From cd94717df70890ed71f07ae976b859247c886a82 Mon Sep 17 00:00:00 2001
From: Paul Hauner <paul@paulhauner.com>
Date: Wed, 9 Sep 2020 21:11:36 +1000
Subject: [PATCH] Add committees at slot field

---
 beacon_node/http_api/src/lib.rs                     | 1 +
 beacon_node/http_api/tests/tests.rs                 | 1 +
 common/eth2/src/types.rs                            | 2 ++
 consensus/types/src/attestation_duty.rs             | 2 ++
 consensus/types/src/beacon_state/committee_cache.rs | 1 +
 5 files changed, 7 insertions(+)

diff --git a/beacon_node/http_api/src/lib.rs b/beacon_node/http_api/src/lib.rs
index 6e98036fad9..200eb200c55 100644
--- a/beacon_node/http_api/src/lib.rs
+++ b/beacon_node/http_api/src/lib.rs
@@ -950,6 +950,7 @@ pub fn serve<T: BeaconChainTypes>(
                             Ok(api_types::AttesterData {
                                 pubkey: pubkey.into(),
                                 validator_index,
+                                committees_at_slot: duty.committees_at_slot,
                                 committee_index: duty.index,
                                 committee_length: duty.committee_len as u64,
                                 validator_committee_index: duty.committee_position as u64,
diff --git a/beacon_node/http_api/tests/tests.rs b/beacon_node/http_api/tests/tests.rs
index 5f14597f000..7197fbb7917 100644
--- a/beacon_node/http_api/tests/tests.rs
+++ b/beacon_node/http_api/tests/tests.rs
@@ -1071,6 +1071,7 @@ impl ApiTester {
                         let expected = AttesterData {
                             pubkey: state.validators[i as usize].pubkey.clone().into(),
                             validator_index: i,
+                            committees_at_slot: duty.committees_at_slot,
                             committee_index: duty.index,
                             committee_length: duty.committee_len as u64,
                             validator_committee_index: duty.committee_position as u64,
diff --git a/common/eth2/src/types.rs b/common/eth2/src/types.rs
index 318f258853d..597f23dc4b2 100644
--- a/common/eth2/src/types.rs
+++ b/common/eth2/src/types.rs
@@ -353,6 +353,8 @@ pub struct AttesterData {
     #[serde(with = "serde_utils::quoted_u64")]
     pub validator_index: u64,
     #[serde(with = "serde_utils::quoted_u64")]
+    pub committees_at_slot: u64,
+    #[serde(with = "serde_utils::quoted_u64")]
     pub committee_index: CommitteeIndex,
     #[serde(with = "serde_utils::quoted_u64")]
     pub committee_length: u64,
diff --git a/consensus/types/src/attestation_duty.rs b/consensus/types/src/attestation_duty.rs
index c32e4683e18..b1a53d22518 100644
--- a/consensus/types/src/attestation_duty.rs
+++ b/consensus/types/src/attestation_duty.rs
@@ -12,4 +12,6 @@ pub struct AttestationDuty {
     pub committee_position: usize,
     /// The total number of attesters in the committee.
     pub committee_len: usize,
+    /// The committee count at `attestation_slot`.
+    pub committees_at_slot: u64,
 }
diff --git a/consensus/types/src/beacon_state/committee_cache.rs b/consensus/types/src/beacon_state/committee_cache.rs
index f71ad2e893e..a6018df304c 100644
--- a/consensus/types/src/beacon_state/committee_cache.rs
+++ b/consensus/types/src/beacon_state/committee_cache.rs
@@ -185,6 +185,7 @@ impl CommitteeCache {
                     index,
                     committee_position,
                     committee_len,
+                    committees_at_slot: self.committees_per_slot(),
                 })
             })
     }