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scheduler.cc File Reference

#include "copyright.h"
#include "scheduler.h"
#include "system.h"
#include "thread.h"
#include <signal.h>
#include <time.h>
#include <unistd.h>
#include <setjmp.h>

Go to the source code of this file.

Functions

void SetPreemption ()
void timerInit ()
void schedule ()

Variables

sigjmp_buf schd_jmp
Thread bogus_th ("starter")
sigset_t timer_mask
timer_t timer_id
itimerspec timer_value
itimerspec timer_empty
bool preempt = false

Function Documentation

void schedule (   ) 
 

Definition at line 198 of file scheduler.cc.

References bogus_th, Thread::cbuff, currentThread, DEBUG(), Interrupt::Enable(), Scheduler::FindNextToRun(), Thread::getName(), interrupt, Scheduler::ReadyToRun(), RUNNING, scheduler, Thread::setStatus(), Thread::started, SWITCH(), threadToBeDestroyed, timer_empty, timer_id, timer_mask, and timer_value.

Referenced by main(), Scheduler::timerIntH(), and Thread::Yield().

00199 {
00200     Thread *nextThread = 0;
00201 
00202     // disarm the alarm
00203     timer_settime(timer_id, 0, &timer_empty, 0);
00204 
00205     nextThread = scheduler->FindNextToRun();
00206 
00207     if (threadToBeDestroyed != NULL)
00208     {
00209         currentThread = 0;
00210         DEBUG('t', "Purge Thread \"%s\"\n", threadToBeDestroyed->getName());
00211         delete threadToBeDestroyed;
00212         threadToBeDestroyed = NULL;
00213     }
00214 
00215     if (nextThread != NULL)
00216     {
00217         if (currentThread)
00218             scheduler->ReadyToRun(currentThread); // set to READY
00219 
00220         currentThread = nextThread;    // switch to the next thread
00221         //swap over here
00222         if (!currentThread->started)
00223         {
00224             currentThread->started = 1;
00225             currentThread->setStatus(RUNNING);    // set to RUNNING
00226             DEBUG('t', "^Create^ \"%s\"\n", currentThread->getName());
00227             interrupt->Enable();
00228             timer_settime(timer_id, 0, &timer_value, 0);
00229             // use the NachOS switch to get the thread going for the
00230             // time and then begin to use the siglongjmp way
00231             SWITCH(&bogus_th, currentThread);
00232         }
00233         else
00234         {
00235             DEBUG('t', "Sched \"%s\"\n", currentThread->getName());
00236             currentThread->setStatus(RUNNING);    // set to RUNNING
00237             interrupt->Enable();
00238             timer_settime(timer_id, 0, &timer_value, 0);
00239             siglongjmp(currentThread->cbuff, 1);
00240         }
00241     }
00242     else if (currentThread)// only a single thread is left
00243     {
00244             DEBUG('t', "Only Thread \"%s\"\n", currentThread->getName());
00245             currentThread->setStatus(RUNNING);    // set to RUNNING
00246             interrupt->Enable();
00247             timer_settime(timer_id, 0, &timer_value, 0);
00248             sigprocmask(SIG_UNBLOCK, &timer_mask, 0);
00249             siglongjmp(currentThread->cbuff, 1);
00250     }
00251     else
00252     {
00253         // we are spinning while something is sleeping
00254         interrupt->Enable();
00255         timer_settime(timer_id, 0, &timer_value, 0);
00256     }
00257 }

void SetPreemption (   ) 
 

Definition at line 45 of file scheduler.cc.

References preempt.

00046 {
00047   preempt = true;
00048 }

void timerInit (   ) 
 

Definition at line 162 of file scheduler.cc.

References NSECS_PER_SEC, timer_empty, timer_id, timer_mask, and timer_value.

Referenced by main().

00163 {
00164     struct sigaction tact;
00165 
00166     //setup the timer handler and tell it to use an alternative signal stack
00167     memset(&tact, 0, sizeof(struct sigaction));
00168     tact.sa_handler = Scheduler::timerIntH;
00169     tact.sa_flags = 0;
00170     sigemptyset(&tact.sa_mask);
00171 
00172     sigemptyset(&timer_mask);
00173     sigaddset(&timer_mask, SIGALRM);
00174 
00175     if (sigaction(SIGALRM, &tact, NULL) != 0)
00176         printf("Failed to set the alarm handler\n");
00177 
00178     timer_create(CLOCK_REALTIME, 0, &timer_id);
00179     memset(&timer_value, 0, sizeof(struct itimerspec));
00180     memset(&timer_empty, 0, sizeof(struct itimerspec));
00181     timer_value.it_value.tv_sec = 0;
00182     timer_value.it_value.tv_nsec = NSECS_PER_SEC / 15;  // 0.0666 sec
00183     timer_settime(timer_id, 0, &timer_value, 0);
00184 }

Variable Documentation

Thread bogus_th("starter")
 

Referenced by schedule().

bool preempt = false
 

Definition at line 38 of file scheduler.cc.

Referenced by SetPreemption(), and Scheduler::timerIntH().

sigjmp_buf schd_jmp
 

Definition at line 31 of file scheduler.cc.

itimerspec timer_empty
 

Definition at line 36 of file scheduler.cc.

Referenced by schedule(), and timerInit().

timer_t timer_id
 

Definition at line 34 of file scheduler.cc.

Referenced by Cleanup(), schedule(), timerInit(), and Scheduler::timerIntH().

sigset_t timer_mask
 

Definition at line 33 of file scheduler.cc.

Referenced by schedule(), Interrupt::SetLevel(), and timerInit().

itimerspec timer_value
 

Definition at line 35 of file scheduler.cc.

Referenced by schedule(), timerInit(), and Scheduler::timerIntH().

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