-/*
- * handle.c: Handle to object in native code
+/**
+ * \file
+ * Handle to object in native code
*
* Authors:
* - Ludovic Henry <ludovic@xamarin.com>
We could then generate neat type safe wrappers.
*/
+/*
+ * NOTE: Async suspend
+ *
+ * If we are running with cooperative GC, all the handle stack
+ * manipulation will complete before a GC thread scans the handle
+ * stack. If we are using async suspend, however, a thread may be
+ * trying to allocate a new handle, or unwind the handle stack when
+ * the GC stops the world.
+ *
+ * In particular, we need to ensure that if the mutator thread is
+ * suspended while manipulating the handle stack, the stack is in a
+ * good enough state to be scanned. In particular, the size of each
+ * chunk should be updated before an object is written into the
+ * handle, and chunks to be scanned (between bottom and top) should
+ * always be valid.
+ *
+ * Note that the handle stack is scanned PRECISELY (see
+ * sgen_client_scan_thread_data ()). That means there should not be
+ * stale objects scanned. So when we manipulate the size of a chunk,
+ * wemust ensure that the newly scannable slot is either null or
+ * points to a valid value.
+ */
+
const MonoObjectHandle mono_null_value_handle = NULL;
#define THIS_IS_AN_OK_NUMBER_OF_HANDLES 100
-/* Actual handles implementation */
+enum {
+ HANDLE_CHUNK_PTR_OBJ = 0x0, /* chunk element points to beginning of a managed object */
+ HANDLE_CHUNK_PTR_INTERIOR = 0x1, /* chunk element points into the middle of a managed object */
+ HANDLE_CHUNK_PTR_MASK = 0x1
+};
+
+/* number of bits in each word of the interior pointer bitmap */
+#define INTERIOR_HANDLE_BITMAP_BITS_PER_WORD (sizeof(guint32) << 3)
+
+static gboolean
+bitset_bits_test (guint32 *bitmaps, int idx)
+{
+ int w = idx / INTERIOR_HANDLE_BITMAP_BITS_PER_WORD;
+ int b = idx % INTERIOR_HANDLE_BITMAP_BITS_PER_WORD;
+ guint32 bitmap = bitmaps [w];
+ guint32 mask = 1u << b;
+ return ((bitmap & mask) != 0);
+}
+
+static void
+bitset_bits_set (guint32 *bitmaps, int idx)
+{
+ int w = idx / INTERIOR_HANDLE_BITMAP_BITS_PER_WORD;
+ int b = idx % INTERIOR_HANDLE_BITMAP_BITS_PER_WORD;
+ guint32 *bitmap = &bitmaps [w];
+ guint32 mask = 1u << b;
+ *bitmap |= mask;
+}
+static void
+bitset_bits_clear (guint32 *bitmaps, int idx)
+{
+ int w = idx / INTERIOR_HANDLE_BITMAP_BITS_PER_WORD;
+ int b = idx % INTERIOR_HANDLE_BITMAP_BITS_PER_WORD;
+ guint32 *bitmap = &bitmaps [w];
+ guint32 mask = ~(1u << b);
+ *bitmap &= mask;
+}
+
+static gpointer*
+chunk_element_objslot_init (HandleChunk *chunk, int idx, gboolean interior)
+{
+ if (interior)
+ bitset_bits_set (chunk->interior_bitmap, idx);
+ else
+ bitset_bits_clear (chunk->interior_bitmap, idx);
+ return &chunk->elems [idx].o;
+}
+
+static HandleChunkElem*
+chunk_element (HandleChunk *chunk, int idx)
+{
+ return &chunk->elems[idx];
+}
+
+static guint
+chunk_element_kind (HandleChunk *chunk, int idx)
+{
+ return bitset_bits_test (chunk->interior_bitmap, idx) ? HANDLE_CHUNK_PTR_INTERIOR : HANDLE_CHUNK_PTR_OBJ;
+}
+
+static HandleChunkElem*
+handle_to_chunk_element (MonoObjectHandle o)
+{
+ return (HandleChunkElem*)o;
+}
+
+/* Given a HandleChunkElem* search through the current handle stack to find its chunk and offset. */
+static HandleChunk*
+chunk_element_to_chunk_idx (HandleStack *stack, HandleChunkElem *elem, int *out_idx)
+{
+ HandleChunk *top = stack->top;
+ HandleChunk *cur = stack->bottom;
+
+ *out_idx = 0;
+
+ while (cur != NULL) {
+ HandleChunkElem *front = &cur->elems [0];
+ HandleChunkElem *back = &cur->elems [cur->size];
+
+ if (front <= elem && elem < back) {
+ *out_idx = (int)(elem - front);
+ return cur;
+ }
+
+ if (cur == top)
+ break; /* didn't find it. */
+ cur = cur->next;
+ }
+ return NULL;
+}
+
+#ifdef MONO_HANDLE_TRACK_OWNER
+#define SET_OWNER(chunk,idx) do { (chunk)->elems[(idx)].owner = owner; } while (0)
+#else
+#define SET_OWNER(chunk,idx) do { } while (0)
+#endif
+
MonoRawHandle
+#ifndef MONO_HANDLE_TRACK_OWNER
mono_handle_new (MonoObject *object)
+#else
+mono_handle_new (MonoObject *object const char *owner)
+#endif
+{
+#ifndef MONO_HANDLE_TRACK_OWNER
+ return mono_handle_new_full (object, FALSE);
+#else
+ return mono_handle_new_full (object, FALSE, owner);
+#endif
+}
+/* Actual handles implementation */
+MonoRawHandle
+#ifndef MONO_HANDLE_TRACK_OWNER
+mono_handle_new_full (gpointer rawptr, gboolean interior)
+#else
+mono_handle_new_full (gpointer rawptr, gboolean interior, const char *owner)
+#endif
{
MonoThreadInfo *info = mono_thread_info_current ();
HandleStack *handles = (HandleStack *)info->handle_stack;
retry:
if (G_LIKELY (top->size < OBJECTS_PER_HANDLES_CHUNK)) {
- MonoObject **h = &top->objects [top->size++];
- *h = object;
- return h;
+ int idx = top->size;
+ gpointer* objslot = chunk_element_objslot_init (top, idx, interior);
+ /* can be interrupted anywhere here, so:
+ * 1. make sure the new slot is null
+ * 2. make the new slot scannable (increment size)
+ * 3. put a valid object in there
+ *
+ * (have to do 1 then 3 so that if we're interrupted
+ * between 1 and 2, the object is still live)
+ */
+ *objslot = NULL;
+ mono_memory_write_barrier ();
+ top->size++;
+ mono_memory_write_barrier ();
+ *objslot = rawptr;
+ SET_OWNER (top,idx);
+ return objslot;
}
if (G_LIKELY (top->next)) {
+ top->next->size = 0;
+ /* make sure size == 0 is visible to a GC thread before it sees the new top */
+ mono_memory_write_barrier ();
top = top->next;
- top->size = 0;
handles->top = top;
goto retry;
}
HandleChunk *new_chunk = g_new (HandleChunk, 1);
new_chunk->size = 0;
+ memset (new_chunk->interior_bitmap, 0, INTERIOR_HANDLE_BITMAP_WORDS);
new_chunk->prev = top;
new_chunk->next = NULL;
+ /* make sure size == 0 before new chunk is visible */
+ mono_memory_write_barrier ();
top->next = new_chunk;
handles->top = new_chunk;
goto retry;
HandleStack *stack = g_new (HandleStack, 1);
HandleChunk *chunk = g_new (HandleChunk, 1);
- stack->top = stack->bottom = chunk;
chunk->size = 0;
+ memset (chunk->interior_bitmap, 0, INTERIOR_HANDLE_BITMAP_WORDS);
chunk->prev = chunk->next = NULL;
+ mono_memory_write_barrier ();
+ stack->top = stack->bottom = chunk;
return stack;
}
if (!stack)
return;
HandleChunk *c = stack->bottom;
+ stack->top = stack->bottom = NULL;
+ mono_memory_write_barrier ();
while (c) {
HandleChunk *next = c->next;
g_free (c);
c = next;
}
g_free (c);
+ g_free (stack);
}
void
-mono_handle_stack_scan (HandleStack *stack, GcScanFunc func, gpointer gc_data)
+mono_handle_stack_scan (HandleStack *stack, GcScanFunc func, gpointer gc_data, gboolean precise)
{
+ /*
+ We're called twice - on the imprecise pass we call func to pin the
+ objects where the handle points to its interior. On the precise
+ pass, we scan all the objects where the handles point to the start of
+ the object.
+
+ Note that if we're running, we know the world is stopped.
+ */
HandleChunk *cur = stack->bottom;
HandleChunk *last = stack->top;
return;
while (cur) {
- int i;
- for (i = 0; i < cur->size; ++i)
- func ((gpointer*)&cur->objects [i], gc_data);
+ /* assume that object pointers will be much more common than interior pointers.
+ * scan the object pointers by iterating over the chunk elements.
+ * scan the interior pointers by iterating over the bitmap bits.
+ */
+ if (precise) {
+ for (int i = 0; i < cur->size; ++i) {
+ HandleChunkElem* elem = chunk_element (cur, i);
+ int kind = chunk_element_kind (cur, i);
+ gpointer* obj_slot = &elem->o;
+ if (kind == HANDLE_CHUNK_PTR_OBJ && *obj_slot != NULL)
+ func (obj_slot, gc_data);
+ }
+ } else {
+ int elem_idx = 0;
+ for (int i = 0; i < INTERIOR_HANDLE_BITMAP_WORDS; ++i) {
+ elem_idx = i * INTERIOR_HANDLE_BITMAP_BITS_PER_WORD;
+ if (elem_idx >= cur->size)
+ break;
+ /* no interior pointers in the range */
+ if (cur->interior_bitmap [i] == 0)
+ continue;
+ for (int j = 0; j < INTERIOR_HANDLE_BITMAP_BITS_PER_WORD && elem_idx < cur->size; ++j,++elem_idx) {
+ HandleChunkElem *elem = chunk_element (cur, elem_idx);
+ int kind = chunk_element_kind (cur, elem_idx);
+ gpointer *ptr_slot = &elem->o;
+ if (kind == HANDLE_CHUNK_PTR_INTERIOR && *ptr_slot != NULL)
+ func (ptr_slot, gc_data);
+ }
+ }
+ }
if (cur == last)
break;
cur = cur->next;
}
if (size > THIS_IS_AN_OK_NUMBER_OF_HANDLES)
- printf ("%s USED %d handles\n", func_name, size);
+ g_warning ("%s USED %d handles\n", func_name, size);
}
/*
MonoRawHandle
mono_stack_mark_pop_value (MonoThreadInfo *info, HandleStackMark *stackmark, MonoRawHandle value)
{
- g_error ("impl me");
+ MonoObject *obj = value ? *((MonoObject**)value) : NULL;
+ mono_stack_mark_pop (info, stackmark);
+#ifndef MONO_HANDLE_TRACK_OWNER
+ return mono_handle_new (obj);
+#else
+ return mono_handle_new (obj, "<mono_stack_mark_pop_value>");
+#endif
}
/* Temporary place for some of the handle enabled wrapper functions*/
MonoStringHandle
-mono_string_new_handle (MonoDomain *domain, const char *data)
+mono_string_new_handle (MonoDomain *domain, const char *data, MonoError *error)
{
- return MONO_HANDLE_NEW (MonoString, mono_string_new (domain, data));
+ return MONO_HANDLE_NEW (MonoString, mono_string_new_checked (domain, data, error));
}
MonoArrayHandle
return MONO_HANDLE_NEW (MonoArray, mono_array_new_checked (domain, eclass, n, error));
}
+MonoArrayHandle
+mono_array_new_full_handle (MonoDomain *domain, MonoClass *array_class, uintptr_t *lengths, intptr_t *lower_bounds, MonoError *error)
+{
+ return MONO_HANDLE_NEW (MonoArray, mono_array_new_full_checked (domain, array_class, lengths, lower_bounds, error));
+}
+
#ifdef ENABLE_CHECKED_BUILD
/* Checked build helpers */
void
}
#endif
+
+uintptr_t
+mono_array_handle_length (MonoArrayHandle arr)
+{
+ MONO_REQ_GC_UNSAFE_MODE;
+
+ return MONO_HANDLE_RAW (arr)->max_length;
+}
+
+uint32_t
+mono_gchandle_from_handle (MonoObjectHandle handle, mono_bool pinned)
+{
+ /* FIXME: chunk_element_to_chunk_idx does a linear search through the
+ * chunks and we only need it for the assert */
+ MonoThreadInfo *info = mono_thread_info_current ();
+ HandleStack *stack = (HandleStack*) info->handle_stack;
+ HandleChunkElem* elem = handle_to_chunk_element (handle);
+ int elem_idx = 0;
+ HandleChunk *chunk = chunk_element_to_chunk_idx (stack, elem, &elem_idx);
+ /* gchandles cannot deal with interior pointers */
+ g_assert (chunk != NULL);
+ g_assert (chunk_element_kind (chunk, elem_idx) != HANDLE_CHUNK_PTR_INTERIOR);
+ return mono_gchandle_new (MONO_HANDLE_RAW (handle), pinned);
+}
+
+MonoObjectHandle
+mono_gchandle_get_target_handle (uint32_t gchandle)
+{
+ return MONO_HANDLE_NEW (MonoObject, mono_gchandle_get_target (gchandle));
+}
+
+gpointer
+mono_array_handle_pin_with_size (MonoArrayHandle handle, int size, uintptr_t idx, uint32_t *gchandle)
+{
+ g_assert (gchandle != NULL);
+ *gchandle = mono_gchandle_from_handle (MONO_HANDLE_CAST(MonoObject,handle), TRUE);
+ MonoArray *raw = MONO_HANDLE_RAW (handle);
+ return mono_array_addr_with_size (raw, size, idx);
+}
+
+void
+mono_array_handle_memcpy_refs (MonoArrayHandle dest, uintptr_t dest_idx, MonoArrayHandle src, uintptr_t src_idx, uintptr_t len)
+{
+ mono_array_memcpy_refs (MONO_HANDLE_RAW (dest), dest_idx, MONO_HANDLE_RAW (src), src_idx, len);
+}
+
+gboolean
+mono_handle_stack_is_empty (HandleStack *stack)
+{
+ return (stack->top == stack->bottom && stack->top->size == 0);
+}
projects / mono.git / blobdiff