merge: split update() into goto() and merge()

Summary:
merge.update() had a lot of complicated arg checking to differentiate simple working copy updates from tricker three way merges. In particular, the eden and nativeupdate code paths only support the simple update case.

To make things clearer, let's separate update() into goto() and merge(). goto() handles the simple case, and moving it to Rust will be the (achievable) goal of some upcoming work. merge() handles the full enchilada, and isn't ripe for Rustification at this point.

Reviewed By: zzl0

Differential Revision: D49058005

fbshipit-source-id: f8106c04c48bfba0e7fad244e1dd9933142674e1

eden/scm/sapling/commands/__init__.py

@@ -784,13 +784,11 @@ def _dobackout(ui, repo, node=None, rev=None, **opts):
         dsguard = dirstateguard.dirstateguard(repo, "backout")
         try:
             ui.setconfig("ui", "forcemerge", opts.get("tool", ""), "backout")
-            stats = mergemod.update(
-                repo, parent, branchmerge=True, force=True, ancestor=node
-            )
+            stats = mergemod.merge(repo, parent, force=True, ancestor=node)
             repo.setparents(op1, op2)
 
             # Ensure reverse-renames are preserved during the backout. In theory
-            # merge.update() should handle this, but it's extremely complex, so
+            # merge.merge() should handle this, but it's extremely complex, so
             # let's just double check it here.
             _replayrenames(repo, node)
 

eden/scm/sapling/eden_update.py

@@ -9,26 +9,18 @@
 instead of doing a normal scan of the filesystem.
 """
 
-from . import error, localrepo, merge as mergemod, progress, pycompat, util
+from . import error, merge as mergemod, progress, pycompat, util
 from .i18n import _
 
-
-_repoclass = localrepo.localrepository
-
-
-# This function is called by merge.update() in the fast path
+# This function is called by merge.goto() in the fast path
 # to ask the eden daemon to perform the update operation.
 @util.timefunction("edenupdate", 0, "ui")
 def update(
     repo,
     node,
-    branchmerge,
-    force,
-    ancestor=None,
-    mergeancestor=False,
+    force=False,
     labels=None,
     updatecheck=None,
-    wc=None,
 ):
     repo.ui.debug("using eden update code path\n")
 
@@ -138,7 +130,7 @@ def update(
                 repo.dirstate.clear()
             # TODO(mbolin): Set the second parent, if appropriate.
             repo.setparents(destctx.node())
-            mergemod.recordupdates(repo, actions, branchmerge)
+            mergemod.recordupdates(repo, actions, False)
 
             # Clear the update state
             util.unlink(vfs.join("updatestate"))

eden/scm/sapling/ext/extlib/watchmanclient/__init__.py

@@ -377,7 +377,7 @@ def __enter__(self):
     def enter(self):
         # Make sure we have a wlock prior to sending notifications to watchman.
         # We don't want to race with other actors. In the update case,
-        # merge.update is going to take the wlock almost immediately. We are
+        # merge.merge/goto is going to take the wlock almost immediately. We are
         # effectively extending the lock around several short sanity checks.
         if self.oldnode is None:
             self.oldnode = self.repo["."].node()

eden/scm/sapling/ext/hgevents/__init__.py

@@ -39,7 +39,8 @@
 
 
 def extsetup(ui):
-    extensions.wrapfunction(merge, "update", wrapupdate)
+    extensions.wrapfunction(merge, "goto", wrapgoto)
+    extensions.wrapfunction(merge, "merge", wrapmerge)
     extensions.wrapfunction(filemerge, "_xmerge", _xmerge)
 
 
@@ -103,11 +104,10 @@ def staterelease():
 # and state-leave commands.  This allows clients to perform more intelligent
 # settling during bulk file change scenarios
 # https://facebook.github.io/watchman/docs/cmd/subscribe.html#advanced-settling
-def wrapupdate(
+def wrapmerge(
     orig,
     repo,
     node,
-    branchmerge=False,
     wc=None,
     **kwargs,
 ):
@@ -117,7 +117,6 @@ def wrapupdate(
         return orig(
             repo,
             node,
-            branchmerge=branchmerge,
             wc=wc,
             **kwargs,
         )
@@ -132,17 +131,42 @@ def wrapupdate(
         oldnode=oldnode,
         newnode=newnode,
         distance=distance,
-        metadata={"merge": branchmerge},
+        metadata={"merge": True},
     ):
         return orig(
             repo,
             node,
-            branchmerge=branchmerge,
             wc=wc,
             **kwargs,
         )
 
 
+def wrapgoto(
+    orig,
+    repo,
+    node,
+    **kwargs,
+):
+    distance = 0
+    oldnode = repo["."].node()
+    newnode = repo[node].node()
+    distance = watchmanclient.calcdistance(repo, oldnode, newnode)
+
+    with watchmanclient.state_update(
+        repo,
+        name="hg.update",
+        oldnode=oldnode,
+        newnode=newnode,
+        distance=distance,
+        metadata={"merge": False},
+    ):
+        return orig(
+            repo,
+            node,
+            **kwargs,
+        )
+
+
 def _xmerge(origfunc, repo, mynode, orig, fcd, fco, fca, toolconf, files, labels=None):
     # _xmerge is called when an external merge tool is invoked.
     with state_filemerge(repo, fcd.path()):

eden/scm/sapling/ext/histedit.py

@@ -913,7 +913,7 @@ def run(self):
             with self.repo.wlock(), self.repo.lock(), self.repo.transaction(
                 "histedit-base"
             ):
-                mergemod.update(self.repo, self.node, force=True)
+                mergemod.goto(self.repo, self.node, force=True)
         return self.continueclean()
 
     def continuedirty(self):

eden/scm/sapling/ext/rebase.py

@@ -1709,7 +1709,7 @@ def rebasenode(repo, rev, p1, base, state, collapse, dest, wctx):
     else:
         if repo["."].rev() != p1:
             repo.ui.debug(" update to %s\n" % (repo[p1]))
-            mergemod.update(repo, p1, force=True)
+            mergemod.goto(repo, p1, force=True)
         else:
             repo.ui.debug(" already in destination\n")
         # This is, alas, necessary to invalidate workingctx's manifest cache,
@@ -1727,10 +1727,9 @@ def rebasenode(repo, rev, p1, base, state, collapse, dest, wctx):
         labels = ["dest", "source"]
     # When collapsing in-place, the parent is the common ancestor, we
     # have to allow merging with it.
-    stats = mergemod.update(
+    stats = mergemod.merge(
         repo,
         rev,
-        branchmerge=True,
         force=True,
         ancestor=base,
         mergeancestor=collapse,
@@ -2159,7 +2158,7 @@ def abort(repo, originalwd, destmap, state, activebookmark=None) -> int:
 
             # Update away from the rebase if necessary
             if shouldupdate or needupdate(repo, state):
-                mergemod.update(repo, originalwd, force=True)
+                mergemod.goto(repo, originalwd, force=True)
 
             # Strip from the first rebased revision
             if rebased:

eden/scm/sapling/ext/reset.py

@@ -95,7 +95,7 @@ def _moveto(repo, bookmark, ctx, clean=False):
     """
     # Move working copy over
     if clean:
-        merge.update(
+        merge.goto(
             repo,
             ctx.node(),
             force=True,

eden/scm/sapling/ext/sparse.py

@@ -368,22 +368,22 @@ def _calculateupdates(
 
     extensions.wrapfunction(mergemod, "calculateupdates", _calculateupdates)
 
-    def _update(orig, repo, node, branchmerge=False, **kwargs):
+    def _goto(orig, repo, node, **kwargs):
         try:
-            results = orig(repo, node, branchmerge=branchmerge, **kwargs)
+            results = orig(repo, node, **kwargs)
         except Exception:
             if _hassparse(repo):
                 repo._clearpendingprofileconfig()
             raise
 
         # If we're updating to a location, clean up any stale temporary includes
         # (ex: this happens during hg rebase --abort).
-        if not branchmerge and hasattr(repo, "sparsematch"):
+        if hasattr(repo, "sparsematch"):
             repo.prunetemporaryincludes()
 
         return results
 
-    extensions.wrapfunction(mergemod, "update", _update)
+    extensions.wrapfunction(mergemod, "goto", _goto)
 
 
 def _setupcommit(ui) -> None:

eden/scm/sapling/ext/undo.py

@@ -166,9 +166,12 @@ def log(orig, *args, **kwargs):
     #
     # To detect a write command, wrap all possible entries:
     #  - transaction.__init__
-    #  - merge.update
+    #  - merge.goto
+    #  - merge.merge
     w = extensions.wrappedfunction
-    with w(merge, "update", log), w(transaction.transaction, "__init__", log):
+    with w(merge, "goto", log), w(merge, "merge", log), w(
+        transaction.transaction, "__init__", log
+    ):
         try:
             result = orig(lui, repo, cmd, fullargs, *args)
         finally:

eden/scm/sapling/hg.py

@@ -891,7 +891,7 @@ def updaterepo(repo, node, overwrite, updatecheck=None):
     When overwrite is set, changes are clobbered, merged else
 
     returns stats (see pydoc merge.applyupdates)"""
-    return mergemod.update(
+    return mergemod.goto(
         repo,
         node,
         force=overwrite,
@@ -1009,7 +1009,7 @@ def updatetotally(
 def merge(repo, node, force=False, remind: bool = True, labels=None):
     """Branch merge with node, resolving changes. Return true if any
     unresolved conflicts."""
-    stats = mergemod.update(repo, node, branchmerge=True, force=force, labels=labels)
+    stats = mergemod.merge(repo, node, force=force, labels=labels)
     _showstats(repo, stats)
     if stats[3]:
         repo.ui.status(