From 423b482c0bf33cf1f150dcb62482177841bba5e0 Mon Sep 17 00:00:00 2001
From: Florent Pillet <fpillet@gmail.com>
Date: Tue, 3 Jan 2017 08:39:30 +0100
Subject: [PATCH 1/4] Rewrote `executing` observable To guarantee consistent
 delivery of true / false values

---
 Sources/Action/Action.swift | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/Sources/Action/Action.swift b/Sources/Action/Action.swift
index 82511e28..78ed9aac 100644
--- a/Sources/Action/Action.swift
+++ b/Sources/Action/Action.swift
@@ -98,19 +98,14 @@ public final class Action<Input, Element> {
             .of(notEnabledError, underlyingError)
             .merge()
 
-        let executionStart = executionObservables
-        let executionEnd = executionObservables
-            .flatMap { observable -> Observable<Void> in
-                return observable
-                    .flatMap { _ in Observable<Void>.empty() }
-                    .concat(Observable.just())
-                    .catchErrorJustReturn()
+        executing = executionObservables.flatMap {
+                Observable
+                    .just(true)
+                    .concat($0.ignoreElements().map { _ in true }.catchError { _ in Observable.empty() })
+                    .concat(Observable.just(false))
             }
-
-        executing = Observable
-            .of(executionStart.map { _ in true }, executionEnd.map { _ in false })
-            .merge()
             .startWith(false)
+            .shareReplay(1)
 
         Observable
             .combineLatest(executing, enabledIf) { !$0 && $1 }

From ee0ebfcfb0ed11f9fad030525e4fad9a5984c481 Mon Sep 17 00:00:00 2001
From: Florent Pillet <fpillet@gmail.com>
Date: Tue, 3 Jan 2017 08:41:31 +0100
Subject: [PATCH 2/4] Remove incorrect information about delivery the
 `executing` events are not guaranteed to be delivered on MainScheduler

---
 Sources/Action/Action.swift | 1 -
 1 file changed, 1 deletion(-)

diff --git a/Sources/Action/Action.swift b/Sources/Action/Action.swift
index 78ed9aac..3c812658 100644
--- a/Sources/Action/Action.swift
+++ b/Sources/Action/Action.swift
@@ -38,7 +38,6 @@ public final class Action<Input, Element> {
     public let elements: Observable<Element>
 
     /// Whether or not we're currently executing. 
-    /// Always observed on MainScheduler.
     public let executing: Observable<Bool>
 
     /// Observables returned by the workFactory.

From 96850ff517562308188467e22f97f317bf9af808 Mon Sep 17 00:00:00 2001
From: Florent Pillet <fpillet@gmail.com>
Date: Tue, 3 Jan 2017 09:30:49 +0100
Subject: [PATCH 3/4] An even better and clearer way to write the `executing`
 concatenation

---
 Sources/Action/Action.swift | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/Sources/Action/Action.swift b/Sources/Action/Action.swift
index 3c812658..33420071 100644
--- a/Sources/Action/Action.swift
+++ b/Sources/Action/Action.swift
@@ -98,10 +98,10 @@ public final class Action<Input, Element> {
             .merge()
 
         executing = executionObservables.flatMap {
-                Observable
-                    .just(true)
-                    .concat($0.ignoreElements().map { _ in true }.catchError { _ in Observable.empty() })
-                    .concat(Observable.just(false))
+                Observable.concat([
+                    Observable.just(true),
+                    $0.ignoreElements().map { _ in true }.catchError { _ in Observable.empty() },
+                    Observable.just(false)])
             }
             .startWith(false)
             .shareReplay(1)

From 5a17cfeb9dc2452cec4b0404ca4af0d42d1a7d24 Mon Sep 17 00:00:00 2001
From: Florent Pillet <fpillet@gmail.com>
Date: Tue, 3 Jan 2017 09:57:37 +0100
Subject: [PATCH 4/4] Tweaked `executing` observable code as per @ishkawa's
 suggestion

---
 Sources/Action/Action.swift | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/Sources/Action/Action.swift b/Sources/Action/Action.swift
index 33420071..8d0b50fe 100644
--- a/Sources/Action/Action.swift
+++ b/Sources/Action/Action.swift
@@ -98,10 +98,14 @@ public final class Action<Input, Element> {
             .merge()
 
         executing = executionObservables.flatMap {
-                Observable.concat([
-                    Observable.just(true),
-                    $0.ignoreElements().map { _ in true }.catchError { _ in Observable.empty() },
-                    Observable.just(false)])
+                execution -> Observable<Bool> in
+                let execution = execution
+                    .flatMap { _ in Observable<Bool>.empty() }
+                    .catchError { _ in Observable.empty()}
+
+                return Observable.concat([Observable.just(true),
+                                          execution,
+                                          Observable.just(false)])
             }
             .startWith(false)
             .shareReplay(1)
@@ -117,7 +121,7 @@ public final class Action<Input, Element> {
         defer {
             inputs.onNext(value)
         }
-        
+
         let execution = executionObservables
             .take(1)
             .flatMap { $0 }