gevent.events – Publish/subscribe event infrastructure

Publish/subscribe event infrastructure.

When certain “interesting” things happen during the lifetime of the process, gevent will “publish” an event (an object). That event is delivered to interested “subscribers” (functions that take one parameter, the event object).

Higher level frameworks may take this foundation and build richer models on it.

zope.event will be used to provide the functionality of notify and subscribers. See zope.event.classhandler for a simple class-based approach to subscribing to a filtered list of events, and see zope.component for a much higher-level, flexible system. If you are using one of these systems, you generally will not want to directly modify subscribers.

Added in version 1.3b1.

Changed in version 23.7.0: Now uses importlib.metadata instead of pkg_resources to locate entry points.

exception DoNotPatch

Bases: BaseException

Subscribers to will-patch events can raise instances of this class to tell gevent not to patch that particular item.

interface IEventLoopBlocked

The event emitted when the event loop is blocked.

This event is emitted in the monitor thread.

Changed in version 24.11.1: Add the hub attribute.

greenlet

The greenlet that appeared to be blocking the loop.

blocking_time

The approximate time in seconds the loop has been blocked.

info

A list of string lines providing extra info. You may modify this list.

hub

If not None, the hub being blocked.

interface IGeventDidPatchAllEvent

Extends: gevent.events.IGeventDidPatchEvent

Event emitted after gevent has patched all modules, both builtin and those provided by plugins/subscribers.

The values of the source and target attributes are undefined.

interface IGeventDidPatchBuiltinModulesEvent

Extends: gevent.events.IGeventDidPatchEvent

Event emitted after the builtin modules have been patched.

If you’re going to monkey-patch a third-party library, this is usually the event to listen for.

The values of the source and target attributes are undefined.

patch_all_arguments

A dictionary of all the arguments to gevent.monkey.patch_all. This dictionary should not be modified.

patch_all_kwargs

A dictionary of the extra arguments to gevent.monkey.patch_all. This dictionary should not be modified.

interface IGeventDidPatchEvent

Extends: gevent.events.IGeventPatchEvent

An event emitted after gevent has patched something.

interface IGeventDidPatchModuleEvent

Extends: gevent.events.IGeventDidPatchEvent

An event emitted after gevent has completed patching a specific module.

module_name

The name of the module being patched. This is the same as target.__name__.

interface IGeventPatchEvent

The root for all monkey-patch events gevent emits.

source

The source object containing the patches.

target

The destination object to be patched.

interface IGeventWillPatchAllEvent

Extends: gevent.events.IGeventWillPatchEvent

An event emitted before gevent begins patching the system.

Following this event will be a series of IGeventWillPatchModuleEvent and IGeventDidPatchModuleEvent for each patched module.

Once the gevent builtin modules have been processed, IGeventDidPatchBuiltinModulesEvent will be emitted. Processing this event is an ideal time for third-party modules to be imported and patched (which may trigger its own will/did patch module events).

Finally, a IGeventDidPatchAllEvent will be sent.

If a subscriber to this event raises DoNotPatch, no patching will be done.

The source and target attributes have undefined values.

patch_all_arguments

A dictionary of all the arguments to gevent.monkey.patch_all. This dictionary should not be modified.

patch_all_kwargs

A dictionary of the extra arguments to gevent.monkey.patch_all. This dictionary should not be modified.

will_patch_module(module_name)

Return whether the module named module_name will be patched.

interface IGeventWillPatchEvent

Extends: gevent.events.IGeventPatchEvent

An event emitted before gevent monkey-patches something.

If a subscriber raises DoNotPatch, then patching this particular item will not take place.

interface IGeventWillPatchModuleEvent

Extends: gevent.events.IGeventWillPatchEvent

An event emitted before gevent begins patching a specific module.

Both source and target attributes are module objects.

module_name

The name of the module being patched. This is the same as target.__name__.

target_item_names

The list of item names to patch. This can be modified in place with caution.

interface IMemoryUsageThresholdExceeded

The event emitted when the memory usage threshold is exceeded.

This event is emitted only while memory continues to grow above the threshold. Only if the condition or stabilized is corrected (memory usage drops) will the event be emitted in the future.

This event is emitted in the monitor thread.

mem_usage

The current process memory usage, in bytes.

max_allowed

The maximum allowed memory usage, in bytes.

memory_info

The tuple of memory usage stats return by psutil.

interface IMemoryUsageUnderThreshold

The event emitted when the memory usage drops below the threshold after having previously been above it.

This event is emitted only the first time memory usage is detected to be below the threshold after having previously been above it. If memory usage climbs again, a IMemoryUsageThresholdExceeded event will be broadcast, and then this event could be broadcast again.

This event is emitted in the monitor thread.

mem_usage

The current process memory usage, in bytes.

max_allowed

The maximum allowed memory usage, in bytes.

max_memory_usage

The memory usage that caused the previous IMemoryUsageThresholdExceeded event.

memory_info

The tuple of memory usage stats return by psutil.

interface IPeriodicMonitorThread

The contract for the periodic monitoring thread that is started by the hub.

add_monitoring_function(function, period)

Schedule the function to be called approximately every period fractional seconds.

The function receives one argument, the hub being monitored. It is called in the monitoring thread, not the hub thread. It must not attempt to use the gevent asynchronous API.

If the function is already a monitoring function, then its period will be updated for future runs.

If the period is None, then the function will be removed.

A period less than or equal to zero is not allowed.

interface IPeriodicMonitorThreadStartedEvent

The event emitted when a hub starts a periodic monitoring thread.

You can use this event to add additional monitoring functions.

monitor

The instance of IPeriodicMonitorThread that was started.

class EventLoopBlocked(greenlet, blocking_time, info, *, hub=None)

Bases: object

The event emitted when the event loop is blocked.

Implements IEventLoopBlocked.

class GeventDidPatchAllEvent(patch_all_arguments, patch_all_kwargs)

Bases: _PatchAllMixin, GeventDidPatchEvent

Implementation of IGeventDidPatchAllEvent.

ENTRY_POINT_NAME = 'gevent.plugins.monkey.did_patch_all'

The name of the setuptools entry point that is called when this event is emitted.

class GeventDidPatchBuiltinModulesEvent(patch_all_arguments, patch_all_kwargs)

Bases: _PatchAllMixin, GeventDidPatchEvent

Implementation of IGeventDidPatchBuiltinModulesEvent.

ENTRY_POINT_NAME = 'gevent.plugins.monkey.did_patch_builtins'

The name of the setuptools entry point that is called when this event is emitted.

class GeventDidPatchModuleEvent(module_name, source, target)

Bases: GeventDidPatchEvent

Implementation of IGeventDidPatchModuleEvent.

ENTRY_POINT_NAME = 'gevent.plugins.monkey.did_patch_module'

The name of the setuptools entry point that is called when this event is emitted.

class GeventPatchEvent(source, target)

Bases: object

Implementation of IGeventPatchEvent.

class GeventWillPatchAllEvent(patch_all_arguments, patch_all_kwargs)

Bases: _PatchAllMixin, GeventWillPatchEvent

Implementation of IGeventWillPatchAllEvent.

ENTRY_POINT_NAME = 'gevent.plugins.monkey.will_patch_all'

The name of the setuptools entry point that is called when this event is emitted.

class GeventWillPatchEvent(source, target)

Bases: GeventPatchEvent

Implementation of IGeventWillPatchEvent.

class GeventWillPatchModuleEvent(module_name, source, target, items)

Bases: GeventWillPatchEvent

Implementation of IGeventWillPatchModuleEvent.

ENTRY_POINT_NAME = 'gevent.plugins.monkey.will_patch_module'

The name of the setuptools entry point that is called when this event is emitted.

class MemoryUsageThresholdExceeded(mem_usage, max_allowed, memory_info)

Bases: _AbstractMemoryEvent

Implementation of IMemoryUsageThresholdExceeded.

class MemoryUsageUnderThreshold(mem_usage, max_allowed, memory_info, max_usage)

Bases: _AbstractMemoryEvent

Implementation of IMemoryUsageUnderThreshold.

class PeriodicMonitorThreadStartedEvent(monitor)

Bases: object

The implementation of IPeriodicMonitorThreadStartedEvent.

Changed in version 24.11.1: Now actually implements the promised interface.

ENTRY_POINT_NAME = 'gevent.plugins.hub.periodic_monitor_thread_started'

The name of the setuptools entry point that is called when this event is emitted.

subscribers = []

Applications may register for notification of events by appending a callable to the subscribers list.

Each subscriber takes a single argument, which is the event object being published.

Exceptions raised by subscribers will be propagated without running any remaining subscribers.

This is an alias for zope.event.subscribers; prefer to use that attribute directly.