Improve tokio task execution (#1181)

* Add logging on shutdown

* Replace tokio::spawn with handle.spawn

* Upgrade tokio

* Add a task executor

* Beacon chain tasks use task executor

* Validator client tasks use task executor

* Rename runtime_handle to executor

* Add duration histograms; minor fixes

* Cleanup

* Fix logs

* Fix tests

* Remove random file

* Get enr dependency instead of libp2p

* Address some review comments

* Libp2p takes a TaskExecutor

* Ugly fix libp2p tests

* Move TaskExecutor to own file

* Upgrade Dockerfile rust version

* Minor fixes

* Revert "Ugly fix libp2p tests"

This reverts commit 58d4bb690f.

* Pretty fix libp2p tests

* Add spawn_without_exit; change Counter to Gauge

* Tidy

* Move log from RuntimeContext to TaskExecutor

* Fix errors

* Replace histogram with int_gauge for async tasks

* Fix todo

* Fix memory leak in test by exiting all spawned tasks at the end

beacon_node/network/Cargo.toml

@@ -10,6 +10,7 @@ genesis = { path = "../genesis" }
 lazy_static = "1.4.0"
 matches = "0.1.8"
 tempfile = "3.1.0"
+exit-future = "0.2.0"
 
 [dependencies]
 beacon_chain =  { path = "../beacon_chain" }
@@ -25,7 +26,7 @@ eth2_ssz = "0.1.2"
 tree_hash = "0.1.0"
 futures = "0.3.5"
 error-chain = "0.12.2"
-tokio = { version = "0.2.20", features = ["full"] }
+tokio = { version = "0.2.21", features = ["full"] }
 parking_lot = "0.10.2"
 smallvec = "1.4.0"
 # TODO: Remove rand crate for mainnet
@@ -34,3 +35,4 @@ fnv = "1.0.6"
 rlp = "0.4.5"
 lazy_static = "1.4.0"
 lighthouse_metrics = { path = "../../common/lighthouse_metrics" }
+environment = { path = "../../lighthouse/environment" }