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Unified Diff: include/core/SkTDArray.h

Issue 150663014: Change growth function for SkWriter32 (Closed) Base URL: https://skia.googlesource.com/skia.git@no_external_test
Patch Set: Read back reserved space in case it is bigger Created 6 years, 10 months ago
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Index: include/core/SkTDArray.h
diff --git a/include/core/SkTDArray.h b/include/core/SkTDArray.h
index 67254ccc9a88fa93fe6489ea82bccb6efe8959e6..e51f2cd008e5ad07f451377c3ebaedcd4421fdd2 100644
--- a/include/core/SkTDArray.h
+++ b/include/core/SkTDArray.h
@@ -151,25 +151,43 @@ public:
fCount = 0;
}
+ /**
+ * Sets the number of elements in the array.
+ * If the array does not have space for count elements, it will increase
+ * the storage allocated to some amount greater than that required.
+ * It will never shrink the shrink the storage.
+ */
void setCount(int count) {
+ // TODO(mtklein): eliminate this method, setCountExact -> setCount
+ SkASSERT(count >= 0);
if (count > fReserve) {
- this->growBy(count - fCount);
- } else {
- fCount = count;
+ resizeStorageToAtLeast(count);
}
+ fCount = count;
+ }
+
+ /**
+ * Sets the number of elements in the array.
+ * If the array does not have space for count elements, it will increase
+ * the storage allocated to exactly the amount required, with no remaining
+ * reserved space.
+ * It will never shrink the shrink the storage.
+ */
+ void setCountExact(int count) {
+ if (count > fReserve) {
+ this->resizeStorageToExact(count);
+ }
+ fCount = count;
}
void setReserve(int reserve) {
if (reserve > fReserve) {
- SkASSERT(reserve > fCount);
- int count = fCount;
- this->growBy(reserve - fCount);
- fCount = count;
+ resizeStorageToAtLeast(reserve);
}
}
T* prepend() {
- this->growBy(1);
+ this->adjustCount(1);
memmove(fArray + 1, fArray, (fCount - 1) * sizeof(T));
return fArray;
}
@@ -183,7 +201,7 @@ public:
SkASSERT(src == NULL || fArray == NULL ||
src + count <= fArray || fArray + oldCount <= src);
- this->growBy(count);
+ this->adjustCount(count);
if (src) {
memcpy(fArray + oldCount, src, sizeof(T) * count);
}
@@ -204,7 +222,7 @@ public:
SkASSERT(count);
SkASSERT(index <= fCount);
size_t oldCount = fCount;
- this->growBy(count);
+ this->adjustCount(count);
T* dst = fArray + index;
memmove(dst + count, dst, sizeof(T) * (oldCount - index));
if (src) {
@@ -356,20 +374,43 @@ private:
int fReserve;
int fCount;
- void growBy(int extra) {
- SkASSERT(extra);
-
- if (fCount + extra > fReserve) {
- int size = fCount + extra + 4;
- size += size >> 2;
+ /**
+ * Adjusts the number of elements in the array.
+ * This is the same as calling setCount(count() + delta).
+ */
+ void adjustCount(int delta) {
+ setCount(fCount + delta);
+ }
- fArray = (T*)sk_realloc_throw(fArray, size * sizeof(T));
+ /**
+ * This resizes the storage to *exactly* count elements, growing or
+ * shrinking the allocation as needed. It does not ASSERT anything about
+ * the previous allocation size, or about fCount.
+ *
+ * note: does NOT modify fCount
+ */
+ void resizeStorageToExact(int count) {
+ SkASSERT(count >= 0);
+ fArray = (T*)sk_realloc_throw(fArray, count * sizeof(T));
#ifdef SK_DEBUG
- fData = (ArrayT*)fArray;
+ fData = (ArrayT*)fArray;
#endif
- fReserve = size;
- }
- fCount += extra;
+ fReserve = count;
+ }
+
+ /**
+ * Increase the storage allocation such that it can hold (fCount + extra)
+ * elements.
+ * It never shrinks the allocation, and it may increase the allocation by
+ * more than is strictly required, based on a private growth heuristic.
+ *
+ * note: does NOT modify fCount
+ */
+ void resizeStorageToAtLeast(int count) {
+ SkASSERT(count > fReserve);
+ int space = count + 4;
+ space += space>>2;
+ resizeStorageToExact(space);
}
};
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