Function getRange

fdbclient/NativeAPI.actor.cpp:4238–4554

GetKeyValuesReply or GetMappedKeyValuesReply (It would be nice if we could use REPLY_TYPE(GetKeyValuesFamilyRequest) instead of specify it as a separate template element)

                                               // we could use REPLY_TYPE(GetKeyValuesFamilyRequest) instead of specify
                                               // it as a separate template element)
                class RangeResultFamily // RangeResult or MappedRangeResult
                >
Future<RangeResultFamily> getRange(Reference<TransactionState> trState,
                                   Future<Version> fVersion,
                                   KeySelector begin,
                                   KeySelector end,
                                   Key mapper,
                                   GetRangeLimits limits,
                                   Promise<std::pair<Key, Key>> conflictRange,
                                   int matchIndex,
                                   Snapshot snapshot,
                                   Reverse reverse,
                                   UseTenant useTenant = UseTenant::True) {
	//	state using RangeResultRefFamily = typename RangeResultFamily::RefType;
	state GetRangeLimits originalLimits(limits);
	state KeySelector originalBegin = begin;
	state KeySelector originalEnd = end;
	state RangeResultFamily output;
	state Span span("NAPI:getRange"_loc, trState->spanContext);
	if (useTenant && trState->tenant().present()) {
		span.addAttribute("tenant"_sr, trState->tenant().get());
	}

	try {
		state Version version = wait(fVersion);
		trState->cx->validateVersion(version);

		state double startTime = now();
		state Version readVersion = version; // Needed for latestVersion requests; if more, make future requests at the
		                                     // version that the first one completed
		                                     // FIXME: Is this really right?  Weaken this and see if there is a problem;
		                                     // if so maybe there is a much subtler problem even with this.

		if (begin.getKey() == allKeys.begin && begin.offset < 1) {
			output.readToBegin = true;
			begin = KeySelector(firstGreaterOrEqual(begin.getKey()), begin.arena());
		}

		ASSERT(!limits.isReached());
		ASSERT((!limits.hasRowLimit() || limits.rows >= limits.minRows) && limits.minRows >= 0);

		loop {
			if (end.getKey() == allKeys.begin && (end.offset < 1 || end.isFirstGreaterOrEqual())) {
				getRangeFinished(
				    trState, startTime, originalBegin, originalEnd, snapshot, conflictRange, reverse, output);
				return output;
			}

			Key locationKey = reverse ? Key(end.getKey(), end.arena()) : Key(begin.getKey(), begin.arena());
			Reverse locationBackward{ reverse ? (end - 1).isBackward() : begin.isBackward() };
			state KeyRangeLocationInfo beginServer =
			    wait(getKeyLocation(trState,
			                        locationKey,
			                        getRangeRequestStream<GetKeyValuesFamilyRequest>(),
			                        locationBackward,
			                        useTenant,
			                        version));
			state KeyRange shard = beginServer.range;