From a23176e6d3399bbeb75cf6a173543bf5d5f85187 Mon Sep 17 00:00:00 2001
From: Mikko Rasa <tdb@tdb.fi>
Date: Mon, 22 Apr 2013 13:54:32 +0300
Subject: [PATCH] Make the Thread state machine more strict

Trying to re-launch a thread after it has finished now throws a
logic_error.

Added a state to indicate the thread having finished.
---
 source/core/thread.cpp | 39 ++++++++++++++++++++++++---------------
 source/core/thread.h   | 17 ++++++++++++++++-
 2 files changed, 40 insertions(+), 16 deletions(-)

diff --git a/source/core/thread.cpp b/source/core/thread.cpp
index cfc0c37..6c542e6 100644
--- a/source/core/thread.cpp
+++ b/source/core/thread.cpp
@@ -4,8 +4,11 @@
 #include <pthread.h>
 #include <signal.h>
 #endif
+#include <stdexcept>
 #include "thread.h"
 
+using namespace std;
+
 namespace Msp {
 
 struct Thread::Private
@@ -19,33 +22,35 @@ struct Thread::Private
 	Private(): handle(0) { }
 
 #ifdef WIN32
-	static DWORD WINAPI main_wrapper(void *t)
-	{ reinterpret_cast<Thread *>(t)->main(); return 0; }
+	static DWORD WINAPI
 #else
-	static void *main_wrapper(void *t)
-	{ reinterpret_cast<Thread *>(t)->main(); return 0; }
+	static void *
 #endif
+	main_wrapper(void *a)
+	{
+		Thread *t = reinterpret_cast<Thread *>(a);
+		t->main();
+		t->state_ = FINISHED;
+		return 0;
+	}
 };
 
 
 Thread::Thread():
 	priv_(new Private),
-	launched_(false)
+	state_(PENDING)
 { }
 
 Thread::~Thread()
 {
-	if(launched_)
-	{
-		kill();
-		join();
-	}
+	kill();
+	join();
 	delete priv_;
 }
 
 void Thread::join()
 {
-	if(!launched_)
+	if(state_>=JOINED)
 		return;
 
 #ifdef WIN32
@@ -53,22 +58,26 @@ void Thread::join()
 #else
 	pthread_join(priv_->handle, 0);
 #endif
-	launched_ = false;
+	state_ = JOINED;
 }
 
 void Thread::kill()
 {
+	if(state_!=RUNNING)
+		return;
+
 #ifdef WIN32
 	TerminateThread(priv_->handle, 0);
 #else
 	pthread_kill(priv_->handle, SIGKILL);
 #endif
+	state_ = KILLED;
 }
 
 void Thread::launch()
 {
-	if(launched_)
-		return;
+	if(state_>=RUNNING)
+		throw logic_error("already launched");
 
 #ifdef WIN32
 	DWORD dummy;  // Win9x needs the lpTthreadId parameter
@@ -76,7 +85,7 @@ void Thread::launch()
 #else
 	pthread_create(&priv_->handle, 0, &Private::main_wrapper, this);
 #endif
-	launched_ = true;
+	state_ = RUNNING;
 }
 
 } // namespace Msp
diff --git a/source/core/thread.h b/source/core/thread.h
index ae25707..81494ea 100644
--- a/source/core/thread.h
+++ b/source/core/thread.h
@@ -15,8 +15,17 @@ class Thread
 private:
 	struct Private;
 
+	enum State
+	{
+		PENDING,
+		RUNNING,
+		FINISHED,
+		KILLED,
+		JOINED
+	};
+
 	Private *priv_;
-	bool launched_;
+	State state_;
 
 protected:
 	Thread();
@@ -26,6 +35,9 @@ private:
 public:
 	virtual ~Thread();
 
+	/** Indicates whether the thread has finished running. */
+	bool is_finished() { return state_>=FINISHED; }
+
 	/** Waits for the thread to exit.  Calling this from the thread will cause a
 	deadlock. */
 	void join();
@@ -33,8 +45,11 @@ public:
 	/** Violently terminates the thread.  This should only be used as a last
 	resort, as the thread gets no chance to clean up. */
 	void kill();
+
 protected:
+	/** Starts the thread.  Can only be called once for each Thread instance. */
 	void launch();
+
 	virtual void main() = 0;
 };
 
-- 
2.45.2