fix(NODE-3630): remove float parser and test edge cases for Double

[aditi-khare-mongoDB]

Description

What is changing?

Is there new documentation needed for these changes?

No

What is the motivation for this change?

The old custom float parsing (in float_parser.ts) did not support NaN with payload preservation, while native JS does.

Double check the following

• Ran npm run lint script
• Self-review completed using the steps outlined here
• PR title follows the correct format: <type>(NODE-xxxx)<!>: <description>
• Changes are covered by tests
• New TODOs have a related JIRA ticket

[aditi-khare-mongoDB]

Serialization - Perf Improvement:

- cpu: Apple M1
- cores: 8
- os: darwin
- ram: 16GB
- iterations: 1,000,000
testing: Double Serialization

BEFORE making DV ALLOCATION GLOBAL: local    - v 37c8edb - avg 0.00041684ms
AFTER making DV ALLOCATION GLOBAL:  local    - v 37c8edb - avg 0.00024913ms

released       - v 4.6.4                                 - avg 0.00036335ms
previous major - v 1.1.6                                 - avg 0.00036459ms
bson-ext       - v 4.0.2                                 - avg 0.00163558ms

Summary:

By replacing the old custom float parser logic with DataView allocation, NaN with payloads are now preserved in serialization-deserialization round-trips.

When dv is allocated in serializeNumber() and serializeDouble() functions, serialization is slower than before DataView implementation.

When dv is allocated as a global variable (how it is now), serialization is actually faster than before DataView Implementation.

[aditi-khare-mongoDB]

Deserialization - Perf Slight Decline:

(specs are same as previous comment)

testing: Double Deserialization
local             - v e45f7d0  - avg 0.00025402ms
released          - v 4.6.4    - avg 0.00020516ms
previous major    - v 1.1.6    - avg 0.00017792ms
bson-ext          - v 4.0.2    - avg 0.00036723ms

^^ Deserialization with DV Allocation does show some slower performance when compared to previous versions. Since there must be a new allocation every time, this not resolvable with a global variable.

testing: Many Doubles Deserialization
ALLOCATING ONCE                local          - v e45f7d0  - avg 0.00026782ms
ALLOCATING FOR EACH DOUBLE     local          - v e45f7d0  - avg 0.00026212ms
released       - v 4.6.4    - avg 0.00022623ms
previous major - v 1.1.6    - avg 0.00021576ms
bson-ext       - v 4.0.2    - avg 0.00040693ms

^^ With the deserialization of an array of many doubles, if we change the allocation to only happen once in the function, rather than once for every double, the performance does not change significantly.

[dariakp]

Just a bit of extra clean up on the tests - thanks a lot for making the other changes, much easier to read now!

[dariakp]

what's the significance of promoteValues: false here? what happens with promoteValues: true?

[aditi-khare-mongoDB]

This is so we get the raw BSON instead of the value as a double; this lets us check for payload in the BSON buffer

[dariakp]

could you add a comment above this line explaining that? also @nbbeeken is there a more precise option we can use than the general promoteValues?

[nbbeeken]

Unfortunately Doubles do not have a dedicated promote option, promoteValues: false is the only way to get the deserializer to return instanceof Double. chaos

[dariakp]

I resolved the addressed comments, but see my replies on two others