Merge pull request #1599 from holochain/signal-shutdown

Signal shutdown

CHANGELOG-UNRELEASED.md

@@ -7,6 +7,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 ### Added
 - **BREAKING:** Zomes must now include a `validate_agent` callback. If this rejects in any zome the DNA will not start. This can be used to enforce membrane requirements. [#1497](https://github.com/holochain/holochain-rust/pull/1497)
 - Added a `get_links_count` method which allows the user to get number of links by base and tag [#1568](https://github.com/holochain/holochain-rust/pull/1568)### Changed
+- The Conductor will shut down gracefully when receiving SIGINT (i.e. Ctrl+C) or SIGKILL, also causing a graceful shutdown of an attached n3h instance, if running [#1599](https://github.com/holochain/holochain-rust/pull/1599)
 
 ### Deprecated
 

conductor/Cargo.toml

@@ -8,6 +8,7 @@ holochain_core_types = { path = "../core_types" }
 holochain_conductor_api = { path = "../conductor_api" }
 lib3h_sodium = "=0.0.7"
 holochain_common = { path = "../common" }
+signal-hook = "=0.1.9"
 structopt = "=0.2.15"
 tiny_http = "=0.6.2"
 ws = "=0.8.0"

conductor/src/main.rs

@@ -17,14 +17,16 @@
 extern crate holochain_conductor_api;
 extern crate holochain_core_types;
 extern crate lib3h_sodium;
+extern crate signal_hook;
 extern crate structopt;
 
 use holochain_conductor_api::{
     conductor::{mount_conductor_from_config, Conductor, CONDUCTOR},
     config::{self, load_configuration, Configuration},
 };
 use holochain_core_types::error::HolochainError;
-use std::{fs::File, io::prelude::*, path::PathBuf, sync::Arc, thread::sleep, time::Duration};
+use signal_hook::{iterator::Signals, SIGINT, SIGTERM};
+use std::{fs::File, io::prelude::*, path::PathBuf, sync::Arc};
 use structopt::StructOpt;
 
 #[derive(StructOpt, Debug)]
@@ -43,6 +45,8 @@ fn main() {
         .config
         .unwrap_or(config::default_persistence_dir().join("conductor-config.toml"));
     let config_path_str = config_path.to_str().unwrap();
+    let termination_signals =
+        Signals::new(&[SIGINT, SIGTERM]).expect("Couldn't create signals list");
     println!("Using config path: {}", config_path_str);
     match bootstrap_from_config(config_path_str) {
         Ok(()) => {
@@ -66,9 +70,24 @@ fn main() {
                     .expect("Could not start UI servers!");
             }
 
-            // TODO wait for a SIGKILL or SIGINT instead here.
-            loop {
-                sleep(Duration::from_secs(1))
+            for _sig in termination_signals.forever() {
+                let mut conductor_guard = CONDUCTOR.lock().unwrap();
+                let conductor = std::mem::replace(&mut *conductor_guard, None);
+                let refs = Arc::strong_count(&CONDUCTOR);
+                if refs == 1 {
+                    println!("Gracefully shutting down conductor...");
+                } else {
+                    println!(
+                        "Explicitly shutting down conductor. {} other threads were referencing it, so if unwrap errors follow, that might be why.",
+                        refs - 1
+                    );
+                    conductor
+                        .expect("No conductor running")
+                        .shutdown()
+                        .expect("Error shutting down conductor");
+                }
+                break;
+                // NB: conductor is dropped here and should shut down itself
             }
         }
         Err(error) => println!("Error while trying to boot from config: {:?}", error),

conductor_api/src/conductor/base.rs

@@ -117,7 +117,10 @@ impl Drop for Conductor {
                 kill();
             }
         }
-        self.shutdown();
+
+        self.shutdown()
+            .unwrap_or_else(|err| println!("Error during shutdown, continuing anyway: {:?}", err));
+
         if let Some(network) = self.n3h_keepalive_network.take() {
             if let Err(err) = network.stop() {
                 println!("ERROR stopping network thread: {:?}", err);
@@ -446,16 +449,14 @@ impl Conductor {
     }
 
     /// Stop and clear all instances
-    /// @QUESTION: why don't we care about errors on shutdown?
-    pub fn shutdown(&mut self) {
-        let _ = self
-            .stop_all_instances()
-            .map_err(|error| notify(format!("Error during shutdown: {}", error)));
+    pub fn shutdown(&mut self) -> Result<(), HolochainInstanceError> {
+        self.stop_all_instances()?;
         self.stop_all_interfaces();
         self.signal_multiplexer_kill_switch
             .as_ref()
             .map(|sender| sender.send(()));
         self.instances = HashMap::new();
+        Ok(())
     }
 
     pub fn spawn_network(&mut self) -> Result<SpawnResult, HolochainError> {
@@ -564,7 +565,7 @@ impl Conductor {
         }
 
         let config = self.config.clone();
-        self.shutdown();
+        self.shutdown().map_err(|e| e.to_string())?;
 
         self.start_signal_multiplexer();