diff mercurial/localrepo.py @ 39700:b10d145837bc

localrepo: extract resolving of opener options to standalone functions

Requirements and config options are converted into a dict which is
available to the store vfs to consult. This is how storage options
are communicated from the repo layer to the storage layer.

Currently, we do that option resolution in a private method on the
repo instance. And there is a single method doing that resolution.

Opener options are logically specific to the storage backend they
apply to. And, opener options may wish to influence how the repo
object/type is constructed. So it makes sense to have more granular
storage option resolution that occurs before the repo object is
instantiated.

This commit extracts the code for resolving opener options into new
module-level functions. These functions are run before the repo
instance is constructed.

As part of the code move, we split the option resolution into
generic and revlog-specific options. After this commit, we no longer
add revlog-specific options to repos that don't have a revlog
requirement.

Some of these opener options and associated config options might make
sense on alternate storage backends. We can always reuse config
options and opener option names for other backends. But we shouldn't
be passing opener options to storage backends that won't recognize
them. I haven't done it here, but after this commit it should be
possible for store backends to validate the set of opener options
it receives.

Because localrepository.openerreqs is no longer used after this commit,
it has been removed.

I'm not super thrilled about the code outside of localrepo that is
adding requirements and updating opener options. We'll probably want
to create a more formal API for that use case that constructs a new
repo instance and poisons the old repo object. But this was a
pre-existing issue and can be dealt with later. I have little doubt
it will cause me troubles as I continue to refactor how repository
objects are instantiated.

.. api::

   ``localrepository.openerreqs`` has been removed. Override
   ``localrepo.resolvestorevfsoptions()`` to add custom opener options.

.. api::

   ``localrepository._applyopenerreqs()`` has been removed. Use
   ``localrepo.resolvestorevfsoptions()`` to add custom opener options.

Differential Revision: https://phab.mercurial-scm.org/D4576

--- a/mercurial/localrepo.py	Wed Sep 12 15:17:47 2018 -0700
+++ b/mercurial/localrepo.py	Wed Sep 12 15:59:26 2018 -0700
@@ -481,9 +481,11 @@
     # of them.
     store = makestore(requirements, storebasepath,
                       lambda base: vfsmod.vfs(base, cacheaudited=True))
-
     hgvfs.createmode = store.createmode
 
+    storevfs = store.vfs
+    storevfs.options = resolvestorevfsoptions(ui, requirements)
+
     # The cache vfs is used to manage cache files.
     cachevfs = vfsmod.vfs(cachepath, cacheaudited=True)
     cachevfs.createmode = store.createmode
@@ -578,6 +580,92 @@
 
     return storemod.basicstore(path, vfstype)
 
+def resolvestorevfsoptions(ui, requirements):
+    """Resolve the options to pass to the store vfs opener.
+
+    The returned dict is used to influence behavior of the storage layer.
+    """
+    options = {}
+
+    if b'treemanifest' in requirements:
+        options[b'treemanifest'] = True
+
+    # experimental config: format.manifestcachesize
+    manifestcachesize = ui.configint(b'format', b'manifestcachesize')
+    if manifestcachesize is not None:
+        options[b'manifestcachesize'] = manifestcachesize
+
+    # In the absence of another requirement superseding a revlog-related
+    # requirement, we have to assume the repo is using revlog version 0.
+    # This revlog format is super old and we don't bother trying to parse
+    # opener options for it because those options wouldn't do anything
+    # meaningful on such old repos.
+    if b'revlogv1' in requirements or REVLOGV2_REQUIREMENT in requirements:
+        options.update(resolverevlogstorevfsoptions(ui, requirements))
+
+    return options
+
+def resolverevlogstorevfsoptions(ui, requirements):
+    """Resolve opener options specific to revlogs."""
+
+    options = {}
+
+    if b'revlogv1' in requirements:
+        options[b'revlogv1'] = True
+    if REVLOGV2_REQUIREMENT in requirements:
+        options[b'revlogv2'] = True
+
+    if b'generaldelta' in requirements:
+        options[b'generaldelta'] = True
+
+    # experimental config: format.chunkcachesize
+    chunkcachesize = ui.configint(b'format', b'chunkcachesize')
+    if chunkcachesize is not None:
+        options[b'chunkcachesize'] = chunkcachesize
+
+    deltabothparents = ui.configbool(b'storage',
+                                     b'revlog.optimize-delta-parent-choice')
+    options[b'deltabothparents'] = deltabothparents
+
+    options[b'lazydeltabase'] = not scmutil.gddeltaconfig(ui)
+
+    chainspan = ui.configbytes(b'experimental', b'maxdeltachainspan')
+    if 0 <= chainspan:
+        options[b'maxdeltachainspan'] = chainspan
+
+    mmapindexthreshold = ui.configbytes(b'experimental',
+                                        b'mmapindexthreshold')
+    if mmapindexthreshold is not None:
+        options[b'mmapindexthreshold'] = mmapindexthreshold
+
+    withsparseread = ui.configbool(b'experimental', b'sparse-read')
+    srdensitythres = float(ui.config(b'experimental',
+                                     b'sparse-read.density-threshold'))
+    srmingapsize = ui.configbytes(b'experimental',
+                                  b'sparse-read.min-gap-size')
+    options[b'with-sparse-read'] = withsparseread
+    options[b'sparse-read-density-threshold'] = srdensitythres
+    options[b'sparse-read-min-gap-size'] = srmingapsize
+
+    sparserevlog = SPARSEREVLOG_REQUIREMENT in requirements
+    options[b'sparse-revlog'] = sparserevlog
+    if sparserevlog:
+        options[b'generaldelta'] = True
+
+    maxchainlen = None
+    if sparserevlog:
+        maxchainlen = revlogconst.SPARSE_REVLOG_MAX_CHAIN_LENGTH
+    # experimental config: format.maxchainlen
+    maxchainlen = ui.configint(b'format', b'maxchainlen', maxchainlen)
+    if maxchainlen is not None:
+        options[b'maxchainlen'] = maxchainlen
+
+    for r in requirements:
+        if r.startswith(b'exp-compression-'):
+            options[b'compengine'] = r[len(b'exp-compression-'):]
+
+    return options
+
 @interfaceutil.implementer(repository.completelocalrepository)
 class localrepository(object):
 
@@ -602,11 +690,6 @@
         'exp-sparse',
         'internal-phase'
     }
-    openerreqs = {
-        'revlogv1',
-        'generaldelta',
-        'treemanifest',
-    }
 
     # list of prefix for file which can be written without 'wlock'
     # Extensions should extend this list when needed
@@ -712,7 +795,6 @@
                 self.svfs.vfs.audit = self._getsvfsward(self.svfs.vfs.audit)
             else: # standard vfs
                 self.svfs.audit = self._getsvfsward(self.svfs.audit)
-        self._applyopenerreqs()
 
         self._dirstatevalidatewarned = False
 
@@ -817,56 +899,6 @@
             caps.add('bundle2=' + urlreq.quote(capsblob))
         return caps
 
-    def _applyopenerreqs(self):
-        self.svfs.options = {r: True for r in self.requirements
-                             if r in self.openerreqs}
-        # experimental config: format.chunkcachesize
-        chunkcachesize = self.ui.configint('format', 'chunkcachesize')
-        if chunkcachesize is not None:
-            self.svfs.options['chunkcachesize'] = chunkcachesize
-        # experimental config: format.manifestcachesize
-        manifestcachesize = self.ui.configint('format', 'manifestcachesize')
-        if manifestcachesize is not None:
-            self.svfs.options['manifestcachesize'] = manifestcachesize
-        deltabothparents = self.ui.configbool('storage',
-            'revlog.optimize-delta-parent-choice')
-        self.svfs.options['deltabothparents'] = deltabothparents
-        self.svfs.options['lazydeltabase'] = not scmutil.gddeltaconfig(self.ui)
-        chainspan = self.ui.configbytes('experimental', 'maxdeltachainspan')
-        if 0 <= chainspan:
-            self.svfs.options['maxdeltachainspan'] = chainspan
-        mmapindexthreshold = self.ui.configbytes('experimental',
-                                                 'mmapindexthreshold')
-        if mmapindexthreshold is not None:
-            self.svfs.options['mmapindexthreshold'] = mmapindexthreshold
-        withsparseread = self.ui.configbool('experimental', 'sparse-read')
-        srdensitythres = float(self.ui.config('experimental',
-                                              'sparse-read.density-threshold'))
-        srmingapsize = self.ui.configbytes('experimental',
-                                           'sparse-read.min-gap-size')
-        self.svfs.options['with-sparse-read'] = withsparseread
-        self.svfs.options['sparse-read-density-threshold'] = srdensitythres
-        self.svfs.options['sparse-read-min-gap-size'] = srmingapsize
-        sparserevlog = SPARSEREVLOG_REQUIREMENT in self.requirements
-        self.svfs.options['sparse-revlog'] = sparserevlog
-        if sparserevlog:
-            self.svfs.options['generaldelta'] = True
-        maxchainlen = None
-        if sparserevlog:
-            maxchainlen = revlogconst.SPARSE_REVLOG_MAX_CHAIN_LENGTH
-        # experimental config: format.maxchainlen
-        maxchainlen = self.ui.configint('format', 'maxchainlen', maxchainlen)
-        if maxchainlen is not None:
-            self.svfs.options['maxchainlen'] = maxchainlen
-
-        for r in self.requirements:
-            if r.startswith('exp-compression-'):
-                self.svfs.options['compengine'] = r[len('exp-compression-'):]
-
-        # TODO move "revlogv2" to openerreqs once finalized.
-        if REVLOGV2_REQUIREMENT in self.requirements:
-            self.svfs.options['revlogv2'] = True
-
     def _writerequirements(self):
         scmutil.writerequires(self.vfs, self.requirements)