* Refactor the peerstore into interface, in-memory implementation, datastore implementation. 
* Create common test suites to test all implementations against. 
* Normalise naming: rename AddrMgr => AddrBook everywhere. 
* Create interface PeerMetadata, with in-memory implementation.
* Adjust wait times in time-dependent tests.

…marks.

* Introduce tests for KeyBook to increase coverage.
* Change usages of []peer.ID to IDSlice, which supports sorting.
* Restructure AddrBook tests into subtests.
* Import aliases.

Migrate to ds.TxnDatastore, optimisations++, cache changes, benchmarks

Store-native TTL management

Adapt peerstore for ds.NewTransaction() now returning error

Datastore-backed implementations of KeyBook and PeerMetadata

We switched to a slice to reduce the amount of memory the peerstore ended up
taking up unfortunately, this really killed us in allocations. Looking at
go-ipfs profiles, I'm worried that memory fragmentation is killing us so I'd
like to revert to the old behavior.

Note: The real solution here is dealing with "address abusers".

There are better ways to do this but pausing dialing once an hour likely isn't
going to break anything and is the simplest approach.

reduce allocations and garbage collect the in-memory peerstore

leveldb disabled for now, until TTL shim is implemented.

Replace b58-encoded keys with b32 (no padding) + test against multiple ds. Resolves #38.

Hopefully, this reduces the space wasted by using maps (see the comment in the
committed code).

store expiring addrs by pointer

This is a "more correct" API and we might as well fix this before it becomes
used all over the place. The new API returns ErrNoPublicKey when there is no
inlined key.

This *also* fixes a bug where the datastore-backed keystore would panic if
`ExtractPublicKey` returned `nil, nil`.

update to match new ExtractPublicKey API

RandTestKeyPair uses RSA keys but we now forbid any RSA key under 512 bits.

fix the inline key test

License: MIT
Signed-off-by: Adrian Lanzafame <adrianlanzafame92@gmail.com>

License: MIT
Signed-off-by: Adrian Lanzafame <adrianlanzafame92@gmail.com>

License: MIT
Signed-off-by: Adrian Lanzafame <adrianlanzafame92@gmail.com>

PeerInfo UnMarshal Error #393

Each entry in the address book KV store now represents a full peer
with all its addresses. Expiries and TTLs are kept inline. Records are
serialised with Protobuf.

Housekeeping is performed on retrieve, and via a periodic GC routine.
The architecture mimics a write-through cache, although not strictly.

Deterministic benchmark order; Keybook interface benchmarks

Introduces custom types in protobuf to serde directly into multiaddrs
and peer IDs. Simplify purge by ordering addrs by expiry. In general,
getting this readier for merge.

The GC procedure consists of two tiers: lookahead and purge. The
lookahead tier runs less frequently (default 12 hours) than the purge
tier (default 5 minutes).

A lookahead round traverses the entire store and picks entries that
need to be visited in the current lookahead window, pinning those
entries in a separate region in the KV store, indexed by the next visit
timestamp.

A purge round iterates over the lookahead window only, and refreshes
the entries that require a visit. It removes them from the lookahead
region unless the entry requires another visit within the current
window.

disable inline-peer id test

Add unit test to verify AddAddr doesn't shorten TTL