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We used to store module runtime and environment pointers in the static lists Vmodule_runtimes and Vmodule_environments. However, this is incorrect because these objects have to be kept per-thread. With this naive approach, interleaving module function calls in separate threads leads to environments being removed in the wrong order, which in turn can cause local module values to be incorrectly garbage-collected. The fix isn't completely trivial: specbinding the lists wouldn't work either, because then the garbage collector wouldn't find the environments in other threads than the current ones, again leading to objects being garbage-collected incorrectly. While introducing custom pseudovector types would fix this, it's simpler to put the runtime and environment pointers into the specbinding list as new specbinding kinds. This works since we need to unwind them anyway, and we only ever treat the lists as a stack. The thread switching machinery ensures that the specbinding lists are thread-local, and that all elements of the specbinding lists in all threads are marked during garbage collection. Module assertions now have to walk the specbinding list for the current thread, which is more correct since they now only find environments for the current thread. As a result, we can now remove the faulty Vmodule_runtimes and Vmodule_environments variables entirely. Also add a unit test that exemplifies the problem. It interleaves two module calls in two threads so that the first call ends while the second one is still active. Without this change, this test triggers an assertion failure. * src/lisp.h (enum specbind_tag): Add new tags for module runtimes and environments. * src/eval.c (record_unwind_protect_module): New function to record a module object in the specpdl list. (do_one_unbind): Unwind module objects. (backtrace_eval_unrewind, default_toplevel_binding, lexbound_p) (Fbacktrace__locals): Deal with new specbinding types. (mark_specpdl): Mark module environments as needed. * src/alloc.c (garbage_collect): Remove call to 'mark-modules'. Garbage collection of module values is now handled as part of marking the specpdl of each thread. * src/emacs-module.c (Fmodule_load, funcall_module): Use specpdl to record module runtimes and environments. (module_assert_runtime, module_assert_env, value_to_lisp): Walk through specpdl list instead of list variables. (mark_module_environment): Rename from 'mark_modules'. Don't attempt to walk though current thread's environments only, since that would miss other threads. (initialize_environment, finalize_environment): Don't change Vmodule_environments variable; environments are now in the specpdl list. (finalize_environment_unwind, finalize_runtime_unwind): Make 'extern' since do_one_unbind now calls them. (finalize_runtime_unwind): Don't change Vmodule_runtimes variable; runtimes are now in the specpdl list. (syms_of_module): Remove Vmodule_runtimes and Vmodule_environments. * test/data/emacs-module/mod-test.c (Fmod_test_funcall): New test function. (emacs_module_init): Bind it. * test/src/emacs-module-tests.el (emacs-module-tests--variable): New helper type to guard access to state in a thread-safe way. (emacs-module-tests--wait-for-variable) (emacs-module-tests--change-variable): New helper functions. (emacs-module-tests/interleaved-threads): New unit test. |
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Copyright (C) 2008-2020 Free Software Foundation, Inc.
See the end of the file for license conditions.
This directory contains files intended to test various aspects of
Emacs's functionality. Please help add tests!
See the file file-organization.org for the details of the directory
structure and file-naming conventions.
Emacs uses ERT, Emacs Lisp Regression Testing, for testing. See (info
"(ert)") or https://www.gnu.org/software/emacs/manual/html_node/ert/
for more information on writing and running tests.
Tests could be tagged by the developer. In this test directory, the
following tags are recognized:
* :expensive-test
The test needs a serious amount of time to run. It is not intended
to run on a regular basis by users. Instead, it runs on demand
only, or during regression tests.
* :unstable
The test is under development. It shall run on demand only.
The Makefile in this directory supports the following targets:
* make check
Run all tests as defined in the directory. Expensive and unstable
tests are suppressed. The result of the tests for <filename>.el is
stored in <filename>.log.
* make check-maybe
Like "make check", but run only the tests for files which have
unresolved prerequisites.
* make check-expensive
Like "make check", but run also the tests marked as expensive.
* make check-all
Like "make check", but run all tests.
* make <filename> -or- make <filename>.log
Run all tests declared in <filename>.el. This includes expensive
tests. In the former case the output is shown on the terminal, in
the latter case the output is written to <filename>.log.
<filename> could be either a relative file name like
"lisp/files-tests", or a package name like "files-tests".
ERT offers selectors, which make it possible to filter out which test
cases shall run. The make variable $(SELECTOR) gives you a simple
mean to use your own selectors. The ERT manual describes how
selectors are constructed, see (info "(ert)Test Selectors") or
https://www.gnu.org/software/emacs/manual/html_node/ert/Test-Selectors.html
You could use predefined selectors of the Makefile. "make <filename>
SELECTOR='$(SELECTOR_DEFAULT)'" runs all tests for <filename>.el
except the tests tagged as expensive or unstable.
If your test file contains the tests "test-foo", "test2-foo" and
"test-foo-remote", and you want to run only the former two tests, you
could use a selector regexp (note that the "$" needs to be doubled to
protect against "make" variable expansion):
make <filename> SELECTOR='"foo$$"'
In case you want to use the symbol name of a test as selector, you can
use it directly:
make <filename> SELECTOR='test-foo-remote'
Note that although the test files are always compiled (unless they set
no-byte-compile), the source files will be run when expensive or
unstable tests are involved, to give nicer backtraces. To run the
compiled version of a test use
make TEST_LOAD_EL=no ...
Some tests might take long time to run. In order to summarize the
<nn> tests with the longest duration, call
make SUMMARIZE_TESTS=<nn> ...
The backtrace of failing tests are truncated to the default value of
'ert-batch-backtrace-right-margin'. To see more of the backtrace, use
make TEST_BACKTRACE_LINE_LENGTH=<nn> ...
The tests are run in batch mode by default; sometimes it's useful to
get precisely the same environment but run in interactive mode for
debugging. To do that, use
make TEST_INTERACTIVE=yes ...
Some of the tests require a remote temporary directory
(autorevert-tests.el, filenotify-tests.el, shadowfile-tests.el and
tramp-tests.el). Per default, a mock-up connection method is used
(this might not be possible when running on MS Windows). If you want
to test a real remote connection, set $REMOTE_TEMPORARY_FILE_DIRECTORY
to a suitable value in order to overwrite the default value:
env REMOTE_TEMPORARY_FILE_DIRECTORY=/ssh:host:/tmp make ...
There are also continuous integration tests on
<https://hydra.nixos.org/jobset/gnu/emacs-trunk> (see
admin/notes/hydra) and <https://emba.gnu.org/emacs/emacs> (see
admin/notes/emba). Both environments provide an environment variable,
which could be used to determine, whether the tests run in one of
these test environments.
$EMACS_HYDRA_CI indicates the hydra environment, and $EMACS_EMBA_CI
indicates the emba environment, respectively.
(Also, see etc/compilation.txt for compilation mode font lock tests.)
This file is part of GNU Emacs.
GNU Emacs is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
GNU Emacs is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>.