Update ChannelManager's ChannelMonitor Arc to be a Deref

[rust-lightning] / lightning / src / chain / chaininterface.rs

diff --git a/lightning/src/chain/chaininterface.rs b/lightning/src/chain/chaininterface.rs
index 4f5eeeac58772120382accdcd16def25a2d3bbd4..3a2e69cd1cbe2bad22b8a06e58802fbe8a9f2dc9 100644 (file)
--- a/lightning/src/chain/chaininterface.rs
+++ b/lightning/src/chain/chaininterface.rs
@@ -14,9 +14,11 @@ use bitcoin::network::constants::Network;
 
 use util::logger::Logger;
 
-use std::sync::{Mutex,Weak,MutexGuard,Arc};
+use std::sync::{Mutex, MutexGuard, Arc};
 use std::sync::atomic::{AtomicUsize, Ordering};
 use std::collections::HashSet;
+use std::ops::Deref;
+use std::marker::PhantomData;
 
 /// Used to give chain error details upstream
 pub enum ChainError {
@@ -205,26 +207,48 @@ impl ChainWatchedUtil {
        }
 }
 
+/// BlockNotifierArc is useful when you need a BlockNotifier that points to ChainListeners with
+/// static lifetimes, e.g. when you're using lightning-net-tokio (since tokio::spawn requires
+/// parameters with static lifetimes). Other times you can afford a reference, which is more
+/// efficient, in which case BlockNotifierRef is a more appropriate type. Defining these type
+/// aliases prevents issues such as overly long function definitions.
+pub type BlockNotifierArc = Arc<BlockNotifier<'static, Arc<ChainListener>>>;
+
+/// BlockNotifierRef is useful when you want a BlockNotifier that points to ChainListeners
+/// with nonstatic lifetimes. This is useful for when static lifetimes are not needed. Nonstatic
+/// lifetimes are more efficient but less flexible, and should be used by default unless static
+/// lifetimes are required, e.g. when you're using lightning-net-tokio (since tokio::spawn
+/// requires parameters with static lifetimes), in which case BlockNotifierArc is a more
+/// appropriate type. Defining these type aliases for common usages prevents issues such as
+/// overly long function definitions.
+pub type BlockNotifierRef<'a> = BlockNotifier<'a, &'a ChainListener>;
+
 /// Utility for notifying listeners about new blocks, and handling block rescans if new watch
 /// data is registered.
-pub struct BlockNotifier {
-       listeners: Mutex<Vec<Weak<ChainListener>>>, //TODO(vmw): try removing Weak
+///
+/// Rather than using a plain BlockNotifier, it is preferable to use either a BlockNotifierArc
+/// or a BlockNotifierRef for conciseness. See their documentation for more details, but essentially
+/// you should default to using a BlockNotifierRef, and use a BlockNotifierArc instead when you
+/// require ChainListeners with static lifetimes, such as when you're using lightning-net-tokio.
+pub struct BlockNotifier<'a, CL: Deref<Target = ChainListener + 'a> + 'a> {
+       listeners: Mutex<Vec<CL>>,
        chain_monitor: Arc<ChainWatchInterface>,
+       phantom: PhantomData<&'a ()>,
 }
 
-impl BlockNotifier {
+impl<'a, CL: Deref<Target = ChainListener + 'a> + 'a> BlockNotifier<'a, CL> {
        /// Constructs a new BlockNotifier without any listeners.
-       pub fn new(chain_monitor: Arc<ChainWatchInterface>) -> BlockNotifier {
+       pub fn new(chain_monitor: Arc<ChainWatchInterface>) -> BlockNotifier<'a, CL> {
                BlockNotifier {
                        listeners: Mutex::new(Vec::new()),
                        chain_monitor,
+                       phantom: PhantomData,
                }
        }
 
-       /// Register the given listener to receive events. Only a weak pointer is provided and
-       /// the registration should be freed once that pointer expires.
+       /// Register the given listener to receive events.
        // TODO: unregister
-       pub fn register_listener(&self, listener: Weak<ChainListener>) {
+       pub fn register_listener(&self, listener: CL) {
                let mut vec = self.listeners.lock().unwrap();
                vec.push(listener);
        }
@@ -250,12 +274,9 @@ impl BlockNotifier {
        pub fn block_connected_checked(&self, header: &BlockHeader, height: u32, txn_matched: &[&Transaction], indexes_of_txn_matched: &[u32]) -> bool {
                let last_seen = self.chain_monitor.reentered();
 
-               let listeners = self.listeners.lock().unwrap().clone();
+               let listeners = self.listeners.lock().unwrap();
                for listener in listeners.iter() {
-                       match listener.upgrade() {
-                               Some(arc) => arc.block_connected(header, height, txn_matched, indexes_of_txn_matched),
-                               None => ()
-                       }
+                       listener.block_connected(header, height, txn_matched, indexes_of_txn_matched);
                }
                return last_seen != self.chain_monitor.reentered();
        }
@@ -263,12 +284,9 @@ impl BlockNotifier {
 
        /// Notify listeners that a block was disconnected.
        pub fn block_disconnected(&self, header: &BlockHeader, disconnected_height: u32) {
-               let listeners = self.listeners.lock().unwrap().clone();
+               let listeners = self.listeners.lock().unwrap();
                for listener in listeners.iter() {
-                       match listener.upgrade() {
-                               Some(arc) => arc.block_disconnected(&header, disconnected_height),
-                               None => ()
-                       }
+                       listener.block_disconnected(&header, disconnected_height);
                }
        }