The controller must know the ID of the forked child in order to
propagate dependencies to it, so forking+starting the module run cannot
happen entirely on the target, without some additional mechanism to
wait-and-repropagate the deps as they arrive on the target.
Rework things so that init_child() also handles starting the fork parent,
and returns it along with the context's home directory in a single round
trip.
Now master knows the identity of the fork parent, it can directly create
fork children and call run_module_async() in them. This necessitates 2
roundtrips to start an asynchronous task.
This whole thing sucks and entirely needs simplified, but for now things
almost work, so keeping it.
connection.py:
* Expect ContextService to return the entire dict return value of
init_child(). Store the fork_contxt from the return value.
planner.py:
* Rework Planner to store the invocation as an instance attribute, to
simplify method calls.
* Add Planner.get_push_files() and Planner.get_module_deps().
* Add _propagate_deps() which takes a Planner and ensures the deps it
describes are sent to a (non forked or forked) context.
* Move async task logic out of target.py and into invoke() /
_invoke_*().
process.py:
* Services no longer need references to each other. planner.py handles
sending module deps with one extra RPC.
services.py:
* Return "init_child_result" key instead of simple "home_dir" key.
* Get rid of dep propagation from ModuleDepService, it lives in
planner.py now.
target.py:
* Get rid of async task start logic, lives in planner.py now.
planner.py:
* Rather than grant FileService access to a file for children, use
PushFileService to trigger deduplicating send of the file through
the hierarchy immediately.
* Send the complete list of Ansible module imports to the target so
runner.py knows which files and scripts must be loaded via
PushFileService prior to detaching.
runner.py:
* Teach NewStyleRunner to use the full module map to block until
everything is loaded prior to detach().
target.py:
* Delete old _get_file(), replace get_file() with get_small_file()
which uses PushFileService instead.
Closes#186
For "ansible -m setup" over a 25ms link, avoids 65 roundtrips and
reduces runtime from 5.7s to 4.1s (-28%).
For "ansible -m setup" over a simulated 250 ms link, reduces runtime
from m27.015s to 0m8.254s (-69%).
This may come back to bite later, but in the meantime it avoids shipping
up to 12KiB of junk metadata for every single task invocation.
For detachment (aka. async), we must ensure the target has two types of
preloads completed (modules and module_utils files) before detaching.
And by "compatible" I mean "terrible". This does not implement async job
timeouts, but I'm not going to bother, upstream async implementation is
so buggy and inconsistent it resists even having its behaviour captured
in tests.
Closes#105.
References #155.
mitogen/service.py:
Refactor services to support individually exposed methods with
different security policies for each method.
- @mitogen.service.expose() to expose a method and set its policy
- @mitogen.service.arg_spec() to validate input.
- Require basic service message format to be a tuple of
`(method, kwargs)`, where kwargs is always a dict.
- Update DeduplicatingService to match the new scheme.
ansible_mitogen/connection.py:
- Rename 'method' to 'method_name' to disambiguate it from the
service.call()'s method= argument.
ansible_mitogen/planner.py:
- Generate an ID for every job, sync or not, and fetch job results
from JobResultService rather than via the initiating function
call's return value.
- Planner subclasses now get to select whether their Runner should
run in a forked process. The base implementation requests this if
the 'mitogen_isolation_mode=fork' task variable is present.
ansible_mitogen/runner.py:
Teach runners to deliver their result via JobResultService executing
in their indirect parent mux process.
ansible_mitogen/plugins/actions/mitogen_async_status.py:
Split the implementation up into methods, and more compatibly
emulate Ansible's existing output.
ansible_mitogen/process.py:
Mux processes now host JobResultService.
ansible_mitogen/services.py:
Update existing services to the new mitogen.service scheme, and
implement JobResultService:
* listen() method for synchronous jobs. planner.invoke() registers a
Sender with the service prior to invoking the job, then sleeps
waiting for the service to write the job result to the
corresponding Receiver.
* Non-blocking get() method for implementing mitogen_async_status
action.
* Child-accessible push() method for delivering task results.
ansible_mitogen/target.py:
New helpers for spawning a virginal subprocess on startup, from
which asynchronous and mitogen_task_isolation=fork jobs are forked.
Necessary to avoid a task inheriting potentially
polluted/monkey-patched parent environment, since remaining jobs
continue to run in the original child process.
docs/ansible.rst:
Add/merge/remove some behaviours/risks.
tests/ansible/integration:
New tests for forking/async.
Rather than assume any structure about the Python code:
* Delete the exit_json/fail_json monkeypatches.
* Patch SystemExit rather than a magic monkeypatch-thrown exception
* Setup fake cStringIO stdin, stdout, stderr and return those along with
SystemExit exit status
* Setup _ANSIBLE_ARGS as we used to, since we still want to override
that with '{}' to prevent accidental import hangs, but also provide
the same string via sys.stdin.
* Compile the module bytecode once and re-execute it for every
invocation. May change this back again later, once some benchmarks are
done.
* Remove the fixups stuff for now, it's handled by ^ above.
Should support any "somewhat new style" Python module, including those
that just give up and dump stuff to stdout directly.
Refactor planner.py to look a lot more like runner.py. This 'structural
cutpaste' looks messy -- probably we can simplify this code, even though
it's pretty simple already.
David Wilson