extensions: register functions always at loading extension (issue5601)

extensions: register functions always at loading extension (issue5601)

Before this patch, functions defined in extensions are registered via
extra loaders only in _dispatch(). Therefore, loading extensions in
other code paths like below omits registration of functions.

  - WSGI service
  - operation across repositories (e.g. subrepo)
  - test-duplicateoptions.py, using extensions.loadall() directly

To register functions always at loading new extension, this patch
moves implementation for extra loading from dispatch._dispatch() to
extensions.loadall().

AFAIK, only commands module causes cyclic dependency between
extensions module, but this patch imports all related modules just
before extra loading in loadall(), in order to centralize them.

This patch makes extensions.py depend on many other modules, even
though extensions.py itself doesn't. It should be avoided if possible,
but I don't have any better idea. Some other places like below aren't
reasonable for extra loading, IMHO.

  - specific function in newly added module:
    existing callers of extensions.loadall() should invoke it, too

  - hg.repository() or so:
    no-repo commands aren't covered by this.

BTW, this patch removes _loaded.add(name) on relocation, because
dispatch._loaded is used only for extraloaders (for similar reason,
"exts" variable is removed, too).

--- a/mercurial/dispatch.py	Sat Jun 24 23:09:21 2017 -0400
+++ b/mercurial/dispatch.py	Sat Jun 24 02:39:20 2017 +0900
@@ -30,17 +30,12 @@
     error,
     extensions,
     fancyopts,
-    fileset,
     help,
     hg,
     hook,
     profiling,
     pycompat,
-    revset,
     scmutil,
-    templatefilters,
-    templatekw,
-    templater,
     ui as uimod,
     util,
 )
@@ -727,22 +722,6 @@
 
 _loaded = set()
 
-# list of (objname, loadermod, loadername) tuple:
-# - objname is the name of an object in extension module, from which
-#   extra information is loaded
-# - loadermod is the module where loader is placed
-# - loadername is the name of the function, which takes (ui, extensionname,
-#   extraobj) arguments
-extraloaders = [
-    ('cmdtable', commands, 'loadcmdtable'),
-    ('colortable', color, 'loadcolortable'),
-    ('filesetpredicate', fileset, 'loadpredicate'),
-    ('revsetpredicate', revset, 'loadpredicate'),
-    ('templatefilter', templatefilters, 'loadfilter'),
-    ('templatefunc', templater, 'loadfunction'),
-    ('templatekeyword', templatekw, 'loadkeyword'),
-]
-
 def _dispatch(req):
     args = req.args
     ui = req.ui
@@ -770,19 +749,11 @@
         # reposetup. Programs like TortoiseHg will call _dispatch several
         # times so we keep track of configured extensions in _loaded.
         extensions.loadall(lui)
-        exts = [ext for ext in extensions.extensions() if ext[0] not in _loaded]
         # Propagate any changes to lui.__class__ by extensions
         ui.__class__ = lui.__class__
 
         # (uisetup and extsetup are handled in extensions.loadall)
 
-        for name, module in exts:
-            for objname, loadermod, loadername in extraloaders:
-                extraobj = getattr(module, objname, None)
-                if extraobj is not None:
-                    getattr(loadermod, loadername)(ui, name, extraobj)
-            _loaded.add(name)
-
         # (reposetup is handled in hg.repository)
 
         addaliases(lui, commands.table)

--- a/mercurial/extensions.py	Sat Jun 24 23:09:21 2017 -0400
+++ b/mercurial/extensions.py	Sat Jun 24 02:39:20 2017 +0900
@@ -243,6 +243,43 @@
     # entries could result in double execution. See issue4646.
     _aftercallbacks.clear()
 
+    # delay importing avoids cyclic dependency (especially commands)
+    from . import (
+        color,
+        commands,
+        fileset,
+        revset,
+        templatefilters,
+        templatekw,
+        templater,
+    )
+
+    # list of (objname, loadermod, loadername) tuple:
+    # - objname is the name of an object in extension module,
+    #   from which extra information is loaded
+    # - loadermod is the module where loader is placed
+    # - loadername is the name of the function,
+    #   which takes (ui, extensionname, extraobj) arguments
+    extraloaders = [
+        ('cmdtable', commands, 'loadcmdtable'),
+        ('colortable', color, 'loadcolortable'),
+        ('filesetpredicate', fileset, 'loadpredicate'),
+        ('revsetpredicate', revset, 'loadpredicate'),
+        ('templatefilter', templatefilters, 'loadfilter'),
+        ('templatefunc', templater, 'loadfunction'),
+        ('templatekeyword', templatekw, 'loadkeyword'),
+    ]
+
+    for name in _order[newindex:]:
+        module = _extensions[name]
+        if not module:
+            continue # loading this module failed
+
+        for objname, loadermod, loadername in extraloaders:
+            extraobj = getattr(module, objname, None)
+            if extraobj is not None:
+                getattr(loadermod, loadername)(ui, name, extraobj)
+
 def afterloaded(extension, callback):
     '''Run the specified function after a named extension is loaded.
 

--- a/tests/test-extension.t	Sat Jun 24 23:09:21 2017 -0400
+++ b/tests/test-extension.t	Sat Jun 24 02:39:20 2017 +0900
@@ -77,15 +77,25 @@
   >     print "3) %s extsetup" % name
   > def reposetup(ui, repo):
   >    print "4) %s reposetup" % name
+  > 
+  > # custom predicate to check registration of functions at loading
+  > from mercurial import (
+  >     registrar,
+  >     smartset,
+  > )
+  > revsetpredicate = registrar.revsetpredicate()
+  > @revsetpredicate(name, safe=True) # safe=True for query via hgweb
+  > def custompredicate(repo, subset, x):
+  >     return smartset.baseset([r for r in subset if r in {0}])
   > EOF
 
   $ cp foo.py bar.py
   $ echo 'foo = foo.py' >> $HGRCPATH
   $ echo 'bar = bar.py' >> $HGRCPATH
 
-Command with no output, we just want to see the extensions loaded:
+Check normal command's load order of extensions and registration of functions
 
-  $ hg paths
+  $ hg log -r "foo() and bar()" -q
   1) foo imported
   1) bar imported
   2) foo uisetup
@@ -94,8 +104,9 @@
   3) bar extsetup
   4) foo reposetup
   4) bar reposetup
+  0:c24b9ac61126
 
-Check hgweb's load order:
+Check hgweb's load order of extensions and registration of functions
 
   $ cat > hgweb.cgi <<EOF
   > #!$PYTHON
@@ -118,6 +129,14 @@
   4) foo reposetup
   4) bar reposetup
 
+(check that revset predicate foo() and bar() are available)
+
+  $ REQUEST_METHOD='GET' PATH_INFO='/shortlog' SCRIPT_NAME='' \
+  >     QUERY_STRING='rev=foo() and bar()' \
+  >     SERVER_PORT='80' SERVER_NAME='localhost' python hgweb.cgi \
+  >     | grep '<a href="/rev/[0-9a-z]*">'
+     <a href="/rev/c24b9ac61126">add file</a>
+
   $ echo 'foo = !' >> $HGRCPATH
   $ echo 'bar = !' >> $HGRCPATH