Fix block processing blowup, upgrade metrics (#500)

* Renamed fork_choice::process_attestation_from_block

* Processing attestation in fork choice

* Retrieving state from store and checking signature

* Looser check on beacon state validity.

* Cleaned up get_attestation_state

* Expanded fork choice api to provide latest validator message.

* Checking if the an attestation contains a latest message

* Correct process_attestation error handling.

* Copy paste error in comment fixed.

* Tidy ancestor iterators

* Getting attestation slot via helper method

* Refactored attestation creation in test utils

* Revert "Refactored attestation creation in test utils"

This reverts commit 4d277fe4239a7194758b18fb5c00dfe0b8231306.

* Integration tests for free attestation processing

* Implicit conflicts resolved.

* formatting

* Do first pass on Grants code

* Add another attestation processing test

* Tidy attestation processing

* Remove old code fragment

* Add non-compiling half finished changes

* Simplify, fix bugs, add tests for chain iters

* Remove attestation processing from op pool

* Fix bug with fork choice, tidy

* Fix overly restrictive check in fork choice.

* Ensure committee cache is build during attn proc

* Ignore unknown blocks at fork choice

* Various minor fixes

* Make fork choice write lock in to read lock

* Remove unused method

* Tidy comments

* Fix attestation prod. target roots change

* Fix compile error in store iters

* Reject any attestation prior to finalization

* Begin metrics refactor

* Move beacon_chain to new metrics structure.

* Make metrics not panic if already defined

* Use global prometheus gather at rest api

* Unify common metric fns into a crate

* Add heavy metering to block processing

* Remove hypen from prometheus metric name

* Add more beacon chain metrics

* Add beacon chain persistence metric

* Prune op pool on finalization

* Add extra prom beacon chain metrics

* Prefix BeaconChain metrics with "beacon_"

* Add more store metrics

* Add basic metrics to libp2p

* Add metrics to HTTP server

* Remove old `http_server` crate

* Update metrics names to be more like standard

* Fix broken beacon chain metrics, add slot clock metrics

* Add lighthouse_metrics gather fn

* Remove http args

* Fix wrong state given to op pool prune

* Make prom metric names more consistent

* Add more metrics, tidy existing metrics

* Fix store block read metrics

* Tidy attestation metrics

* Fix minor PR comments

* Allow travis failures on beta (see desc)

There's a non-backward compatible change in `cargo fmt`. Stable and beta
do not agree.

* Tidy `lighthouse_metrics` docs

* Fix typo

eth2/utils/slot_clock/src/lib.rs

@@ -1,9 +1,15 @@
+#[macro_use]
+extern crate lazy_static;
+
+mod metrics;
 mod system_time_slot_clock;
 mod testing_slot_clock;
 
+use std::time::Duration;
+
 pub use crate::system_time_slot_clock::{Error as SystemTimeSlotClockError, SystemTimeSlotClock};
 pub use crate::testing_slot_clock::{Error as TestingSlotClockError, TestingSlotClock};
-use std::time::Duration;
+pub use metrics::scrape_for_metrics;
 pub use types::Slot;
 
 pub trait SlotClock: Send + Sync + Sized {
@@ -17,4 +23,6 @@ pub trait SlotClock: Send + Sync + Sized {
     fn present_slot(&self) -> Result<Option<Slot>, Self::Error>;
 
     fn duration_to_next_slot(&self) -> Result<Option<Duration>, Self::Error>;
+
+    fn slot_duration_millis(&self) -> u64;
 }

eth2/utils/slot_clock/src/metrics.rs

@@ -0,0 +1,32 @@
+use crate::SlotClock;
+pub use lighthouse_metrics::*;
+use types::{EthSpec, Slot};
+
+lazy_static! {
+    pub static ref PRESENT_SLOT: Result<IntGauge> =
+        try_create_int_gauge("slotclock_present_slot", "The present wall-clock slot");
+    pub static ref PRESENT_EPOCH: Result<IntGauge> =
+        try_create_int_gauge("slotclock_present_epoch", "The present wall-clock epoch");
+    pub static ref SLOTS_PER_EPOCH: Result<IntGauge> =
+        try_create_int_gauge("slotclock_slots_per_epoch", "Slots per epoch (constant)");
+    pub static ref MILLISECONDS_PER_SLOT: Result<IntGauge> = try_create_int_gauge(
+        "slotclock_slot_time_milliseconds",
+        "The duration in milliseconds between each slot"
+    );
+}
+
+/// Update the global metrics `DEFAULT_REGISTRY` with info from the slot clock.
+pub fn scrape_for_metrics<T: EthSpec, U: SlotClock>(clock: &U) {
+    let present_slot = match clock.present_slot() {
+        Ok(Some(slot)) => slot,
+        _ => Slot::new(0),
+    };
+
+    set_gauge(&PRESENT_SLOT, present_slot.as_u64() as i64);
+    set_gauge(
+        &PRESENT_EPOCH,
+        present_slot.epoch(T::slots_per_epoch()).as_u64() as i64,
+    );
+    set_gauge(&SLOTS_PER_EPOCH, T::slots_per_epoch() as i64);
+    set_gauge(&MILLISECONDS_PER_SLOT, clock.slot_duration_millis() as i64);
+}

eth2/utils/slot_clock/src/system_time_slot_clock.rs

@@ -52,6 +52,10 @@ impl SlotClock for SystemTimeSlotClock {
     fn duration_to_next_slot(&self) -> Result<Option<Duration>, Error> {
         duration_to_next_slot(self.genesis_seconds, self.slot_duration_seconds)
     }
+
+    fn slot_duration_millis(&self) -> u64 {
+        self.slot_duration_seconds * 1000
+    }
 }
 
 impl From<SystemTimeError> for Error {

eth2/utils/slot_clock/src/testing_slot_clock.rs

@@ -40,6 +40,10 @@ impl SlotClock for TestingSlotClock {
     fn duration_to_next_slot(&self) -> Result<Option<Duration>, Error> {
         Ok(Some(Duration::from_secs(1)))
     }
+
+    fn slot_duration_millis(&self) -> u64 {
+        0
+    }
 }
 
 #[cfg(test)]