API¶
Executors¶
-
class
futurist.
GreenThreadPoolExecutor
(max_workers=1000, check_and_reject=None)¶ Executor that uses a green thread pool to execute calls asynchronously.
See: https://docs.python.org/dev/library/concurrent.futures.html and http://eventlet.net/doc/modules/greenpool.html for information on how this works.
It gathers statistics about the submissions executed for post-analysis...
-
__init__
(max_workers=1000, check_and_reject=None)¶ Initializes a green thread pool executor.
Parameters: - max_workers (int) – maximum number of workers that can be simulatenously active at the same time, further submitted work will be queued up when this limit is reached.
- check_and_reject (callback) – a callback function that will be provided
two position arguments, the first argument
will be this executor instance, and the second
will be the number of currently queued work
items in this executors backlog; the callback
should raise a
RejectedSubmission
exception if it wants to have this submission rejected.
-
alive
¶ Accessor to determine if the executor is alive/active.
-
statistics
¶ ExecutorStatistics
about the executors executions.
-
submit
(fn, *args, **kwargs)¶ Submit some work to be executed (and gather statistics).
Parameters: - args (list) – non-keyworded arguments
- kwargs (dictionary) – key-value arguments
-
-
class
futurist.
ProcessPoolExecutor
(max_workers=None)¶ Executor that uses a process pool to execute calls asynchronously.
It gathers statistics about the submissions executed for post-analysis...
See: https://docs.python.org/dev/library/concurrent.futures.html
-
alive
¶ Accessor to determine if the executor is alive/active.
-
statistics
¶ ExecutorStatistics
about the executors executions.
-
submit
(fn, *args, **kwargs)¶ Submit some work to be executed (and gather statistics).
-
-
class
futurist.
SynchronousExecutor
(green=False, run_work_func=<function <lambda>>)¶ Executor that uses the caller to execute calls synchronously.
This provides an interface to a caller that looks like an executor but will execute the calls inside the caller thread instead of executing it in a external process/thread for when this type of functionality is useful to provide...
It gathers statistics about the submissions executed for post-analysis...
-
__init__
(green=False, run_work_func=<function <lambda>>)¶ Synchronous executor constructor.
Parameters: - green (bool) – when enabled this forces the usage of greened lock classes and green futures (so that the internals of this object operate correctly under eventlet)
- run_work_func – callable that takes a single work item and runs it (typically in a blocking manner)
- run_work_func – callable
-
alive
¶ Accessor to determine if the executor is alive/active.
-
restart
()¶ Restarts this executor (iff previously shutoff/shutdown).
NOTE(harlowja): clears any previously gathered statistics.
-
statistics
¶ ExecutorStatistics
about the executors executions.
-
submit
(fn, *args, **kwargs)¶ Submit some work to be executed (and gather statistics).
-
-
class
futurist.
ThreadPoolExecutor
(max_workers=None, check_and_reject=None)¶ Executor that uses a thread pool to execute calls asynchronously.
It gathers statistics about the submissions executed for post-analysis...
See: https://docs.python.org/dev/library/concurrent.futures.html
-
__init__
(max_workers=None, check_and_reject=None)¶ Initializes a thread pool executor.
Parameters: - max_workers (int) – maximum number of workers that can be simultaneously active at the same time, further submitted work will be queued up when this limit is reached.
- check_and_reject (callback) – a callback function that will be provided
two position arguments, the first argument
will be this executor instance, and the second
will be the number of currently queued work
items in this executors backlog; the callback
should raise a
RejectedSubmission
exception if it wants to have this submission rejected.
-
alive
¶ Accessor to determine if the executor is alive/active.
-
statistics
¶ ExecutorStatistics
about the executors executions.
-
submit
(fn, *args, **kwargs)¶ Submit some work to be executed (and gather statistics).
-
Futures¶
-
class
futurist.
Future
¶ Represents the result of an asynchronous computation.
-
add_done_callback
(fn)¶ Attaches a callable that will be called when the future finishes.
- Args:
- fn: A callable that will be called with this future as its only
- argument when the future completes or is cancelled. The callable will always be called by a thread in the same process in which it was added. If the future has already completed or been cancelled then the callable will be called immediately. These callables are called in the order that they were added.
-
cancel
()¶ Cancel the future if possible.
Returns True if the future was cancelled, False otherwise. A future cannot be cancelled if it is running or has already completed.
-
cancelled
()¶ Return True if the future has cancelled.
-
done
()¶ Return True of the future was cancelled or finished executing.
-
exception
(timeout=None)¶ Return the exception raised by the call that the future represents.
- Args:
- timeout: The number of seconds to wait for the exception if the
- future isn’t done. If None, then there is no limit on the wait time.
- Returns:
- The exception raised by the call that the future represents or None if the call completed without raising.
- Raises:
CancelledError: If the future was cancelled. TimeoutError: If the future didn’t finish executing before the given
timeout.
-
exception_info
(timeout=None)¶ Return a tuple of (exception, traceback) raised by the call that the future represents.
- Args:
- timeout: The number of seconds to wait for the exception if the
- future isn’t done. If None, then there is no limit on the wait time.
- Returns:
- The exception raised by the call that the future represents or None if the call completed without raising.
- Raises:
CancelledError: If the future was cancelled. TimeoutError: If the future didn’t finish executing before the given
timeout.
-
result
(timeout=None)¶ Return the result of the call that the future represents.
- Args:
- timeout: The number of seconds to wait for the result if the future
- isn’t done. If None, then there is no limit on the wait time.
- Returns:
- The result of the call that the future represents.
- Raises:
CancelledError: If the future was cancelled. TimeoutError: If the future didn’t finish executing before the given
timeout.Exception: If the call raised then that exception will be raised.
-
running
()¶ Return True if the future is currently executing.
-
set_exception
(exception)¶ Sets the result of the future as being the given exception.
Should only be used by Executor implementations and unit tests.
-
set_exception_info
(exception, traceback)¶ Sets the result of the future as being the given exception and traceback.
Should only be used by Executor implementations and unit tests.
-
set_result
(result)¶ Sets the return value of work associated with the future.
Should only be used by Executor implementations and unit tests.
-
set_running_or_notify_cancel
()¶ Mark the future as running or process any cancel notifications.
Should only be used by Executor implementations and unit tests.
If the future has been cancelled (cancel() was called and returned True) then any threads waiting on the future completing (though calls to as_completed() or wait()) are notified and False is returned.
If the future was not cancelled then it is put in the running state (future calls to running() will return True) and True is returned.
This method should be called by Executor implementations before executing the work associated with this future. If this method returns False then the work should not be executed.
- Returns:
- False if the Future was cancelled, True otherwise.
- Raises:
- RuntimeError: if this method was already called or if set_result()
- or set_exception() was called.
-
-
class
futurist.
GreenFuture
¶ Represents the result of an asynchronous computation.
Periodics¶
-
class
futurist.periodics.
PeriodicWorker
(callables, log=None, executor_factory=None, cond_cls=<function Condition>, event_cls=<function Event>, schedule_strategy='last_started', now_func=<function monotonic>, on_failure=None)¶ Calls a collection of callables periodically (sleeping as needed...).
NOTE(harlowja): typically the
start()
method is executed in a background thread so that the periodic callables are executed in the background/asynchronously (using the defined periods to determine when each is called).-
BUILT_IN_STRATEGIES
= {'aligned_last_finished_jitter': (<function _aligned_last_finished_strategy_with_jitter at 0x7f3bc9a372a8>, <function _now_plus_periodicity at 0x7f3bc9a499b0>), 'last_finished_jitter': (<function _last_finished_strategy_with_jitter at 0x7f3bc9a37230>, <function _now_plus_periodicity at 0x7f3bc9a499b0>), 'last_finished': (<function _last_finished_strategy at 0x7f3bc9a49848>, <function _now_plus_periodicity at 0x7f3bc9a499b0>), 'aligned_last_finished': (<function _aligned_last_finished_strategy at 0x7f3bc9a49938>, <function _now_plus_periodicity at 0x7f3bc9a499b0>), 'last_started': (<function _last_started_strategy at 0x7f3bc9a498c0>, <function _now_plus_periodicity at 0x7f3bc9a499b0>), 'last_started_jitter': (<function _last_started_strategy_with_jitter at 0x7f3bc9a371b8>, <function _now_plus_periodicity at 0x7f3bc9a499b0>)}¶ Built in scheduling strategies (used to determine when next to run a periodic callable).
The first element is the strategy to use after the initial start and the second element is the strategy to use for the initial start.
These are made somewhat pluggable so that we can easily add-on different types later (perhaps one that uses a cron-style syntax for example).
-
DEFAULT_JITTER
= Fraction(1, 20)¶ Default jitter percentage the built-in strategies (that have jitter support) will use.
-
MAX_LOOP_IDLE
= 30¶ Max amount of time to wait when running (forces a wakeup when elapsed).
-
__init__
(callables, log=None, executor_factory=None, cond_cls=<function Condition>, event_cls=<function Event>, schedule_strategy='last_started', now_func=<function monotonic>, on_failure=None)¶ Creates a new worker using the given periodic callables.
Parameters: - callables (iterable) – a iterable of tuple objects previously decorated
with the
periodic()
decorator, each item in the iterable is expected to be in the format of(cb, args, kwargs)
wherecb
is the decorated function andargs
andkwargs
are any positional and keyword arguments to send into the callback when it is activated (bothargs
andkwargs
may be provided as none to avoid using them) - log (logger) – logger to use when creating a new worker (defaults to the module logger if none provided), it is currently only used to report callback failures (if they occur)
- executor_factory (ExecutorFactory or any callable) – factory callable that can be used to generate
executor objects that will be used to
run the periodic callables (if none is
provided one will be created that uses
the
SynchronousExecutor
class) - cond_cls (callable) – callable object that can
produce
threading.Condition
(or compatible/equivalent) objects - event_cls (callable) – callable object that can produce
threading.Event
(or compatible/equivalent) objects - schedule_strategy (string) – string to select one of the built-in strategies that can return the next time a callable should run
- now_func (callable) – callable that can return the current time offset from some point (used in calculating elapsed times and next times to run); preferably this is monotonically increasing
- on_failure (callable) – callable that will be called whenever a periodic
function fails with an error, it will be provided
four positional arguments and one keyword
argument, the first positional argument being the
callable that failed, the second being the type
of activity under which it failed (
IMMEDIATE
orPERIODIC
), the third being the spacing that the callable runs at and the fourthexc_info
tuple of the failure. The keyword argumenttraceback
will also be provided that may be be a string that caused the failure (this is required for executors which run out of process, as those can not currently transfer stack frames across process boundaries); if no callable is provided then a default failure logging function will be used instead (do note that any user provided callable should not raise exceptions on being called)
- callables (iterable) – a iterable of tuple objects previously decorated
with the
-
__len__
()¶ How many callables/periodic work units are currently active.
-
add
(cb, *args, **kwargs)¶ Adds a new periodic callback to the current worker.
Returns a
Watcher
if added successfully or the valueNone
if not (or raises aValueError
if the callback is not correctly formed and/or decorated).Parameters: cb (callable) – a callable object/method/function previously decorated with the periodic()
decorator
-
classmethod
create
(objects, exclude_hidden=True, log=None, executor_factory=None, cond_cls=<function Condition>, event_cls=<function Event>, schedule_strategy='last_started', now_func=<function monotonic>, on_failure=None, args=(), kwargs={})¶ Automatically creates a worker by analyzing object(s) methods.
Only picks up methods that have been tagged/decorated with the
periodic()
decorator (does not match against private or protected methods unless explicitly requested to).Parameters: - objects (iterable) – the objects to introspect for decorated members
- exclude_hidden (bool) – exclude hidden members (ones that start with an underscore)
- log (logger) – logger to use when creating a new worker (defaults to the module logger if none provided), it is currently only used to report callback failures (if they occur)
- executor_factory (ExecutorFactory or any callable) – factory callable that can be used to generate
executor objects that will be used to
run the periodic callables (if none is
provided one will be created that uses
the
SynchronousExecutor
class) - cond_cls (callable) – callable object that can
produce
threading.Condition
(or compatible/equivalent) objects - event_cls (callable) – callable object that can produce
threading.Event
(or compatible/equivalent) objects - schedule_strategy (string) – string to select one of the built-in strategies that can return the next time a callable should run
- now_func (callable) – callable that can return the current time offset from some point (used in calculating elapsed times and next times to run); preferably this is monotonically increasing
- on_failure (callable) – callable that will be called whenever a periodic
function fails with an error, it will be provided
four positional arguments and one keyword
argument, the first positional argument being the
callable that failed, the second being the type
of activity under which it failed (
IMMEDIATE
orPERIODIC
), the third being the spacing that the callable runs at and the fourthexc_info
tuple of the failure. The keyword argumenttraceback
will also be provided that may be be a string that caused the failure (this is required for executors which run out of process, as those can not currently transfer stack frames across process boundaries); if no callable is provided then a default failure logging function will be used instead (do note that any user provided callable should not raise exceptions on being called) - args (tuple) – positional arguments to be passed to all callables
- kwargs (dict) – keyword arguments to be passed to all callables
-
iter_watchers
()¶ Iterator/generator over all the currently maintained watchers.
-
reset
()¶ Resets the workers internal state.
-
start
(allow_empty=False)¶ Starts running (will not return until
stop()
is called).Parameters: allow_empty (bool) – instead of running with no callbacks raise when this worker has no contained callables (this can be set to true and add()
can be used to add new callables on demand), note that when enabled and no callbacks exist this will block and sleep (until either stopped or callbacks are added)
-
stop
()¶ Sets the tombstone (this stops any further executions).
-
wait
(timeout=None)¶ Waits for the
start()
method to gracefully exit.An optional timeout can be provided, which will cause the method to return within the specified timeout. If the timeout is reached, the returned value will be False.
Parameters: timeout (float/int) – Maximum number of seconds that the wait()
method should block for
-
-
futurist.periodics.
periodic
(spacing, run_immediately=False, enabled=True)¶ Tags a method/function as wanting/able to execute periodically.
Parameters: - spacing (float/int) – how often to run the decorated function (required)
- run_immediately (boolean) – option to specify whether to run immediately or wait until the spacing provided has elapsed before running for the first time
- enabled (boolean) – whether the task is enabled to run
-
class
futurist.periodics.
Watcher
(metrics, work)¶ A read-only object representing a periodic callback’s activities.
-
average_elapsed
¶ Avg. amount of time the periodic callback has ran for.
This may raise a
ZeroDivisionError
if there has been no runs.
-
average_elapsed_waiting
¶ Avg. amount of time the periodic callback has waited to run for.
This may raise a
ZeroDivisionError
if there has been no runs.
-
elapsed
¶ Total amount of time the periodic callback has ran for.
-
elapsed_waiting
¶ Total amount of time the periodic callback has waited to run for.
-
failures
¶ How many times the periodic callback ran unsuccessfully.
-
runs
¶ How many times the periodic callback has been ran.
-
successes
¶ How many times the periodic callback ran successfully.
-
work
¶ Read-only named work tuple this object watches.
-
Miscellaneous¶
-
class
futurist.
ExecutorStatistics
(failures=0, executed=0, runtime=0.0, cancelled=0)¶ Holds immutable information about a executors executions.
-
average_runtime
¶ The average runtime of all submissions executed.
Returns: average runtime of all submissions executed Return type: number Raises: ZeroDivisionError when no executions have occurred.
-
cancelled
¶ How many submissions were cancelled before executing.
Returns: how many submissions were cancelled before executing Return type: number
-
executed
¶ How many submissions were executed (failed or not).
Returns: how many submissions were executed Return type: number
-
failures
¶ How many submissions ended up raising exceptions.
Returns: how many submissions ended up raising exceptions Return type: number
-
runtime
¶ Total runtime of all submissions executed (failed or not).
Returns: total runtime of all submissions executed Return type: number
-
Exceptions¶
-
class
futurist.
RejectedSubmission
¶ Exception raised when a submitted call is rejected (for some reason).
Waiters¶
-
futurist.waiters.
wait_for_any
(fs, timeout=None)¶ Wait for one (any) of the futures to complete.
Works correctly with both green and non-green futures (but not both together, since this can’t be guaranteed to avoid dead-lock due to how the waiting implementations are different when green threads are being used).
Returns pair (done futures, not done futures).
-
futurist.waiters.
wait_for_all
(fs, timeout=None)¶ Wait for all of the futures to complete.
Works correctly with both green and non-green futures (but not both together, since this can’t be guaranteed to avoid dead-lock due to how the waiting implementations are different when green threads are being used).
Returns pair (done futures, not done futures).
-
class
futurist.waiters.
DoneAndNotDoneFutures
(done, not_done)¶ Named tuple returned from
wait_for*
calls.