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Rework BList's Resize() functionality: instead of altering the size of the list a block at a time,

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we now double/halve the current size of the list, starting with the constructor blocksize as a baseline.
This has the net effect that when doing large numbers of inserts/removes, the number of resize operations 
needed scales logarithmically to the number of operations, which should yield a decent performance 
improvement in such cases.

Review welcome. This does not yet affect ticket #2363 that I'm aware of, as I'm currently in the process
of attempting to find a copy of said app to test with.



git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@25916 a95241bf-73f2-0310-859d-f6bbb57e9c96
This commit is contained in:
Rene Gollent 2008-06-10 22:10:13 +00:00
parent 97403a77f1
commit 864ace1845
1 changed files with 11 additions and 5 deletions
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16
src/kits/support/List.cpp
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@ -174,7 +174,7 @@ BList::RemoveItem(int32 index)
if (index >= 0 && index < fItemCount) { if (index >= 0 && index < fItemCount) {
item = fObjectList[index]; item = fObjectList[index];
move_items(fObjectList + index + 1, -1, fItemCount - index - 1); move_items(fObjectList + index + 1, -1, fItemCount - index - 1);
Resize(fItemCount - 1); Resize(fItemCount - 1);
} }
return item; return item;
} }
@ -433,11 +433,17 @@ bool
BList::Resize(int32 count) BList::Resize(int32 count)
{ {
bool result = true; bool result = true;
// calculate the new physical size // calculate the new physical size
int32 newSize = count; // by doubling the existing size
if (newSize <= 0) // until we can hold at least count items
newSize = 1; int32 newSize = fBlockSize;
newSize = ((newSize - 1) / fBlockSize + 1) * fBlockSize; if (count <= 0)
count = fBlockSize;
if ((size_t)count != fPhysicalSize)
while (newSize < count)
newSize <<= 1;
// resize if necessary // resize if necessary
if ((size_t)newSize != fPhysicalSize) { if ((size_t)newSize != fPhysicalSize) {
void** newObjectList void** newObjectList