Use atomic for _lowest and _highest in proton::LidStateVector.

2 files changed, 40 insertions, 45 deletions

diff --git a/searchcore/src/vespa/searchcore/proton/documentmetastore/lidstatevector.cpp b/searchcore/src/vespa/searchcore/proton/documentmetastore/lidstatevector.cpp
index 7309f7a518c..27b9cfdd197 100644
--- a/searchcore/src/vespa/searchcore/proton/documentmetastore/lidstatevector.cpp
+++ b/searchcore/src/vespa/searchcore/proton/documentmetastore/lidstatevector.cpp
@@ -23,9 +23,11 @@ LidStateVector::~LidStateVector() = default;
 void
 LidStateVector::resizeVector(uint32_t newSize, uint32_t newCapacity)
 {
-    assert(!_trackLowest || _lowest <= _bv.size());
-    assert(!_trackHighest || _bv.size() == 0 || _highest < _bv.size());
-    bool nolowest(_lowest == _bv.size());
+    uint32_t lowest = getLowest();
+    uint32_t highest = getHighest();
+    assert(!_trackLowest || lowest <= _bv.size());
+    assert(!_trackHighest || _bv.size() == 0 || highest < _bv.size());
+    bool nolowest(lowest == _bv.size());
     if (_bv.size() > newSize) {
         _bv.shrink(newSize);
     }
@@ -36,55 +38,44 @@ LidStateVector::resizeVector(uint32_t newSize, uint32_t newCapacity)
         _bv.extend(newSize);
     }
     if (_trackLowest) {
-        if (nolowest) {
-            _lowest = _bv.size();
-        }
-        if (_lowest > _bv.size()) {
-            _lowest = _bv.size();
+        if (nolowest || lowest > _bv.size()) {
+            lowest = _bv.size();
+            _lowest.store(lowest, std::memory_order_relaxed);
         }
     }
     if (_trackHighest) {
-        if (_highest >= _bv.size()) {
-            _highest = _bv.size() > 0 ? _bv.getPrevTrueBit(_bv.size() - 1) : 0;
+        if (highest >= _bv.size()) {
+            highest = _bv.size() > 0 ? _bv.getPrevTrueBit(_bv.size() - 1) : 0;
+            _highest.store(highest, std::memory_order_relaxed);
         }
     }
-    maybeUpdateLowest();
-    maybeUpdateHighest();
 }
 
 void
-LidStateVector::updateLowest()
+LidStateVector::updateLowest(uint32_t lowest)
 {
-    if (_lowest >= _bv.size())
-        return;
-    if (_bv.testBit(_lowest))
-        return;
-    uint32_t lowest = _bv.getNextTrueBit(_lowest);
+    lowest = _bv.getNextTrueBit(lowest);
     assert(lowest <= _bv.size());
-    _lowest = lowest;
+    _lowest.store(lowest, std::memory_order_relaxed);
 }
 
 void
-LidStateVector::updateHighest()
+LidStateVector::updateHighest(uint32_t highest)
 {
-    if (_highest == 0)
-        return;
-    if (_bv.testBit(_highest))
-        return;
-    uint32_t highest = _bv.getPrevTrueBit(_highest);
+    highest = _bv.getPrevTrueBit(highest);
     assert(_bv.size() == 0 || highest < _bv.size());
-    _highest = highest;
+    _highest.store(highest, std::memory_order_relaxed);
 }
 
 void
 LidStateVector::setBit(unsigned int idx)
 {
     assert(idx < _bv.size());
-    if (_trackLowest && idx < _lowest) {
-        _lowest = idx;
+    if (_trackLowest && idx < getLowest()) {
+        _lowest.store(idx, std::memory_order_relaxed);
     }
-    if (_trackHighest && idx > _highest) {
-        _highest = idx;
+    if (_trackHighest && idx > getHighest()) {
+        _highest.store(idx, std::memory_order_relaxed);
     }
     assert(!_bv.testBit(idx));
     _bv.setBitAndMaintainCount(idx);
@@ -111,11 +102,11 @@ LidStateVector::assert_is_not_set_then_set_bits_helper(const std::vector<uint32_
         }
     }
     if (do_set) {
-        if (_trackLowest && low < _lowest) {
-            _lowest = low;
+        if (_trackLowest && low < getLowest()) {
+            _lowest.store(low, std::memory_order_relaxed);
         }
-        if (_trackHighest && high > _highest) {
-            _highest = high;
+        if (_trackHighest && high > getHighest()) {
+            _highest.store(high, std::memory_order_relaxed);
         }
     }
     return high;
diff --git a/searchcore/src/vespa/searchcore/proton/documentmetastore/lidstatevector.h b/searchcore/src/vespa/searchcore/proton/documentmetastore/lidstatevector.h
index c0db4e99fa5..592ca23e63c 100644
--- a/searchcore/src/vespa/searchcore/proton/documentmetastore/lidstatevector.h
+++ b/searchcore/src/vespa/searchcore/proton/documentmetastore/lidstatevector.h
@@ -3,27 +3,31 @@
 #pragma once
 
 #include <vespa/searchlib/common/growablebitvector.h>
+#include <atomic>
 
 namespace proton {
 
 class LidStateVector
 {
     search::GrowableBitVector _bv;
-    uint32_t _lowest;
-    uint32_t _highest;
+    std::atomic<uint32_t> _lowest;
+    std::atomic<uint32_t> _highest;
     bool     _trackLowest;
     bool     _trackHighest;
 
-    void updateLowest();
-    void updateHighest(); 
+    void updateLowest(uint32_t lowest);
+    void updateHighest(uint32_t highest);
     void maybeUpdateLowest() {
-        if (_trackLowest && _lowest < _bv.size() && !_bv.testBit(_lowest))
-            updateLowest();
+        uint32_t lowest = getLowest();
+        if (_trackLowest && lowest < _bv.size() && !_bv.testBit(lowest)) {
+            updateLowest(lowest);
+        }
     }
-
     void maybeUpdateHighest() {
-        if (_trackHighest && _highest != 0 && !_bv.testBit(_highest))
-            updateHighest();
+        uint32_t highest = getHighest();
+        if (_trackHighest && highest != 0 && !_bv.testBit(highest)) {
+            updateHighest(highest);
+        }
     }
     template <bool do_set>
     uint32_t assert_is_not_set_then_set_bits_helper(const std::vector<uint32_t>& idxs);
@@ -51,8 +55,8 @@ public:
         return _bv.extraByteSize() + sizeof(LidStateVector);
     }
     bool empty() const { return count() == 0u; }
-    unsigned int getLowest() const { return _lowest; }
-    unsigned int getHighest() const { return _highest; }
+    unsigned int getLowest() const { return _lowest.load(std::memory_order_relaxed); }
+    unsigned int getHighest() const { return _highest.load(std::memory_order_relaxed); }
 
     /**
      * Get cached number of bits set in vector.  Called by read or