From: valentinewallace <valentinewallace@users.noreply.github.com>
Date: Tue, 26 Apr 2022 17:02:29 +0000 (-0400)
Subject: Merge pull request #1436 from TheBlueMatt/2022-04-event-process-try-lock
X-Git-Tag: v0.0.107~55
X-Git-Url: http://git.bitcoin.ninja/index.cgi?a=commitdiff_plain;h=72069bfc9d082d3d142cfa09dca2bf6e1f085710;hp=-c;p=rust-lightning

Merge pull request #1436 from TheBlueMatt/2022-04-event-process-try-lock

Reorder the BP loop to make manager persistence more reliable
---

72069bfc9d082d3d142cfa09dca2bf6e1f085710
diff --combined lightning-background-processor/src/lib.rs
index 7a1512b7,255fb245..e23737c0
--- a/lightning-background-processor/src/lib.rs
+++ b/lightning-background-processor/src/lib.rs
@@@ -203,10 -203,22 +203,22 @@@ impl BackgroundProcessor 
  			let mut have_pruned = false;
  
  			loop {
- 				peer_manager.process_events(); // Note that this may block on ChannelManager's locking
  				channel_manager.process_pending_events(&event_handler);
  				chain_monitor.process_pending_events(&event_handler);
  
+ 				// Note that the PeerManager::process_events may block on ChannelManager's locks,
+ 				// hence it comes last here. When the ChannelManager finishes whatever it's doing,
+ 				// we want to ensure we get into `persist_manager` as quickly as we can, especially
+ 				// without running the normal event processing above and handing events to users.
+ 				//
+ 				// Specifically, on an *extremely* slow machine, we may see ChannelManager start
+ 				// processing a message effectively at any point during this loop. In order to
+ 				// minimize the time between such processing completing and persisting the updated
+ 				// ChannelManager, we want to minimize methods blocking on a ChannelManager
+ 				// generally, and as a fallback place such blocking only immediately before
+ 				// persistence.
+ 				peer_manager.process_events();
+ 
  				// We wait up to 100ms, but track how long it takes to detect being put to sleep,
  				// see `await_start`'s use below.
  				let await_start = Instant::now();
@@@ -335,9 -347,10 +347,9 @@@ mod tests 
  	use bitcoin::blockdata::constants::genesis_block;
  	use bitcoin::blockdata::transaction::{Transaction, TxOut};
  	use bitcoin::network::constants::Network;
 -	use lightning::chain::chaininterface::{BroadcasterInterface, FeeEstimator};
 -	use lightning::chain::{BestBlock, Confirm, chainmonitor, self};
 +	use lightning::chain::{BestBlock, Confirm, chainmonitor};
  	use lightning::chain::channelmonitor::ANTI_REORG_DELAY;
 -	use lightning::chain::keysinterface::{InMemorySigner, Recipient, KeysInterface, KeysManager, Sign};
 +	use lightning::chain::keysinterface::{InMemorySigner, Recipient, KeysInterface, KeysManager};
  	use lightning::chain::transaction::OutPoint;
  	use lightning::get_event_msg;
  	use lightning::ln::channelmanager::{BREAKDOWN_TIMEOUT, ChainParameters, ChannelManager, SimpleArcChannelManager};
@@@ -347,13 -360,15 +359,13 @@@
  	use lightning::routing::network_graph::{NetworkGraph, NetGraphMsgHandler};
  	use lightning::util::config::UserConfig;
  	use lightning::util::events::{Event, MessageSendEventsProvider, MessageSendEvent};
 -	use lightning::util::logger::Logger;
  	use lightning::util::ser::Writeable;
  	use lightning::util::test_utils;
  	use lightning::util::persist::KVStorePersister;
  	use lightning_invoice::payment::{InvoicePayer, RetryAttempts};
  	use lightning_invoice::utils::DefaultRouter;
  	use lightning_persister::FilesystemPersister;
 -	use std::fs::{self, File};
 -	use std::ops::Deref;
 +	use std::fs;
  	use std::path::PathBuf;
  	use std::sync::{Arc, Mutex};
  	use std::time::Duration;
@@@ -396,6 -411,7 +408,6 @@@
  	}
  
  	struct Persister {
 -		data_dir: String,
  		graph_error: Option<(std::io::ErrorKind, &'static str)>,
  		manager_error: Option<(std::io::ErrorKind, &'static str)>,
  		filesystem_persister: FilesystemPersister,
@@@ -404,7 -420,7 +416,7 @@@
  	impl Persister {
  		fn new(data_dir: String) -> Self {
  			let filesystem_persister = FilesystemPersister::new(data_dir.clone());
 -			Self { data_dir, graph_error: None, manager_error: None, filesystem_persister }
 +			Self { graph_error: None, manager_error: None, filesystem_persister }
  		}
  
  		fn with_graph_error(self, error: std::io::ErrorKind, message: &'static str) -> Self {