| // Copyright 2023 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| //go:build wasip1 |
| |
| package runtime |
| |
| // wasm has no support for threads yet. There is no preemption. |
| // See proposal: https://github.com/WebAssembly/threads |
| // Waiting for a mutex or timeout is implemented as a busy loop |
| // while allowing other goroutines to run. |
| |
| const ( |
| mutex_unlocked = 0 |
| mutex_locked = 1 |
| |
| active_spin = 4 |
| active_spin_cnt = 30 |
| ) |
| |
| func lock(l *mutex) { |
| lockWithRank(l, getLockRank(l)) |
| } |
| |
| func lock2(l *mutex) { |
| if l.key == mutex_locked { |
| // wasm is single-threaded so we should never |
| // observe this. |
| throw("self deadlock") |
| } |
| gp := getg() |
| if gp.m.locks < 0 { |
| throw("lock count") |
| } |
| gp.m.locks++ |
| l.key = mutex_locked |
| } |
| |
| func unlock(l *mutex) { |
| unlockWithRank(l) |
| } |
| |
| func unlock2(l *mutex) { |
| if l.key == mutex_unlocked { |
| throw("unlock of unlocked lock") |
| } |
| gp := getg() |
| gp.m.locks-- |
| if gp.m.locks < 0 { |
| throw("lock count") |
| } |
| l.key = mutex_unlocked |
| } |
| |
| // One-time notifications. |
| func noteclear(n *note) { |
| n.key = 0 |
| } |
| |
| func notewakeup(n *note) { |
| if n.key != 0 { |
| print("notewakeup - double wakeup (", n.key, ")\n") |
| throw("notewakeup - double wakeup") |
| } |
| n.key = 1 |
| } |
| |
| func notesleep(n *note) { |
| throw("notesleep not supported by wasi") |
| } |
| |
| func notetsleep(n *note, ns int64) bool { |
| throw("notetsleep not supported by wasi") |
| return false |
| } |
| |
| // same as runtimeĀ·notetsleep, but called on user g (not g0) |
| func notetsleepg(n *note, ns int64) bool { |
| gp := getg() |
| if gp == gp.m.g0 { |
| throw("notetsleepg on g0") |
| } |
| |
| deadline := nanotime() + ns |
| for { |
| if n.key != 0 { |
| return true |
| } |
| if sched_yield() != 0 { |
| throw("sched_yield failed") |
| } |
| Gosched() |
| if ns >= 0 && nanotime() >= deadline { |
| return false |
| } |
| } |
| } |
| |
| func beforeIdle(int64, int64) (*g, bool) { |
| return nil, false |
| } |
| |
| func checkTimeouts() {} |
| |
| //go:wasmimport wasi_snapshot_preview1 sched_yield |
| func sched_yield() errno |