ObjectIdSubclassMap: Micro-optimize wrapping at end of table
During a review of the class, Josh Bloch pointed out we can use "i = (i + 1) & mask" to wrap around at the end of the table, instead of a conditional with a branch. This is generally faster due to one less branch that will be mis-predicted by the CPU. Change-Id: Ic88c00455ebc6adde9708563a6ad4d0377442bba Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
This commit is contained in:
parent
42f0b11153
commit
d1e47df0da
|
@ -92,16 +92,15 @@ public void clear() {
|
|||
* @return the instance mapped to toFind, or null if no mapping exists.
|
||||
*/
|
||||
public V get(final AnyObjectId toFind) {
|
||||
int i = toFind.w1 & mask;
|
||||
final int msk = mask;
|
||||
int i = toFind.w1 & msk;
|
||||
final V[] tbl = table;
|
||||
final int end = tbl.length;
|
||||
V obj;
|
||||
|
||||
while ((obj = tbl[i]) != null) {
|
||||
if (AnyObjectId.equals(obj, toFind))
|
||||
return obj;
|
||||
if (++i == end)
|
||||
i = 0;
|
||||
i = (i + 1) & msk;
|
||||
}
|
||||
return null;
|
||||
}
|
||||
|
@ -157,16 +156,15 @@ public <Q extends V> void add(final Q newValue) {
|
|||
* type of instance to store.
|
||||
*/
|
||||
public <Q extends V> V addIfAbsent(final Q newValue) {
|
||||
int i = newValue.w1 & mask;
|
||||
final int msk = mask;
|
||||
int i = newValue.w1 & msk;
|
||||
final V[] tbl = table;
|
||||
final int end = tbl.length;
|
||||
V obj;
|
||||
|
||||
while ((obj = tbl[i]) != null) {
|
||||
if (AnyObjectId.equals(obj, newValue))
|
||||
return obj;
|
||||
if (++i == end)
|
||||
i = 0;
|
||||
i = (i + 1) & msk;
|
||||
}
|
||||
|
||||
if (++size == grow) {
|
||||
|
@ -218,13 +216,11 @@ public void remove() {
|
|||
}
|
||||
|
||||
private void insert(final V newValue) {
|
||||
int j = newValue.w1 & mask;
|
||||
final int msk = mask;
|
||||
int j = newValue.w1 & msk;
|
||||
final V[] tbl = table;
|
||||
final int end = tbl.length;
|
||||
while (tbl[j] != null) {
|
||||
if (++j == end)
|
||||
j = 0;
|
||||
}
|
||||
while (tbl[j] != null)
|
||||
j = (j + 1) & msk;
|
||||
tbl[j] = newValue;
|
||||
}
|
||||
|
||||
|
|
Loading…
Reference in New Issue