Stackless-Python C-API¶
Stackless-Python provides the following C functions.
Tasklets¶
-
PyTaskletObject *
PyTasklet_New
(PyTypeObject *type, PyObject *func)¶ Return a new tasklet object. type must be derived from
PyTasklet_Type
orNULL
. func must be a callable object orNULL
orPy_None
. If func isNULL
orPy_None
you must set it later withPyTasklet_BindEx()
.
-
int
PyTasklet_Setup
(PyTaskletObject *task, PyObject *args, PyObject *kwds)¶ Binds a tasklet function to parameters, making it ready to run and inserts in into the runnables queue. Returns
0
if successful or-1
in the case of failure.
-
int
PyTasklet_BindEx
(PyTaskletObject *task, PyObject *func, PyObject *args, PyObject *kwargs)¶ Binds a tasklet to a function and/or to parameters, making it ready to run. This is the C equivalent to method
tasklet.bind()
. The arguments func, args and kwargs are optional and may beNULL
or Py_None. Returns0
if successful or-1
in the case of failure.
-
int
PyTasklet_BindThread
(PyTaskletObject *task, long thread_id)¶ Binds a tasklet function to a thread. This is the C equivalent to method
tasklet.bind_thread()
. Returns0
if successful or-1
in the case of failure.
-
int
PyTasklet_Run
(PyTaskletObject *task)¶ Forces task to run immediately. Returns
0
if successful, and-1
in the case of failure.
-
int
PyTasklet_Run_nr
(PyTaskletObject *task)¶ Forces task to run immediately, soft switching if possible. Returns
1
if the call soft switched,0
if the call hard switched and -1 in the case of failure.
-
int
PyTasklet_Switch
(PyTaskletObject *task)¶ Forces task to run immediately. The previous tasklet is paused. Returns
0
if successful, and-1
in the case of failure.
-
int
PyTasklet_Switch_nr
(PyTaskletObject *task)¶ Forces task to run immediately, soft switching if possible. The previous tasklet is paused. Returns
1
if the call soft switched,0
if the call hard switched and -1 in the case of failure.
-
int
PyTasklet_Remove
(PyTaskletObject *task)¶ Removes task from the runnables queue. Be careful! If this tasklet has a C stack attached, you need to either resume running it or kill it. Just dropping it might give an inconsistent system state. Returns
0
if successful, and-1
in the case of failure.
-
int
PyTasklet_Insert
(PyTaskletObject *task)¶ Insert task into the runnables queue, if it isn’t already there. If it is blocked or dead, the function returns
-1
and aRuntimeError
is raised.
-
int
PyTasklet_RaiseException
(PyTaskletObject *self, PyObject *klass, PyObject *args)¶ Raises an instance of the klass exception on the self tasklet. klass must be a subclass of
Exception
. Returns1
if the call soft switched,0
if the call hard switched and-1
in the case of failure.Note
Raising
TaskletExit
on a tasklet can be done to silently kill it, seePyTasklet_Kill()
.
-
int
PyTasklet_Throw
(PyTaskletObject *self, int pending, PyObject *exc, PyObject *val, PyObject *tb)¶ Raises (exc, val, tb) on the self tasklet. This is the C equivalent to method
tasklet.throw()
. Returns1
if the call soft switched,0
if the call hard switched and-1
in the case of failure.
-
int
PyTasklet_Kill
(PyTaskletObject *self)¶ Raises
TaskletExit
on tasklet self. This should result in task being silently killed. (This exception is ignored by tasklet_end and does not invoke main as exception handler.) Returns1
if the call soft switched,0
if the call hard switched and-1
in the case of failure.
-
int
PyTasklet_KillEx
(PyTaskletObject *self, int pending)¶ Raises
TaskletExit
on tasklet self. This is the C equivalent to methodtasklet.kill()
. Returns1
if the call soft switched,0
if the call hard switched and-1
in the case of failure.
-
int
PyTasklet_GetAtomic
(PyTaskletObject *task)¶ Returns
1
if task is atomic, otherwise0
.
-
int
PyTasklet_SetAtomic
(PyTaskletObject *task, int flag)¶ Returns
1
if task is currently atomic, otherwise0
. Sets the atomic attribute to the logical value of flag.
-
int
PyTasklet_GetIgnoreNesting
(PyTaskletObject *task)¶ Returns
1
if task ignores its nesting level when choosing whether to auto-schedule it, otherwise0
.
-
int
PyTasklet_SetIgnoreNesting
(PyTaskletObject *task, int flag)¶ Returns the existing value of the ignore_nesting attribute for the tasklet task, setting it to the logical value of flag. If true, the tasklet may be auto-scheduled even if its nesting_level is >
0
.
-
int
PyTasklet_GetBlockTrap
(PyTaskletObject *task)¶ Returns
1
if task is designated as not being allowed to be blocked on a channel, otherwise0
.
-
void
PyTasklet_SetBlockTrap
(PyTaskletObject *task, int value)¶ Returns
1
if task was already designated as not being allowed to be blocked on a channel, otherwise0
. This attribute is set to the logical value of value.
-
PyObject *
PyTasklet_GetFrame
(PyTaskletObject *task)¶ Returns the current frame that task is executing in, or NULL
-
int
PyTasklet_IsMain
(PyTaskletObject *task)¶ Returns
1
if task is the main tasklet, otherwise0
.
-
int
PyTasklet_IsCurrent
(PyTaskletObject *task)¶ Returns
1
if task is the current tasklet, otherwise0
.
-
int
PyTasklet_GetRecursionDepth
(PyTaskletObject *task)¶ Return the current recursion depth of task.
-
int
PyTasklet_GetNestingLevel
(PyTaskletObject *task)¶ Return the current nesting level of task.
-
int
PyTasklet_Alive
(PyTaskletObject *task)¶ Returns
1
if task is alive (has an associated frame), otherwise0
if it is dead.
-
int
PyTasklet_Paused
(PyTaskletObject *task)¶ Returns
1
if task is paused, otherwise0
. A tasklet is paused if it is alive, but not scheduled or blocked on a channel.
-
int
PyTasklet_Scheduled
(PyTaskletObject *task)¶ Returns
1
if task is scheduled, otherwise0
. In the context of this function a tasklet is considered to be scheduled if it is alive, and in the scheduler runnables list or blocked on a channel.
-
int
PyTasklet_Restorable
(PyTaskletObject *task)¶ Returns
1
if task can be fully unpickled, otherwise0
. A tasklet can be pickled whether it is fully restorable or not for the purposes of debugging and introspection. A tasklet that has been hard-switched cannot be fully pickled, for instance.
Channels¶
-
PyChannelObject*
PyChannel_New
(PyTypeObject *type)¶ Return a new channel object, or NULL in the case of failure. type must be derived from
PyChannel_Type
or be NULL, otherwise aTypeError
is raised.
-
int
PyChannel_Send
(PyChannelObject *self, PyObject *arg)¶ Send arg on the channel self. Returns
0
if the operation was successful, or-1
in the case of failure.
-
int
PyChannel_Send_nr
(PyChannelObject *self, PyObject *arg)¶ Send arg on the channel self, soft switching if possible. Returns
1
if the call soft switched,0
if the call hard switched and -1 in the case of failure.
-
PyObject *
PyChannel_Receive
(PyChannelObject *self)¶ Receive on the channel self. Returns a Python® object if the operation was successful, or NULL in the case of failure.
-
PyObject *
PyChannel_Receive_nr
(PyChannelObject *self)¶ Receive on the channel self, soft switching if possible. Returns a Python® object if the operation was successful,
Py_UnwindToken
if a soft switch occurred, or NULL in the case of failure.
-
int
PyChannel_SendException
(PyChannelObject *self, PyObject *klass, PyObject *value)¶ Returns
0
if successful or-1
in the case of failure. An instance of the exception type klass is raised on the first tasklet blocked on channel self.
-
int
PyChannel_SendThrow
(PyChannelObject *self, PyObject *exc, PyObject *val, PyObject *tb)¶ Returns
0
if successful or-1
in the case of failure. (exc, val, tb) is raised on the first tasklet blocked on channel self.
-
PyObject *
PyChannel_GetQueue
(PyChannelObject *self)¶ Returns the first tasklet in the channel self’s queue, or NULL in the case the queue is empty.
-
void
PyChannel_Close
(PyChannelObject *self)¶ Marks the channel self as closing. No further tasklets can be blocked on the it from this point, unless it is later reopened.
-
void
PyChannel_Open
(PyChannelObject *self)¶ Reopens the channel self. This allows tasklets to once again send and receive on it, if those operations would otherwise block the given tasklet.
-
int
PyChannel_GetClosing
(PyChannelObject *self)¶ Returns
1
if the channel self is marked as closing, otherwise0
.
-
int
PyChannel_GetClosed
(PyChannelObject *self)¶ Returns
1
if the channel self is marked as closing and there are no tasklets blocked on it, otherwise0
.
-
int
PyChannel_GetPreference
(PyChannelObject *self)¶ Returns the current scheduling preference value of self. See
channel.preference
.
-
void
PyChannel_SetPreference
(PyChannelObject *self, int val)¶ Sets the current scheduling preference value of self. See
channel.preference
.
-
int
PyChannel_GetScheduleAll
(PyChannelObject *self)¶ Gets the schedule_all override flag for self. See
channel.schedule_all
.
-
void
PyChannel_SetScheduleAll
(PyChannelObject *self, int val)¶ Sets the schedule_all override flag for self. See
channel.schedule_all
.
-
int
PyChannel_GetBalance
(PyChannelObject *self)¶ Gets the balance for self. See
channel.balance
.
stackless module¶
-
PyObject *
PyStackless_Schedule
(PyObject *retval, int remove)¶ Suspend the current tasklet and schedule the next one in the cyclic chain. if remove is nonzero, the current tasklet will be removed from the chain. retval = success NULL = failure
-
PyObject *
PyStackless_Schedule_nr
(PyObject *retval, int remove)¶ retval = success NULL = failure retval == Py_UnwindToken: soft switched
-
int
PyStackless_GetRunCount
()¶ get the number of runnable tasks of the current thread, including the current one. -1 = failure
-
long
PyStackless_GetCurrentId
()¶ Get a unique integer ID for the current tasklet
Threadsafe.
This is useful for benchmarking code that needs to get some sort of a stack identifier and must not worry about the GIL being present and so on.
Note
- the “main” tasklet on each thread will have the same id, even if a proper tasklet has not been initialized.
- IDs may get recycled for new tasklets.
-
PyObject *
PyStackless_RunWatchdog
(long timeout)¶ Runs the scheduler until there are no tasklets remaining within it, or until one of the scheduled tasklets runs for timeout VM instructions without blocking. Returns None if the scheduler is empty, a tasklet object if that tasklet timed out, or NULL in the case of failure. If a timed out tasklet is returned, it should be killed or reinserted.
This function can only be called from the main tasklet. During the run, main is suspended, but will be invoked after the action. You will write your exception handler here, since every uncaught exception will be directed to main.
-
PyObject *
PyStackless_RunWatchdogEx
(long timeout, int flags)¶ Wraps
PyStackless_RunWatchdog()
, but allows its behaviour to be customised by the value of flags which may contain any of the following bits:Py_WATCHDOG_THREADBLOCK
- Allows a thread to block if it runs out of tasklets. Ideally it will be awakened by other threads using channels which its blocked tasklets are waiting on.
Py_WATCHDOG_SOFT
- Instead of interrupting a tasklet, we wait until the next tasklet scheduling moment to return. Always returns Py_None, as everything is in order.
Py_WATCHDOG_IGNORE_NESTING
- Allows interrupts at all levels, effectively acting as though the ignore_nesting attribute were set on all tasklets.
Py_WATCHDOG_TIMEOUT
- Interprets timeout as a fixed run time, rather than a per-tasklet run limit. The function will then attempt to interrupt execution once this many total opcodes have been executed since the call was made.
debugging and monitoring functions¶
-
int
PyStackless_SetChannelCallback
(PyObject *callable)¶ channel debugging. The callable will be called on every send or receive. Passing NULL removes the handler. Parameters of the callable: channel, tasklet, int sendflag, int willblock -1 = failure
-
int
PyStackless_SetScheduleCallback
(PyObject *callable)¶ scheduler monitoring. The callable will be called on every scheduling. Passing NULL removes the handler. Parameters of the callable: from, to When a tasklet dies, to is None. After death or when main starts up, from is None. -1 = failure
-
void
PyStackless_SetScheduleFastcallback
(slp_schedule_hook_func func)¶ Scheduler monitoring with a faster interface.
Interface functions¶
Most of the above functions can be called both from “inside” and “outside” stackless. “inside” means there should be a running (c)frame on top which acts as the “main tasklet”. The functions do a check whether the main tasklet exists, and wrap themselves if it is necessary. The following routines are used to support this, and you may use them as well if you need to make your specific functions always available.