/**
* Calculate the insertKey that places a CrawlURI in the desired spot. First bytes are always
* classKey (usu. host) based -- ensuring grouping by host -- terminated by a zero byte. Then 8
* bytes of data ensuring desired ordering within that 'queue' are used. The first byte of these 8
* is priority -- allowing 'immediate' and 'soon' items to sort above regular. Next 1 byte is
* 'precedence'. Last 6 bytes are ordinal serial number, ensuring earlier-discovered URIs sort
* before later.
*
* <p>NOTE: Dangers here are: (1) priorities or precedences over 2^7 (signed byte comparison) (2)
* ordinals over 2^48
*
* <p>Package access & static for testing purposes.
*
* @param curi
* @return a DatabaseEntry key for the CrawlURI
*/
static DatabaseEntry calculateInsertKey(CrawlURI curi) {
byte[] classKeyBytes = null;
int len = 0;
classKeyBytes = curi.getClassKey().getBytes(Charsets.UTF_8);
len = classKeyBytes.length;
byte[] keyData = new byte[len + 9];
System.arraycopy(classKeyBytes, 0, keyData, 0, len);
keyData[len] = 0;
long ordinalPlus = curi.getOrdinal() & 0x0000FFFFFFFFFFFFL;
ordinalPlus = ((long) curi.getSchedulingDirective() << 56) | ordinalPlus;
long precedence = Math.min(curi.getPrecedence(), 127);
ordinalPlus = (((precedence) & 0xFFL) << 48) | ordinalPlus;
ArchiveUtils.longIntoByteArray(ordinalPlus, keyData, len + 1);
return new DatabaseEntry(keyData);
}
