re-implement istaskstarted

base/exports.jl

@@ -1011,6 +1011,7 @@ export
     consume,
     current_task,
     istaskdone,
+    istaskstarted,
     lock,
     notify,
     produce,

base/serialize.jl

@@ -348,15 +348,18 @@ end
 
 function serialize(s::SerializationState, t::Task)
     serialize_cycle(s, t) && return
-    if !istaskdone(t)
+    if istaskstarted(t) && !istaskdone(t)
         error("cannot serialize a running Task")
     end
+    state = [t.code,
+        t.storage,
+        t.state == :queued || t.state == :runnable ? (:runnable) : t.state,
+        t.result,
+        t.exception]
     writetag(s.io, TASK_TAG)
-    serialize(s, t.code)
-    serialize(s, t.storage)
-    serialize(s, t.state == :queued || t.state == :runnable ? (:runnable) : t.state)
-    serialize(s, t.result)
-    serialize(s, t.exception)
+    for fld in state
+        serialize(s, fld)
+    end
 end
 
 function serialize_type_data(s, t)

base/task.jl

@@ -66,6 +66,7 @@ end
 
 current_task() = ccall(:jl_get_current_task, Any, ())::Task
 istaskdone(t::Task) = ((t.state == :done) | (t.state == :failed))
+istaskstarted(t::Task) = ccall(:jl_is_task_started, Cint, (Any,), t) != 0
 
 yieldto(t::Task, x::ANY = nothing) = ccall(:jl_switchto, Any, (Any, Any), t, x)
 

src/julia.h

@@ -1465,7 +1465,8 @@ typedef struct _jl_task_t {
     jl_jmp_buf ctx;
     size_t bufsz;
     void *stkbuf;
-    size_t ssize;
+    size_t ssize:31;
+    size_t started:1;
 
     // current exception handler
     jl_handler_t *eh;

src/task.c

@@ -240,6 +240,7 @@ static void NOINLINE NORETURN start_task(void)
     // this runs the first time we switch to a task
     jl_task_t *t = jl_current_task;
     jl_value_t *res;
+    t->started = 1;
     if (t->exception != NULL && t->exception != jl_nothing) {
         record_backtrace();
         res = t->exception;
@@ -863,6 +864,7 @@ DLLEXPORT jl_task_t *jl_new_task(jl_function_t *start, size_t ssize)
     t->gcstack = NULL;
     t->stkbuf = NULL;
     t->tid = 0;
+    t->started = 0;
 
 #ifdef COPY_STACKS
     t->bufsz = 0;
@@ -952,6 +954,7 @@ void jl_init_root_task(void *stack, size_t ssize)
     jl_current_task->ssize = ssize;
     jl_current_task->stkbuf = stack;
 #endif
+    jl_current_task->started = 1;
     jl_current_task->parent = jl_current_task;
     jl_current_task->current_module = jl_current_module;
     jl_current_task->tls = jl_nothing;
@@ -972,6 +975,11 @@ void jl_init_root_task(void *stack, size_t ssize)
     jl_task_arg_in_transit = (jl_value_t*)jl_nothing;
 }
 
+DLLEXPORT int jl_is_task_started(jl_task_t *t)
+{
+    return t->started;
+}
+
 #ifdef __cplusplus
 }
 #endif