feat: add message system (#3)

* Setup repo

* Create LICENSE

* Bump golangci/golangci-lint-action from 3 to 4 (#1)

Bumps [golangci/golangci-lint-action](https://github.com/golangci/golangci-lint-action) from 3 to 4.
- [Release notes](https://github.com/golangci/golangci-lint-action/releases)
- [Commits](golangci/golangci-lint-action@v3...v4)

---
updated-dependencies:
- dependency-name: golangci/golangci-lint-action
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

* Initial foundation pseudocode

* Bump go version

* Add message proto definitions

* Add initial collector logic

* Add temporary fetch messages to the collector

* Significantly simplify the message storage

* Add unit tests for the collector

* Remove dupl lint

* Split up the subscribe unit test

* Simplify remove case

* Drop old message queue

* Change AddMessage sig

* Tidy go mod

* Remove leftover pb.go

* Tidy go mod

---------

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/golangci.yaml

@@ -7,6 +7,8 @@ run:
   modules-download-mode: readonly
   allow-parallel-runners: false
   go: ""
+  skip-dirs: # Temporary
+    - core
 
 output:
   uniq-by-line: false
@@ -77,7 +79,6 @@ linters:
     - goimports # Unused imports
     - goconst # Repeated strings that could be replaced by a constant
     - dogsled # Checks assignments with too many blank identifiers (e.g. x, , , _, := f())
-    - dupl # Code clone detection
     - errname # Checks that sentinel errors are prefixed with the Err and error types are suffixed with the Error
     - errorlint # errorlint is a linter for that can be used to find code that will cause problems with the error wrapping scheme introduced in Go 1.13
     - unused # Checks Go code for unused constants, variables, functions and types

Makefile

@@ -16,4 +16,4 @@ fixalign:
 protoc:
 	# Make sure the following prerequisites are installed before running these commands:
 	# https://grpc.io/docs/languages/go/quickstart/#prerequisites
-	protoc --proto_path=./ --go_out=./ --go-grpc_out=./ ./messages/proto/*.proto
+	protoc --go_out=./ ./messages/proto/*.proto

go.mod

@@ -2,4 +2,14 @@ module github.com/gnolang/go-tendermint
 
 go 1.21
 
-require google.golang.org/protobuf v1.32.0
+require (
+	github.com/rs/xid v1.5.0
+	github.com/stretchr/testify v1.8.4
+	google.golang.org/protobuf v1.32.0
+)
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)

go.sum

@@ -1,6 +1,18 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/google/go-cmp v0.5.5 h1:Khx7svrCpmxxtHBq5j2mp/xVjsi8hQMfNLvJFAlrGgU=
 github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/rs/xid v1.5.0 h1:mKX4bl4iPYJtEIxp6CYiUuLQ/8DYMoz0PUdtGgMFRVc=
+github.com/rs/xid v1.5.0/go.mod h1:trrq9SKmegXys3aeAKXMUTdJsYXVwGY3RLcfgqegfbg=
+github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
+github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 google.golang.org/protobuf v1.32.0 h1:pPC6BG5ex8PDFnkbrGU3EixyhKcQ2aDuBS36lqK/C7I=
 google.golang.org/protobuf v1.32.0/go.mod h1:c6P6GXX6sHbq/GpV6MGZEdwhWPcYBgnhAHhKbcUYpos=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

messages/collector.go

@@ -0,0 +1,117 @@
+package messages
+
+import (
+	"fmt"
+	"sync"
+)
+
+// msgType is the combined message type interface,
+// for easy reference and type safety
+type msgType interface {
+	ProposalMessage | PrevoteMessage | PrecommitMessage
+}
+
+type (
+	// collection are the actual received messages.
+	// Maps a unique identifier -> their message (of a specific type) to avoid duplicates.
+	// Identifiers are derived from <sender ID, height, round>.
+	// Each validator in the consensus needs to send at most 1 message of every type
+	// (minus the PROPOSAL, which is only sent by the proposer),
+	// so the message system needs to keep track of only 1 message per type, per validator, per view
+	collection[T msgType] map[string]*T
+)
+
+// Collector is a single message type collector
+type Collector[T msgType] struct {
+	collection    collection[T]    // the message storage
+	subscriptions subscriptions[T] // the active message subscriptions
+
+	collectionMux    sync.RWMutex
+	subscriptionsMux sync.RWMutex
+}
+
+// NewCollector creates a new message collector
+func NewCollector[T msgType]() *Collector[T] {
+	return &Collector[T]{
+		collection:    make(collection[T]),
+		subscriptions: make(subscriptions[T]),
+	}
+}
+
+// Subscribe creates a new collector subscription.
+// Returns the channel for receiving messages,
+// as well as the unsubscribe method
+func (c *Collector[T]) Subscribe() (<-chan MsgCallback[T], func()) {
+	c.subscriptionsMux.Lock()
+	defer c.subscriptionsMux.Unlock()
+
+	// Create a new subscription
+	id, ch := c.subscriptions.add()
+
+	// Create the unsubscribe callback
+	unsubscribeFn := func() {
+		c.subscriptionsMux.Lock()
+		defer c.subscriptionsMux.Unlock()
+
+		c.subscriptions.remove(id)
+	}
+
+	// Notify the subscription immediately,
+	// since there can be existing messages in the collection.
+	// This action assumes the channel is not blocking (created with initial size),
+	// since the calling context does not have access to it yet at this point
+	notifySubscription(ch, c.GetMessages)
+
+	return ch, unsubscribeFn
+}
+
+// GetMessages returns the currently present messages in the collector
+func (c *Collector[T]) GetMessages() []*T {
+	c.collectionMux.RLock()
+	defer c.collectionMux.RUnlock()
+
+	// Fetch the messages in the collection
+	return c.collection.getMessages()
+}
+
+// getMessages fetches the messages in the collection
+func (c *collection[T]) getMessages() []*T {
+	messages := make([]*T, 0, len(*c))
+
+	for _, senderMessage := range *c {
+		messages = append(messages, senderMessage)
+	}
+
+	return messages
+}
+
+// AddMessage adds a new message to the collector
+func (c *Collector[T]) AddMessage(view *View, from []byte, message *T) {
+	c.collectionMux.Lock()
+
+	// Add the message
+	c.collection.addMessage(
+		getCollectionKey(from, view),
+		message,
+	)
+
+	c.collectionMux.Unlock()
+
+	// Notify the subscriptions
+	c.subscriptionsMux.RLock()
+	defer c.subscriptionsMux.RUnlock()
+
+	c.subscriptions.notify(c.GetMessages)
+}
+
+// addMessage adds a new message to the collection
+func (c *collection[T]) addMessage(key string, message *T) {
+	(*c)[key] = message
+}
+
+// getCollectionKey constructs a key based on the
+// message sender and view information.
+// This key guarantees uniqueness in the message store
+func getCollectionKey(from []byte, view *View) string {
+	return fmt.Sprintf("%s_%d_%d", from, view.Height, view.Round)
+}