layout.conf: make the pregenerated cache format controllable

Controllable via 'cache-format', currently it supports only one cache;
'pms', and defaults to it.  If an unsupported cache-format is specified,
the cache is disabled.  If pms is specified and metadata/cache directory
doesn't exist, the cache is disabled.

Finally, this rips out the best module support for locally overriding
the cache format used for pregenerated caches; this functionality made
zero sense (upstream determines the format, we use what is available).

5 files changed, 24 insertions, 18 deletions

diff --git a/bin/egencache b/bin/egencache
index 7766e786e..26660c1a9 100755
--- a/bin/egencache
+++ b/bin/egencache
@@ -38,6 +38,7 @@ except ImportError:
 from portage import os, _encodings, _unicode_encode, _unicode_decode
 from _emerge.MetadataRegen import MetadataRegen
 from portage.cache.cache_errors import CacheError, StatCollision
+from portage.cache import metadata
 from portage.manifest import guessManifestFileType
 from portage.util import cmp_sort_key, writemsg_level
 from portage import cpv_getkey
@@ -214,8 +215,7 @@ class GenCache(object):
 			consumer=self._metadata_callback,
 			max_jobs=max_jobs, max_load=max_load)
 		self.returncode = os.EX_OK
-		metadbmodule = portdb.settings.load_best_module("portdbapi.metadbmodule")
-		self._trg_cache = metadbmodule(portdb.porttrees[0],
+		self._trg_cache = metadata.database(portdb.porttrees[0],
 			"metadata/cache", portage.auxdbkeys[:])
 		if rsync:
 			self._trg_cache.raise_stat_collision = True
diff --git a/pym/_emerge/actions.py b/pym/_emerge/actions.py
index 08f70df05..70a92c972 100644
--- a/pym/_emerge/actions.py
+++ b/pym/_emerge/actions.py
@@ -1660,14 +1660,6 @@ def action_metadata(settings, portdb, myopts, porttrees=None):
 	porttrees_data = []
 	for path in porttrees:
 		src_db = portdb._pregen_auxdb.get(path)
-		if src_db is None and \
-			os.path.isdir(os.path.join(path, 'metadata', 'cache')):
-			src_db = portdb.metadbmodule(
-				path, 'metadata/cache', auxdbkeys, readonly=True)
-			try:
-				src_db.ec = portdb._repo_info[path].eclass_db
-			except AttributeError:
-				pass
 
 		if src_db is not None:
 			porttrees_data.append(TreeData(portdb.auxdb[path],
diff --git a/pym/portage/dbapi/porttree.py b/pym/portage/dbapi/porttree.py
index ef2e08870..f48741b84 100644
--- a/pym/portage/dbapi/porttree.py
+++ b/pym/portage/dbapi/porttree.py
@@ -120,8 +120,6 @@ class portdbapi(dbapi):
 		self._have_root_eclass_dir = os.path.isdir(
 			os.path.join(self.settings.repositories.mainRepoLocation(), "eclass"))
 
-		self.metadbmodule = self.settings.load_best_module("portdbapi.metadbmodule")
-
 		#if the portdbapi is "frozen", then we assume that we can cache everything (that no updates to it are happening)
 		self.xcache = {}
 		self.frozen = 0
@@ -214,10 +212,10 @@ class portdbapi(dbapi):
 			for x in self.porttrees:
 				if x in self._pregen_auxdb:
 					continue
-				if os.path.isdir(os.path.join(x, "metadata", "cache")):
-					conf = self.repositories.get_repo_for_location(x)
-					cache = self._pregen_auxdb[x] = self.metadbmodule(
-						x, "metadata/cache", filtered_auxdbkeys, readonly=True)
+				conf = self.repositories.get_repo_for_location(x)
+				cache = conf.get_pregenerated_cache(filtered_auxdbkeys, readonly=True)
+				if cache is not None:
+					self._pregen_auxdb[x] = cache
 					try:
 						cache.ec = self._repo_info[x].eclass_db
 					except AttributeError:
diff --git a/pym/portage/package/ebuild/config.py b/pym/portage/package/ebuild/config.py
index 73af0660e..37dcbb4cf 100644
--- a/pym/portage/package/ebuild/config.py
+++ b/pym/portage/package/ebuild/config.py
@@ -311,7 +311,6 @@ class config(object):
 			if self.modules["user"] is None:
 				self.modules["user"] = {}
 			self.modules["default"] = {
-				"portdbapi.metadbmodule": "portage.cache.metadata.database",
 				"portdbapi.auxdbmodule":  "portage.cache.flat_hash.database",
 			}
 
diff --git a/pym/portage/repository/config.py b/pym/portage/repository/config.py
index 2490b65da..9a5473820 100644
--- a/pym/portage/repository/config.py
+++ b/pym/portage/repository/config.py
@@ -48,7 +48,7 @@ class RepoConfig(object):
 		'eclass_overrides', 'eclass_locations', 'format', 'location',
 		'main_repo', 'manifest_hashes', 'masters', 'missing_repo_name',
 		'name', 'priority', 'sign_manifest', 'sync', 'thin_manifest',
-		'user_location')
+		'user_location', 'cache_format')
 
 	def __init__(self, name, repo_opts):
 		"""Build a RepoConfig with options in repo_opts
@@ -126,6 +126,16 @@ class RepoConfig(object):
 		self.create_manifest = True
 		self.disable_manifest = False
 		self.manifest_hashes = None
+		self.cache_format = None
+
+	def get_pregenerated_cache(self, auxdbkeys, readonly=True):
+		if self.cache_format is None:
+			return None
+		elif self.cache_format == 'pms':
+			from portage.cache.metadata import database
+			return database(self.location, 'metadata/cache',
+				auxdbkeys, readonly=readonly)
+		return None
 
 	def load_manifest(self, *args, **kwds):
 		kwds['thin'] = self.thin_manifest
@@ -377,6 +387,13 @@ class RepoConfigLoader(object):
 			repo.create_manifest = manifest_policy != 'false'
 			repo.disable_manifest = manifest_policy == 'false'
 
+			# for compatibility w/ PMS, fallback to pms; but also check if the
+			# cache exists or not.
+			repo.cache_format = layout_data.get('cache-format', 'pms').lower()
+			if repo.cache_format == 'pms' and not os.path.isdir(
+				os.path.join(repo.location, 'metadata', 'cache')):
+				repo.cache_format = None
+
 			manifest_hashes = layout_data.get('manifest-hashes')
 			if manifest_hashes is not None:
 				manifest_hashes = frozenset(manifest_hashes.upper().split())