/**
* Initialize this kernel. Creates a synchronized console and sets the
* processor's exception handler.
*/
public void initialize(String[] args) {
super.initialize(args);
console = new SynchConsole(Machine.console());
Machine.processor().setExceptionHandler(new Runnable() {
public void run() { exceptionHandler(); }
});
}
public class SwapFile {
public static OpenFile swapFile;
private static String swapName;
private static int PAGESIZE = Machine.processor().pageSize;
public static List<Integer> freePages;
public static List<Integer> allocatedPages;
private static Lock swapLock;
private static byte[] memory = Machine.processor().getMemory();
public static void initialize(String filename) {
swapFile = ThreadedKernel.fileSystem.open(filename, true);
swapName = filename;
freePages = new LinkedList<Integer>();
allocatedPages = new LinkedList<Integer>();
swapLock = new Lock();
}
public static void close() {
swapFile.close();
ThreadedKernel.fileSystem.remove(swapName);
}
public static int insertPage(int spn, int ppn) {
swapLock.acquire();
int numBits = swapFile.write(spn * PAGESIZE, memory, ppn * PAGESIZE, PAGESIZE);
// assert that numBits == PAGESIZE
allocatedPages.add(spn);
swapLock.release();
return spn;
}
/* we will try to allocate a free page from the freepages*/
public static int insertPage(int ppn) {
int numBits = 0;
int spn = swapFile.length() / PAGESIZE;
if (freePages.size() > 0) {
spn = freePages.remove(0);
}
return insertPage(spn, ppn);
}
public static void readPage(int spn, int ppn) {
if (allocatedPages.contains(spn)) {
swapLock.acquire();
swapFile.read(spn * PAGESIZE, memory, ppn * PAGESIZE, PAGESIZE);
swapLock.release();
} else {
}
}
public static void free(int page) {
swapLock.acquire();
freePages.add(page);
swapLock.release();
}
}
/**
* Wake up at most one thread sleeping on this condition variable. The current thread must hold
* the associated lock.
*/
public void wake() {
Lib.assertTrue(conditionLock.isHeldByCurrentThread());
boolean intStatus = Machine.interrupt().disable(); // +hy+
((KThread) waitQueue.removeFirst()).ready(); // +hy+
Machine.interrupt().restore(intStatus); // +hy+
}
private void syncTLB() {
for (int i = 0; i < Machine.processor().getTLBSize(); i++) {
TranslationEntry tE = Machine.processor().readTLBEntry(i);
if (tE.valid) {
pageTable[tE.vpn].dirty = tE.dirty;
pageTable[tE.vpn].used = tE.used;
}
}
}
public void wakeJoinedThreads() {
boolean oldInterruptStatus = Machine.interrupt().disable();
KThread thread = null;
do {
thread = waitingKThreadListToJoin.nextThread();
if (thread != null) {
thread.ready();
}
} while (thread != null);
Machine.interrupt().restore(oldInterruptStatus);
}
/** Moves this thread to the ready state and adds this to the scheduler's ready queue. */
public void ready() {
Lib.debug(dbgThread, "Ready thread: " + toString());
Lib.assertTrue(Machine.interrupt().disabled());
Lib.assertTrue(status != statusReady);
status = statusReady;
if (this != idleThread) readyQueue.waitForAccess(this);
Machine.autoGrader().readyThread(this);
}
/**
* Atomically release the associated lock and go to sleep on this condition variable until another
* thread wakes it using <tt>wake()</tt>. The current thread must hold the associated lock. The
* thread will automatically reacquire the lock before <tt>sleep()</tt> returns.
*/
public void sleep() {
Lib.assertTrue(conditionLock.isHeldByCurrentThread());
boolean intStatus = Machine.interrupt().disable();
conditionLock.release();
waitQueue.waitForAccess(KThread.currentThread());
KThread.sleep();
conditionLock.acquire();
Machine.interrupt().restore(intStatus);
}
/**
* Wake up at most one thread sleeping on this condition variable. The current thread must hold
* the associated lock.
*/
public void wake() {
Lib.assertTrue(conditionLock.isHeldByCurrentThread());
boolean intStatus = Machine.interrupt().disable();
KThread thread = waitQueue.nextThread();
if (thread != null) {
thread.ready();
}
Machine.interrupt().restore(intStatus);
}
/**
* Save the state of this process in preparation for a context switch. Called by
* <tt>UThread.saveState()</tt>.
*/
public void saveState() {
for (int i = 0; i < Machine.processor().getTLBSize(); i++) {
TranslationEntry tE = Machine.processor().readTLBEntry(i);
if (tE.valid) {
pageTable[tE.vpn].dirty = tE.dirty;
pageTable[tE.vpn].used = tE.used;
}
tE.valid = false;
Machine.processor().writeTLBEntry(i, tE);
// savedState[i] = tE.vpn;
}
}
/**
* Relinquish the CPU if any other thread is ready to run. If so, put the current thread on the
* ready queue, so that it will eventually be rescheuled.
*
* <p>Returns immediately if no other thread is ready to run. Otherwise returns when the current
* thread is chosen to run again by <tt>readyQueue.nextThread()</tt>.
*
* <p>Interrupts are disabled, so that the current thread can atomically add itself to the ready
* queue and switch to the next thread. On return, restores interrupts to the previous state, in
* case <tt>yield()</tt> was called with interrupts disabled.
*/
public static void yield() {
Lib.debug(dbgThread, "Yielding thread: " + currentThread.toString());
Lib.assertTrue(currentThread.status == statusRunning);
boolean intStatus = Machine.interrupt().disable();
currentThread.ready();
runNextThread();
Machine.interrupt().restore(intStatus);
}
public void run() {
long wakeTime = randomDelay();
System.out.println(
"** "
+ name
+ ": Sleeping for "
+ wakeTime
+ " (i.e., until time="
+ (wakeTime + Machine.timer().getTime())
+ ")");
ThreadedKernel.alarm.waitUntil(wakeTime);
System.out.println(name + " is Done Sleeping (time=" + Machine.timer().getTime() + ")");
}
/**
* Put the current thread to sleep for at least <i>x</i> ticks, waking it up in the timer
* interrupt handler. The thread must be woken up (placed in the scheduler ready set) during the
* first timer interrupt where
*
* <p>
*
* <blockquote>
*
* (current time) >= (WaitUntil called time)+(x)
*
* </blockquote>
*
* @param x the minimum number of clock ticks to wait.
* @see nachos.machine.Timer#getTime()
*/
public void waitUntil(long x) {
// disable interrupts
Machine.interrupt().disable(); // let's see if this works? DAC DEBUG
// calculate wakeTime
long wakeTime = Machine.timer().getTime() + x;
// create AlarmBucket
AlarmBucket Abuck = new AlarmBucket(wakeTime, KThread.currentThread());
// add current thread (alarm bucket) to waitQueue
waitQueue.add(Abuck);
// put current thread to sleep
KThread.currentThread().sleep();
return;
}
/**
* Finish the current thread and schedule it to be destroyed when it is safe to do so. This method
* is automatically called when a thread's <tt>run</tt> method returns, but it may also be called
* directly.
*
* <p>The current thread cannot be immediately destroyed because its stack and other execution
* state are still in use. Instead, this thread will be destroyed automatically by the next thread
* to run, when it is safe to delete this thread.
*/
public static void finish() {
Lib.debug(dbgThread, "Finishing thread: " + currentThread.toString());
Machine.interrupt().disable();
Machine.autoGrader().finishingCurrentThread();
Lib.assertTrue(toBeDestroyed == null);
toBeDestroyed = currentThread;
currentThread.status = statusFinished;
sleep();
}
/**
* Dispatch the CPU to this thread. Save the state of the current thread, switch to the new thread
* by calling <tt>TCB.contextSwitch()</tt>, and load the state of the new thread. The new thread
* becomes the current thread.
*
* <p>If the new thread and the old thread are the same, this method must still call
* <tt>saveState()</tt>, <tt>contextSwitch()</tt>, and <tt>restoreState()</tt>.
*
* <p>The state of the previously running thread must already have been changed from running to
* blocked or ready (depending on whether the thread is sleeping or yielding).
*
* @param finishing <tt>true</tt> if the current thread is finished, and should be destroyed by
* the new thread.
*/
private void run() {
Lib.assertTrue(Machine.interrupt().disabled());
Machine.yield();
currentThread.saveState();
Lib.debug(dbgThread, "Switching from: " + currentThread.toString() + " to: " + toString());
currentThread = this;
tcb.contextSwitch();
currentThread.restoreState();
}
/**
* Waits for this thread to finish. If this thread is already finished, return immediately. This
* method must only be called once; the second call is not guaranteed to return. This thread must
* not be the current thread.
*/
public void join() {
Lib.debug(dbgThread, "Joining to thread: " + toString());
// FIXME Touhid :: join() edit starts
boolean intStatus = Machine.interrupt().setStatus(false);
if (status != statusFinished) { // Joinee is not finished yet
waitingKThreadListToJoin.waitForAccess(currentThread());
KThread.sleep();
}
Machine.interrupt().restore(intStatus);
// join() edit ends
Lib.assertTrue(this != currentThread);
}
/**
* The exception handler. This handler is called by the processor whenever
* a user instruction causes a processor exception.
*
* <p>
* When the exception handler is invoked, interrupts are enabled, and the
* processor's cause register contains an integer identifying the cause of
* the exception (see the <tt>exceptionZZZ</tt> constants in the
* <tt>Processor</tt> class). If the exception involves a bad virtual
* address (e.g. page fault, TLB miss, read-only, bus error, or address
* error), the processor's BadVAddr register identifies the virtual address
* that caused the exception.
*/
public void exceptionHandler() {
Lib.assert(KThread.currentThread() instanceof UThread);
UserProcess process = ((UThread) KThread.currentThread()).process;
int cause = Machine.processor().readRegister(Processor.regCause);
process.handleException(cause);
}
/**
* Transfer data from the specified array to this process's virtual memory. This method handles
* address translation details. This method must <i>not</i> destroy the current process if an
* error occurs, but instead should return the number of bytes successfully copied (or zero if no
* data could be copied).
*
* @param vaddr the first byte of virtual memory to write.
* @param data the array containing the data to transfer.
* @param offset the first byte to transfer from the array.
* @param length the number of bytes to transfer from the array to virtual memory.
* @return the number of bytes successfully transferred.
*/
public int writeVirtualMemory(int vaddr, byte[] data, int offset, int length) {
Lib.assertTrue(offset >= 0 && length >= 0 && offset + length <= data.length);
byte[] memory = Machine.processor().getMemory();
int transferred = 0;
while (length > 0 && offset < data.length) {
int addrOffset = vaddr % 1024;
int virtualPage = vaddr / 1024;
if (virtualPage >= pageTable.length || virtualPage < 0) {
break;
}
TranslationEntry pte = pageTable[virtualPage];
if (!pte.valid || pte.readOnly) {
break;
}
pte.used = true;
pte.dirty = true;
int physPage = pte.ppn;
int physAddr = physPage * 1024 + addrOffset;
int transferLength = Math.min(data.length - offset, Math.min(length, 1024 - addrOffset));
System.arraycopy(data, offset, memory, physAddr, transferLength);
vaddr += transferLength;
offset += transferLength;
length -= transferLength;
transferred += transferLength;
}
return transferred;
}
/**
* Waits for this thread to finish. If this thread is already finished, return immediately. This
* method must only be called once; the second call is not guaranteed to return. This thread must
* not be the current thread.
*/
public void join() {
boolean intStatus = Machine.interrupt().disable();
Lib.debug(dbgThread, "Joining to thread: " + toString());
Lib.assertTrue(this != currentThread);
if (cont == 0) {
cont = 1;
if (this.status == statusFinished) {
return;
} else {
this.joinList.add(currentThread);
currentThread.sleep();
}
}
Machine.interrupt().restore(intStatus);
}
/**
* Prepare this thread to be run. Set <tt>status</tt> to <tt>statusRunning</tt> and check
* <tt>toBeDestroyed</tt>.
*/
protected void restoreState() {
Lib.debug(dbgThread, "Running thread: " + currentThread.toString());
Lib.assertTrue(Machine.interrupt().disabled());
Lib.assertTrue(this == currentThread);
Lib.assertTrue(tcb == TCB.currentTCB());
Machine.autoGrader().runningThread(this);
status = statusRunning;
if (toBeDestroyed != null) {
toBeDestroyed.tcb.destroy();
toBeDestroyed.tcb = null;
toBeDestroyed = null;
}
}
@Override
protected void init() {
super.init();
System.out.println("\ninitializing VMGrader..");
System.out.println("physical pages = " + Machine.processor().getNumPhysPages());
if (hasArgument(SwapFile)) swapFile = getStringArgument(SwapFile);
}
/**
* Finish the current thread and schedule it to be destroyed when it is safe to do so. This method
* is automatically called when a thread's <tt>run</tt> method returns, but it may also be called
* directly.
*
* <p>The current thread cannot be immediately destroyed because its stack and other execution
* state are still in use. Instead, this thread will be destroyed automatically by the next thread
* to run, when it is safe to delete this thread.
*/
public static void finish() {
Lib.debug(dbgThread, "Finishing thread: " + currentThread.toString());
// FIXME Touhid :: Wake threads that have joined the currently running
// thread
currentThread.wakeJoinedThreads();
Machine.interrupt().disable();
Machine.autoGrader().finishingCurrentThread();
Lib.assertTrue(toBeDestroyed == null);
toBeDestroyed = currentThread;
currentThread.status = statusFinished;
sleep();
}
/**
* Allocate a new Alarm. Set the machine's timer interrupt handler to this alarm's callback.
*
* <p><b>Note</b>: Nachos will not function correctly with more than one alarm.
*/
public Alarm() {
Machine.timer()
.setInterruptHandler(
new Runnable() {
public void run() {
timerInterrupt();
}
});
}
/**
* Wait for a thread to speak through this communicator, and then return the <i>word</i> that
* thread passed to <tt>speak()</tt>.
*
* @return the integer transferred.
*/
public int listen() {
boolean intStatus = Machine.interrupt().disable();
condLock.acquire();
listenCount++;
speakCond.wake();
if (msgList.isEmpty()) listenCond.sleep();
condLock.release();
Machine.interrupt().restore(intStatus);
// Must have msg if reach here.
return msgList.remove(0);
}
/**
* Relinquish the CPU, because the current thread has either finished or it is blocked. This
* thread must be the current thread.
*
* <p>If the current thread is blocked (on a synchronization primitive, i.e. a <tt>Semaphore</tt>,
* <tt>Lock</tt>, or <tt>Condition</tt>), eventually some thread will wake this thread up, putting
* it back on the ready queue so that it can be rescheduled. Otherwise, <tt>finish()</tt> should
* have scheduled this thread to be destroyed by the next thread to run.
*/
public static void sleep() {
Lib.debug(dbgThread, "Sleeping thread: " + currentThread.toString());
Lib.assertTrue(Machine.interrupt().disabled());
if (currentThread.status != statusFinished) currentThread.status = statusBlocked;
runNextThread();
}
/** Handle the halt() system call. */
private int handleHalt() {
if (this.process_id != ROOT) {
return 0;
}
Machine.halt();
Lib.assertNotReached("Machine.halt() did not halt machine!");
return 0;
}
private void begin() {
Lib.debug(dbgThread, "Beginning thread: " + toString());
Lib.assertTrue(this == currentThread);
restoreState();
Machine.interrupt().enable();
}
/**
* Start running user programs, by creating a process and running a shell
* program in it. The name of the shell program it must run is returned by
* <tt>Machine.getShellProgramName()</tt>.
*
* @see nachos.machine.Machine#getShellProgramName
*/
public void run() {
super.run();
UserProcess process = UserProcess.newUserProcess();
String shellProgram = Machine.getShellProgramName();
Lib.assert(process.execute(shellProgram, new String[] { }));
KThread.currentThread().finish();
}
/**
* Wait for a thread to listen through this communicator, and then transfer <i>word</i> to the
* listener.
*
* <p>Does not return until this thread is paired up with a listening thread. Exactly one listener
* should receive <i>word</i>.
*
* @param word the integer to transfer.
*/
public void speak(int word) {
boolean intStatus = Machine.interrupt().disable();
condLock.acquire();
if (listenCount == 0) {
speakCond.sleep();
}
listenCount--;
msgList.add(word);
listenCond.wake();
condLock.release();
Machine.interrupt().restore(intStatus);
}
/**
* Causes this thread to begin execution. The result is that two threads are running concurrently:
* the current thread (which returns from the call to the <tt>fork</tt> method) and the other
* thread (which executes its target's <tt>run</tt> method).
*/
public void fork() {
Lib.assertTrue(status == statusNew);
Lib.assertTrue(target != null);
Lib.debug(dbgThread, "Forking thread: " + toString() + " Runnable: " + target);
boolean intStatus = Machine.interrupt().disable();
tcb.start(
new Runnable() {
public void run() {
runThread();
}
});
ready();
Machine.interrupt().restore(intStatus);
}
@Override
protected int handleTestSystemCall(int type, int a0, int a1, int a2) {
switch (type) {
case ActionPhyPages:
return Machine.processor().getNumPhysPages();
case ActionGetSwapSize:
return getSwapSize();
default:
return super.handleTestSystemCall(type, a0, a1, a2);
}
}