GitLab

In case we're sending a _lot_ of wants:

* Prioritize cancels.
* Then targeted wants.
* Finally broadcast wants.

This removes one goroutine per peer which tends to be a pretty big deal. This
brings go-ipfs down from 5.5 to 4.5 goroutines per peer.

* fix: ensure broadcast when peer becomes unavailable and all other peers sent DONT_HAVE for CID

* fix: lint warnings

* refactor: simplify session want sender DONT_HAVE list

* fix: flaky test

* test: add session exhausted wants test

* docs: improve sessionWantSender processAvailability docs

This:

* Makes it easy to send immediately if we wait too long and/or if we have enough
to send.
* Is significantly more efficient than the debounce library as it doesn't spin
off a bunch of "after" timers.

fixes #245

This makes reading the docs much easier as it's clear what's "private" and
what's not.

fixes #238

This commit extends the bitswap protocol with two additional wantlist properties:

* WANT_HAVE/HAVE: Instead of asking for a block, a node can specify that they
  want to know if any peers "have" the block.
* WANT_HAVE_NOT/HAVE_NOT: Instead of waiting for a timeout, a node can explicitly
  request to be told immediately if their peers don't currently have the given
  block.

Additionally, nodes now tell their peers how much data they have queued to send
them when sending messages. This allows peers to better distribute requests,
keeping all peers busy but not overloaded.

Changes in this PR are described in: https://github.com/ipfs/go-bitswap/issues/186

Make sure rebroadcast timer doesn't get reset if it's nil

Provide a failsafe to losing wants on other end by rebroadcasting a wantlist every thirty seconds

fix #99, fix #65

Remove code that should have been cleaned up in last message queue fix

Revert to the old go-routine architecture for the messagequeue, which I believe is still compatible
w/ wantlist w/o mutex

fix #92

Seperate want list into differentiated types - session tracking and regular

fix #13

Move refcnt tracking from the messagequeue to the peermanager, where it's relevant

repace get/set with getOrCreate to keep operations atomic

Breakup Startup function so that wantlists are not sent with each call to SendMessage

If wantlist changes are present, send them immediately on startup, rather than as a seperate message

Limit retrying sending of a message even when a successful reconnect occurs

per https://github.com/golang/go/wiki/CodeReviewComments#comment-sentences

Extract session manager from bitswap
Extract session manager & want manager to package
Move want manager message queue to seperate file
Move Message Queue to subpackage
Respond to PR Comments