*: adjust subscription-related doc

Add a warning about received events modification where applicable.

pkg/core/blockchain.go

@@ -2142,7 +2142,8 @@ func (bc *Blockchain) GetConfig() config.Blockchain {
 // SubscribeForBlocks adds given channel to new block event broadcasting, so when
 // there is a new block added to the chain you'll receive it via this channel.
 // Make sure it's read from regularly as not reading these events might affect
-// other Blockchain functions.
+// other Blockchain functions. Make sure you're not changing the received blocks,
+// as it may affect the functionality of Blockchain and other subscribers.
 func (bc *Blockchain) SubscribeForBlocks(ch chan *block.Block) {
 	bc.subCh <- ch
 }
@@ -2150,7 +2151,9 @@ func (bc *Blockchain) SubscribeForBlocks(ch chan *block.Block) {
 // SubscribeForTransactions adds given channel to new transaction event
 // broadcasting, so when there is a new transaction added to the chain (in a
 // block) you'll receive it via this channel. Make sure it's read from regularly
-// as not reading these events might affect other Blockchain functions.
+// as not reading these events might affect other Blockchain functions. Make sure
+// you're not changing the received transactions, as it may affect the
+// functionality of Blockchain and other subscribers.
 func (bc *Blockchain) SubscribeForTransactions(ch chan *transaction.Transaction) {
 	bc.subCh <- ch
 }
@@ -2161,7 +2164,8 @@ func (bc *Blockchain) SubscribeForTransactions(ch chan *transaction.Transaction)
 // successful transactions are broadcasted, if you're interested in failed
 // transactions use SubscribeForExecutions instead. Make sure this channel is
 // read from regularly as not reading these events might affect other Blockchain
-// functions.
+// functions. Make sure you're not changing the received notification events, as
+// it may affect the functionality of Blockchain and other subscribers.
 func (bc *Blockchain) SubscribeForNotifications(ch chan *state.ContainedNotificationEvent) {
 	bc.subCh <- ch
 }
@@ -2169,7 +2173,9 @@ func (bc *Blockchain) SubscribeForNotifications(ch chan *state.ContainedNotifica
 // SubscribeForExecutions adds given channel to new transaction execution event
 // broadcasting, so when an in-block transaction execution happens you'll receive
 // the result of it via this channel. Make sure it's read from regularly as not
-// reading these events might affect other Blockchain functions.
+// reading these events might affect other Blockchain functions. Make sure you're
+// not changing the received execution results, as it may affect the
+// functionality of Blockchain and other subscribers.
 func (bc *Blockchain) SubscribeForExecutions(ch chan *state.AppExecResult) {
 	bc.subCh <- ch
 }

pkg/core/mempool/subscriptions.go

@@ -27,7 +27,8 @@ func (mp *Pool) StopSubscriptions() {
 
 // SubscribeForTransactions adds the given channel to the new mempool event broadcasting, so when
 // there is a new transactions added to the mempool or an existing transaction removed from
-// the mempool, you'll receive it via this channel.
+// the mempool, you'll receive it via this channel. Make sure you're not changing the received
+// mempool events, as it may affect the functionality of other subscribers.
 func (mp *Pool) SubscribeForTransactions(ch chan<- mempoolevent.Event) {
 	if mp.subscriptionsOn.Load() {
 		mp.subCh <- ch

pkg/network/server.go

@@ -552,7 +552,8 @@ func (s *Server) tryStartServices() {
 // broadcasting, so when a new P2PNotaryRequest is received or an existing
 // P2PNotaryRequest is removed from the pool you'll receive it via this channel.
 // Make sure it's read from regularly as not reading these events might affect
-// other Server functions.
+// other Server functions. Make sure you're not changing the received mempool
+// events, as it may affect the functionality of Blockchain and other subscribers.
 // Ensure that P2PSigExtensions are enabled before calling this method.
 func (s *Server) SubscribeForNotaryRequests(ch chan<- mempoolevent.Event) {
 	if !s.chain.P2PSigExtensionsEnabled() {

pkg/rpcclient/wsclient.go

@@ -33,7 +33,9 @@ type WSClient struct {
 	// it wants to use subscription mechanism. Failing to do so will cause
 	// WSClient to block even regular requests. This channel is not buffered.
 	// In case of protocol error or upon connection closure, this channel will
-	// be closed, so make sure to handle this.
+	// be closed, so make sure to handle this. Make sure you're not changing the
+	// received notifications, as it may affect the functionality of other
+	// notification receivers.
 	//
 	// Deprecated: please, use custom channels with ReceiveBlocks, ReceiveTransactions,
 	// ReceiveExecutionNotifications, ReceiveExecutions, ReceiveNotaryRequests
@@ -659,11 +661,13 @@ func (c *WSClient) SubscribeForNewBlocks(primary *int) (string, error) {
 // ReceiveBlocks registers provided channel as a receiver for the new block events.
 // Events can be filtered by the given BlockFilter, nil value doesn't add any filter.
 // The receiver channel must be properly read and drained after usage in order not
-// to block other notification receivers. If multiple subscriptions share the same
+// to block other notification receivers. Make sure you're not changing the received
-// receiver channel, then matching notification is only sent once per channel. The
+// blocks, as it may affect the functionality of other notification receivers.
-// receiver channel will be closed by the WSClient immediately after MissedEvent is
+// If multiple subscriptions share the same receiver channel, then matching
-// received from the server; no unsubscription is performed in this case, so it's the
+// notification is only sent once per channel. The receiver channel will be closed
-// user responsibility to unsubscribe.
+// by the WSClient immediately after MissedEvent is received from the server;
+// no unsubscription is performed in this case, so it's the user responsibility
+// to unsubscribe.
 func (c *WSClient) ReceiveBlocks(flt *neorpc.BlockFilter, rcvr chan<- *block.Block) (string, error) {
 	if rcvr == nil {
 		return "", ErrNilNotificationReceiver
@@ -704,11 +708,13 @@ func (c *WSClient) SubscribeForNewTransactions(sender *util.Uint160, signer *uti
 // ReceiveTransactions registers provided channel as a receiver for new transaction
 // events. Events can be filtered by the given TxFilter, nil value doesn't add any
 // filter. The receiver channel must be properly read and drained after usage in
-// order not to block other notification receivers. If multiple subscriptions share
+// order not to block other notification receivers. Make sure you're not changing
-// the same receiver channel, then matching notification is only sent once per channel.
+// the received transactions, as it may affect the functionality of other
-// The receiver channel will be closed by the WSClient immediately after MissedEvent is
+// notification receivers.If multiple subscriptions share the same receiver channel,
-// received from the server; no unsubscription is performed in this case, so it's the
+// then matching notification is only sent once per channel. The receiver channel
-// user responsibility to unsubscribe.
+// will be closed by the WSClient immediately after MissedEvent is received from
+// the server; no unsubscription is performed in this case, so it's the user
+// responsibility to unsubscribe.
 func (c *WSClient) ReceiveTransactions(flt *neorpc.TxFilter, rcvr chan<- *transaction.Transaction) (string, error) {
 	if rcvr == nil {
 		return "", ErrNilNotificationReceiver
@@ -750,11 +756,13 @@ func (c *WSClient) SubscribeForExecutionNotifications(contract *util.Uint160, na
 // ReceiveExecutionNotifications registers provided channel as a receiver for execution
 // events. Events can be filtered by the given NotificationFilter, nil value doesn't add
 // any filter. The receiver channel must be properly read and drained after usage in
-// order not to block other notification receivers. If multiple subscriptions share the
+// order not to block other notification receivers. Make sure you're not changing the
-// same receiver channel, then matching notification is only sent once per channel. The
+// received notification events, as it may affect the functionality of other
-// receiver channel will be closed by the WSClient immediately after MissedEvent is
+// notification receivers. If multiple subscriptions share the same receiver channel,
-// received from the server; no unsubscription is performed in this case, so it's the
+// then matching notification is only sent once per channel. The receiver channel will
-// user responsibility to unsubscribe.
+// be closed by the WSClient immediately after MissedEvent is received from the server;
+// no unsubscription is performed in this case, so it's the user responsibility to
+// unsubscribe.
 func (c *WSClient) ReceiveExecutionNotifications(flt *neorpc.NotificationFilter, rcvr chan<- *state.ContainedNotificationEvent) (string, error) {
 	if rcvr == nil {
 		return "", ErrNilNotificationReceiver
@@ -800,11 +808,13 @@ func (c *WSClient) SubscribeForTransactionExecutions(state *string) (string, err
 // application execution result events generated during transaction execution.
 // Events can be filtered by the given ExecutionFilter, nil value doesn't add any filter.
 // The receiver channel must be properly read and drained after usage in order not
-// to block other notification receivers. If multiple subscriptions share the same
+// to block other notification receivers. Make sure you're not changing the received
-// receiver channel, then matching notification is only sent once per channel. The
+// execution results, as it may affect the functionality of other notification
-// receiver channel will be closed by the WSClient immediately after MissedEvent is
+// receivers. If multiple subscriptions share the same receiver channel, then
-// received from the server; no unsubscription is performed in this case, so it's the
+// matching notification is only sent once per channel. The receiver channel will
-// user responsibility to unsubscribe.
+// be closed by the WSClient immediately after MissedEvent is received from the
+// server; no unsubscription is performed in this case, so it's the user responsibility
+// to unsubscribe.
 func (c *WSClient) ReceiveExecutions(flt *neorpc.ExecutionFilter, rcvr chan<- *state.AppExecResult) (string, error) {
 	if rcvr == nil {
 		return "", ErrNilNotificationReceiver
@@ -853,11 +863,13 @@ func (c *WSClient) SubscribeForNotaryRequests(sender *util.Uint160, mainSigner *
 // where sender corresponds to notary request sender (the second fallback transaction
 // signer) and signer corresponds to main transaction signers. nil value doesn't add
 // any filter. The receiver channel must be properly read and drained after usage in
-// order not to block other notification receivers. If multiple subscriptions share
+// order not to block other notification receivers. Make sure you're not changing the
-// the same receiver channel, then matching notification is only sent once per channel.
+// received notary requests, as it may affect the functionality of other notification
-// The receiver channel will be closed by the WSClient immediately after MissedEvent
+// receivers. If multiple subscriptions share the same receiver channel, then matching
-// is received from the server; no unsubscription is performed in this case, so it's the
+// notification is only sent once per channel. The receiver channel will be closed by
-// user responsibility to unsubscribe.
+// the WSClient immediately after MissedEvent is received from the server; no
+// unsubscription is performed in this case, so it's the user responsibility to
+// unsubscribe.
 func (c *WSClient) ReceiveNotaryRequests(flt *neorpc.TxFilter, rcvr chan<- *result.NotaryRequestEvent) (string, error) {
 	if rcvr == nil {
 		return "", ErrNilNotificationReceiver