Title: [145601] trunk/Source/WebCore
- Revision
- 145601
- Author
- [email protected]
- Date
- 2013-03-12 15:39:02 -0700 (Tue, 12 Mar 2013)
Log Message
Add a single character cache to WidthCache
https://bugs.webkit.org/show_bug.cgi?id=112084
Patch by Benjamin Poulain <[email protected]> on 2013-03-12
Reviewed by Geoffrey Garen.
More than half of the values stored in WidthCache are values
for a single character.
Previously, we were creating a new SmallStringKey for each one of
them, causing a lot of extra memory operations even for the simple
cases.
This patch adds a second map, m_singleCharMap, to simplify the
computation for the common case of a single char TextRun.
* platform/graphics/WidthCache.h:
(WebCore::WidthCache::clear):
(WidthCache):
(WebCore::WidthCache::addSlowCase):
Modified Paths
Diff
Modified: trunk/Source/WebCore/ChangeLog (145600 => 145601)
--- trunk/Source/WebCore/ChangeLog 2013-03-12 22:38:45 UTC (rev 145600)
+++ trunk/Source/WebCore/ChangeLog 2013-03-12 22:39:02 UTC (rev 145601)
@@ -1,3 +1,25 @@
+2013-03-12 Benjamin Poulain <[email protected]>
+
+ Add a single character cache to WidthCache
+ https://bugs.webkit.org/show_bug.cgi?id=112084
+
+ Reviewed by Geoffrey Garen.
+
+ More than half of the values stored in WidthCache are values
+ for a single character.
+
+ Previously, we were creating a new SmallStringKey for each one of
+ them, causing a lot of extra memory operations even for the simple
+ cases.
+
+ This patch adds a second map, m_singleCharMap, to simplify the
+ computation for the common case of a single char TextRun.
+
+ * platform/graphics/WidthCache.h:
+ (WebCore::WidthCache::clear):
+ (WidthCache):
+ (WebCore::WidthCache::addSlowCase):
+
2013-03-12 Philip Rogers <[email protected]>
Replace static_casts for SVG transformable and locatable elements
Modified: trunk/Source/WebCore/platform/graphics/WidthCache.h (145600 => 145601)
--- trunk/Source/WebCore/platform/graphics/WidthCache.h 2013-03-12 22:38:45 UTC (rev 145600)
+++ trunk/Source/WebCore/platform/graphics/WidthCache.h 2013-03-12 22:39:02 UTC (rev 145601)
@@ -144,20 +144,38 @@
return addSlowCase(run, entry);
}
+ void clear()
+ {
+ m_singleCharMap.clear();
+ m_map.clear();
+ }
+
+private:
float* addSlowCase(const TextRun& run, float entry)
{
- SmallStringKey smallStringKey;
- if (run.is8Bit())
- smallStringKey = SmallStringKey(run.characters8(), run.length());
- else
- smallStringKey = SmallStringKey(run.characters16(), run.length());
+ int length = run.length();
+ bool isNewEntry;
+ float *value;
+ if (length == 1) {
+ SingleCharMap::AddResult addResult = m_singleCharMap.add(run[0], entry);
+ isNewEntry = addResult.isNewEntry;
+ value = &addResult.iterator->value;
+ } else {
+ SmallStringKey smallStringKey;
+ if (run.is8Bit())
+ smallStringKey = SmallStringKey(run.characters8(), length);
+ else
+ smallStringKey = SmallStringKey(run.characters16(), length);
- Map::AddResult addResult = m_map.add(smallStringKey, entry);
+ Map::AddResult addResult = m_map.add(smallStringKey, entry);
+ isNewEntry = addResult.isNewEntry;
+ value = &addResult.iterator->value;
+ }
// Cache hit: ramp up by sampling the next few words.
- if (!addResult.isNewEntry) {
+ if (!isNewEntry) {
m_interval = s_minInterval;
- return &addResult.iterator->value;
+ return value;
}
// Cache miss: ramp down by increasing our sampling interval.
@@ -165,23 +183,24 @@
++m_interval;
m_countdown = m_interval;
- if (m_map.size() < s_maxSize)
- return &addResult.iterator->value;
+ if ((m_singleCharMap.size() + m_map.size()) < s_maxSize)
+ return value;
- m_map.clear(); // No need to be fancy: we're just trying to avoid pathological growth.
+ // No need to be fancy: we're just trying to avoid pathological growth.
+ m_singleCharMap.clear();
+ m_map.clear();
return 0;
}
- void clear() { m_map.clear(); }
-
-private:
typedef HashMap<SmallStringKey, float, SmallStringKeyHash, SmallStringKeyHashTraits> Map;
+ typedef HashMap<UChar, float> SingleCharMap;
static const int s_minInterval = -3; // A cache hit pays for about 3 cache misses.
static const int s_maxInterval = 20; // Sampling at this interval has almost no overhead.
static const int s_maxSize = 500000; // Just enough to guard against pathological growth.
int m_interval;
int m_countdown;
+ SingleCharMap m_singleCharMap;
Map m_map;
};
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