static {
SIZE_OF_ELEMENT = UnsafeAccess.UNSAFE.arrayIndexScale(Object[].class);
if (4 == SIZE_OF_ELEMENT) {
REF_ELEMENT_SHIFT = 2 + SPARSE_SHIFT;
} else if (8 == SIZE_OF_ELEMENT) {
REF_ELEMENT_SHIFT = 3 + SPARSE_SHIFT;
} else {
throw new IllegalStateException("Unknown pointer size");
}
// Including the buffer pad in the array base offset
REF_ARRAY_BASE =
UnsafeAccess.UNSAFE.arrayBaseOffset(Object[].class)
+ (BUFFER_PAD << (REF_ELEMENT_SHIFT - SPARSE_SHIFT));
}
static {
try {
HEAD_OFFSET =
UnsafeAccess.UNSAFE.objectFieldOffset(
MpmcConcurrentQueueSMHeadField.class.getDeclaredField("head"));
} catch (NoSuchFieldException e) {
throw new RuntimeException(e);
}
}
protected final boolean casHead(long expect, long newValue) {
return UnsafeAccess.UNSAFE.compareAndSwapLong(this, HEAD_OFFSET, expect, newValue);
}