Apply Go linter suggestions

Linting the Go code resulted in several suggestions for code
improvement. This commit appies those suggestions. Changes include:
- adding missing comments
- imroving existing comments
- renaming `DiagnosticsRegistry` type/func to `Registry` (same
  change conducted also in keep-core project)

Author: michalinacienciala

pkg/chain/ethlike/block_counter.go

@@ -8,6 +8,7 @@ import (
 	"time"
 )
 
+// BlockCounter represents a block counter
 type BlockCounter struct {
 	structMutex         sync.Mutex
 	latestBlockHeight   uint64
@@ -25,6 +26,7 @@ type watcher struct {
 	channel chan uint64
 }
 
+// WaitForBlockHeight waits for a given block height
 func (bc *BlockCounter) WaitForBlockHeight(blockNumber uint64) error {
 	waiter, err := bc.BlockHeightWaiter(blockNumber)
 	if err != nil {
@@ -34,6 +36,7 @@ func (bc *BlockCounter) WaitForBlockHeight(blockNumber uint64) error {
 	return nil
 }
 
+// BlockHeightWaiter returns a waiter for the given block
 func (bc *BlockCounter) BlockHeightWaiter(
 	blockNumber uint64,
 ) (<-chan uint64, error) {
@@ -56,10 +59,12 @@ func (bc *BlockCounter) BlockHeightWaiter(
 	return newWaiter, nil
 }
 
+// CurrentBlock returns the current block
 func (bc *BlockCounter) CurrentBlock() (uint64, error) {
 	return bc.latestBlockHeight, nil
 }
 
+// WatchBlocks watches the blocks
 func (bc *BlockCounter) WatchBlocks(ctx context.Context) <-chan uint64 {
 	watcher := &watcher{
 		ctx:     ctx,
@@ -206,6 +211,7 @@ func (bc *BlockCounter) subscribeBlocks(
 	return nil
 }
 
+// CreateBlockCounter creates a block counter
 func CreateBlockCounter(chainReader ChainReader) (*BlockCounter, error) {
 	ctx := context.Background()
 

pkg/chain/ethlike/token.go

@@ -8,11 +8,12 @@ import (
 	"strings"
 )
 
+// Token represents a token
 type Token struct {
 	*big.Int
 }
 
-// UnmarshalText is a function used to parse an ETH-like token.
+// UnmarshalToken is a function used to parse an ETH-like token.
 func (t *Token) UnmarshalToken(text []byte, units map[string]float64) error {
 	re := regexp.MustCompile(`^(\d+[\.]?[\d]*)[ ]?([\w]*)$`)
 	matched := re.FindSubmatch(text)

pkg/diagnostics/diagnostics.go

@@ -1,4 +1,4 @@
-// Package `diagnostics` provides some tools useful for gathering and
+// Package diagnostics provides some tools useful for gathering and
 // exposing arbitrary diagnositcs information for external monitoring tools.
 //
 // Possible usage: integration nodes list into dashboard
@@ -18,21 +18,21 @@ var logger = log.Logger("keep-diagnostics")
 
 // Registry performs all management of diagnostic. Specifically, it allows
 // to registering new diagnostics sources and exposing them through the diagnostics server.
-type DiagnosticsRegistry struct {
+type Registry struct {
 	diagnosticsSources map[string]func() string
 	diagnosticsMutex   sync.RWMutex
 }
 
 // NewRegistry creates a new metrics registry.
-func NewRegistry() *DiagnosticsRegistry {
-	return &DiagnosticsRegistry{
+func NewRegistry() *Registry {
+	return &Registry{
 		diagnosticsSources: make(map[string]func() string),
 	}
 }
 
 // EnableServer enables the diagnostics server on the given port. Data will
 // be exposed on `/diagnostics` path in JSON format.
-func (r *DiagnosticsRegistry) EnableServer(port int) {
+func (r *Registry) EnableServer(port int) {
 	server := &http.Server{Addr: ":" + strconv.Itoa(port)}
 
 	http.HandleFunc("/diagnostics", func(response http.ResponseWriter, _ *http.Request) {
@@ -48,20 +48,20 @@ func (r *DiagnosticsRegistry) EnableServer(port int) {
 	}()
 }
 
-// Registers diagnostics source callback with a given name. 
+// RegisterSource registers diagnostics source callback with a given name.
 // Name will be used as a key and callback result as a value in JSON object
-// during composing diagnostics JSON. 
-// Note: function will override existing diagnostics source on attempt 
+// during composing diagnostics JSON.
+// Note: function will override existing diagnostics source on attempt
 // to register another one with the same name.
-func (r *DiagnosticsRegistry) RegisterSource(name string, source func() string) {
+func (r *Registry) RegisterSource(name string, source func() string) {
 	r.diagnosticsMutex.Lock()
 	defer r.diagnosticsMutex.Unlock()
 
 	r.diagnosticsSources[name] = source
 }
 
 // Exposes all registered diagnostics sources in a single JSON document.
-func (r *DiagnosticsRegistry) exposeDiagnostics() string {
+func (r *Registry) exposeDiagnostics() string {
 	r.diagnosticsMutex.RLock()
 	defer r.diagnosticsMutex.RUnlock()
 

pkg/metrics/registry.go

@@ -1,4 +1,4 @@
-// Package `metrics` provides some tools useful for gathering and
+// Package metrics provides some tools useful for gathering and
 // exposing system metrics for external monitoring tools.
 //
 // Currently, this package is intended to use with Prometheus but

pkg/rate/limiter.go

@@ -59,6 +59,7 @@ func NewLimiter(
 	return l
 }
 
+// AcquirePermit acquires the permit
 func (l *Limiter) AcquirePermit() error {
 	ctx, cancel := context.WithTimeout(
 		context.Background(),
@@ -83,6 +84,7 @@ func (l *Limiter) AcquirePermit() error {
 	return nil
 }
 
+// ReleasePermit releases the permit
 func (l *Limiter) ReleasePermit() {
 	if l.semaphore != nil {
 		l.semaphore.Release(1)