+#define BUFFER_MIN_INIT_SIZE 4096
+#define BUFFER_MIN_SHRINK_SIZE 65536
+
+/* define the factor alpha for the exponential smoothing
+ * that is used in the average size calculation. a shift
+ * of 7 results in an alpha of 1/2^7. */
+#define BUFFER_AVG_SIZE_SHIFT 7
+
+static size_t buffer_req_size(Buffer *buffer, size_t len)
+{
+ return MAX(BUFFER_MIN_INIT_SIZE,
+ pow2ceil(buffer->offset + len));
+}
+
+static void buffer_adj_size(Buffer *buffer, size_t len)
+{
+ size_t old = buffer->capacity;
+ buffer->capacity = buffer_req_size(buffer, len);
+ buffer->buffer = g_realloc(buffer->buffer, buffer->capacity);
+ trace_buffer_resize(buffer->name ?: "unnamed",
+ old, buffer->capacity);
+
+ /* make it even harder for the buffer to shrink, reset average size
+ * to current capacity if it is larger than the average. */
+ buffer->avg_size = MAX(buffer->avg_size,
+ buffer->capacity << BUFFER_AVG_SIZE_SHIFT);
+}