CBD-6348: [BP] [ubsan] Let random value be uint32_t

The comment states it may be any value, but ubsan complains with:

    hash_table.cc:629:22: runtime error: negation of -2147483648 cannot be represented in type 'int'; cast to an unsigned type to negate this value to itself

Just flip the value to uint32_t as that's what it really is

Change-Id: I89c6e027360c12e3d2498bbb3bc54bd9b73b3275
Reviewed-on: https://review.couchbase.org/c/kv_engine/+/235073
Tested-by: Trond Norbye <[email protected]>
Well-Formed: Restriction Checker
Reviewed-by: Jim Walker <[email protected]>

Author: trondn

engines/ep/src/hash_table.cc

@@ -365,8 +365,8 @@ HashTable::UnlockedFindResult HashTable::unlocked_find(
     return {foundCmt, foundPend};
 }
 
-HashTable::RandomKeyVisitor::RandomKeyVisitor(size_t size, int random)
-    : random(std::abs(random)) {
+HashTable::RandomKeyVisitor::RandomKeyVisitor(size_t size, uint32_t random)
+    : random(random) {
     setup(size);
 }
 
@@ -397,11 +397,11 @@ void HashTable::RandomKeyVisitor::setup(size_t size) {
     }
 
     currentSize = size;
-    currentBucket = random % (currentSize);
+    currentBucket = random % static_cast<uint32_t>(currentSize);
     bucketsVisited = 0;
 }
 
-std::unique_ptr<Item> HashTable::getRandomKey(CollectionID cid, int rnd) {
+std::unique_ptr<Item> HashTable::getRandomKey(CollectionID cid, uint32_t rnd) {
     return getRandomKey(cid, RandomKeyVisitor{getSize(), rnd});
 }
 

engines/ep/src/hash_table.h

@@ -937,7 +937,7 @@ class HashTable {
      *
      * @return an item -- NULL if not fount
      */
-    std::unique_ptr<Item> getRandomKey(CollectionID cid, int random);
+    std::unique_ptr<Item> getRandomKey(CollectionID cid, uint32_t random);
 
     /**
      * Set an Item into the this hashtable
@@ -1490,7 +1490,7 @@ class HashTable {
          *        should be the result of a random generator. There is no limit
          *        on this value.
          */
-        RandomKeyVisitor(size_t size, int random);
+        RandomKeyVisitor(size_t size, uint32_t random);
 
         /**
          * Return the bucket to use, this internally increments (and wraps) for
@@ -1517,7 +1517,7 @@ class HashTable {
         size_t currentSize{0};
         size_t currentBucket{0};
         size_t bucketsVisited{0};
-        int random{0};
+        uint32_t random{0};
     };
 
     /**

engines/ep/tests/module_tests/hash_table_test.cc

@@ -1244,12 +1244,12 @@ class GetRandomHashTable : public HashTable {
         : HashTable(st, std::move(svFactory), initialSize, locks) {
     }
 
-    void testIntialiseVisitor(size_t size, int random) {
+    void testIntialiseVisitor(size_t size, uint32_t random) {
         HashTable::RandomKeyVisitor visitor{size, random};
         EXPECT_LT(visitor.getNextBucket(), size);
     }
 
-    void testVisitor(size_t size, int random) {
+    void testVisitor(size_t size, uint32_t random) {
         HashTable::RandomKeyVisitor visitor{size, random};
         EXPECT_FALSE(visitor.visitComplete());
         EXPECT_FALSE(visitor.maybeReset(size));
@@ -1294,7 +1294,7 @@ class GetRandomHashTable : public HashTable {
 
         // Initialise the visitor so it computes a start point very close to the
         // end a place which definitely does not exist after the resize
-        HashTable::RandomKeyVisitor visitor{getSize(), int(size - 10)};
+        HashTable::RandomKeyVisitor visitor{getSize(), uint32_t(size - 10)};
 
         // Ensure if resize is called after the visitor is constructed
         // getRandomKey does not generate any faults
@@ -1318,7 +1318,7 @@ class GetRandomHashTable : public HashTable {
 
         // Initialise the visitor so it computes a start point very close to the
         // end a place which definitely does not exist after the resize
-        HashTable::RandomKeyVisitor visitor{getSize(), int(size - 10)};
+        HashTable::RandomKeyVisitor visitor{getSize(), uint32_t(size - 10)};
 
         // Increase the keys in the HT
         keys = generateKeys(500, 100 /*start key*/);