diff mercurial/exchange.py @ 45117:b1e51ef4e536

phases: sparsify phase lists

When the internal and archived phase was added, allphase became a large,
sparsely populated list. This dramatically increased the number of
lookup operations for public relations in `phasecache.phase`. As a first
step, define allphases and related lists explicitly to contain only the
actual phases. Make phasenames a dictionary and create corresponding
dictionaries for mapping phase names back to numbers. Adjust various
list to be sparse as well with the exception of phaseroots and phasesets
members of phasecache. Keep those as a separate step as it involves
changes to the C module.

Differential Revision: https://phab.mercurial-scm.org/D8697

--- a/mercurial/exchange.py	Tue Jul 07 22:00:02 2020 +0200
+++ b/mercurial/exchange.py	Wed Jul 08 00:15:15 2020 +0200
@@ -1024,12 +1024,12 @@
     hasphaseheads = b'heads' in b2caps.get(b'phases', ())
     if pushop.remotephases is not None and hasphaseheads:
         # check that the remote phase has not changed
-        checks = [[] for p in phases.allphases]
+        checks = {p: [] for p in phases.allphases}
         checks[phases.public].extend(pushop.remotephases.publicheads)
         checks[phases.draft].extend(pushop.remotephases.draftroots)
-        if any(checks):
-            for nodes in checks:
-                nodes.sort()
+        if any(pycompat.itervalues(checks)):
+            for phase in checks:
+                checks[phase].sort()
             checkdata = phases.binaryencode(checks)
             bundler.newpart(b'check:phases', data=checkdata)
 
@@ -1104,7 +1104,7 @@
     """push phase information through a bundle2 - binary part"""
     pushop.stepsdone.add(b'phases')
     if pushop.outdatedphases:
-        updates = [[] for p in phases.allphases]
+        updates = {p: [] for p in phases.allphases}
         updates[0].extend(h.node() for h in pushop.outdatedphases)
         phasedata = phases.binaryencode(updates)
         bundler.newpart(b'phase-heads', data=phasedata)
@@ -2658,9 +2658,9 @@
                     headsbyphase[phases.public].add(node(r))
 
         # transform data in a format used by the encoding function
-        phasemapping = []
-        for phase in phases.allphases:
-            phasemapping.append(sorted(headsbyphase[phase]))
+        phasemapping = {
+            phase: sorted(headsbyphase[phase]) for phase in phases.allphases
+        }
 
         # generate the actual part
         phasedata = phases.binaryencode(phasemapping)