WIP map every goroutine to a new OS thread

Author: aykevl

GNUmakefile

@@ -934,6 +934,7 @@ endif
 	@cp -rp lib/musl/src/malloc          build/release/tinygo/lib/musl/src
 	@cp -rp lib/musl/src/mman            build/release/tinygo/lib/musl/src
 	@cp -rp lib/musl/src/math            build/release/tinygo/lib/musl/src
+	@cp -rp lib/musl/src/misc            build/release/tinygo/lib/musl/src
 	@cp -rp lib/musl/src/multibyte       build/release/tinygo/lib/musl/src
 	@cp -rp lib/musl/src/signal          build/release/tinygo/lib/musl/src
 	@cp -rp lib/musl/src/stdio           build/release/tinygo/lib/musl/src

builder/musl.go

@@ -127,6 +127,7 @@ var libMusl = Library{
 			"malloc/mallocng/*.c",
 			"mman/*.c",
 			"math/*.c",
+			"misc/*.c",
 			"multibyte/*.c",
 			"signal/" + arch + "/*.s",
 			"signal/*.c",

compileopts/config.go

@@ -340,6 +340,7 @@ func (c *Config) CFlags(libclang bool) []string {
 			"-nostdlibinc",
 			"-isystem", filepath.Join(path, "include"),
 			"-isystem", filepath.Join(root, "lib", "musl", "arch", arch),
+			"-isystem", filepath.Join(root, "lib", "musl", "arch", "generic"),
 			"-isystem", filepath.Join(root, "lib", "musl", "include"),
 		)
 	case "wasi-libc":

compileopts/options.go

@@ -10,7 +10,7 @@ import (
 var (
 	validBuildModeOptions     = []string{"default", "c-shared"}
 	validGCOptions            = []string{"none", "leaking", "conservative", "custom", "precise"}
-	validSchedulerOptions     = []string{"none", "tasks", "asyncify"}
+	validSchedulerOptions     = []string{"none", "tasks", "asyncify", "threads"}
 	validSerialOptions        = []string{"none", "uart", "usb", "rtt"}
 	validPrintSizeOptions     = []string{"none", "short", "full"}
 	validPanicStrategyOptions = []string{"print", "trap"}

compileopts/options_test.go

@@ -10,7 +10,7 @@ import (
 func TestVerifyOptions(t *testing.T) {
 
 	expectedGCError := errors.New(`invalid gc option 'incorrect': valid values are none, leaking, conservative, custom, precise`)
-	expectedSchedulerError := errors.New(`invalid scheduler option 'incorrect': valid values are none, tasks, asyncify`)
+	expectedSchedulerError := errors.New(`invalid scheduler option 'incorrect': valid values are none, tasks, asyncify, threads`)
 	expectedPrintSizeError := errors.New(`invalid size option 'incorrect': valid values are none, short, full`)
 	expectedPanicStrategyError := errors.New(`invalid panic option 'incorrect': valid values are print, trap`)
 

compileopts/target.go

@@ -414,6 +414,7 @@ func defaultTarget(options *Options) (*TargetSpec, error) {
 		}
 		spec.ExtraFiles = append(spec.ExtraFiles,
 			"src/internal/task/futex_linux.c",
+			"src/internal/task/task_threads.c",
 			"src/runtime/runtime_unix.c",
 			"src/runtime/signal.c")
 	case "windows":

src/internal/task/futex_linux.c

@@ -5,6 +5,7 @@
 
 #include <stdint.h>
 #include <sys/syscall.h>
+#include <time.h>
 #include <unistd.h>
 
 #define FUTEX_WAIT    0
@@ -15,6 +16,13 @@ void tinygo_futex_wait(uint32_t *addr, uint32_t cmp) {
     syscall(SYS_futex, addr, FUTEX_WAIT|FUTEX_PRIVATE, cmp, NULL, NULL, 0);
 }
 
+void tinygo_futex_wait_timeout(uint32_t *addr, uint32_t cmp, uint64_t timeout) {
+    struct timespec ts = {0};
+    ts.tv_sec = timeout / 1000000000;
+    ts.tv_nsec = timeout % 1000000000;
+    syscall(SYS_futex, addr, FUTEX_WAIT|FUTEX_PRIVATE, cmp, &ts, NULL, 0);
+}
+
 void tinygo_futex_wake(uint32_t *addr, uint32_t num) {
     syscall(SYS_futex, addr, FUTEX_WAKE|FUTEX_PRIVATE, num, NULL, NULL, 0);
 }

src/internal/task/futex_linux.go

@@ -31,6 +31,11 @@ func (f *Futex) Wait(cmp uint32) bool {
 	return false
 }
 
+// Like Wait, but times out after the number of nanoseconds in timeout.
+func (f *Futex) WaitUntil(cmp uint32, timeout uint64) {
+	tinygo_futex_wait_timeout((*uint32)(unsafe.Pointer(&f.Uint32)), cmp, timeout)
+}
+
 // Wake a single waiter.
 func (f *Futex) Wake() {
 	tinygo_futex_wake((*uint32)(unsafe.Pointer(&f.Uint32)), 1)
@@ -45,5 +50,8 @@ func (f *Futex) WakeAll() {
 //export tinygo_futex_wait
 func tinygo_futex_wait(addr *uint32, cmp uint32)
 
+//export tinygo_futex_wait_timeout
+func tinygo_futex_wait_timeout(addr *uint32, cmp uint32, timeout uint64)
+
 //export tinygo_futex_wake
 func tinygo_futex_wake(addr *uint32, num uint32)

src/internal/task/linux.go

@@ -0,0 +1,9 @@
+//go:build linux && !baremetal
+
+package task
+
+import "unsafe"
+
+// Musl uses a pointer (or unsigned long for C++) so unsafe.Pointer should be
+// fine.
+type threadID unsafe.Pointer

src/internal/task/semaphore.go

@@ -0,0 +1,32 @@
+package task
+
+// Barebones semaphore implementation.
+// The main limitation is that if there are multiple waiters, a single Post()
+// call won't do anything. Only when Post() has been called to awaken all
+// waiters will the waiters proceed.
+// This limitation is not a problem when there will only be a single waiter.
+type Semaphore struct {
+	futex Futex
+}
+
+// Post (unlock) the semaphore, incrementing the value in the semaphore.
+func (s *Semaphore) Post() {
+	newValue := s.futex.Add(1)
+	if newValue == 0 {
+		s.futex.WakeAll()
+	}
+}
+
+// Wait (lock) the semaphore, decrementing the value in the semaphore.
+func (s *Semaphore) Wait() {
+	delta := int32(-1)
+	value := s.futex.Add(uint32(delta))
+	for {
+		if int32(value) >= 0 {
+			// Semaphore unlocked!
+			return
+		}
+		s.futex.Wait(value)
+		value = s.futex.Load()
+	}
+}