sqldirstate: extract the upgrade and downgrade logic

Summary: This is to make implementation of automatic upgrade easier.

Test Plan: Will add a test for it in one of the next diffs

Reviewers: #mercurial, durham, ttung

Subscribers: mjpieters

Differential Revision: https://phabricator.intern.facebook.com/D3356494

sqldirstate/__init__.py

@@ -71,6 +71,33 @@ def wrapshelveaborttransaction(orig, repo):
     else:
         return orig(repo)
 
+def upgrade(ui, repo):
+    if issqldirstate(repo):
+        raise error.Abort('repo already has sqldirstate')
+    wlock = repo.wlock()
+    try:
+        repo.dirstate._read()
+        tosql(repo.dirstate)
+        repo.requirements.add('sqldirstate')
+        repo._writerequirements()
+        repo.dirstate._opener.unlink('dirstate')
+        del repo.dirstate
+    finally:
+        wlock.release()
+
+def downgrade(ui, repo):
+    if not issqldirstate(repo):
+        raise error.Abort('repo doesn\'t have sqldirstate')
+    wlock = repo.lock()
+    try:
+        toflat(repo.dirstate)
+        repo.requirements.remove('sqldirstate')
+        repo._writerequirements()
+        repo.dirstate._opener.unlink('dirstate.sqlite3')
+        del repo.dirstate
+    finally:
+        wlock.release()
+
 def featuresetup(ui, supported):
     # don't die on seeing a repo with the sqldirstate requirement
     supported |= set(['sqldirstate'])
@@ -92,25 +119,14 @@ def uisetup(ui):
 # debug commands
 cmdtable = {}
 command = cmdutil.command(cmdtable)
+
 @command('debugsqldirstate', [], 'hg debugsqldirstate [on|off]')
 def debugsqldirstate(ui, repo, cmd, **opts):
     """ migrate to sqldirstate """
 
     if cmd == "on":
-        if 'sqldirstate' not in repo.requirements:
-            repo.dirstate._read()
-            tosql(repo.dirstate)
-            repo.requirements.add('sqldirstate')
-            repo._writerequirements()
-            repo.dirstate._opener.unlink('dirstate')
-        else:
-            raise error.Abort("sqldirstate is already enabled")
-
-    if cmd == "off":
-        if 'sqldirstate' in repo.requirements:
-            toflat(repo.dirstate)
-            repo.requirements.remove('sqldirstate')
-            repo._writerequirements()
-            repo.dirstate._opener.unlink('dirstate.sqlite3')
-        else:
-            raise error.Abort("sqldirstate is disabled")
+        upgrade(ui, repo)
+    elif cmd == "off":
+        downgrade(ui, repo)
+    else:
+        raise error.Abort("bad command")

sqldirstate/sqldirstate.py

@@ -416,7 +416,11 @@ def makedirstate(cls):
     return sqldirstate
 
 def tosql(dirstate):
-    # converts a flat dirstate to sqldirstate
+    """" converts flat dirstate to sqldirstate
+
+    note: the sole responsibility of this function is to write the new dirstate
+    it's not touching anything but the DBFILE
+    """
     sqlfilename = dirstate._opener.join(DBFILE)
     try:
         os.unlink(sqlfilename)
@@ -455,6 +459,11 @@ def tosql(dirstate):
     sqlconn.commit()
 
 def toflat(sqldirstate):
+    """" converts sqldirstate to flat dirstate
+
+    note: the sole responsibility of this function is to write the new dirstate
+    it's not touching anything but the dirstate file
+    """
     # converts a sqldirstate to a flat one
     st = sqldirstate._opener("dirstate", "w", atomictemp=True)
     newmap = {}