Make Jmeter able to support nanoseconds for testing and reporting

[junyejiang]

In my test experience, when the performance of the system under test is much too fast (for example, when testing Redis), the milliseconds is too large to reflect the performance of the system under test, so the following changes are made:

1. Change the unit of Jmeter Result from milliseconds to nanoseconds.
2. Statistical calculations use BigDecimal/BigInteger to make the statistical results more accurate and no overflow.
3. The test report uses ms/ns as the final output unit according to the Properties configuration.

Description

Motivation and Context

How Has This Been Tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• I have updated the documentation accordingly.