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// +build linux, darwin, freebsd
// +private
package thread
import "core:runtime"
import "core:intrinsics"
import "core:sync"
import "core:sys/unix"
// NOTE(tetra): Aligned here because of core/unix/pthread_linux.odin/pthread_t.
// Also see core/sys/darwin/mach_darwin.odin/semaphore_t.
Thread_Os_Specific :: struct #align 16 {
unix_thread: unix.pthread_t, // NOTE: very large on Darwin, small on Linux.
// NOTE: pthread has a proc to query this, but it is marked
// as non-portable ("np") so we do this instead.
done: bool,
// since libpthread doesn't seem to have a way to create a thread
// in a suspended state, we have it wait on this gate, which we
// signal to start it.
// destroyed after thread is started.
start_gate: sync.Condition,
start_mutex: sync.Mutex,
// if true, the thread has been started and the start_gate has been destroyed.
started: bool,
// NOTE: with pthreads, it is undefined behavior for multiple threads
// to call join on the same thread at the same time.
// this value is atomically updated to detect this.
// See the comment in `join`.
already_joined: bool,
}
//
// Creates a thread which will run the given procedure.
// It then waits for `start` to be called.
//
_create :: proc(procedure: Thread_Proc, priority := Thread_Priority.Normal) -> ^Thread {
__linux_thread_entry_proc :: proc "c" (t: rawptr) -> rawptr {
context = runtime.default_context();
t := (^Thread)(t);
sync.condition_wait_for(&t.start_gate);
sync.condition_destroy(&t.start_gate);
sync.mutex_destroy(&t.start_mutex);
t.start_gate = {};
t.start_mutex = {};
c := context;
if ic, ok := t.init_context.?; ok {
c = ic;
}
context = c;
t.procedure(t);
if t.init_context == nil {
if context.temp_allocator.data == &runtime.global_default_temp_allocator_data {
runtime.default_temp_allocator_destroy(auto_cast context.temp_allocator.data);
}
}
intrinsics.atomic_store(&t.done, true);
return nil;
}
attrs: unix.pthread_attr_t;
if unix.pthread_attr_init(&attrs) != 0 {
return nil; // NOTE(tetra, 2019-11-01): POSIX OOM.
}
defer unix.pthread_attr_destroy(&attrs);
// NOTE(tetra, 2019-11-01): These only fail if their argument is invalid.
assert(unix.pthread_attr_setdetachstate(&attrs, unix.PTHREAD_CREATE_JOINABLE) == 0);
assert(unix.pthread_attr_setinheritsched(&attrs, unix.PTHREAD_EXPLICIT_SCHED) == 0);
thread := new(Thread);
if thread == nil {
return nil;
}
thread.creation_allocator = context.allocator;
// Set thread priority.
policy: i32;
res := unix.pthread_attr_getschedpolicy(&attrs, &policy);
assert(res == 0);
params: unix.sched_param;
res = unix.pthread_attr_getschedparam(&attrs, ¶ms);
assert(res == 0);
low := unix.sched_get_priority_min(policy);
high := unix.sched_get_priority_max(policy);
switch priority {
case .Normal: // Okay
case .Low: params.sched_priority = low + 1;
case .High: params.sched_priority = high;
}
res = unix.pthread_attr_setschedparam(&attrs, ¶ms);
assert(res == 0);
if unix.pthread_create(&thread.unix_thread, &attrs, __linux_thread_entry_proc, thread) != 0 {
free(thread, thread.creation_allocator);
return nil;
}
thread.procedure = procedure;
sync.mutex_init(&thread.start_mutex);
sync.condition_init(&thread.start_gate, &thread.start_mutex);
return thread;
}
_start :: proc(t: ^Thread) {
if intrinsics.atomic_xchg(&t.started, true) {
return;
}
sync.condition_signal(&t.start_gate);
}
_is_done :: proc(t: ^Thread) -> bool {
return intrinsics.atomic_load(&t.done);
}
_join :: proc(t: ^Thread) {
if unix.pthread_equal(unix.pthread_self(), t.unix_thread) {
return;
}
// if unix.pthread_self().x == t.unix_thread.x do return;
// NOTE(tetra): It's apparently UB for multiple threads to join the same thread
// at the same time.
// If someone else already did, spin until the thread dies.
// See note on `already_joined` field.
// TODO(tetra): I'm not sure if we should do this, or panic, since I'm not
// sure it makes sense to need to join from multiple threads?
if intrinsics.atomic_xchg(&t.already_joined, true) {
for {
if intrinsics.atomic_load(&t.done) {
return;
}
intrinsics.cpu_relax();
}
}
// NOTE(tetra): If we're already dead, don't bother calling to pthread_join as that
// will just return 3 (ESRCH).
// We do this instead because I don't know if there is a danger
// that you may join a different thread from the one you called join on,
// if the thread handle is reused.
if intrinsics.atomic_load(&t.done) {
return;
}
ret_val: rawptr;
_ = unix.pthread_join(t.unix_thread, &ret_val);
if !intrinsics.atomic_load(&t.done) {
panic("thread not done after join");
}
}
_join_multiple :: proc(threads: ..^Thread) {
for t in threads {
_join(t);
}
}
_destroy :: proc(t: ^Thread) {
_join(t);
sync.condition_destroy(&t.start_gate);
sync.mutex_destroy(&t.start_mutex);
t.unix_thread = {};
free(t, t.creation_allocator);
}
_terminate :: proc(t: ^Thread, exit_code: int) {
// TODO(bill)
}
_yield :: proc() {
unix.sched_yield();
}
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