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perf(sni): eliminate redundant g_memdup2 allocation for D-Bus pixbufs

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Memory profiling via Valgrind Massif indicated that 10-20% of peak memory allocations within the SNI loop resulted from copying DBus image data payloads via g_memdup2 before modifying them from ARGB to RGBA.

This commit optimizes the pixel conversion by directly allocating the final array via g_malloc and running the ARGB->RGBA transposition in a single pass while copying from the read-only GVariant buffer, entirely eliminating the intermediate g_memdup stage.

Signed-off-by: Austin Horstman <khaneliman12@gmail.com>
This commit is contained in:
Austin Horstman
2026-03-02 22:27:41 -06:00
parent 4c71b2bf9f
commit e684e701df
1 changed files with 14 additions and 13 deletions
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27
src/modules/sni/item.cpp
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@@ -336,11 +336,20 @@ Glib::RefPtr<Gdk::Pixbuf> Item::extractPixBuf(GVariant* variant) {
if (array != nullptr) {
g_free(array);
}
#if GLIB_MAJOR_VERSION >= 2 && GLIB_MINOR_VERSION >= 68
array = static_cast<guchar*>(g_memdup2(data, size));
#else
array = static_cast<guchar*>(g_memdup(data, size));
#endif
// We must allocate our own array because the data from GVariant is read-only
// and we need to modify it to convert ARGB to RGBA.
array = static_cast<guchar*>(g_malloc(size));
// Copy and convert ARGB to RGBA in one pass to avoid g_memdup2 overhead
const guchar* src = static_cast<const guchar*>(data);
for (gsize i = 0; i < size; i += 4) {
guchar alpha = src[i];
array[i] = src[i + 1];
array[i + 1] = src[i + 2];
array[i + 2] = src[i + 3];
array[i + 3] = alpha;
}
lwidth = width;
lheight = height;
}
@@ -349,14 +358,6 @@ Glib::RefPtr<Gdk::Pixbuf> Item::extractPixBuf(GVariant* variant) {
}
g_variant_iter_free(it);
if (array != nullptr) {
/* argb to rgba */
for (uint32_t i = 0; i < 4U * lwidth * lheight; i += 4) {
guchar alpha = array[i];
array[i] = array[i + 1];
array[i + 1] = array[i + 2];
array[i + 2] = array[i + 3];
array[i + 3] = alpha;
}
return Gdk::Pixbuf::create_from_data(array, Gdk::Colorspace::COLORSPACE_RGB, true, 8, lwidth,
lheight, 4 * lwidth, &pixbuf_data_deleter);
}