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-rw-r--r--src/vlib/buffer_funcs.h62
1 files changed, 62 insertions, 0 deletions
diff --git a/src/vlib/buffer_funcs.h b/src/vlib/buffer_funcs.h
index 4831eb5ebac..cc56db7762c 100644
--- a/src/vlib/buffer_funcs.h
+++ b/src/vlib/buffer_funcs.h
@@ -1004,6 +1004,68 @@ vlib_validate_buffer_set_in_use (vlib_buffer_t * b, u32 expected)
#endif
}
+/** minimum data size of first buffer in a buffer chain */
+#define VLIB_BUFFER_CHAIN_MIN_FIRST_DATA_SIZE (256)
+
+/**
+ * @brief compress buffer chain in a way where the first buffer is at least
+ * VLIB_BUFFER_CHAIN_MIN_FIRST_DATA_SIZE long
+ *
+ * @param[in] vm - vlib_main
+ * @param[in,out] first - first buffer in chain
+ * @param[in,out] discard_vector - vector of buffer indexes which were removed
+ * from the chain
+ */
+always_inline void
+vlib_buffer_chain_compress (vlib_main_t * vm,
+ vlib_buffer_t * first, u32 ** discard_vector)
+{
+ if (first->current_length >= VLIB_BUFFER_CHAIN_MIN_FIRST_DATA_SIZE ||
+ !(first->flags & VLIB_BUFFER_NEXT_PRESENT))
+ {
+ /* this is already big enough or not a chain */
+ return;
+ }
+ /* probe free list to find allocated buffer size to avoid overfill */
+ u32 index;
+ vlib_buffer_free_list_t *free_list =
+ vlib_buffer_get_buffer_free_list (vm, first, &index);
+
+ u32 want_first_size = clib_min (VLIB_BUFFER_CHAIN_MIN_FIRST_DATA_SIZE,
+ free_list->n_data_bytes -
+ first->current_data);
+ do
+ {
+ vlib_buffer_t *second = vlib_get_buffer (vm, first->next_buffer);
+ u32 need = want_first_size - first->current_length;
+ u32 amount_to_copy = clib_min (need, second->current_length);
+ clib_memcpy (((u8 *) vlib_buffer_get_current (first)) +
+ first->current_length,
+ vlib_buffer_get_current (second), amount_to_copy);
+ first->current_length += amount_to_copy;
+ vlib_buffer_advance (second, amount_to_copy);
+ if (first->flags & VLIB_BUFFER_TOTAL_LENGTH_VALID)
+ {
+ first->total_length_not_including_first_buffer -= amount_to_copy;
+ }
+ if (!second->current_length)
+ {
+ vec_add1 (*discard_vector, first->next_buffer);
+ if (second->flags & VLIB_BUFFER_NEXT_PRESENT)
+ {
+ first->next_buffer = second->next_buffer;
+ }
+ else
+ {
+ first->flags &= ~VLIB_BUFFER_NEXT_PRESENT;
+ }
+ second->flags &= ~VLIB_BUFFER_NEXT_PRESENT;
+ }
+ }
+ while ((first->current_length < want_first_size) &&
+ (first->flags & VLIB_BUFFER_NEXT_PRESENT));
+}
+
#endif /* included_vlib_buffer_funcs_h */
/*