sse implementation that sheds stuck clients

WORKSPACE

@@ -385,7 +385,21 @@ load("@com_github_atlassian_bazel_tools//gometalinter:deps.bzl", "gometalinter_d
 
 gometalinter_dependencies()
 
-load("@bazel_gazelle//:deps.bzl", "gazelle_dependencies")
+load("@bazel_gazelle//:deps.bzl", "gazelle_dependencies", "go_repository")
+
+go_repository(
+    name = "com_github_r3labs_sse_v2",
+    importpath = "github.com/r3labs/sse/v2",
+    sum = "h1:hFEkLLFY4LDifoHdiCN/LlGBAdVJYsANaLqNYa1l/v0=",
+    version = "v2.10.0",
+)
+
+go_repository(
+    name = "in_gopkg_cenkalti_backoff_v1",
+    importpath = "gopkg.in/cenkalti/backoff.v1",
+    sum = "h1:Arh75ttbsvlpVA7WtVpH4u9h6Zl46xuptxqLxPiSo4Y=",
+    version = "v1.1.0",
+)
 
 gazelle_dependencies()
 

api/server/structs/BUILD.bazel

@@ -33,7 +33,10 @@ go_library(
         "//encoding/bytesutil:go_default_library",
         "//math:go_default_library",
         "//proto/engine/v1:go_default_library",
+        "//proto/eth/v1:go_default_library",
+        "//proto/eth/v2:go_default_library",
         "//proto/prysm/v1alpha1:go_default_library",
+        "//runtime/version:go_default_library",
         "@com_github_ethereum_go_ethereum//common:go_default_library",
         "@com_github_ethereum_go_ethereum//common/hexutil:go_default_library",
         "@com_github_pkg_errors//:go_default_library",

api/server/structs/conversions.go

@@ -15,7 +15,10 @@ import (
 	"github.com/prysmaticlabs/prysm/v5/encoding/bytesutil"
 	"github.com/prysmaticlabs/prysm/v5/math"
 	enginev1 "github.com/prysmaticlabs/prysm/v5/proto/engine/v1"
+	ethv1 "github.com/prysmaticlabs/prysm/v5/proto/eth/v1"
+	ethv2 "github.com/prysmaticlabs/prysm/v5/proto/eth/v2"
 	eth "github.com/prysmaticlabs/prysm/v5/proto/prysm/v1alpha1"
+	"github.com/prysmaticlabs/prysm/v5/runtime/version"
 )
 
 var errNilValue = errors.New("nil value")
@@ -1508,3 +1511,88 @@ func PendingConsolidationsFromConsensus(cs []*eth.PendingConsolidation) []*Pendi
 	}
 	return consolidations
 }
+
+func HeadEventFromV1(event *ethv1.EventHead) *HeadEvent {
+	return &HeadEvent{
+		Slot:                      fmt.Sprintf("%d", event.Slot),
+		Block:                     hexutil.Encode(event.Block),
+		State:                     hexutil.Encode(event.State),
+		EpochTransition:           event.EpochTransition,
+		ExecutionOptimistic:       event.ExecutionOptimistic,
+		PreviousDutyDependentRoot: hexutil.Encode(event.PreviousDutyDependentRoot),
+		CurrentDutyDependentRoot:  hexutil.Encode(event.CurrentDutyDependentRoot),
+	}
+}
+
+func FinalizedCheckpointEventFromV1(event *ethv1.EventFinalizedCheckpoint) *FinalizedCheckpointEvent {
+	return &FinalizedCheckpointEvent{
+		Block:               hexutil.Encode(event.Block),
+		State:               hexutil.Encode(event.State),
+		Epoch:               fmt.Sprintf("%d", event.Epoch),
+		ExecutionOptimistic: event.ExecutionOptimistic,
+	}
+}
+
+func LightClientFinalityUpdateEventFromV2(event *ethv2.LightClientFinalityUpdateWithVersion) *LightClientFinalityUpdateEvent {
+	var finalityBranch []string
+	for _, b := range event.Data.FinalityBranch {
+		finalityBranch = append(finalityBranch, hexutil.Encode(b))
+	}
+	return &LightClientFinalityUpdateEvent{
+		Version: version.String(int(event.Version)),
+		Data: &LightClientFinalityUpdate{
+			AttestedHeader: &BeaconBlockHeader{
+				Slot:          fmt.Sprintf("%d", event.Data.AttestedHeader.Slot),
+				ProposerIndex: fmt.Sprintf("%d", event.Data.AttestedHeader.ProposerIndex),
+				ParentRoot:    hexutil.Encode(event.Data.AttestedHeader.ParentRoot),
+				StateRoot:     hexutil.Encode(event.Data.AttestedHeader.StateRoot),
+				BodyRoot:      hexutil.Encode(event.Data.AttestedHeader.BodyRoot),
+			},
+			FinalizedHeader: &BeaconBlockHeader{
+				Slot:          fmt.Sprintf("%d", event.Data.FinalizedHeader.Slot),
+				ProposerIndex: fmt.Sprintf("%d", event.Data.FinalizedHeader.ProposerIndex),
+				ParentRoot:    hexutil.Encode(event.Data.FinalizedHeader.ParentRoot),
+				StateRoot:     hexutil.Encode(event.Data.FinalizedHeader.StateRoot),
+			},
+			FinalityBranch: finalityBranch,
+			SyncAggregate: &SyncAggregate{
+				SyncCommitteeBits:      hexutil.Encode(event.Data.SyncAggregate.SyncCommitteeBits),
+				SyncCommitteeSignature: hexutil.Encode(event.Data.SyncAggregate.SyncCommitteeSignature),
+			},
+			SignatureSlot: fmt.Sprintf("%d", event.Data.SignatureSlot),
+		},
+	}
+}
+
+func LightClientOptimisticUpdateWithVersionFromV2(event *ethv2.LightClientOptimisticUpdateWithVersion) *LightClientOptimisticUpdateEvent {
+	return &LightClientOptimisticUpdateEvent{
+		Version: version.String(int(event.Version)),
+		Data: &LightClientOptimisticUpdate{
+			AttestedHeader: &BeaconBlockHeader{
+				Slot:          fmt.Sprintf("%d", event.Data.AttestedHeader.Slot),
+				ProposerIndex: fmt.Sprintf("%d", event.Data.AttestedHeader.ProposerIndex),
+				ParentRoot:    hexutil.Encode(event.Data.AttestedHeader.ParentRoot),
+				StateRoot:     hexutil.Encode(event.Data.AttestedHeader.StateRoot),
+				BodyRoot:      hexutil.Encode(event.Data.AttestedHeader.BodyRoot),
+			},
+			SyncAggregate: &SyncAggregate{
+				SyncCommitteeBits:      hexutil.Encode(event.Data.SyncAggregate.SyncCommitteeBits),
+				SyncCommitteeSignature: hexutil.Encode(event.Data.SyncAggregate.SyncCommitteeSignature),
+			},
+			SignatureSlot: fmt.Sprintf("%d", event.Data.SignatureSlot),
+		},
+	}
+}
+
+func EventChainReorgFromV1(event *ethv1.EventChainReorg) *ChainReorgEvent {
+	return &ChainReorgEvent{
+		Slot:                fmt.Sprintf("%d", event.Slot),
+		Depth:               fmt.Sprintf("%d", event.Depth),
+		OldHeadBlock:        hexutil.Encode(event.OldHeadBlock),
+		NewHeadBlock:        hexutil.Encode(event.NewHeadBlock),
+		OldHeadState:        hexutil.Encode(event.OldHeadState),
+		NewHeadState:        hexutil.Encode(event.NewHeadState),
+		Epoch:               fmt.Sprintf("%d", event.Epoch),
+		ExecutionOptimistic: event.ExecutionOptimistic,
+	}
+}

beacon-chain/blockchain/testing/mock.go

@@ -159,6 +159,11 @@ func (msn *MockStateNotifier) StateFeed() *event.Feed {
 	return msn.feed
 }
 
+// NewSimpleStateNotifier makes a state feed without the custom mock feed machinery.
+func NewSimpleStateNotifier() *MockStateNotifier {
+	return &MockStateNotifier{feed: new(event.Feed)}
+}
+
 // OperationNotifier mocks the same method in the chain service.
 func (s *ChainService) OperationNotifier() opfeed.Notifier {
 	if s.opNotifier == nil {

beacon-chain/rpc/eth/events/BUILD.bazel

@@ -28,13 +28,17 @@ go_library(
         "//time/slots:go_default_library",
         "@com_github_ethereum_go_ethereum//common/hexutil:go_default_library",
         "@com_github_pkg_errors//:go_default_library",
+        "@com_github_sirupsen_logrus//:go_default_library",
         "@io_opencensus_go//trace:go_default_library",
     ],
 )
 
 go_test(
     name = "go_default_test",
-    srcs = ["events_test.go"],
+    srcs = [
+        "events_test.go",
+        "http_test.go",
+    ],
     embed = [":go_default_library"],
     deps = [
         "//beacon-chain/blockchain/testing:go_default_library",
@@ -49,9 +53,9 @@ go_test(
         "//consensus-types/primitives:go_default_library",
         "//proto/eth/v1:go_default_library",
         "//proto/prysm/v1alpha1:go_default_library",
-        "//testing/assert:go_default_library",
         "//testing/require:go_default_library",
         "//testing/util:go_default_library",
         "@com_github_ethereum_go_ethereum//common:go_default_library",
+        "@com_github_r3labs_sse_v2//:go_default_library",
     ],
 )