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Add fiber type to better support custom fiber APIs #7105

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Merged
merged 1 commit into from
Jun 7, 2021
+15 −9
Merged

Add fiber type to better support custom fiber APIs #7105

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15 changes: 8 additions & 7 deletions Zend/zend_fibers.c
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Original file line number Diff line number Diff line change
Expand Up @@ -199,7 +199,7 @@ static ZEND_NORETURN void zend_fiber_trampoline(transfer_t transfer)
abort();
}

ZEND_API bool zend_fiber_init_context(zend_fiber_context *context, zend_fiber_coroutine coroutine, size_t stack_size)
ZEND_API bool zend_fiber_init_context(zend_fiber_context *context, void *kind, zend_fiber_coroutine coroutine, size_t stack_size)
{
if (UNEXPECTED(!zend_fiber_stack_allocate(&context->stack, stack_size))) {
return false;
Expand All @@ -211,6 +211,7 @@ ZEND_API bool zend_fiber_init_context(zend_fiber_context *context, zend_fiber_co
context->handle = make_fcontext(stack, context->stack.size, zend_fiber_trampoline);
ZEND_ASSERT(context->handle != NULL && "make_fcontext() never returns NULL");

context->kind = kind;
context->function = coroutine;

return true;
Expand Down Expand Up @@ -256,7 +257,7 @@ static void zend_fiber_suspend_from(zend_fiber *fiber)
ZEND_ASSERT(fiber->caller && "Fiber has no caller");

zend_fiber_capture_vm_state(&state);
zend_fiber_switch_context(zend_fiber_get_context(fiber->caller));
zend_fiber_switch_context(fiber->caller);
zend_fiber_restore_vm_state(&state);
}

Expand All @@ -267,7 +268,7 @@ static void zend_fiber_switch_to(zend_fiber *fiber)

zend_observer_fiber_switch_notify(EG(current_fiber), context);

fiber->caller = zend_fiber_from_context(EG(current_fiber));
fiber->caller = EG(current_fiber);

zend_fiber_capture_vm_state(&state);
zend_fiber_switch_context(context);
Expand Down Expand Up @@ -352,7 +353,7 @@ static ZEND_STACK_ALIGNED zend_fiber_context *zend_fiber_execute(zend_fiber_cont
fiber->execute_data = NULL;
fiber->stack_bottom = NULL;

return zend_fiber_get_context(fiber->caller);
return fiber->caller;
}

static zend_object *zend_fiber_object_create(zend_class_entry *ce)
Expand Down Expand Up @@ -451,7 +452,7 @@ ZEND_API void zend_fiber_start(zend_fiber *fiber, zval *params, uint32_t param_c
fiber->fci.param_count = param_count;
fiber->fci.named_params = named_params;

if (!zend_fiber_init_context(zend_fiber_get_context(fiber), zend_fiber_execute, EG(fiber_stack_size))) {
if (!zend_fiber_init_context(zend_fiber_get_context(fiber), zend_ce_fiber, zend_fiber_execute, EG(fiber_stack_size))) {
RETURN_THROWS();
}

Expand Down Expand Up @@ -481,7 +482,7 @@ ZEND_METHOD(Fiber, start)

ZEND_API void zend_fiber_suspend(zval *value, zval *return_value)
{
if (UNEXPECTED(EG(current_fiber) == EG(main_fiber))) {
if (UNEXPECTED(EG(current_fiber)->kind != zend_ce_fiber)) {
zend_throw_error(zend_ce_fiber_error, "Cannot suspend outside of a fiber");
RETURN_THROWS();
}
Expand Down Expand Up @@ -692,7 +693,7 @@ ZEND_METHOD(Fiber, this)
{
ZEND_PARSE_PARAMETERS_NONE();

if (EG(current_fiber) == EG(main_fiber)) {
if (EG(current_fiber)->kind != zend_ce_fiber) {
RETURN_NULL();
}

Expand Down
9 changes: 7 additions & 2 deletions Zend/zend_fibers.h
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Original file line number Diff line number Diff line change
Expand Up @@ -72,7 +72,10 @@ typedef zend_fiber_context *(*zend_fiber_coroutine)(zend_fiber_context *context)

/* Defined as a macro to allow anonymous embedding. */
#define ZEND_FIBER_CONTEXT_FIELDS \
/* Handle to fiber state as needed by boost.context */ \
void *handle; \
/* Pointer that identifies the fiber type. */ \
void *kind; \
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Should this use zend_class_entry *, if a CE is used for identification?

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This is specified as void * to support fibers that are not exposed to PHP userland (pure C fibers) aswell hence restricting it to zend_class_entry * would be difficult due to no class entry being present. In essence this pointer just needs to be a unique address for each type of fiber. I decided to use zend_fiber_ce because it satisfies this requirement and is easy to associate with the fiber.

zend_fiber_coroutine function; \
zend_fiber_stack stack; \
zend_fiber_status status; \
Expand All @@ -98,7 +101,7 @@ struct _zend_fiber {
zend_object std;

/* Fiber that resumed us. */
zend_fiber *caller;
zend_fiber_context *caller;

/* Fiber context fields (embedded to avoid memory allocation). */
ZEND_FIBER_CONTEXT_FIELDS;
Expand Down Expand Up @@ -128,14 +131,16 @@ ZEND_API void zend_fiber_resume(zend_fiber *fiber, zval *value, zval *return_val
ZEND_API void zend_fiber_throw(zend_fiber *fiber, zval *exception, zval *return_value);

/* These functions may be used to create custom fibers (coroutines) using the bundled fiber switching context. */
ZEND_API zend_bool zend_fiber_init_context(zend_fiber_context *context, zend_fiber_coroutine coroutine, size_t stack_size);
ZEND_API bool zend_fiber_init_context(zend_fiber_context *context, void *kind, zend_fiber_coroutine coroutine, size_t stack_size);
ZEND_API void zend_fiber_destroy_context(zend_fiber_context *context);
ZEND_API void zend_fiber_switch_context(zend_fiber_context *to);

END_EXTERN_C()

static zend_always_inline zend_fiber *zend_fiber_from_context(zend_fiber_context *context)
{
ZEND_ASSERT(context->kind == zend_ce_fiber && "Fiber context does not belong to a Zend fiber");

return (zend_fiber *)(((char *) context) - XtOffsetOf(zend_fiber, handle));
}

Expand Down