fix(NODE-5840): heartbeat duration includes socket creation

[nbbeeken]

Description

What is changing?

• Refactor connect to be async
• Rename and refactor makeConnection -> makeSocket
• Add makeConnection function
• Refactor monitor to record start time after socket is created, before handshake
• socket failures set heartbeat failed duration to -1
• Refactor tests using callback style connect
• Test duration does not include socket creation by artificially delaying it

Is there new documentation needed for these changes?

What is the motivation for this change?

The duration field of hb started and failed should match the definition in the spec.

Release Highlight

Fixed heartbeat duration including socket creation

The ServerHeartbeatSucceeded and ServerHeartbeatFailed event have a duration property that represents the time it took to perform the hello handshake with MongoDB. The Monitor responsible for issuing heartbeats mistakenly included the time it took to create the socket in this field, which inflates the value with the time it takes to perform a DNS lookup, TCP, and TLS handshakes.

Double-check the following

• Ran npm run check:lint script
• Self-review completed using the steps outlined here
• PR title follows the correct format: type(NODE-xxxx)[!]: description
  • Example: feat(NODE-1234)!: rewriting everything in coffeescript
• Changes are covered by tests
• New TODOs have a related JIRA ticket