/**
* Context switch between the current TCB and this TCB. This TCB will become the new current TCB.
* It is acceptable for this TCB to be the current TCB.
*/
public void contextSwitch() {
/* Probably unnecessary sanity check: we make sure that the current
* thread is bound to the current TCB. This check can only fail if
* non-Nachos threads invoke start().
*/
Lib.assertTrue(currentTCB.javaThread == Thread.currentThread());
// make sure AutoGrader.runningThread() called associateThread()
Lib.assertTrue(currentTCB.associated);
currentTCB.associated = false;
// can't switch from a TCB to itself
if (this == currentTCB) return;
/* There are some synchronization concerns here. As soon as we wake up
* the next thread, we cannot assume anything about static variables,
* or about any TCB's state. Therefore, before waking up the next
* thread, we must latch the value of currentTCB, and set its running
* flag to false (so that, in case we get interrupted before we call
* yield(), the interrupt will set the running flag and yield() won't
* block).
*/
TCB previous = currentTCB;
previous.running = false;
this.interrupt();
previous.yield();
}
/**
* Nachos main entry point.
*
* @param args the command line arguments.
*/
public static void main(final String[] args) {
System.out.print("nachos 5.0j initializing...");
Lib.assertTrue(Machine.args == null);
Machine.args = args;
processArgs();
Config.load(configFileName);
// get the current directory (.)
baseDirectory = new File(new File("").getAbsolutePath());
// get the nachos directory (./nachos)
nachosDirectory = new File(baseDirectory, "nachos");
String testDirectoryName = Config.getString("FileSystem.testDirectory");
// get the test directory
if (testDirectoryName != null) {
testDirectory = new File(testDirectoryName);
} else {
// use ../test
testDirectory = new File(baseDirectory.getParentFile(), "test");
}
securityManager = new NachosSecurityManager(testDirectory);
privilege = securityManager.getPrivilege();
privilege.machine = new MachinePrivilege();
TCB.givePrivilege(privilege);
privilege.stats = stats;
securityManager.enable();
createDevices();
checkUserClasses();
autoGrader = (AutoGrader) Lib.constructObject(autoGraderClassName);
new TCB()
.start(
new Runnable() {
public void run() {
autoGrader.start(privilege);
}
});
}
/** Terminate Nachos. Same as <tt>TCB.die()</tt>. */
public static void terminate() {
TCB.die();
}
public void authorizeDestroy(KThread thread) {
TCB.authorizeDestroy(thread);
}
public void associateThread(KThread thread) {
Lib.assertTrue(currentTCB != null);
currentTCB.associateThread(thread);
}