feat(jobs): nats driver

[rustatian]

Reason for This PR

closes: #24

Description of Changes

• Add NATS driver support.
• RR2 uses the new JetStream NATS API - https://docs.nats.io/jetstream/concepts. It's not compatible with the base pub-sub.
• Base pub-sub might be supported in future releases if needed.
• 20mb reconnect buffer. That means if NATS connection is interrupted, the user is allowed to push up to 20mb of data. After the connection gets online, this buffer will be flushed to the NATS.
• NATS server built-in metrics: https://docs.nats.io/jetstream/monitoring

Nats config:

nats:
  addr: "demo.nats.io"

jobs:
  num_pollers: 10
  pipeline_size: 100000
  pool:
    num_workers: 10
    max_jobs: 0
    allocate_timeout: 60s
    destroy_timeout: 60s

  pipelines:
    test-1:
      driver: nats
      prefetch: 100
      subject: "default"
      stream: "foo"
      deliver_new: "true"
      rate_limit: 100
      delete_stream_on_stop: false
      delete_after_ack: false
      priority: 2

  consume: [ "test-1" ]

Where:

• nats: global section.
• addr: nats server address

Pipeline configuration:

• driver - driver's name.
• prefetch - listener channel prefetch.
• subject - NATS subject. Might be a wildcard like foo.*.
• stream - NATS stream name.
• deliver_new - deliver messages from the point where the listener started (Do not redeliver the whole stream).
• rate_limit - NATS JS rate limiter.
• delete_stream_on_stop - delete stream when pipeline stopped.
• delete_after_ack - delete the message after it would be successfully acknowledged.

Build-in options:

• connect timeout - 1 minute
• max reconnects - are not limited
• ping interval - 10 seconds
• reconnect buffer size - 20mb
• reconnect wait time - 1 second (driver will try to reconnect every second after connection gets offline)

License Acceptance

By submitting this pull request, I confirm that my contribution is made under the terms of the MIT license.

PR Checklist

[Author TODO: Meet these criteria.] [Reviewer TODO: Verify that these criteria are met. Request changes if not]

• [x] All commits in this PR are signed (git commit -s).
• [x] The reason for this PR is clearly provided (issue no. or explanation).
• [x] The description of changes is clear and encompassing.
• [x] Any required documentation changes (code and docs) are included in this PR.
• [x] Any user-facing changes are mentioned in CHANGELOG.md.
• [x] All added/changed functionality is tested.

[codecov[bot]]

Codecov Report

Merging #68 (6334a1d) into master (9138560) will increase coverage by 0.35%. The diff coverage is 68.56%.

@@            Coverage Diff             @@
##           master      #68      +/-   ##
==========================================
+ Coverage   68.62%   68.98%   +0.35%     
==========================================
  Files         112      118       +6     
  Lines        9327     9920     +593     
==========================================
+ Hits         6401     6843     +442     
- Misses       2293     2403     +110     
- Partials      633      674      +41     

Impacted Files	Coverage Δ
amqp/plugin.go	90.90% <ø> (ø)
boltdb/boltjobs/item.go	46.66% <0.00%> (-0.71%)	:arrow_down:
memory/memoryjobs/item.go	78.68% <0.00%> (-2.67%)	:arrow_down:
websockets/executor/executor.go	68.18% <0.00%> (ø)
jobs/plugin.go	61.83% <14.28%> (-1.94%)	:arrow_down:
jobs/listener.go	47.65% <23.80%> (-4.98%)	:arrow_down:
amqp/amqpjobs/listener.go	83.33% <25.00%> (+4.76%)	:arrow_up:
nats/natsjobs/item.go	46.55% <46.55%> (ø)
jobs/protocol/error.go	47.82% <47.82%> (ø)
jobs/pipeline/pipeline.go	72.91% <50.00%> (+0.82%)	:arrow_up:
... and 39 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more Δ = absolute <relative> (impact), ø = not affected, ? = missing data Powered by Codecov. Last update 9138560...6334a1d. Read the comment docs.