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rt: Simplify reap_dead_tasks

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This commit is contained in:
Brian Anderson 2012-03-02 01:39:19 -08:00
parent 8efe4b8913
commit f057f00300
1 changed files with 13 additions and 20 deletions
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33
src/rt/rust_task_thread.cpp
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@ -122,33 +122,26 @@ rust_task_thread::number_of_live_tasks() {
void
rust_task_thread::reap_dead_tasks() {
I(this, lock.lock_held_by_current_thread());
if (dead_tasks.length() == 0) {
return;
}
// First make a copy of the dead_task list with the lock held
size_t dead_tasks_len = dead_tasks.length();
rust_task **dead_tasks_copy = (rust_task**)
srv->malloc(sizeof(rust_task*) * dead_tasks_len);
for (size_t i = 0; i < dead_tasks_len; ++i) {
dead_tasks_copy[i] = dead_tasks.pop_value();
}
A(this, dead_tasks.length() == 1,
"Only one task should die during a single turn of the event loop");
// Now unlock again because we have to actually free the dead tasks,
// and that may end up wanting to lock the kernel lock. We have
// a kernel lock -> scheduler lock locking order that we need
// to maintain.
// First make a copy of the dead_task list with the lock held
rust_task *dead_task = dead_tasks.pop_value();
// Dereferencing the task will probably cause it to be released
// from the scheduler, which may end up trying to take this lock
lock.unlock();
for (size_t i = 0; i < dead_tasks_len; ++i) {
rust_task *task = dead_tasks_copy[i];
// Release the task from the kernel so nobody else can get at it
kernel->release_task_id(task->id);
task->delete_all_stacks();
// Deref the task, which may cause it to request us to release it
task->deref();
}
srv->free(dead_tasks_copy);
// Release the task from the kernel so nobody else can get at it
kernel->release_task_id(dead_task->id);
dead_task->delete_all_stacks();
// Deref the task, which may cause it to request us to release it
dead_task->deref();
lock.lock();
}