lncli: show fee_per_vbyte and local_close_tx in closechannel and closeallchannels output #10300

Suvrat1629 · 2025-10-18T05:40:52Z

Change Description

This PR updates the lncli closechannel and closeallchannels commands to include fee_per_vbyte and local_close_tx in their JSON output when available.

Refactors executeChannelClose to send all close details (txid, fee, local flag) via a struct.
Ensures both single and batch close flows print these fields in their output.

Fixes #9831

Steps to Test

Open a channel and close it using lncli closechannel with a custom fee.
Confirm the JSON output includes closing_txid, fee_per_vbyte, and local_close_tx.
Run lncli closeallchannels and confirm the output for each channel includes the new fields.

Pull Request Checklist

Testing

Your PR passes all CI checks.
Tests covering the positive and negative (error paths) are included.
Bug fixes contain tests triggering the bug to prevent regressions.

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The change obeys the Code Documentation and Commenting guidelines, and lines wrap at 80.
Commits follow the Ideal Git Commit Structure.
Any new logging statements use an appropriate subsystem and logging level.
Any new lncli commands have appropriate tags in the comments for the rpc in the proto file.
There is a change description in the release notes, or [skip ci] in the commit message for small changes.

📝 Please see our Contribution Guidelines for further guidance.

…loseallchannels output - Update closechannel and closeallchannels commands to display fee_per_vbyte and local_close_tx in the JSON output when available. - Refactor executeChannelClose to send all close details (txid, fee, local flag) via a struct.

gemini-code-assist · 2025-10-18T05:41:08Z

Summary of Changes

Hello @Suvrat1629, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly improves the user experience for lncli channel closing commands by enriching their JSON output. Users can now immediately access critical information such as the transaction fee per vbyte and whether the closure was initiated locally or remotely, directly from the closechannel and closeallchannels commands. This enhancement provides more comprehensive details for better monitoring and automation of channel management.

Highlights

Enhanced lncli Output: The lncli closechannel and closeallchannels commands now include fee_per_vbyte and local_close_tx in their JSON output, providing more detailed information about channel closures.
Refactored Channel Closing Logic: The executeChannelClose function has been refactored to pass all channel closing details (transaction ID, fee, and local/remote flag) via a dedicated CloseInfo struct, improving data encapsulation.
Consistent Information Across Commands: Both single channel and batch channel closing operations now consistently display these new fields in their output, ensuring a uniform user experience.

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Code Review

This pull request refactors the closechannel and closeallchannels commands to include fee_per_vbyte and local_close_tx in their JSON output. The change introduces a new CloseInfo struct and modifies executeChannelClose to communicate more details about the channel closure. The implementation is mostly correct, but there is a critical issue that can lead to deadlocks in both commands if the channel close stream ends before sending closing transaction details. I've provided comments and suggestions to fix this by ensuring the communication channel is always closed and handling this case in the receiving goroutines.

gemini-code-assist · 2025-10-18T05:43:08Z

cmd/commands/commands.go

 func executeChannelClose(ctxc context.Context, client lnrpc.LightningClient,
-	req *lnrpc.CloseChannelRequest, txidChan chan<- string, block bool) error {
+	req *lnrpc.CloseChannelRequest, closeInfoChan chan<- CloseInfo, block bool) error {



To prevent a potential deadlock in the calling functions (closeChannel and closeAllChannels), closeInfoChan should be closed when this function exits. If executeChannelClose returns without sending a value (for example, if the stream ends with io.EOF before a ClosePending update), the receiving goroutines will block indefinitely. Using defer to close the channel is the idiomatic way to ensure it's closed on all execution paths.

defer close(closeInfoChan)

gemini-code-assist · 2025-10-18T05:43:08Z

cmd/commands/commands.go

+		closeInfo := <-closeInfoChan
+		printJSON(closeInfo)


To complement the proposed change of always closing closeInfoChan in executeChannelClose, this read operation should be updated to handle the case where the channel is closed without a value being sent. Using the two-variable assignment form of a channel receive (value, ok := <-ch) allows checking whether a value was received before attempting to use it, preventing the printing of an empty JSON object if no close information is sent.

closeInfo, ok := <-closeInfoChan if ok { printJSON(closeInfo) }

gemini-code-assist · 2025-10-18T05:43:08Z

cmd/commands/commands.go

+			closeInfo := <-closeInfoChan
+			res.ClosingTxid = closeInfo.ClosingTxid
+			res.FeePerVbyte = closeInfo.FeePerVbyte
+			res.LocalCloseTx = closeInfo.LocalCloseTx


This blocking read from closeInfoChan can lead to a deadlock if executeChannelClose returns without sending data. To fix this, you should handle the case where the channel is closed without a value being sent. In the context of closeAllChannels, not receiving close information when no error occurred should be treated as a failure for that specific channel closure, and an appropriate error message should be set in the result.

closeInfo, ok := <-closeInfoChan if !ok { res.FailErr = "channel close stream ended " + "before sending closing transaction" return } res.ClosingTxid = closeInfo.ClosingTxid res.FeePerVbyte = closeInfo.FeePerVbyte res.LocalCloseTx = closeInfo.LocalCloseTx

NishantBansal2003

Nice work 👍, the direction looks good

My main comment is FeePerVbyte and LocalCloseTx are only populated when the node opts for rbf-coop-close, otherwise, these values are not set. When returning the response, they appear with default (wrong) values, so we should decide whether this is the intended behavior or if they should be updated in all cases.

NishantBansal2003 · 2025-10-19T08:40:52Z

cmd/commands/commands.go

+			if feeRate > 0 {
+				fmt.Fprintf(os.Stderr, "Fee rate: %d sat/vbyte\n", feeRate)
+			}


How would feeRate ever be negative?

NishantBansal2003 · 2025-10-19T08:42:10Z

cmd/commands/commands.go

+			var closeTypeMsg string
+			if isLocalClose {
+				closeTypeMsg = " (local close)"
+			} else {
+				closeTypeMsg = " (remote close)"
+			}
+
 			fmt.Fprintf(os.Stderr, "Channel close transaction "+
-				"broadcasted: %v\n", txid)
+				"broadcasted: %v%s\n", txid, closeTypeMsg)


I would say not required, since I can get this info from the JSON response anyway

NishantBansal2003 · 2025-10-19T08:45:00Z

cmd/commands/commands.go

-			txidChan := make(chan string, 1)
-			err = executeChannelClose(ctxc, client, req, txidChan, false)
+			closeInfoChan := make(chan CloseInfo, 1)
+			err = executeChannelClose(ctxc, client, req, closeInfoChan, false)


Required reading: https://github.com/lightningnetwork/lnd/blob/master/docs/development_guidelines.md

NishantBansal2003 · 2025-10-19T08:48:50Z

cmd/commands/commands.go

+			if !sentCloseInfo {
+				closeInfo := CloseInfo{
+					ClosingTxid:  txid.String(),
+					FeePerVbyte:  feeRate,
+					LocalCloseTx: isLocalClose,
+				}
+				closeInfoChan <- closeInfo
+				sentCloseInfo = true
+			}


Q: In which case could the CloseStatusUpdate_ClosePending stream be received more than once?

gemini-code-assist bot reviewed Oct 18, 2025

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NishantBansal2003 reviewed Oct 19, 2025

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lncli: show fee_per_vbyte and local_close_tx in closechannel and closeallchannels output #10300

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Suvrat1629 commented Oct 18, 2025 •

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Change Description

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Suvrat1629 commented Oct 18, 2025 •

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