feat(session): add support for multiple sessions per client

[princjef]

Addresses https://github.com/noodlefrenzy/node-amqp10/issues/331 by adding the ability to create multiple sessions on the same client/connection and providing policy options for reestablishing the session on end. This feature set is designed to better align the capabilities of amqp10 with the session pattern supported by Azure Service Bus and bring the retry logic inline with what is used for reattach and reconnect.

Features

• [x] Add createSession() in AMQPClient to create user sessions
  • [x] Support custom policy overrides
• [x] Allow an optional session to be passed in on createSender(), createSenderStream(), createReceiver(), createReceiverStream()
• [x] Create the default session associated with the client only when needed
• [x] restart policy option for reestablishing the session after it is ended

Tests

• [x] createSession()
• [x] Optional session parameter for createSender(), createSenderStream(), createReceiver(), createReceiverStream()
• [x] Creating default client session on demand
• [x] Session policy - restart

Please take a look and let me know what you think of the change. I'm open to changing the design/approach if people have other thoughts.

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This change is 

[princjef]

I also pulled in the change from https://github.com/noodlefrenzy/node-amqp10/pull/330 for now so that I can get useful information from the Travis CI build. That change looks good to me and I think it's worth merging in before this goes in.

[princjef]

Review status: 0 of 10 files reviewed at latest revision, 1 unresolved discussion, some commit checks failed.

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lib/policies/policy.js, line 127 at r1 (raw file):

      enableSessionFlowControl: true,
      closeOnLinkError: false,
      reattach: null

I'm not wild about calling this reattach, since the concept of attach/detach applies to links, not sessions. The equivalent for the session terminology would be rebegin or remap, but neither really feels right to me. Thoughts?

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Comments from Reviewable

[princjef]

I decided to remove the endOnLinkDetach policy from the session because it's not a part of the spec and was causing more problems than it was solving. The other changes have stood up well to my testing though

[pierreca]

reestablish? the spec talks about establishing and ending sessions

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In reply to: 328216141 [](ancestors = 328216141)

[princjef]

ah i like that. reestablish sounds better to me than restart

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Comments from Reviewable

[princjef]

lib/amqp_client.js, line 176 at r2 (raw file):

Previously, princjef (Jeff Principe) wrote…

i think it's reasonable to do the merge on the built-in one (this line). the user one is weird because the `begin()` here is a hidden operation. the policy for the session is specified separately so i don't want to override it if it's already there. i'll add a comment to that one

Done.

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Comments from Reviewable

[princjef]

test/unit/test_session.js, line 25 at r2 (raw file):

Previously, princjef (Jeff Principe) wrote…

probably had something else and took it out. good catch

Done.

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Comments from Reviewable