view tests/test-trusted.py.out @ 26457:7e81305092a0

demandimport: replace more references to _demandmod instances

_demandmod instances may be referenced by multiple importing modules.
Before this patch, the _demandmod instance only maintained a reference
to its first consumer when using the "from X import Y" syntax. This is
because we only created a single _demandmod instance (attached to the
parent X module). If multiple modules A and B performed
"from X import Y", we'd produce a single _demandmod instance
"demandmod" with the following references:

  X.Y = <demandmod>
  A.Y = <demandmod>
  B.Y = <demandmod>

The locals from the first consumer (A) would be stored in <demandmod1>.
When <demandmod1> was loaded, we'd look at the locals for the first
consumer and replace the symbol, if necessary. This resulted in state:

  X.Y = <module>
  A.Y = <module>
  B.Y = <demandmod>

B's reference to Y wasn't updated and was still using the proxy object
because we just didn't record that B had a reference to <demandmod> that
needed updating!

With this patch, we add support for tracking which modules in addition
to the initial importer have a reference to the _demandmod instance and
we replace those references at module load time.

In the case of posix.py, this fixes an issue where the "encoding" module
was being proxied, resulting in hundreds of thousands of
__getattribute__ lookups on the _demandmod instance during dirstate
operations on mozilla-central, speeding up execution by many
milliseconds. There are likely several other operation that benefit from
this change as well.

The new mechanism isn't perfect: references in locals (not globals) may
likely linger. So, if there is an import inside a function and a symbol
from that module is used in a hot loop, we could have unwanted overhead
from proxying through _demandmod. Non-global imports are discouraged
anyway. So hopefully this isn't a big deal in practice. We could
potentially deploy a code checker that bans use of attribute lookups of
function-level-imported modules inside loops.

This deficiency in theory could be avoided by storing the set of globals
and locals dicts to update in the _demandmod instance. However, I tried
this and it didn't work. One reason is that some globals are _demandmod
instances. We could work around this, but it's a bit more work. There
also might be other module import foo at play. The solution as
implemented is better than what we had and IMO is good enough for the
time being.

It's worth noting that this sub-optimal behavior was made worse by the
introduction of absolute_import and its recommended "from . import X"
syntax for importing modules from the "mercurial" package. If we ever
wrote performance tests, measuring the amount of module imports and
__getattribute__ proxy calls through _demandmod instances would be
something I'd have it check.

# same user, same group
trusted
    global = /some/path
    local = /another/path
untrusted
. . global = /some/path
. . local = /another/path

# same user, different group
trusted
    global = /some/path
    local = /another/path
untrusted
. . global = /some/path
. . local = /another/path

# different user, same group
not trusting file .hg/hgrc from untrusted user abc, group bar
trusted
    global = /some/path
untrusted
. . global = /some/path
. . local = /another/path

# different user, same group, but we trust the group
trusted
    global = /some/path
    local = /another/path
untrusted
. . global = /some/path
. . local = /another/path

# different user, different group
not trusting file .hg/hgrc from untrusted user abc, group def
trusted
    global = /some/path
untrusted
. . global = /some/path
. . local = /another/path

# different user, different group, but we trust the user
trusted
    global = /some/path
    local = /another/path
untrusted
. . global = /some/path
. . local = /another/path

# different user, different group, but we trust the group
trusted
    global = /some/path
    local = /another/path
untrusted
. . global = /some/path
. . local = /another/path

# different user, different group, but we trust the user and the group
trusted
    global = /some/path
    local = /another/path
untrusted
. . global = /some/path
. . local = /another/path

# we trust all users
# different user, different group
trusted
    global = /some/path
    local = /another/path
untrusted
. . global = /some/path
. . local = /another/path

# we trust all groups
# different user, different group
trusted
    global = /some/path
    local = /another/path
untrusted
. . global = /some/path
. . local = /another/path

# we trust all users and groups
# different user, different group
trusted
    global = /some/path
    local = /another/path
untrusted
. . global = /some/path
. . local = /another/path

# we don't get confused by users and groups with the same name
# different user, different group
not trusting file .hg/hgrc from untrusted user abc, group def
trusted
    global = /some/path
untrusted
. . global = /some/path
. . local = /another/path

# list of user names
# different user, different group, but we trust the user
trusted
    global = /some/path
    local = /another/path
untrusted
. . global = /some/path
. . local = /another/path

# list of group names
# different user, different group, but we trust the group
trusted
    global = /some/path
    local = /another/path
untrusted
. . global = /some/path
. . local = /another/path

# Can't figure out the name of the user running this process
# different user, different group
not trusting file .hg/hgrc from untrusted user abc, group def
trusted
    global = /some/path
untrusted
. . global = /some/path
. . local = /another/path

# prints debug warnings
# different user, different group
not trusting file .hg/hgrc from untrusted user abc, group def
trusted
ignoring untrusted configuration option paths.local = /another/path
    global = /some/path
untrusted
. . global = /some/path
.ignoring untrusted configuration option paths.local = /another/path
. local = /another/path

# report_untrusted enabled without debug hides warnings
# different user, different group
trusted
    global = /some/path
untrusted
. . global = /some/path
. . local = /another/path

# report_untrusted enabled with debug shows warnings
# different user, different group
not trusting file .hg/hgrc from untrusted user abc, group def
trusted
ignoring untrusted configuration option paths.local = /another/path
    global = /some/path
untrusted
. . global = /some/path
.ignoring untrusted configuration option paths.local = /another/path
. local = /another/path

# ui.readconfig sections
quux

# read trusted, untrusted, new ui, trusted
not trusting file foobar from untrusted user abc, group def
trusted:
ignoring untrusted configuration option foobar.baz = quux
None
untrusted:
quux

# error handling
# file doesn't exist
# same user, same group
# different user, different group

# parse error
# different user, different group
not trusting file .hg/hgrc from untrusted user abc, group def
('foo', '.hg/hgrc:1')
# same user, same group
('foo', '.hg/hgrc:1')