Fix #14396: Industry production graph showed zero instead of N/A.

Record the number of valid history records per industry so that the graph avoids showing values which are not present as zero.

src/graph_gui.cpp

@@ -222,6 +222,7 @@ protected:
 		const Tprojection &proj; ///< Projection to apply.
 
 		inline void Fill(uint i, const auto &data) const { this->dataset.values[i] = std::invoke(this->proj, data); }
+		inline void MakeInvalid(uint i) const { this->dataset.values[i] = INVALID_DATAPOINT; }
 	};
 
 	/**
@@ -1685,7 +1686,7 @@ struct IndustryProductionGraphWindow : BaseCargoGraphWindow {
 			transported.dash = 2;
 			auto transported_filler = Filler{transported, &Industry::ProducedHistory::transported};
 
-			FillFromHistory<GRAPH_NUM_MONTHS>(p.history, produced_filler, transported_filler);
+			FillFromHistory<GRAPH_NUM_MONTHS>(p.history, i->valid_history, produced_filler, transported_filler);
 		}
 
 		this->SetDirty();

src/industry.h

@@ -89,6 +89,7 @@ struct Industry : IndustryPool::PoolItem<&_industry_pool> {
 	TileArea location{INVALID_TILE, 0, 0}; ///< Location of the industry
 	Town *town = nullptr; ///< Nearest town
 	Station *neutral_station = nullptr; ///< Associated neutral station
+	ValidHistoryMask valid_history = 0; ///< Mask of valid history records.
 	ProducedCargoes produced{}; ///< produced cargo slots
 	AcceptedCargoes accepted{}; ///< accepted cargo slots
 	uint8_t prod_level = 0; ///< general production level

src/industry_cmd.cpp

@@ -1837,6 +1837,8 @@ static void DoCreateNewIndustry(Industry *i, TileIndex tile, IndustryType type,
 		for (auto &p : i->produced) {
 			p.history[LAST_MONTH].production += ScaleByCargoScale(p.rate * 8, false);
 		}
+
+		UpdateValidHistory(i->valid_history);
 	}
 
 	if (indspec->callback_mask.Test(IndustryCallbackMask::DecideColour)) {
@@ -2494,6 +2496,8 @@ void GenerateIndustries()
  */
 static void UpdateIndustryStatistics(Industry *i)
 {
+	UpdateValidHistory(i->valid_history);
+
 	for (auto &p : i->produced) {
 		if (IsValidCargoType(p.cargo)) {
 			if (p.history[THIS_MONTH].production != 0) i->last_prod_year = TimerGameEconomy::year;

src/misc/history_func.hpp

@@ -10,8 +10,18 @@
 #ifndef HISTORY_FUNC_HPP
 #define HISTORY_FUNC_HPP
 
+#include "../core/bitmath_func.hpp"
 #include "history_type.hpp"
 
+/**
+ * Update mask of valid history records.
+ * @param[in,out] valid_history Valid history records.
+ */
+inline void UpdateValidHistory(ValidHistoryMask &valid_history)
+{
+	SB(valid_history, LAST_MONTH, HISTORY_RECORDS - LAST_MONTH, GB(valid_history, LAST_MONTH, HISTORY_RECORDS - LAST_MONTH) << 1ULL | 1ULL);
+}
+
 /**
  * Rotate history.
  * @tparam T type of history data element.
@@ -27,14 +37,19 @@ void RotateHistory(HistoryData<T> &history)
 /**
  * Fill some data with historical data.
  * @param history Historical data to fill from.
+ * @param valid_history Mask of valid history records.
  * @param fillers Fillers to fill with history data.
  */
 template <uint N, typename T, typename... Tfillers>
-void FillFromHistory(const HistoryData<T> &history, Tfillers... fillers)
+void FillFromHistory(const HistoryData<T> &history, ValidHistoryMask valid_history, Tfillers... fillers)
 {
 	for (uint i = 0; i != N; ++i) {
-		auto &data = history[N - i];
-		(fillers.Fill(i, data), ...);
+		if (HasBit(valid_history, N - i)) {
+			auto &data = history[N - i];
+			(fillers.Fill(i, data), ...);
+		} else {
+			(fillers.MakeInvalid(i), ...);
+		}
 	}
 }
 

src/misc/history_type.hpp

@@ -22,4 +22,7 @@ static constexpr uint8_t LAST_MONTH = 1;
 template <typename T>
 using HistoryData = std::array<T, HISTORY_RECORDS>;
 
+/** Mask of valid history records. */
+using ValidHistoryMask = uint64_t;
+
 #endif /* HISTORY_TYPE_HPP */

src/saveload/industry_sl.cpp

@@ -162,6 +162,8 @@ static const SaveLoad _industry_desc[] = {
 	SLE_CONDVAR(Industry, random,                     SLE_UINT16,                SLV_82, SL_MAX_VERSION),
 	SLE_CONDSSTR(Industry, text,     SLE_STR | SLF_ALLOW_CONTROL,     SLV_INDUSTRY_TEXT, SL_MAX_VERSION),
 
+	SLE_CONDVAR(Industry, valid_history, SLE_UINT64, SLV_INDUSTRY_NUM_VALID_HISTORY, SL_MAX_VERSION),
+
 	SLEG_CONDSTRUCTLIST("accepted", SlIndustryAccepted,                          SLV_INDUSTRY_CARGO_REORGANISE, SL_MAX_VERSION),
 	SLEG_CONDSTRUCTLIST("produced", SlIndustryProduced,                          SLV_INDUSTRY_CARGO_REORGANISE, SL_MAX_VERSION),
 };
@@ -228,6 +230,24 @@ struct INDYChunkHandler : ChunkHandler {
 			} else if (IsSavegameVersionBefore(SLV_INDUSTRY_CARGO_REORGANISE)) {
 				LoadMoveAcceptsProduced(i, INDUSTRY_NUM_INPUTS, INDUSTRY_NUM_OUTPUTS);
 			}
+
+			if (IsSavegameVersionBefore(SLV_INDUSTRY_NUM_VALID_HISTORY)) {
+				/* The last month has always been recorded. */
+				size_t oldest_valid = LAST_MONTH;
+				if (!IsSavegameVersionBefore(SLV_PRODUCTION_HISTORY)) {
+					/* History was extended but we did not keep track of valid history, so assume it from the oldest non-zero value. */
+					for (const auto &p : i->produced) {
+						if (!IsValidCargoType(p.cargo)) continue;
+						for (size_t n = LAST_MONTH; n < std::size(p.history); ++n) {
+							if (p.history[n].production == 0 && p.history[n].transported == 0) continue;
+							oldest_valid = std::max(oldest_valid, n);
+						}
+					}
+				}
+				/* Set mask bits up to and including the oldest valid record. */
+				i->valid_history = (std::numeric_limits<uint64_t>::max() >> (std::numeric_limits<uint64_t>::digits - (oldest_valid + 1 - LAST_MONTH))) << LAST_MONTH;
+			}
+
 			Industry::industries[i->type].insert(i->index);
 		}
 	}

src/saveload/saveload.h

@@ -404,6 +404,7 @@ enum SaveLoadVersion : uint16_t {
 	SLV_ORDERS_OWNED_BY_ORDERLIST,          ///< 354  PR#13948 Orders stored in OrderList, pool removed.
 
 	SLV_FACE_STYLES,                        ///< 355  PR#14319 Addition of face styles, replacing gender and ethnicity.
+	SLV_INDUSTRY_NUM_VALID_HISTORY,         ///< 356  PR#14416 Store number of valid history records for industries.
 
 	SL_MAX_VERSION,                         ///< Highest possible saveload version
 };