MB-35297: Evaluate all RangeScan continue limits

The current if/else if block is incorrect and for example means that
if both an item + byte limit are enabled, the item limit is the only
one checked, and the scan may not end at the expected point.

The updated if/else if now checks all limits for each call.

Change-Id: Ib606c164aa9060f459ffba75ca4741d94fb3f71c
Reviewed-on: https://review.couchbase.org/c/kv_engine/+/179901
Tested-by: Jim Walker <jim@couchbase.com>
Reviewed-by: Paolo Cocchi <paolo.cocchi@couchbase.com>

engines/ep/src/range_scans/range_scan.cc

@@ -537,14 +537,17 @@ void RangeScan::incrementValueFromDisk() {
 }
 
 bool RangeScan::areLimitsExceeded() const {
-    if (continueRunState.cState.limits.itemLimit) {
-        return continueRunState.itemCount >=
-               continueRunState.cState.limits.itemLimit;
-    } else if (continueRunState.cState.limits.timeLimit.count()) {
-        return now() >= continueRunState.scanContinueDeadline;
-    } else if (continueRunState.cState.limits.byteLimit) {
-        return continueRunState.byteCount >=
-               continueRunState.cState.limits.byteLimit;
+    if (continueRunState.cState.limits.itemLimit &&
+        continueRunState.itemCount >=
+                continueRunState.cState.limits.itemLimit) {
+        return true;
+    } else if (continueRunState.cState.limits.timeLimit.count() &&
+               now() >= continueRunState.scanContinueDeadline) {
+        return true;
+    } else if (continueRunState.cState.limits.byteLimit &&
+               continueRunState.byteCount >=
+                       continueRunState.cState.limits.byteLimit) {
+        return true;
     }
     return false;
 }

engines/ep/tests/module_tests/range_scan_test.cc

@@ -485,6 +485,19 @@ TEST_P(RangeScanTest, user_prefix_with_item_limit_2) {
                   expectedKeys.size() / 2);
 }
 
+// Test has a smaller byte-limit which must take affect before the item count
+TEST_P(RangeScanTest, user_prefix_with_two_limits) {
+    auto expectedKeys = getUserKeys();
+    testRangeScan(expectedKeys,
+                  scanCollection,
+                  {"user"},
+                  {"user\xFF"},
+                  2, // 2 items
+                  std::chrono::milliseconds(0),
+                  1, // 1 byte
+                  expectedKeys.size());
+}
+
 TEST_P(RangeScanTest, user_prefix_with_time_limit) {
     // Replace time with a function that ticks per call, forcing the scan to
     // yield for every item