargs )
+		self._subdirs = dict()
+	# --- end of __init__ (...) ---
+
+	def get ( self, package_name ):
+		"""Returns a SymlinkDistdir for the given package.
+
+		arguments:
+		* package_name --
+		"""
+		try:
+			return self._subdirs [package_name]
+		except KeyError:
+			self._subdirs [package_name] = self._get ( package_name )
+			return self._subdirs [package_name]
+	# --- end of get (...) ---
+
+# --- end of SymlinkDistroot ---
+
+class ThreadsafeSymlinkDistroot ( SymlinkDistroot ):
+	"""Like SymlinkDistroot, but locks while creating SymlinkDistdirs."""
+
+	# will be removed if SymlinkDistroot is sufficient.
+
+	def __init__ ( self, *args, **kwargs ):
+		super ( ThreadsafeSymlinkDistroot, self ).__init__ ( *args, **kwargs )
+		self._lock = threading.Lock()
+	# --- end of __init__ (...) ---
+
+	def get ( self, package_name ):
+		try:
+			return self._subdirs [package_name]
+		except KeyError:
+			with self._lock:
+				if package_name not in self._subdirs:
+					self._subdirs [package_name] = self._get ( package_name )
+			return self._subdirs [package_name]
+	# --- end of get (...) ---
+
+# --- end of ThreadsafeSymlinkDistroot ---