With these changes, running a simulation is very close to running
an actual testnet. Some checks have been added in the client to
make sure you are not connecting to an incompatible network (e.g.
a network running with a different number of shards).
Passing along no-name command line arguments when using make (from Nimbus) would need make target revamps that are a bit clumsy AFAIK, so using environment variables in the spirit of USE_MULTITAIL to get the number of validators and nodes makes more sense to me.
This lets us run the sim from nim-beacon-chain with
```bash
VALIDATORS=512 NODES=100 USE_MULTITAIL="yes" tests/simulation/start.sh
```
and from Nimbus with:
```bash
VALIDATORS=512 NODES=100 USE_MULTITAIL="yes" make eth2_network_simulation
```
Also makes for a more verbose launch process.
* set epoch_boundary_root - chain finalizes!
* fix slotStart to offset GENESIS_SLOT
* work around bug that will be fixed by
https://github.com/ethereum/eth2.0-specs/pull/732
* compile with debug info (there was a GC-related crash in C land)
* allow running more or fewer validators
* use deterministic key generation for tests to avoid exhausting system
RNG
* update README with simulator docs
* write the data of each validator to separate file, instead of a big
chainstart.json (makes it easier to run different validator counts)
* implement in-memory block graph
* store tail block in database
* resolve unknown parents by syncing them from peers
* introduce concept of resolved blocks and attestations - those that
follow minimal protocol rules
* update state head lazily
* log more stuff
* shortHash -> shortLog
* start 9/10 beacon nodes by default, last can be started manually
* see also #134
* fix start.sh epoch length
* fix initial attestation pool on reordered attestations
* simplify db layer api
* load head block from database on startup, then load state
* significantly changes database format
* move subscriptions to separate proc's
* implement block replay from historical state
* avoid rescheduling epoch actions on block receipt (why?)
* make sure genesis block is created and used
* relax initial state sim parameters a bit
* move attestation pool to separate file
* combine attestations lazily when needed
* advance state when there's a gap while attesting
* compile beacon node with optimizations - it's tooo slow right now
* log when unable to keep up
You'll need the latest versions of nim-eth-p2p, nim-serialization
and nim-json-serialization.
Before starting the simulation script, make sure to delete any previous
json files from the simulation folder:
```
rm tests/simulation/*.json
tests/simulation/start.sh
```
This should survive the creation of few blocks before diying with a
block validation error.
Zahary Karadjov
Jacek Sieka
Bruno Škvorc
Jacek Sieka
Ștefan Talpalaru
Dustin Brody
Mamy Ratsimbazafy
Yuriy Glukhov