Application states

Example

application_states.py
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#!/usr/bin/env python3
import asab
import asyncio


class StatesDemonstrationApplication(asab.Application):

    def __init__(self, args=None):
        super().__init__(args)
        asyncio.ensure_future(self.async_init_task())
        # asyncio.create_task(self.async_init_task())

        print("*****\n1. Synchronous init takes place.")
        print("   Async tasks are being added to the loop, but are never awaited")

    async def initialize(self):
        self.PubSub.subscribe("Application.tick!", self.when_done)
        asyncio.ensure_future(self.async_initialize_task())

        print("*****\n3-5. Asynchronous initializatin takes place.")
        print("   app.initialize is run concurrently")
        print("   \"Application.init!\" is published")
        await asyncio.sleep(1)
        print("*****\n6-8. app.initialize awaited")

    async def async_init_task(self):
        print("*****\n3-5. Scheduled async tasks are run concurrently")
        await asyncio.sleep(2)
        print("*****\n6-8. All scheduled async tasks awaited")

    async def async_initialize_task(self):
        print("*****\n3-5. Even the ones scheuled in futures themselves.")
        await asyncio.sleep(3)
        print("*****\n6-8. Even the ones scheuled in futures themselves.")

    async def main(self):
        asyncio.ensure_future(self.async_main_task())

        print("*****\n7. Run time starts. app.main() is called")
        print("   then async tasks are being handled, until the application is stopped.")
        print("   \"Application.init!\" is published, application also starts ticking")


    async def async_main_task(self):
        print("*****\n8. Scheduled async tasks run concurrenlty")
        await asyncio.sleep(10)

    async def when_done(self, event_type):
        print("*****\n9. app.stop() is called by user code, or application is interupted in terminal")
        print("   Asab waits 3 seconds to let all scheduled async tasks finish and then exits.")
        print("   If some tasks are still pending throws warning.")
        self.stop()

    async def finalize(self):
        print("*****\n10. app.finilize is called, all modules and services are finalized.   ")



if __name__ == '__main__':
    app = StatesDemonstrationApplication()
    print("*****\n2. Now application waits for run method to be called")
    app.run()