Add extended aggregation

[andrewqian2001datadog]

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What does this PR do?

Implements aggregation for histogram, distribution and timing metrics. This is essentially just buffering as these metrics should not be aggregated in the client side (From the V2 section of the design doc, "Both metrics can’t/should not be aggregated on the client side. Histogram would result in wrong metrics and merging distributions is costly while sampling is fast").

This is already implemented for the go client. Go Client PR for adding extended aggregation

Description of the Change

This PR reuses a lot of the existing buffering logic. The buffered_metrics (Histogram, Distribution and Timing) are added to the existing buffer when aggregation is enabled.

Most of the new logic is in buffered_metric_context.py which involves sampling Histograms, Distributions and Timings

Verification Process

Follow steps here to set up local testing for the python client

Replace testapp/main.py with

from datadog import initialize, statsd
import time


options = {
    "statsd_host": "127.0.0.1",
    "statsd_port": 8125,
    "statsd_disable_buffering" : True,
    "statsd_disable_aggregation" : False,
    "statsd_aggregation_flush_interval" : 61
}

initialize(**options)


x = 0
name = "andrew_q_extendedAgg99"
sleepTime = 12
while(1):
  print("-------------------------------------------------")
  print("running :)", x)
  statsd.histogram(name, 1)
  time.sleep(sleepTime)
  statsd.histogram(name, 2)
  time.sleep(sleepTime)
  statsd.histogram(name, 3)
  time.sleep(sleepTime)
  statsd.histogram(name, 4)
  time.sleep(sleepTime)
  statsd.histogram(name, 5)
  x += 1

Search for your metric name in the metrics explorer and verify values are as expected.

Additional Notes

Release Notes

Review checklist (to be filled by reviewers)

• Feature or bug fix MUST have appropriate tests (unit, integration, etc...)
• PR title must be written as a CHANGELOG entry (see why)
• Files changes must correspond to the primary purpose of the PR as described in the title (small unrelated changes should have their own PR)
• PR must have one changelog/ label attached. If applicable it should have the backward-incompatible label attached.
• PR should not have do-not-merge/ label attached.
• If Applicable, issue must have kind/ and severity/ labels attached at least.

[datadog-datadog-prod-us1]

🔴 Code Vulnerability

do not use random (...read more)

Make sure to use values that are actually random. The random module in Python should generally not be used and replaced with the secrets module, as noted in the official Python documentation.

Learn More

• CWE-330
• Python random module documentation
• Python secrets module documentation