From ffee69c35660827cd8bc6833abb4813ea74c1c7a Mon Sep 17 00:00:00 2001
From: Konrad `ktoso` Malawski <ktoso@apple.com>
Date: Thu, 29 Aug 2019 12:27:58 +0900
Subject: [PATCH] =backtrace #61 make use of swift-backtrace

---
 Package.swift                                             | 5 ++++-
 Sources/DistributedActors/ActorSystem.swift               | 6 ++++++
 Sources/DistributedActors/ActorSystemSettings.swift       | 3 +++
 Sources/DistributedActors/Cluster/ClusterShellState.swift | 2 +-
 4 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/Package.swift b/Package.swift
index d97c7f39f..fcd7800c8 100644
--- a/Package.swift
+++ b/Package.swift
@@ -15,6 +15,7 @@ let targets: [PackageDescription.Target] = [
             "SwiftProtobuf",
 
             "Logging", "Metrics",
+            "Backtrace",
 
             "DistributedActorsConcurrencyHelpers",
             "CDistributedActorsMailbox",
@@ -152,8 +153,10 @@ let dependencies: [Package.Dependency] = [
     .package(url: "https://github.com/apple/swift-log.git", from: "1.0.0"),
     .package(url: "https://github.com/apple/swift-metrics.git", from: "1.0.0"),
 
+    .package(url: "https://github.com/ianpartridge/swift-backtrace.git", .branch("master")),
+
     // ~~~ only for samples ~~~
-    .package(url: "https://github.com/MrLotU/SwiftPrometheus", .branch("master")),
+    .package(url: "https://github.com/MrLotU/SwiftPrometheus", .branch("master"))
 ]
 
 let package = Package(
diff --git a/Sources/DistributedActors/ActorSystem.swift b/Sources/DistributedActors/ActorSystem.swift
index 1529b8ef6..b0dfff474 100644
--- a/Sources/DistributedActors/ActorSystem.swift
+++ b/Sources/DistributedActors/ActorSystem.swift
@@ -12,6 +12,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+import Backtrace
 import CDistributedActorsMailbox
 import Dispatch
 import DistributedActorsConcurrencyHelpers
@@ -124,6 +125,11 @@ public final class ActorSystem {
         var settings = settings
         self.name = settings.cluster.node.systemName
 
+        // rely on swift-backtrace for pretty backtraces on crashes
+        if settings.installSwiftBacktrace {
+            Backtrace.install()
+        }
+
         // TODO: we should not rely on NIO for futures
         let eventLoopGroup = MultiThreadedEventLoopGroup(numberOfThreads: settings.threadPoolSize)
         settings.cluster.eventLoopGroup = eventLoopGroup
diff --git a/Sources/DistributedActors/ActorSystemSettings.swift b/Sources/DistributedActors/ActorSystemSettings.swift
index 2004873e5..2170e7a88 100644
--- a/Sources/DistributedActors/ActorSystemSettings.swift
+++ b/Sources/DistributedActors/ActorSystemSettings.swift
@@ -43,6 +43,9 @@ public struct ActorSystemSettings {
         }
     }
 
+    /// Installs a global backtrace (on fault) pretty-print facility upon actor system start.
+    public var installSwiftBacktrace: Bool = true
+
     // FIXME: should have more proper config section
     public var threadPoolSize: Int = ProcessInfo.processInfo.activeProcessorCount
 
diff --git a/Sources/DistributedActors/Cluster/ClusterShellState.swift b/Sources/DistributedActors/Cluster/ClusterShellState.swift
index 352566836..59033d5b3 100644
--- a/Sources/DistributedActors/Cluster/ClusterShellState.swift
+++ b/Sources/DistributedActors/Cluster/ClusterShellState.swift
@@ -178,7 +178,7 @@ extension ClusterShellState {
 
         switch state {
         case .initiated(let initiated):
-            assert(initiated.channel != nil, "Channel should always be present after the initial initialization.")
+            assert(initiated.channel != nil, "Channel should always be present after the initial initialization, state was: \(state)")
             _ = initiated.channel?.close()
         case .wasOfferedHandshake:
             fatalError("abortOutgoingHandshake was called in a context where the handshake was not an outgoing one! Was: \(state)")