Skip to content

Commit

Permalink
WIP map every goroutine to a new OS thread
Browse files Browse the repository at this point in the history
  • Loading branch information
aykevl committed Nov 2, 2024
1 parent 7601c6d commit 28f51ca
Show file tree
Hide file tree
Showing 13 changed files with 984 additions and 2 deletions.
1 change: 1 addition & 0 deletions GNUmakefile
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand Down
1 change: 1 addition & 0 deletions builder/musl.go
Original file line number Diff line number Diff line change
Expand Up @@ -127,6 +127,7 @@ var libMusl = Library{
"malloc/mallocng/*.c",
"mman/*.c",
"math/*.c",
"misc/*.c",
"multibyte/*.c",
"signal/" + arch + "/*.s",
"signal/*.c",
Expand Down
2 changes: 1 addition & 1 deletion compileopts/options.go
Original file line number Diff line number Diff line change
Expand Up @@ -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"}
Expand Down
1 change: 1 addition & 0 deletions compileopts/target.go
Original file line number Diff line number Diff line change
Expand Up @@ -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":
Expand Down
9 changes: 9 additions & 0 deletions src/internal/task/linux.go
Original file line number Diff line number Diff line change
@@ -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
32 changes: 32 additions & 0 deletions src/internal/task/semaphore.go
Original file line number Diff line number Diff line change
@@ -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()
}
}
106 changes: 106 additions & 0 deletions src/internal/task/task_threads.c
Original file line number Diff line number Diff line change
@@ -0,0 +1,106 @@
//go:build none

#define _GNU_SOURCE
#include <pthread.h>
#include <semaphore.h>
#include <signal.h>
#include <stdint.h>
#include <stdio.h>

// BDWGC also uses SIGRTMIN+6 on Linux, which seems like a reasonable choice.
#ifdef __linux__
#define taskPauseSignal (SIGRTMIN + 6)
#endif

// Pointer to the current task.Task structure.
// Ideally the entire task.Task structure would be a thread-local variable but
// this also works.
static __thread void *current_task;

struct state_pass {
void *(*start)(void*);
void *args;
void *task;
sem_t startlock;
};

// Handle the GC pause in Go.
void tinygo_task_gc_pause(int sig);

// Initialize threads from the C side.
void tinygo_task_init(void *mainTask, void *context) {
// Make sure the current task pointer is set correctly for the main
// goroutine as well.
current_task = mainTask;

// Register the "GC pause" signal for the entire process.
// Using pthread_kill, we can still send the signal to a specific thread.
struct sigaction act = { 0 };
act.sa_flags = SA_SIGINFO;
act.sa_handler = &tinygo_task_gc_pause;
sigaction(taskPauseSignal, &act, NULL);
}

void tinygo_task_exited(void*);

// Helper to start a goroutine while also storing the 'task' structure.
static void* start_wrapper(void *arg) {
struct state_pass *state = arg;
void *(*start)(void*) = state->start;
void *args = state->args;
current_task = state->task;

// Notify the caller that the thread has successfully started and
// initialized.
sem_post(&state->startlock);

// Run the goroutine function.
start(args);

// Notify the Go side this thread will exit.
tinygo_task_exited(current_task);

return NULL;
};

// Start a new goroutine in an OS thread.
int tinygo_task_start(uintptr_t fn, void *args, void *task, pthread_t *thread, uint64_t id, void *context) {
// Sanity check. Should get optimized away.
if (sizeof(pthread_t) != sizeof(void*)) {
__builtin_trap();
}

struct state_pass state = {
.start = (void*)fn,
.args = args,
.task = task,
};
sem_init(&state.startlock, 0, 0);
int result = pthread_create(thread, NULL, &start_wrapper, &state);

// Wait until the thread has been crated and read all state_pass variables.
sem_wait(&state.startlock);

return result;
}

// Return the current task (for task.Current()).
void* tinygo_task_current(void) {
return current_task;
}

// Obtain the highest address of the stack.
uintptr_t tinygo_task_stacktop(void) {
pthread_attr_t attr;
pthread_getattr_np(pthread_self(), &attr);
void *stackbase;
size_t stacksize;
pthread_attr_getstack(&attr, &stackbase, &stacksize);
pthread_attr_destroy(&attr);
return (uintptr_t)stackbase + (uintptr_t)stacksize;
}

// Send a signal to cause the task to pause for the GC mark phase.
void tinygo_task_send_gc_signal(pthread_t thread) {
pthread_kill(thread, taskPauseSignal);
}
Loading

0 comments on commit 28f51ca

Please sign in to comment.