Reduce work allocations

[bollhals]

Proposed Changes

4506a70 does move the error handling from the work classes to the WorkService. This eliminates some async state machine allocations.

f1af6ac removes passing the IModel in the Work.Execute, as only the Shutdown required it, so it's now passed in the ctor of it.

Types of Changes

• Bug fix (non-breaking change which fixes issue #NNNN)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause an observable behavior change in existing systems)
• Documentation improvements (corrections, new content, etc)
• Cosmetic change (whitespace, formatting, etc)

Checklist

• I have read the CONTRIBUTING.md document
• I have signed the CA (see https://cla.pivotal.io/sign/rabbitmq)
• All tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have added necessary documentation (if appropriate)
• Any dependent changes have been merged and published in related repositories

Further Comments

Allocations before:

after:

Performance before:

after:

[michaelklishin]

A roughly 27% reduction in execution time for this workload 👏