text: # Copyright 2013-2019 Lawrence Livermore National Security, LLC and other
  # Spack Project Developers. See the top-level COPYRIGHT file for details.
  #
  # SPDX-License-Identifier: (Apache-2.0 OR MIT)
  
  """Caches used by Spack to store data"""
  import os
  
  import llnl.util.lang
  from llnl.util.filesystem import mkdirp
  
  import spack.error
  import spack.paths
  import spack.config
  import spack.fetch_strategy
  import spack.util.file_cache
  import spack.util.path
  
  
  def _misc_cache():
      """The ``misc_cache`` is Spack's cache for small data.
  
      Currently the ``misc_cache`` stores indexes for virtual dependency
      providers and for which packages provide which tags.
      """
      path = spack.config.get('config:misc_cache')
      if not path:
          path = os.path.join(spack.paths.user_config_path, 'cache')
      path = spack.util.path.canonicalize_path(path)
  
      return spack.util.file_cache.FileCache(path)
  
  
  #: Spack's cache for small data
  misc_cache = llnl.util.lang.Singleton(_misc_cache)
  
  
  def _fetch_cache():
      """Filesystem cache of downloaded archives.
  
      This prevents Spack from repeatedly fetch the same files when
      building the same package different ways or multiple times.
      """
      path = spack.config.get('config:source_cache')
      if not path:
          path = os.path.join(spack.paths.var_path, "cache")
      path = spack.util.path.canonicalize_path(path)
  
      return spack.fetch_strategy.FsCache(path)
  
  
  class MirrorCache(object):
      def __init__(self, root):
          self.root = os.path.abspath(root)
  
      def store(self, fetcher, relative_dest):
          """Fetch and relocate the fetcher's target into our mirror cache."""
  
          # Note this will archive package sources even if they would not
          # normally be cached (e.g. the current tip of an hg/git branch)
          dst = os.path.join(self.root, relative_dest)
          mkdirp(os.path.dirname(dst))
          fetcher.archive(dst)
  
      def symlink(self, mirror_ref):
          """Symlink a human readible path in our mirror to the actual
          storage location."""
  
          cosmetic_path = os.path.join(self.root, mirror_ref.cosmetic_path)
          storage_path = os.path.join(self.root, mirror_ref.storage_path)
          relative_dst = os.path.relpath(
              storage_path,
              start=os.path.dirname(cosmetic_path))
  
          if not os.path.exists(cosmetic_path):
              if os.path.lexists(cosmetic_path):
                  # In this case the link itself exists but it is broken: remove
                  # it and recreate it (in order to fix any symlinks broken prior
                  # to https://github.com/spack/spack/pull/13908)
                  os.unlink(cosmetic_path)
              mkdirp(os.path.dirname(cosmetic_path))
              os.symlink(relative_dst, cosmetic_path)
  
  
  #: Spack's local cache for downloaded source archives
  fetch_cache = llnl.util.lang.Singleton(_fetch_cache)
  
  mirror_cache = None
  