mercurial-scm/hg: mercurial/localrepo.py comparison

comparison mercurial/localrepo.py @ 1466:b6d9ea0bc107

Added a lot of comments to changegroupsubset.

author	Eric Hopper <hopper@omnifarious.org>
date	Tue, 11 Oct 2005 18:56:47 -0700
parents	00117edce2dd
children	0847c45ffee6

comparison

equal deleted inserted replaced

-:be6b5ce60b7f
+:b6d9ea0bc107
 cg = self.changegroup(update)
 return remote.addchangegroup(cg)
 def changegroupsubset(self, bases, heads):
+"""This function generates a changegroup consisting of all the nodes
+that are descendents of any of the bases, and ancestors of any of
+the heads.
+It is fairly complex as determining which filenodes and which
+manifest nodes need to be included for the changeset to be complete
+is non-trivial.
+Another wrinkle is doing the reverse, figuring out which changeset in
+the changegroup a particular filenode or manifestnode belongs to."""
+# Set up some initial variables
+# Make it easy to refer to self.changelog
 cl = self.changelog
-# msng = missing
+# msng is short for missing - compute the list of changesets in this
+# changegroup.
 msng_cl_lst, bases, heads = cl.nodesbetween(bases, heads)
-junk = None
+# Some bases may turn out to be superfluous, and some heads may be
+# too.  nodesbetween will return the minimal set of bases and heads
+# necessary to re-create the changegroup.
+# Known heads are the list of heads that it is assumed the recipient
+# of this changegroup will know about.
 knownheads = {}
+# We assume that all parents of bases are known heads.
 for n in bases:
 for p in cl.parents(n):
 if p != nullid:
 knownheads[p] = 1
 knownheads = knownheads.keys()
 if knownheads:
+# Now that we know what heads are known, we can compute which
+# changesets are known.  The recipient must know about all
+# changesets required to reach the known heads from the null
+# changeset.
 has_cl_set, junk, junk = cl.nodesbetween(None, knownheads)
+junk = None
+# Transform the list into an ersatz set.
 has_cl_set = dict.fromkeys(has_cl_set)
 else:
+# If there were no known heads, the recipient cannot be assumed to
+# know about any changesets.
 has_cl_set = {}
+# Make it easy to refer to self.manifest
 mnfst = self.manifest
+# We don't know which manifests are missing yet
 msng_mnfst_set = {}
+# Nor do we know which filenodes are missing.
 msng_filenode_set = {}
 junk = mnfst.index[mnfst.count() - 1] # Get around a bug in lazyindex
 junk = None
+# A changeset always belongs to itself, so the changenode lookup
+# function for a changenode is identity.
 def identity(x):
 return x
+# A function generating function.  Sets up an environment for the
+# inner function.
 def cmp_by_rev_func(revlog):
-def cmpfunc(a, b):
+# Compare two nodes by their revision number in the environment's
+# revision history.  Since the revision number both represents the
+# most efficient order to read the nodes in, and represents a
+# topological sorting of the nodes, this function is often useful.
+def cmp_by_rev(a, b):
 return cmp(revlog.rev(a), revlog.rev(b))
-return cmpfunc
+return cmp_by_rev
+# If we determine that a particular file or manifest node must be a
+# node that the recipient of the changegroup will already have, we can
+# also assume the recipient will have all the parents.  This function
+# prunes them from the set of missing nodes.
 def prune_parents(revlog, hasset, msngset):
 haslst = hasset.keys()
 haslst.sort(cmp_by_rev_func(revlog))
 for node in haslst:
 parentlst = [p for p in revlog.parents(node) if p != nullid]
 p = [p for p in revlog.parents(n) if p != nullid]
 parentlst.extend(p)
 for n in hasset:
 msngset.pop(n, None)
+# This is a function generating function used to set up an environment
+# for the inner function to execute in.
 def manifest_and_file_collector(changedfileset):
+# This is an information gathering function that gathers
+# information from each changeset node that goes out as part of
+# the changegroup.  The information gathered is a list of which
+# manifest nodes are potentially required (the recipient may
+# already have them) and total list of all files which were
+# changed in any changeset in the changegroup.
+#
+# We also remember the first changenode we saw any manifest
+# referenced by so we can later determine which changenode 'owns'
+# the manifest.
 def collect_manifests_and_files(clnode):
 c = cl.read(clnode)
 for f in c[3]:
 # This is to make sure we only have one instance of each
 # filename string for each filename.
 changedfileset.setdefault(f, f)
 msng_mnfst_set.setdefault(c[0], clnode)
 return collect_manifests_and_files
+# Figure out which manifest nodes (of the ones we think might be part
+# of the changegroup) the recipient must know about and remove them
+# from the changegroup.
 def prune_manifests():
 has_mnfst_set = {}
 for n in msng_mnfst_set:
+# If a 'missing' manifest thinks it belongs to a changenode
+# the recipient is assumed to have, obviously the recipient
+# must have that manifest.
 linknode = cl.node(mnfst.linkrev(n))
 if linknode in has_cl_set:
 has_mnfst_set[n] = 1
 prune_parents(mnfst, has_mnfst_set, msng_mnfst_set)
+# Use the information collected in collect_manifests_and_files to say
+# which changenode any manifestnode belongs to.
 def lookup_manifest_link(mnfstnode):
 return msng_mnfst_set[mnfstnode]
+# A function generating function that sets up the initial environment
+# the inner function.
 def filenode_collector(changedfiles):
 next_rev = [0]
+# This gathers information from each manifestnode included in the
+# changegroup about which filenodes the manifest node references
+# so we can include those in the changegroup too.
+#
+# It also remembers which changenode each filenode belongs to.  It
+# does this by assuming the a filenode belongs to the changenode
+# the first manifest that references it belongs to.
 def collect_msng_filenodes(mnfstnode):
 r = mnfst.rev(mnfstnode)
 if r == next_rev[0]:
 # If the last rev we looked at was the one just previous,
 # we only need to see a diff.
 delta = mdiff.patchtext(mnfst.delta(mnfstnode))
+# For each line in the delta
 for dline in delta.splitlines():
+# get the filename and filenode for that line
 f, fnode = dline.split('\0')
 fnode = bin(fnode[:40])
 f = changedfiles.get(f, None)
+# And if the file is in the list of files we care
+# about.
 if f is not None:
+# Get the changenode this manifest belongs to
+clnode = msng_mnfst_set[mnfstnode]
+# Create the set of filenodes for the file if
+# there isn't one already.
+ndset = msng_filenode_set.setdefault(f, {})
+# And set the filenode's changelog node to the
+# manifest's if it hasn't been set already.
+ndset.setdefault(fnode, clnode)
+else:
+# Otherwise we need a full manifest.
+m = mnfst.read(mnfstnode)
+# For every file in we care about.
+for f in changedfiles:
+fnode = m.get(f, None)
+# If it's in the manifest
+if fnode is not None:
+# See comments above.
 clnode = msng_mnfst_set[mnfstnode]
 ndset = msng_filenode_set.setdefault(f, {})
 ndset.setdefault(fnode, clnode)
-else:
+# Remember the revision we hope to see next.
-m = mnfst.read(mnfstnode)
-for f in changedfiles:
-fnode = m.get(f, None)
-if fnode is not None:
-clnode = msng_mnfst_set[mnfstnode]
-ndset = msng_filenode_set.setdefault(f, {})
-ndset.setdefault(fnode, clnode)
 next_rev[0] = r + 1
 return collect_msng_filenodes
+# We have a list of filenodes we think we need for a file, lets remove
+# all those we now the recipient must have.
 def prune_filenodes(f, filerevlog):
 msngset = msng_filenode_set[f]
 hasset = {}
+# If a 'missing' filenode thinks it belongs to a changenode we
+# assume the recipient must have, then the recipient must have
+# that filenode.
 for n in msngset:
 clnode = cl.node(filerevlog.linkrev(n))
 if clnode in has_cl_set:
 hasset[n] = 1
 prune_parents(filerevlog, hasset, msngset)
+# A function generator function that sets up the a context for the
+# inner function.
 def lookup_filenode_link_func(fname):
 msngset = msng_filenode_set[fname]
+# Lookup the changenode the filenode belongs to.
 def lookup_filenode_link(fnode):
 return msngset[fnode]
 return lookup_filenode_link
+# Now that we have all theses utility functions to help out and
+# logically divide up the task, generate the group.
 def gengroup():
+# The set of changed files starts empty.
 changedfiles = {}
+# Create a changenode group generator that will call our functions
+# back to lookup the owning changenode and collect information.
 group = cl.group(msng_cl_lst, identity,
 manifest_and_file_collector(changedfiles))
 for chnk in group:
 yield chnk
+# The list of manifests has been collected by the generator
+# calling our functions back.
 prune_manifests()
 msng_mnfst_lst = msng_mnfst_set.keys()
+# Sort the manifestnodes by revision number.
 msng_mnfst_lst.sort(cmp_by_rev_func(mnfst))
+# Create a generator for the manifestnodes that calls our lookup
+# and data collection functions back.
 group = mnfst.group(msng_mnfst_lst, lookup_manifest_link,
 filenode_collector(changedfiles))
 for chnk in group:
 yield chnk
+# These are no longer needed, dereference and toss the memory for
+# them.
 msng_mnfst_lst = None
 msng_mnfst_set.clear()
 changedfiles = changedfiles.keys()
 changedfiles.sort()
+# Go through all our files in order sorted by name.
 for fname in changedfiles:
 filerevlog = self.file(fname)
+# Toss out the filenodes that the recipient isn't really
+# missing.
 prune_filenodes(fname, filerevlog)
 msng_filenode_lst = msng_filenode_set[fname].keys()
+# If any filenodes are left, generate the group for them,
+# otherwise don't bother.
 if len(msng_filenode_lst) > 0:
 yield struct.pack(">l", len(fname) + 4) + fname
+# Sort the filenodes by their revision #
 msng_filenode_lst.sort(cmp_by_rev_func(filerevlog))
+# Create a group generator and only pass in a changenode
+# lookup function as we need to collect no information
+# from filenodes.
 group = filerevlog.group(msng_filenode_lst,
 lookup_filenode_link_func(fname))
 for chnk in group:
 yield chnk
+# Don't need this anymore, toss it to free memory.
 del msng_filenode_set[fname]
+# Signal that no more groups are left.
 yield struct.pack(">l", 0)
 return util.chunkbuffer(gengroup())
 def changegroup(self, basenodes):
+"""Generate a changegroup of all nodes that we have that a recipient
+doesn't.
+This is much easier than the previous function as we can assume that
+the recipient has any changenode we aren't sending them."""
 cl = self.changelog
 nodes = cl.nodesbetween(basenodes, None)[0]
 revset = dict.fromkeys([cl.rev(n) for n in nodes])
 def identity(x):

Mercurial > public > mercurial-scm > hg

comparison mercurial/localrepo.py @ 1466:b6d9ea0bc107