merge: disable Rust workers if in-memory merge is in progress

Summary: We don't really need the Rust workers for this, as we do not expect thousands of files to be changed during an in-memory merge.

Reviewed By: DurhamG

Differential Revision: D20495141

fbshipit-source-id: e72f8c4b01deee46ee72364dcd6716692c4103ab

eden/scm/edenscm/mercurial/merge.py

@@ -1651,6 +1651,8 @@ def applyupdates(repo, actions, wctx, mctx, overwrite, labels=None, ancestors=No
     numupdates = sum(len(l) for m, l in actions.items() if m != "k")
     z = 0
 
+    rustworkers = repo.ui.configbool("worker", "rustworkers") and not wctx.isinmemory()
+
     # record path conflicts
     with progress.bar(
         repo.ui, _("updating"), _("files"), numupdates
@@ -1684,7 +1686,7 @@ def applyupdates(repo, actions, wctx, mctx, overwrite, labels=None, ancestors=No
 
         # remove in parallel (must come before resolving path conflicts and
         # getting)
-        if repo.ui.configbool("worker", "rustworkers"):
+        if rustworkers:
             numworkers = worker._numworkers(repo.ui)
             remover = rustworker.removerworker(repo.wvfs.base, numworkers)
             for f, args, msg in actions["r"]:
@@ -1718,7 +1720,7 @@ def applyupdates(repo, actions, wctx, mctx, overwrite, labels=None, ancestors=No
         # get in parallel
         writesize = 0
 
-        if repo.ui.configbool("worker", "rustworkers"):
+        if rustworkers:
             numworkers = worker._numworkers(repo.ui)
             writer = rustworker.writerworker(
                 repo.fileslog.contentstore, repo.wvfs.base, numworkers

eden/scm/tests/test-fb-hgext-remotefilelog-worker.t

@@ -22,7 +22,7 @@ Shallow clone
 
   $ clone master shallow --noupdate
   $ cd shallow
-  $ setconfig remotefilelog.useruststore=True worker.rustworkers=True
+  $ setconfig remotefilelog.useruststore=True worker.rustworkers=True extensions.amend= rebase.experimental.inmemory=True
   $ hg up master
   fetching tree '' 6b8f81b9651010925578ea56a4129930688cbf98, found via baeb6587a441
   1 trees fetched over 0.00s
@@ -44,3 +44,15 @@ Shallow clone
   0 files updated, 0 files merged, 1 files removed, 0 files unresolved
   $ test -f dir
   [1]
+
+  $ echo x > x
+  $ hg commit -qAm x
+  $ echo y > y
+  $ hg commit -qAm y
+  $ hg prev
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  [02b5b1] x
+  $ hg amend
+  rebasing 02663ae2e9f7 "y"
+  hint[amend-autorebase]: descendants have been auto-rebased because no merge conflict could have happened - use --no-rebase or set commands.amend.autorebase=False to disable auto rebase
+  hint[hint-ack]: use 'hg hint --ack amend-autorebase' to silence these hints