rust/src/rt/rust_scheduler.cpp

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#include <stdarg.h>
#include "rust_internal.h"
#include "globals.h"
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rust_scheduler::rust_scheduler(rust_kernel *kernel,
rust_message_queue *message_queue, rust_srv *srv,
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const char *name) :
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interrupt_flag(0),
_log(srv, this),
log_lvl(log_note),
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srv(srv),
name(name),
newborn_tasks(this, "newborn"),
running_tasks(this, "running"),
blocked_tasks(this, "blocked"),
dead_tasks(this, "dead"),
cache(this),
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root_task(NULL),
curr_task(NULL),
rval(0),
kernel(kernel),
message_queue(message_queue)
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{
LOGPTR(this, "new dom", (uintptr_t)this);
isaac_init(this, &rctx);
#ifndef __WIN32__
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pthread_attr_init(&attr);
pthread_attr_setstacksize(&attr, 1024 * 1024);
pthread_attr_setdetachstate(&attr, true);
#endif
root_task = create_task(NULL, name);
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}
rust_scheduler::~rust_scheduler() {
DLOG(this, dom, "~rust_scheduler %s @0x%" PRIxPTR, name, (uintptr_t)this);
newborn_tasks.delete_all();
running_tasks.delete_all();
blocked_tasks.delete_all();
dead_tasks.delete_all();
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#ifndef __WIN32__
pthread_attr_destroy(&attr);
#endif
}
void
rust_scheduler::activate(rust_task *task) {
context ctx;
task->ctx.next = &ctx;
DLOG(this, task, "descheduling...");
kernel->scheduler_lock.unlock();
task->ctx.swap(ctx);
kernel->scheduler_lock.lock();
DLOG(this, task, "task has returned");
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}
void
rust_scheduler::log(rust_task* task, uint32_t level, char const *fmt, ...) {
char buf[BUF_BYTES];
va_list args;
va_start(args, fmt);
vsnprintf(buf, sizeof(buf), fmt, args);
_log.trace_ln(task, level, buf);
va_end(args);
}
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void
rust_scheduler::fail() {
log(NULL, log_err, "domain %s @0x%" PRIxPTR " root task failed",
name, this);
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I(this, rval == 0);
rval = 1;
}
size_t
rust_scheduler::number_of_live_tasks() {
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return running_tasks.length() + blocked_tasks.length();
}
/**
* Delete any dead tasks.
*/
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void
rust_scheduler::reap_dead_tasks(int id) {
I(this, kernel->scheduler_lock.lock_held_by_current_thread());
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for (size_t i = 0; i < dead_tasks.length(); ) {
rust_task *task = dead_tasks[i];
// Make sure this task isn't still running somewhere else...
if (task->ref_count == 0 && task->can_schedule(id)) {
I(this, task->tasks_waiting_to_join.is_empty());
dead_tasks.remove(task);
DLOG(this, task,
"deleting unreferenced dead task %s @0x%" PRIxPTR,
task->name, task);
delete task;
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continue;
}
++i;
}
}
/**
* Drains and processes incoming pending messages.
*/
void rust_scheduler::drain_incoming_message_queue(bool process) {
rust_message *message;
while (message_queue->dequeue(&message)) {
DLOG(this, comm, "<== receiving \"%s\" " PTR,
message->label, message);
if (process) {
message->process();
}
delete message;
}
}
/**
* Schedules a running task for execution. Only running tasks can be
* activated. Blocked tasks have to be unblocked before they can be
* activated.
*
* Returns NULL if no tasks can be scheduled.
*/
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rust_task *
rust_scheduler::schedule_task(int id) {
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I(this, this);
// FIXME: in the face of failing tasks, this is not always right.
// I(this, n_live_tasks() > 0);
if (running_tasks.length() > 0) {
size_t k = rand(&rctx);
// Look around for a runnable task, starting at k.
for(size_t j = 0; j < running_tasks.length(); ++j) {
size_t i = (j + k) % running_tasks.length();
if (running_tasks[i]->can_schedule(id)) {
return (rust_task *)running_tasks[i];
}
}
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}
return NULL;
}
void
rust_scheduler::log_state() {
if (log_rt_task < log_note) return;
if (!running_tasks.is_empty()) {
log(NULL, log_note, "running tasks:");
for (size_t i = 0; i < running_tasks.length(); i++) {
log(NULL, log_note, "\t task: %s @0x%" PRIxPTR " timeout: %d",
running_tasks[i]->name,
running_tasks[i],
running_tasks[i]->yield_timer.get_timeout());
}
}
if (!blocked_tasks.is_empty()) {
log(NULL, log_note, "blocked tasks:");
for (size_t i = 0; i < blocked_tasks.length(); i++) {
log(NULL, log_note, "\t task: %s @0x%" PRIxPTR ", blocked on: 0x%"
PRIxPTR " '%s'",
blocked_tasks[i]->name, blocked_tasks[i],
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blocked_tasks[i]->cond, blocked_tasks[i]->cond_name);
}
}
if (!dead_tasks.is_empty()) {
log(NULL, log_note, "dead tasks:");
for (size_t i = 0; i < dead_tasks.length(); i++) {
log(NULL, log_note, "\t task: %s 0x%" PRIxPTR ", ref_count: %d",
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dead_tasks[i]->name, dead_tasks[i],
dead_tasks[i]->ref_count);
}
}
}
/**
* Starts the main scheduler loop which performs task scheduling for this
* domain.
*
* Returns once no more tasks can be scheduled and all task ref_counts
* drop to zero.
*/
int
rust_scheduler::start_main_loop(int id) {
kernel->scheduler_lock.lock();
// Make sure someone is watching, to pull us out of infinite loops.
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//
// FIXME: time-based interruption is not presently working; worked
// in rustboot and has been completely broken in rustc.
//
// rust_timer timer(this);
DLOG(this, dom, "started domain loop %d", id);
while (number_of_live_tasks() > 0) {
A(this, kernel->is_deadlocked() == false, "deadlock");
DLOG(this, dom, "worker %d, number_of_live_tasks = %d",
id, number_of_live_tasks());
drain_incoming_message_queue(true);
rust_task *scheduled_task = schedule_task(id);
// The scheduler busy waits until a task is available for scheduling.
// Eventually we'll want a smarter way to do this, perhaps sleep
// for a minimum amount of time.
if (scheduled_task == NULL) {
log_state();
DLOG(this, task,
"all tasks are blocked, scheduler id %d yielding ...",
id);
kernel->scheduler_lock.unlock();
sync::sleep(100);
kernel->scheduler_lock.lock();
DLOG(this, task,
"scheduler resuming ...");
continue;
}
I(this, scheduled_task->running());
DLOG(this, task,
"activating task %s 0x%" PRIxPTR
", sp=0x%" PRIxPTR
", ref_count=%d"
", state: %s",
scheduled_task->name,
(uintptr_t)scheduled_task,
scheduled_task->rust_sp,
scheduled_task->ref_count,
scheduled_task->state->name);
interrupt_flag = 0;
DLOG(this, task,
"Running task %p on worker %d",
scheduled_task, id);
scheduled_task->running_on = id;
activate(scheduled_task);
scheduled_task->running_on = -1;
DLOG(this, task,
"returned from task %s @0x%" PRIxPTR
" in state '%s', sp=0x%x, worker id=%d" PRIxPTR,
scheduled_task->name,
(uintptr_t)scheduled_task,
scheduled_task->state->name,
scheduled_task->rust_sp,
id);
reap_dead_tasks(id);
}
DLOG(this, dom,
"terminated scheduler loop, reaping dead tasks ...");
while (dead_tasks.length() > 0) {
if (message_queue->is_empty()) {
DLOG(this, dom,
"waiting for %d dead tasks to become dereferenced, "
"scheduler yielding ...",
dead_tasks.length());
log_state();
kernel->scheduler_lock.unlock();
sync::yield();
kernel->scheduler_lock.lock();
} else {
drain_incoming_message_queue(true);
}
reap_dead_tasks(id);
}
DLOG(this, dom, "finished main-loop %d (dom.rval = %d)", id, rval);
kernel->scheduler_lock.unlock();
return rval;
}
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rust_crate_cache *
rust_scheduler::get_cache() {
return &cache;
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}
rust_task *
rust_scheduler::create_task(rust_task *spawner, const char *name) {
rust_task *task =
new (this->kernel) rust_task (this, &newborn_tasks, spawner, name);
DLOG(this, task, "created task: " PTR ", spawner: %s, name: %s",
task, spawner ? spawner->name : "null", name);
newborn_tasks.append(task);
return task;
}
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//
// Local Variables:
// mode: C++
// fill-column: 70;
// indent-tabs-mode: nil
// c-basic-offset: 4
// buffer-file-coding-system: utf-8-unix
// compile-command: "make -k -C .. 2>&1 | sed -e 's/\\/x\\//x:\\//g'";
// End:
//