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8065159: AttributedString has quadratic resize algorithm

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Grow backing arrays geometrically instead of arithmetically

Reviewed-by: naoto, okutsu
This commit is contained in:
Martin Buchholz 2014-11-21 16:30:02 -08:00
parent da2c303927
commit 5ffaffb47e
1 changed files with 23 additions and 30 deletions
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53
jdk/src/java.base/share/classes/java/text/AttributedString.java
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@ -48,21 +48,18 @@ import java.text.AttributedCharacterIterator.Attribute;
*/
public class AttributedString {
// since there are no vectors of int, we have to use arrays.
// We allocate them in chunks of 10 elements so we don't have to allocate all the time.
private static final int ARRAY_SIZE_INCREMENT = 10;
// field holding the text
String text;
// fields holding run attribute information
// run attributes are organized by run
int runArraySize; // current size of the arrays
int runCount; // actual number of runs, <= runArraySize
int runStarts[]; // start index for each run
Vector<Attribute> runAttributes[]; // vector of attribute keys for each run
Vector<Object> runAttributeValues[]; // parallel vector of attribute values for each run
// Fields holding run attribute information.
// Run attributes are organized by run.
// Arrays are always of equal lengths (the current capacity).
// Since there are no vectors of int, we have to use arrays.
private static final int INITIAL_CAPACITY = 10;
int runCount; // actual number of runs, <= current capacity
int[] runStarts; // start index for each run
Vector<Attribute>[] runAttributes; // vector of attribute keys for each run
Vector<Object>[] runAttributeValues; // parallel vector of attribute values for each run
/**
* Constructs an AttributedString instance with the given
@ -416,18 +413,17 @@ public class AttributedString {
private final void createRunAttributeDataVectors() {
// use temporary variables so things remain consistent in case of an exception
int newRunStarts[] = new int[ARRAY_SIZE_INCREMENT];
int[] newRunStarts = new int[INITIAL_CAPACITY];
@SuppressWarnings("unchecked")
Vector<Attribute> newRunAttributes[] = (Vector<Attribute>[]) new Vector<?>[ARRAY_SIZE_INCREMENT];
Vector<Attribute>[] newRunAttributes = (Vector<Attribute>[]) new Vector<?>[INITIAL_CAPACITY];
@SuppressWarnings("unchecked")
Vector<Object> newRunAttributeValues[] = (Vector<Object>[]) new Vector<?>[ARRAY_SIZE_INCREMENT];
Vector<Object>[] newRunAttributeValues = (Vector<Object>[]) new Vector<?>[INITIAL_CAPACITY];
runStarts = newRunStarts;
runAttributes = newRunAttributes;
runAttributeValues = newRunAttributeValues;
runArraySize = ARRAY_SIZE_INCREMENT;
runCount = 1; // assume initial run starting at index 0
}
@ -465,25 +461,22 @@ public class AttributedString {
// we'll have to break up a run
// first, make sure we have enough space in our arrays
if (runCount == runArraySize) {
int newArraySize = runArraySize + ARRAY_SIZE_INCREMENT;
int newRunStarts[] = new int[newArraySize];
int currentCapacity = runStarts.length;
if (runCount == currentCapacity) {
// We need to resize - we grow capacity by 25%.
int newCapacity = currentCapacity + (currentCapacity >> 2);
@SuppressWarnings("unchecked")
Vector<Attribute> newRunAttributes[] = (Vector<Attribute>[]) new Vector<?>[newArraySize];
// use temporary variables so things remain consistent in case of an exception
int[] newRunStarts =
Arrays.copyOf(runStarts, newCapacity);
Vector<Attribute>[] newRunAttributes =
Arrays.copyOf(runAttributes, newCapacity);
Vector<Object>[] newRunAttributeValues =
Arrays.copyOf(runAttributeValues, newCapacity);
@SuppressWarnings("unchecked")
Vector<Object> newRunAttributeValues[] = (Vector<Object>[]) new Vector<?>[newArraySize];
for (int i = 0; i < runArraySize; i++) {
newRunStarts[i] = runStarts[i];
newRunAttributes[i] = runAttributes[i];
newRunAttributeValues[i] = runAttributeValues[i];
}
runStarts = newRunStarts;
runAttributes = newRunAttributes;
runAttributeValues = newRunAttributeValues;
runArraySize = newArraySize;
}
// make copies of the attribute information of the old run that the new one used to be part of