Merge pull request #18114 from vespa-engine/balder/explicit-erase-when-capacity-is-low

Use explicit erase to avoid clearing and resizing the hashtable when …

2 files changed, 13 insertions, 5 deletions

diff --git a/vespalib/src/vespa/vespalib/util/alloc.h b/vespalib/src/vespa/vespalib/util/alloc.h
index f608a244035..a97e8c9f25e 100644
--- a/vespalib/src/vespa/vespalib/util/alloc.h
+++ b/vespalib/src/vespa/vespalib/util/alloc.h
@@ -102,13 +102,21 @@ private:
 namespace vespalib {
 
 /// Rounds up to the closest number that is a power of 2
-inline size_t roundUp2inN(size_t minimum) {
+inline size_t
+roundUp2inN(size_t minimum) {
     return 2ul << Optimized::msbIdx(minimum - 1);
 }
 
 /// Rounds minElems up to the closest number where minElems*elemSize is a power of 2
-inline size_t roundUp2inN(size_t minElems, size_t elemSize) {
+inline size_t
+roundUp2inN(size_t minElems, size_t elemSize) {
     return roundUp2inN(minElems * elemSize)/elemSize;
 }
 
+template <typename T>
+size_t
+roundUp2inN(size_t elems) {
+    return roundUp2inN(elems, sizeof(T));
+}
+
 }
diff --git a/vespalib/src/vespa/vespalib/util/optimized.h b/vespalib/src/vespa/vespalib/util/optimized.h
index 92cf1f0ca24..6c6d1b12a71 100644
--- a/vespalib/src/vespa/vespalib/util/optimized.h
+++ b/vespalib/src/vespa/vespalib/util/optimized.h
@@ -22,9 +22,9 @@ public:
     static int lsbIdx(unsigned int v);
     static int lsbIdx(unsigned long v);
     static int lsbIdx(unsigned long long v);
-    static int popCount(unsigned int v) { return __builtin_popcount(v); }
-    static int popCount(unsigned long v) { return __builtin_popcountl(v); }
-    static int popCount(unsigned long long v) { return __builtin_popcountll(v); }
+    static constexpr int popCount(unsigned int v) { return __builtin_popcount(v); }
+    static constexpr int popCount(unsigned long v) { return __builtin_popcountl(v); }
+    static constexpr int popCount(unsigned long long v) { return __builtin_popcountll(v); }
 };
 
 /**