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memory: clarify nested mappings, add unit test

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This commit is contained in:
Wim Taymans 2012-01-05 16:41:58 +01:00
parent 793dce7f3d
commit b750dc5090
2 changed files with 55 additions and 1 deletions
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13
docs/design/part-memory.txt
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@ -114,6 +114,19 @@ Data Access
After the data has been accessed in the object, the unmap call must be
performed. The call will update the new memory size with the specified size.
It is allowed to map multiple times with different access modes. for each of
the map calls, an corresponding unmap call needs to be made.
The memory pointer returned from the map call is guaranteed to remain valid in
the requested mapping mode until the corresponding unmap call is performed on
the pointer.
When multiple map operations are nested and return the same pointer, the pointer
is valid until the last unmap call is done.
When the final reference on a memory object is dropped, all outstanding
mappings are automatically unmapped.
Copy
~~~~

43
tests/check/gst/gstmemory.c
View file

@ -255,7 +255,7 @@ GST_START_TEST (test_try_new_and_alloc)
#if 0
/* Disabled this part of the test, because it happily succeeds on 64-bit
* machines that have enough memory+swap, because the address space is large
* enough. There's not really any way to test the failure case except by
* enough. There's not really any way to test the failure case except by
* allocating chunks of memory until it fails, which would suck. */
/* now this better fail (don't run in valgrind, it will abort
@ -426,6 +426,46 @@ GST_START_TEST (test_map)
GST_END_TEST;
GST_START_TEST (test_map_nested)
{
GstMemory *mem;
gsize size1, maxsize1, size2, maxsize2;
gpointer data1, data2;
mem = gst_allocator_alloc (NULL, 100, 0);
/* nested mapping */
data1 = gst_memory_map (mem, &size1, &maxsize1, GST_MAP_READ);
fail_unless (data1 != NULL);
fail_unless (size1 == 100);
data2 = gst_memory_map (mem, &size2, &maxsize2, GST_MAP_READ);
fail_unless (data2 == data1);
fail_unless (size2 == 100);
/* unmap in reverse order */
gst_memory_unmap (mem, data2, size2);
gst_memory_unmap (mem, data1, size1);
/* nested mapping */
data1 = gst_memory_map (mem, &size1, &maxsize1, GST_MAP_READ);
fail_unless (data1 != NULL);
fail_unless (size1 == 100);
data2 = gst_memory_map (mem, &size2, &maxsize2, GST_MAP_WRITE);
fail_unless (data2 == data1);
fail_unless (size2 == 100);
/* unmap in different order */
gst_memory_unmap (mem, data1, size1);
gst_memory_unmap (mem, data2, size2);
gst_memory_unref (mem);
}
GST_END_TEST;
static Suite *
gst_memory_suite (void)
{
@ -441,6 +481,7 @@ gst_memory_suite (void)
tcase_add_test (tc_chain, test_try_new_and_alloc);
tcase_add_test (tc_chain, test_resize);
tcase_add_test (tc_chain, test_map);
tcase_add_test (tc_chain, test_map_nested);
return s;
}