archive: prefetch remotefilelog files before executing archive

Summary:
Currently archive is almost useless because it fetches each file
one-by-one. Let's add prefetching.

Differential Revision: D14460880

fbshipit-source-id: 1f06e1ac9d03aae3ab27d3064f9fe6141051be06

edenscm/hgext/remotefilelog/__init__.py

@@ -136,6 +136,7 @@ import traceback
 from contextlib import contextmanager
 
 from edenscm.mercurial import (
+    archival,
     bundle2,
     changegroup,
     changelog,
@@ -580,6 +581,19 @@ def onetimeclientsetup(ui):
 
     wrapfunction(copies, "_computeforwardmissing", computeforwardmissing)
 
+    # prefetch files before archiving
+    def computefiles(orig, ctx, matchfn):
+        files = orig(ctx, matchfn)
+
+        repo = ctx._repo
+        if shallowrepo.requirement in repo.requirements:
+            mf = ctx.manifest()
+            repo.fileservice.prefetch(list((f, hex(mf.get(f))) for f in files))
+
+        return files
+
+    wrapfunction(archival, "computefiles", computefiles)
+
     # close cache miss server connection after the command has finished
     def runcommand(orig, lui, repo, *args, **kwargs):
         try:

edenscm/mercurial/archival.py

@@ -332,10 +332,7 @@ def archive(repo, dest, node, kind, decode=True, matchfn=None, prefix="", mtime=
         if not matchfn or matchfn(name):
             write(name, 0o644, False, lambda: buildmetadata(ctx))
 
-    if matchfn:
-        files = ctx.manifest().matches(matchfn).keys()
-    else:
-        files = ctx.manifest().keys()
+    files = computefiles(ctx, matchfn)
     total = len(files)
     if total:
         files.sort()
@@ -350,3 +347,11 @@ def archive(repo, dest, node, kind, decode=True, matchfn=None, prefix="", mtime=
 
     archiver.done()
     return total
+
+
+def computefiles(ctx, matchfn):
+    if matchfn:
+        files = ctx.manifest().matches(matchfn).keys()
+    else:
+        files = ctx.manifest().keys()
+    return files

tests/test-fb-hgext-remotefilelog-archive.t

@@ -26,4 +26,4 @@ Test blame
 
   $ clearcache
   $ hg archive -r tip -t tar myarchive.tar
-  3 files fetched over 3 fetches - (3 misses, 0.00% hit ratio) over 0.00s
+  3 files fetched over 1 fetches - (3 misses, 0.00% hit ratio) over 0.00s