# (c) Copyright IBM Corp. 2021

# (c) Copyright Instana Inc. 2020

#

# This example illustrates how to carry context from a syncronous tracing context into

# an asynchronous one.

#

# In this use case, we want to launch a series of asyncronous http calls using uvloop and aiohttp

#

import asyncio

import aiohttp

import uvloop

from instana.singletons import async_tracer, tracer

uvloop.install()

async def launch_async_calls(parent_span):

"""

Method to launch a series (1 currently) of asynchronous http calls

using uvloop and aiohttp. This method is run inside of an event loop

with `asyncio.run`, `run_until_complete` or `gather`

"""

# Now that we are inside of the event loop, first thing to do is to initialize

# the tracing context using <parent_span> _and_ the asynchronous tracer <async_tracer>

with async_tracer.start_active_span("launch_async_calls", child_of=parent_span):

async with aiohttp.ClientSession() as session:

session.get("http://127.0.0.1/api/v2/endpoint/1")

session.get("http://127.0.0.1/api/v2/endpoint/2")

session.get("http://127.0.0.1/api/v2/endpoint/3")

#

# Synchronous application code such as from inside a Django or Flask handler

#

# Start an ENTRY span in our synchronous execution scope

with tracer.start_active_span("launch_uvloop") as sync_scope:

sync_scope.span.set_tag("span.kind", "entry")

# You can also retrieve the currently active span with:

# tracer.active_span

# Launch our requests asynchronously

# Enter the event loop and pass in the parent tracing context (sync_scope) manually

asyncio.run(launch_async_calls(sync_scope.span))