From d3b710fc183b8b71ab4726c2ae1b75caf13012b7 Mon Sep 17 00:00:00 2001
From: Brian Norris <banorris@uci.edu>
Date: Thu, 6 Sep 2012 13:17:06 -0700
Subject: [PATCH] threads: add a wait_list

This list will contain all Threads that are waiting on the current Thread. Will
be used for Thread joins, in particular.
---
 threads.cc |  1 +
 threads.h  | 27 +++++++++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/threads.cc b/threads.cc
index a939592..7fa4507 100644
--- a/threads.cc
+++ b/threads.cc
@@ -123,6 +123,7 @@ Thread::Thread(thrd_t *t, void (*func)(void *), void *a) :
 	arg(a),
 	user_thread(t),
 	state(THREAD_CREATED),
+	wait_list(),
 	last_action_val(VALUE_NONE)
 {
 	int ret;
diff --git a/threads.h b/threads.h
index f7efcf9..25b1d64 100644
--- a/threads.h
+++ b/threads.h
@@ -7,6 +7,7 @@
 
 #include <ucontext.h>
 #include <stdint.h>
+#include <vector>
 
 #include "mymemory.h"
 #include "libthreads.h"
@@ -70,6 +71,25 @@ public:
 	/** @return True if this thread is finished executing */
 	bool is_complete() { return state == THREAD_COMPLETED; }
 
+	/** @return True if no threads are waiting on this Thread */
+	bool wait_list_empty() { return wait_list.empty(); }
+
+	/**
+	 * Add a thread to the waiting list for this thread.
+	 * @param t The Thread to add
+	 */
+	void push_wait_list(Thread *t) { wait_list.push_back(t); }
+
+	/**
+	 * Remove one Thread from the waiting list
+	 * @return The Thread that was removed from the waiting list
+	 */
+	Thread * pop_wait_list() {
+		Thread *ret = wait_list.front();
+		wait_list.pop_back();
+		return ret;
+	}
+
 	friend void thread_startup();
 
 	SNAPSHOTALLOC
@@ -86,6 +106,13 @@ private:
 	thread_id_t id;
 	thread_state state;
 
+	/**
+	 * A list of Threads waiting on this Thread. Particularly, this list is
+	 * used for thread joins, where another Thread waits for this Thread to
+	 * complete
+	 */
+	std::vector<Thread *> wait_list;
+
 	/**
 	 * The value returned by the last action in this thread
 	 * @see Thread::set_return_value()
-- 
2.34.1