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https://github.com/tinygo-org/tinygo.git
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Nia Waldvogel
641dcd7c16
This change implements a new "scheduler" for WebAssembly using binaryen's asyncify transform. This is more reliable than the current "coroutines" transform, and works with non-Go code in the call stack. runtime (js/wasm): handle scheduler nesting If WASM calls into JS which calls back into WASM, it is possible for the scheduler to nest. The event from the callback must be handled immediately, so the task cannot simply be deferred to the outer scheduler. This creates a minimal scheduler loop which is used to handle such nesting.
80 lines
1.7 KiB
Go
80 lines
1.7 KiB
Go
//go:build wasm && !wasi
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// +build wasm,!wasi
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package runtime
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import "unsafe"
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type timeUnit float64 // time in milliseconds, just like Date.now() in JavaScript
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// wasmNested is used to detect scheduler nesting (WASM calls into JS calls back into WASM).
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// When this happens, we need to use a reduced version of the scheduler.
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var wasmNested bool
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//export _start
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func _start() {
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// These need to be initialized early so that the heap can be initialized.
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heapStart = uintptr(unsafe.Pointer(&heapStartSymbol))
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heapEnd = uintptr(wasm_memory_size(0) * wasmPageSize)
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wasmNested = true
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run()
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wasmNested = false
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}
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var handleEvent func()
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//go:linkname setEventHandler syscall/js.setEventHandler
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func setEventHandler(fn func()) {
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handleEvent = fn
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}
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//export resume
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func resume() {
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go func() {
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handleEvent()
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}()
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if wasmNested {
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minSched()
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return
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}
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wasmNested = true
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scheduler()
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wasmNested = false
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}
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//export go_scheduler
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func go_scheduler() {
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if wasmNested {
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minSched()
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return
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}
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wasmNested = true
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scheduler()
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wasmNested = false
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}
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func ticksToNanoseconds(ticks timeUnit) int64 {
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// The JavaScript API works in float64 milliseconds, so convert to
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// nanoseconds first before converting to a timeUnit (which is a float64),
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// to avoid precision loss.
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return int64(ticks * 1e6)
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}
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func nanosecondsToTicks(ns int64) timeUnit {
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// The JavaScript API works in float64 milliseconds, so convert to timeUnit
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// (which is a float64) first before dividing, to avoid precision loss.
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return timeUnit(ns) / 1e6
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}
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// This function is called by the scheduler.
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// Schedule a call to runtime.scheduler, do not actually sleep.
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//export runtime.sleepTicks
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func sleepTicks(d timeUnit)
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//export runtime.ticks
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func ticks() timeUnit
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