From f10f29d8291c79eafdd54fe3b91570faf08b09d7 Mon Sep 17 00:00:00 2001
From: Jacek Sieka <jacek@status.im>
Date: Tue, 8 Dec 2020 09:59:40 +0100
Subject: [PATCH] avoid some futures and copies in processing pipeline (#2157)

`addLastNoWait` does the same thing with less task scheduling and
copying
---
 beacon_chain/eth2_processor.nim | 38 ++++++++++++++++++++-------------
 1 file changed, 23 insertions(+), 15 deletions(-)

diff --git a/beacon_chain/eth2_processor.nim b/beacon_chain/eth2_processor.nim
index 1ae9bc0c2..a7e2a2ebf 100644
--- a/beacon_chain/eth2_processor.nim
+++ b/beacon_chain/eth2_processor.nim
@@ -79,13 +79,11 @@ proc updateHead*(self: var Eth2Processor, wallSlot: Slot) =
   # justified and finalized
   let
     oldFinalized = self.chainDag.finalizedHead.blck
-    oldHead = self.chainDag.head
 
   self.chainDag.updateHead(newHead, self.quarantine)
 
   # Cleanup the fork choice v2 if we have a finalized head
   if oldFinalized != self.chainDag.finalizedHead.blck:
-
     self.attestationPool[].prune()
 
 proc dumpBlock[T](
@@ -318,14 +316,19 @@ proc attestationValidator*(
   beacon_attestation_delay.observe(delay.toFloatSeconds())
 
   while self.attestationsQueue.full():
-    let dropped = self.attestationsQueue.popFirst()
-    doAssert dropped.finished, "popFirst sanity"
-    notice "Queue full, dropping attestation",
-      dropped = shortLog(dropped.read().v)
+    try:
+      notice "Queue full, dropping attestation",
+        dropped = shortLog(self.attestationsQueue[0].v)
+      discard self.attestationsQueue.popFirstNoWait()
+    except CatchableError as exc:
+      raiseAssert "If queue is full, we have at least one item! " & exc.msg
 
   trace "Attestation validated"
-  traceAsyncErrors self.attestationsQueue.addLast(
-    AttestationEntry(v: attestation, attesting_indices: v.get()))
+  try:
+    self.attestationsQueue.addLastNoWait(
+      AttestationEntry(v: attestation, attesting_indices: v.get()))
+  except CatchableError as exc:
+    raiseAssert "We just checked that queue is not full! " & exc.msg
 
   ValidationResult.Accept
 
@@ -361,15 +364,20 @@ proc aggregateValidator*(
   beacon_aggregate_delay.observe(delay.toFloatSeconds())
 
   while self.aggregatesQueue.full():
-    let dropped = self.aggregatesQueue.popFirst()
-    doAssert dropped.finished, "popFirst sanity"
-    notice "Queue full, dropping aggregate",
-      dropped = shortLog(dropped.read().v)
+    try:
+      notice "Queue full, dropping aggregate",
+        dropped = shortLog(self.aggregatesQueue[0].v)
+      discard self.aggregatesQueue.popFirstNoWait()
+    except CatchableError as exc:
+      raiseAssert "We just checked that queue is not full! " & exc.msg
 
   trace "Aggregate validated"
-  traceAsyncErrors self.aggregatesQueue.addLast(AggregateEntry(
-    v: signedAggregateAndProof.message.aggregate,
-    attesting_indices: v.get()))
+  try:
+    self.aggregatesQueue.addLastNoWait(AggregateEntry(
+      v: signedAggregateAndProof.message.aggregate,
+      attesting_indices: v.get()))
+  except CatchableError as exc:
+    raiseAssert "We just checked that queue is not full! " & exc.msg
 
   ValidationResult.Accept