Multiple threads can now wait on the same pipe.

sortix/Makefile

@@ -82,6 +82,7 @@ elf.o \
 process.o \
 initrd.o \
 thread.o \
+event.o \
 io.o \
 pipe.o \
 filesystem.o \

sortix/event.cpp

@@ -0,0 +1,67 @@
+/******************************************************************************
+
+	COPYRIGHT(C) JONAS 'SORTIE' TERMANSEN 2011.
+
+	This file is part of Sortix.
+
+	Sortix is free software: you can redistribute it and/or modify it under the
+	terms of the GNU General Public License as published by the Free Software
+	Foundation, either version 3 of the License, or (at your option) any later
+	version.
+
+	Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
+	WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+	FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+	details.
+
+	You should have received a copy of the GNU General Public License along
+	with Sortix. If not, see <http://www.gnu.org/licenses/>.
+
+	event.cpp
+	Each thread can wait for an event to happen and be signaled when it does.
+
+******************************************************************************/
+
+#include "platform.h"
+#include "thread.h"
+#include "syscall.h"
+#include "event.h"
+
+namespace Sortix
+{
+	Event::Event()
+	{
+		waiting = NULL;
+	}
+
+	Event::~Event()
+	{
+		if ( waiting )
+		{
+			Panic("Thread was waiting on event, but it went out of scope");
+		}
+	}
+
+	void Event::Register()
+	{
+		Thread* thread = CurrentThread();
+		if ( thread->event )
+		{
+			Panic("Thread tried to wait on an event, but was already waiting");
+		}
+		thread->event = this;
+		thread->eventnextwaiting = waiting;
+		waiting = thread;
+	}
+
+	void Event::Signal()
+	{
+		while ( waiting )
+		{
+			waiting->event = NULL;
+			Syscall::ScheduleResumption(waiting);
+			waiting = waiting->eventnextwaiting;
+		}		
+	}
+}
+

sortix/event.h

@@ -0,0 +1,49 @@
+/******************************************************************************
+
+	COPYRIGHT(C) JONAS 'SORTIE' TERMANSEN 2011.
+
+	This file is part of Sortix.
+
+	Sortix is free software: you can redistribute it and/or modify it under the
+	terms of the GNU General Public License as published by the Free Software
+	Foundation, either version 3 of the License, or (at your option) any later
+	version.
+
+	Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
+	WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+	FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+	details.
+
+	You should have received a copy of the GNU General Public License along
+	with Sortix. If not, see <http://www.gnu.org/licenses/>.
+
+	event.h
+	Each thread can wait for an event to happen and be signaled when it does.
+
+******************************************************************************/
+
+#ifndef SORTIX_EVENT_H
+#define SORTIX_EVENT_H
+
+namespace Sortix
+{
+	class Thread;
+
+	class Event
+	{
+	public:
+		Event();
+		~Event();
+
+	public:
+		void Register();
+		void Signal();
+
+	private:
+		Thread* waiting;
+
+	};
+}
+
+#endif
+

sortix/pipe.cpp

@@ -25,6 +25,7 @@
 #include "platform.h"
 #include <libmaxsi/error.h>
 #include <libmaxsi/memory.h>
+#include "event.h"
 #include "thread.h"
 #include "process.h"
 #include "syscall.h"
@@ -48,8 +49,8 @@ namespace Sortix
 		size_t buffersize;
 		size_t bufferoffset;
 		size_t bufferused;
-		Thread* readwaiting;
-		Thread* writewaiting;
+		Event readevent;
+		Event writeevent;
 
 	public:
 		virtual ssize_t Read(byte* dest, size_t count);
@@ -65,14 +66,10 @@ namespace Sortix
 		this->buffersize = buffersize;
 		this->bufferoffset = 0;
 		this->bufferused = 0;
-		this->readwaiting = NULL;
-		this->writewaiting = NULL;
 	}
 
 	DevPipeStorage::~DevPipeStorage()
 	{
-		if ( readwaiting ) { Syscall::ScheduleResumption(readwaiting); }
-		if ( writewaiting ) { Syscall::ScheduleResumption(writewaiting); }
 		delete[] buffer;
 	}
 
@@ -91,20 +88,13 @@ namespace Sortix
 			Memory::Copy(dest, buffer + bufferoffset, amount);
 			bufferoffset = (bufferoffset + amount) % buffersize;
 			bufferused -= amount;
-			if ( writewaiting )
-			{
-				Syscall::ScheduleResumption(writewaiting);
-				writewaiting = NULL;
-			}
+			writeevent.Signal();
 			if ( bufferused == 0 || amount == count ) { return amount; }
 			return amount + Read(dest + amount, count - amount);
 		}
 
 		Error::Set(EWOULDBLOCK);
-
-		// TODO: Only one thread can wait on a pipe at the same time.
-		ASSERT(readwaiting == NULL);
-		readwaiting = CurrentThread();
+		readevent.Register();
 		return -1;
 	}
 
@@ -120,20 +110,13 @@ namespace Sortix
 			if ( linear < amount ) { amount = linear; }
 			Memory::Copy(buffer + writeoffset, src, amount);
 			bufferused += amount;
-			if ( readwaiting )
-			{
-				Syscall::ScheduleResumption(readwaiting);
-				readwaiting = NULL;
-			}
+			readevent.Signal();
 			if ( buffersize == bufferused || amount == count ) { return amount; }
 			return amount + Write(src + amount, count - amount);
 		}
 
 		Error::Set(EWOULDBLOCK);
-
-		// TODO: Only one thread can wait on a pipe at the same time.
-		ASSERT(writewaiting == NULL);
-		writewaiting = CurrentThread();
+		writeevent.Register();
 		return -1;
 	}
 

sortix/thread.cpp

@@ -42,6 +42,8 @@ namespace Sortix
 		process = NULL;
 		prevsibling = NULL;
 		nextsibling = NULL;
+		event = NULL;
+		eventnextwaiting = NULL;
 		sleepuntil = 0;
 		nextsleepingthread = NULL;
 		schedulerlistprev = NULL;
@@ -62,6 +64,8 @@ namespace Sortix
 		prevsibling = NULL;
 		nextsibling = NULL;
 		state = forkfrom->state;
+		event = NULL;
+		eventnextwaiting = NULL;
 		sleepuntil = forkfrom->sleepuntil;
 		Maxsi::Memory::Copy(&registers, &forkfrom->registers, sizeof(registers));
 		ready = false;

sortix/thread.h

@@ -29,6 +29,7 @@
 
 namespace Sortix
 {
+	class Event;
 	class Process;
 	class Thread;
 
@@ -62,6 +63,12 @@ namespace Sortix
 		Thread* prevsibling;
 		Thread* nextsibling;
 
+	// These are used internally when a thread is waiting for an Event to
+	// happen. Consider them private.
+	public:
+		Event* event;
+		Thread* eventnextwaiting;
+
 	// These are some things used internally by the scheduler and should not be
 	// touched by anything but it. Consider it private.
 	public: