Keep the same read buffer unless the last message was overly large
[rust-lightning] / lightning / src / ln / peer_handler.rs
index 5836a8d093187785aeee5373ccff95fbe9990217..f771cf4ff2a4b36d25720f526ad577a182e8b1e0 100644 (file)
@@ -33,7 +33,8 @@ use routing::network_graph::{NetworkGraph, NetGraphMsgHandler};
 use prelude::*;
 use io;
 use alloc::collections::LinkedList;
-use sync::{Arc, Mutex, MutexGuard, RwLock};
+use sync::{Arc, Mutex, MutexGuard, FairRwLock};
+use core::sync::atomic::{AtomicBool, Ordering};
 use core::{cmp, hash, fmt, mem};
 use core::ops::Deref;
 use core::convert::Infallible;
@@ -427,7 +428,7 @@ pub struct PeerManager<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, L: De
                L::Target: Logger,
                CMH::Target: CustomMessageHandler {
        message_handler: MessageHandler<CM, RM>,
-       peers: RwLock<PeerHolder<Descriptor>>,
+       peers: FairRwLock<PeerHolder<Descriptor>>,
        /// Only add to this set when noise completes.
        /// Locked *after* peers. When an item is removed, it must be removed with the `peers` write
        /// lock held. Entries may be added with only the `peers` read lock held (though the
@@ -437,6 +438,11 @@ pub struct PeerManager<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, L: De
        /// `peers` write lock to do so, so instead we block on this empty mutex when entering
        /// `process_events`.
        event_processing_lock: Mutex<()>,
+       /// Because event processing is global and always does all available work before returning,
+       /// there is no reason for us to have many event processors waiting on the lock at once.
+       /// Instead, we limit the total blocked event processors to always exactly one by setting this
+       /// when an event process call is waiting.
+       blocked_event_processors: AtomicBool,
        our_node_secret: SecretKey,
        ephemeral_key_midstate: Sha256Engine,
        custom_message_handler: CMH,
@@ -564,11 +570,12 @@ impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, L: Deref, CMH: Deref> P
 
                PeerManager {
                        message_handler,
-                       peers: RwLock::new(PeerHolder {
+                       peers: FairRwLock::new(PeerHolder {
                                peers: HashMap::new(),
                        }),
                        node_id_to_descriptor: Mutex::new(HashMap::new()),
                        event_processing_lock: Mutex::new(()),
+                       blocked_event_processors: AtomicBool::new(false),
                        our_node_secret,
                        ephemeral_key_midstate,
                        peer_counter: AtomicCounter::new(),
@@ -965,7 +972,7 @@ impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, L: Deref, CMH: Deref> P
                                                                if peer.pending_read_is_header {
                                                                        let msg_len = try_potential_handleerror!(peer,
                                                                                peer.channel_encryptor.decrypt_length_header(&peer.pending_read_buffer[..]));
-                                                                       peer.pending_read_buffer = Vec::with_capacity(msg_len as usize + 16);
+                                                                       if peer.pending_read_buffer.capacity() > 8192 { peer.pending_read_buffer = Vec::new(); }
                                                                        peer.pending_read_buffer.resize(msg_len as usize + 16, 0);
                                                                        if msg_len < 2 { // Need at least the message type tag
                                                                                return Err(PeerHandleError{ no_connection_possible: false });
@@ -977,7 +984,8 @@ impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, L: Deref, CMH: Deref> P
                                                                        assert!(msg_data.len() >= 2);
 
                                                                        // Reset read buffer
-                                                                       peer.pending_read_buffer = [0; 18].to_vec();
+                                                                       if peer.pending_read_buffer.capacity() > 8192 { peer.pending_read_buffer = Vec::new(); }
+                                                                       peer.pending_read_buffer.resize(18, 0);
                                                                        peer.pending_read_is_header = true;
 
                                                                        let mut reader = io::Cursor::new(&msg_data[..]);
@@ -1369,11 +1377,34 @@ impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, L: Deref, CMH: Deref> P
        /// You don't have to call this function explicitly if you are using [`lightning-net-tokio`]
        /// or one of the other clients provided in our language bindings.
        ///
+       /// Note that if there are any other calls to this function waiting on lock(s) this may return
+       /// without doing any work. All available events that need handling will be handled before the
+       /// other calls return.
+       ///
        /// [`send_payment`]: crate::ln::channelmanager::ChannelManager::send_payment
        /// [`ChannelManager::process_pending_htlc_forwards`]: crate::ln::channelmanager::ChannelManager::process_pending_htlc_forwards
        /// [`send_data`]: SocketDescriptor::send_data
        pub fn process_events(&self) {
-               let _single_processor_lock = self.event_processing_lock.lock().unwrap();
+               let mut _single_processor_lock = self.event_processing_lock.try_lock();
+               if _single_processor_lock.is_err() {
+                       // While we could wake the older sleeper here with a CV and make more even waiting
+                       // times, that would be a lot of overengineering for a simple "reduce total waiter
+                       // count" goal.
+                       match self.blocked_event_processors.compare_exchange(false, true, Ordering::AcqRel, Ordering::Acquire) {
+                               Err(val) => {
+                                       debug_assert!(val, "compare_exchange failed spuriously?");
+                                       return;
+                               },
+                               Ok(val) => {
+                                       debug_assert!(!val, "compare_exchange succeeded spuriously?");
+                                       // We're the only waiter, as the running process_events may have emptied the
+                                       // pending events "long" ago and there are new events for us to process, wait until
+                                       // its done and process any leftover events before returning.
+                                       _single_processor_lock = Ok(self.event_processing_lock.lock().unwrap());
+                                       self.blocked_event_processors.store(false, Ordering::Release);
+                               }
+                       }
+               }
 
                let mut peers_to_disconnect = HashMap::new();
                let mut events_generated = self.message_handler.chan_handler.get_and_clear_pending_msg_events();
@@ -1720,55 +1751,44 @@ impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, L: Deref, CMH: Deref> P
        ///
        /// [`send_data`]: SocketDescriptor::send_data
        pub fn timer_tick_occurred(&self) {
-               let mut peers_lock = self.peers.write().unwrap();
+               let mut descriptors_needing_disconnect = Vec::new();
                {
-                       let mut descriptors_needing_disconnect = Vec::new();
-                       let peer_count = peers_lock.peers.len();
+                       let peers_lock = self.peers.read().unwrap();
 
-                       peers_lock.peers.retain(|descriptor, peer_mutex| {
+                       for (descriptor, peer_mutex) in peers_lock.peers.iter() {
                                let mut peer = peer_mutex.lock().unwrap();
-                               let mut do_disconnect_peer = false;
                                if !peer.channel_encryptor.is_ready_for_encryption() || peer.their_node_id.is_none() {
                                        // The peer needs to complete its handshake before we can exchange messages. We
                                        // give peers one timer tick to complete handshake, reusing
                                        // `awaiting_pong_timer_tick_intervals` to track number of timer ticks taken
                                        // for handshake completion.
                                        if peer.awaiting_pong_timer_tick_intervals != 0 {
-                                               do_disconnect_peer = true;
+                                               descriptors_needing_disconnect.push(descriptor.clone());
                                        } else {
                                                peer.awaiting_pong_timer_tick_intervals = 1;
-                                               return true;
                                        }
+                                       continue;
                                }
 
                                if peer.awaiting_pong_timer_tick_intervals == -1 {
                                        // Magic value set in `maybe_send_extra_ping`.
                                        peer.awaiting_pong_timer_tick_intervals = 1;
                                        peer.received_message_since_timer_tick = false;
-                                       return true;
+                                       continue;
                                }
 
-                               if do_disconnect_peer
-                                       || (peer.awaiting_pong_timer_tick_intervals > 0 && !peer.received_message_since_timer_tick)
+                               if (peer.awaiting_pong_timer_tick_intervals > 0 && !peer.received_message_since_timer_tick)
                                        || peer.awaiting_pong_timer_tick_intervals as u64 >
-                                               MAX_BUFFER_DRAIN_TICK_INTERVALS_PER_PEER as u64 * peer_count as u64
+                                               MAX_BUFFER_DRAIN_TICK_INTERVALS_PER_PEER as u64 * peers_lock.peers.len() as u64
                                {
                                        descriptors_needing_disconnect.push(descriptor.clone());
-                                       match peer.their_node_id {
-                                               Some(node_id) => {
-                                                       log_trace!(self.logger, "Disconnecting peer with id {} due to ping timeout", node_id);
-                                                       self.node_id_to_descriptor.lock().unwrap().remove(&node_id);
-                                                       self.message_handler.chan_handler.peer_disconnected(&node_id, false);
-                                               }
-                                               None => {},
-                                       }
-                                       return false;
+                                       continue;
                                }
                                peer.received_message_since_timer_tick = false;
 
                                if peer.awaiting_pong_timer_tick_intervals > 0 {
                                        peer.awaiting_pong_timer_tick_intervals += 1;
-                                       return true;
+                                       continue;
                                }
 
                                peer.awaiting_pong_timer_tick_intervals = 1;
@@ -1778,9 +1798,22 @@ impl<Descriptor: SocketDescriptor, CM: Deref, RM: Deref, L: Deref, CMH: Deref> P
                                };
                                self.enqueue_message(&mut *peer, &ping);
                                self.do_attempt_write_data(&mut (descriptor.clone()), &mut *peer);
+                       }
+               }
 
-                               true
-                       });
+               if !descriptors_needing_disconnect.is_empty() {
+                       {
+                               let mut peers_lock = self.peers.write().unwrap();
+                               for descriptor in descriptors_needing_disconnect.iter() {
+                                       if let Some(peer) = peers_lock.peers.remove(&descriptor) {
+                                               if let Some(node_id) = peer.lock().unwrap().their_node_id {
+                                                       log_trace!(self.logger, "Disconnecting peer with id {} due to ping timeout", node_id);
+                                                       self.node_id_to_descriptor.lock().unwrap().remove(&node_id);
+                                                       self.message_handler.chan_handler.peer_disconnected(&node_id, false);
+                                               }
+                                       }
+                               }
+                       }
 
                        for mut descriptor in descriptors_needing_disconnect.drain(..) {
                                descriptor.disconnect_socket();