Add documentation about PaymentSent/Failed event duplication bug

[rust-lightning] / src / util / events.rs

diff --git a/src/util/events.rs b/src/util/events.rs
index 58eec665225659cdbb0cc2afebea8518dabfbbbf..a317f076658acac1f984f2df6c8b6cbcb2c5ff6e 100644 (file)
--- a/src/util/events.rs
+++ b/src/util/events.rs
@@ -1,3 +1,17 @@
+//! Events are returned from various bits in the library which indicate some action must be taken
+//! by the client.
+//!
+//! Because we don't have a built-in runtime, its up to the client to call events at a time in the
+//! future, as well as generate and broadcast funding transactions handle payment preimages and a
+//! few other things.
+//!
+//! Note that many events are handled for you by PeerHandler, so in the common design of having a
+//! PeerManager which marshalls messages to ChannelManager and Router you only need to call
+//! process_events on the PeerHandler and then get_and_clear_pending_events and handle the events
+//! that bubble up to the surface. If, however, you do not have a PeerHandler managing a
+//! ChannelManager you need to handle all of the events which may be generated.
+//TODO: We need better separation of event types ^
+
 use ln::msgs;
 use chain::transaction::OutPoint;
 
@@ -7,6 +21,7 @@ use secp256k1::key::PublicKey;
 
 use std::time::Instant;
 
+/// An Event which you should probably take some action in response to.
 pub enum Event {
        // Events a user will probably have to handle
        /// Used to indicate that the client should generate a funding transaction with the given
@@ -45,6 +60,8 @@ pub enum Event {
        },
        /// Indicates an outbound payment we made succeeded (ie it made it all the way to its target
        /// and we got back the payment preimage for it).
+       /// Note that duplicative PaymentSent Events may be generated - it is your responsibility to
+       /// deduplicate them by payment_preimage (which MUST be unique)!
        PaymentSent {
                /// The preimage to the hash given to ChannelManager::send_payment.
                /// Note that this serves as a payment receipt, if you wish to have such a thing, you must
@@ -53,6 +70,8 @@ pub enum Event {
        },
        /// Indicates an outbound payment we made failed. Probably some intermediary node dropped
        /// something. You may wish to retry with a different route.
+       /// Note that duplicative PaymentFailed Events may be generated - it is your responsibility to
+       /// deduplicate them by payment_hash (which MUST be unique)!
        PaymentFailed {
                /// The hash which was given to ChannelManager::send_payment.
                payment_hash: [u8; 32],
@@ -68,6 +87,7 @@ pub enum Event {
        // TODO: Move these into a separate struct and make a top-level enum
        /// Used to indicate that we've initialted a channel open and should send the open_channel
        /// message provided to the given peer.
+       ///
        /// This event is handled by PeerManager::process_events if you are using a PeerManager.
        SendOpenChannel {
                /// The node_id of the node which should receive this message
@@ -76,6 +96,7 @@ pub enum Event {
                msg: msgs::OpenChannel,
        },
        /// Used to indicate that a funding_created message should be sent to the peer with the given node_id.
+       ///
        /// This event is handled by PeerManager::process_events if you are using a PeerManager.
        SendFundingCreated {
                /// The node_id of the node which should receive this message
@@ -84,6 +105,7 @@ pub enum Event {
                msg: msgs::FundingCreated,
        },
        /// Used to indicate that a funding_locked message should be sent to the peer with the given node_id.
+       ///
        /// This event is handled by PeerManager::process_events if you are using a PeerManager.
        SendFundingLocked {
                /// The node_id of the node which should receive these message(s)
@@ -95,6 +117,7 @@ pub enum Event {
        },
        /// Used to indicate that a series of HTLC update messages, as well as a commitment_signed
        /// message should be sent to the peer with the given node_id.
+       ///
        /// This event is handled by PeerManager::process_events if you are using a PeerManager.
        UpdateHTLCs {
                /// The node_id of the node which should receive these message(s)
@@ -103,6 +126,7 @@ pub enum Event {
                updates: msgs::CommitmentUpdate,
        },
        /// Used to indicate that a shutdown message should be sent to the peer with the given node_id.
+       ///
        /// This event is handled by PeerManager::process_events if you are using a PeerManager.
        SendShutdown {
                /// The node_id of the node which should receive this message
@@ -112,6 +136,7 @@ pub enum Event {
        },
        /// Used to indicate that a channel_announcement and channel_update should be broadcast to all
        /// peers (except the peer with node_id either msg.contents.node_id_1 or msg.contents.node_id_2).
+       ///
        /// This event is handled by PeerManager::process_events if you are using a PeerManager.
        BroadcastChannelAnnouncement {
                /// The channel_announcement which should be sent.
@@ -120,6 +145,7 @@ pub enum Event {
                update_msg: msgs::ChannelUpdate,
        },
        /// Used to indicate that a channel_update should be broadcast to all peers.
+       ///
        /// This event is handled by PeerManager::process_events if you are using a PeerManager.
        BroadcastChannelUpdate {
                /// The channel_update which should be sent.
@@ -128,6 +154,7 @@ pub enum Event {
 
        //Error handling
        /// Broadcast an error downstream to be handled
+       ///
        /// This event is handled by PeerManager::process_events if you are using a PeerManager.
        HandleError {
                /// The node_id of the node which should receive this message
@@ -137,6 +164,9 @@ pub enum Event {
        }
 }
 
+/// A trait indicating an object may generate events
 pub trait EventsProvider {
+       /// Gets the list of pending events which were generated by previous actions, clearing the list
+       /// in the process.
        fn get_and_clear_pending_events(&self) -> Vec<Event>;
 }