First draft of a backpressure enabled pipeline

[garypen]

There's a long way to go, but some interesting aspects of the required changes are implemented here.

I noted that a significant number of errors and glitches and tests are resolved by making these changes. Mainly places where we were calling a service without readying it first or places where we were cloning an inner service without doing the memory "replace" dance.

Because we are using a "trick" to make the router service cloneable right now, there are a few tests which don't work properly. I think for the "full" work, we'll need to make the router service properly cloneable (without requiring a mutex).

This will require some fairly substantial re-working of a wide variety of services and layers. On the plus side, once we've done that work we'll be able to retire a bunch of code that we've written that we will no longer require.

I'll pick this up in the New Year...

[svc-apollo-docs]

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[router-perf]

CI performance tests

• connectors-const - Connectors stress test that runs with a constant number of users
• const - Basic stress test that runs with a constant number of users
• demand-control-instrumented - A copy of the step test, but with demand control monitoring and metrics enabled
• demand-control-uninstrumented - A copy of the step test, but with demand control monitoring enabled
• enhanced-signature - Enhanced signature enabled
• events - Stress test for events with a lot of users and deduplication ENABLED
• events_big_cap_high_rate - Stress test for events with a lot of users, deduplication enabled and high rate event with a big queue capacity
• events_big_cap_high_rate_callback - Stress test for events with a lot of users, deduplication enabled and high rate event with a big queue capacity using callback mode
• events_callback - Stress test for events with a lot of users and deduplication ENABLED in callback mode
• events_without_dedup - Stress test for events with a lot of users and deduplication DISABLED
• events_without_dedup_callback - Stress test for events with a lot of users and deduplication DISABLED using callback mode
• extended-reference-mode - Extended reference mode enabled
• large-request - Stress test with a 1 MB request payload
• no-tracing - Basic stress test, no tracing
• reload - Reload test over a long period of time at a constant rate of users
• step-jemalloc-tuning - Clone of the basic stress test for jemalloc tuning
• step-local-metrics - Field stats that are generated from the router rather than FTV1
• step-with-prometheus - A copy of the step test with the Prometheus metrics exporter enabled
• step - Basic stress test that steps up the number of users over time
• xlarge-request - Stress test with 10 MB request payload
• xxlarge-request - Stress test with 100 MB request payload