Print suggestion messages related to the use of --disable-blocklist-prefetch

TileGenerator.cpp

@@ -1908,6 +1908,50 @@ void TileGenerator::renderMap()
 	}
 	if (progressIndicator && eraseProgress)
 		cout << std::setw(50) << "" << "\r";
+
+	if (m_generateNoPrefetch) {
+		double queryFactor = 1.0 * m_db->getBlocksQueriedCount() / m_db->getBlocksReadCount();
+		if (verboseStatistics >= 4) {
+			std::cout << std::fixed << std::setprecision(2);
+			std::cout << "disable-blocklist-prefetch statistics:" << std::endl
+				<< "    Query factor:   " << queryFactor << std::endl;
+		}
+		if (!(m_silenceSuggestions & SUGGESTION_PREFETCH) && queryFactor >= 10) {
+			std::cout << std::fixed << std::setprecision(2);
+			std::cout << "NOTE: amount of database blocks queried exceeds amount read by a factor " << queryFactor << "." << std::endl
+				<< "      This makes --disable-blocklist-prefetch rather inefficient. Consider disabling it, or" << std::endl
+				<< "      adjusting the vertical limits (e.g. --min-y=" << m_YMinMapped * 16 << " --max-y=" << m_YMaxMapped*16+15 << ")" << std::endl;
+		}
+	}
+	else {
+		double blocksFractionMapped = 1.0 * m_db->getBlocksReadCount() / m_worldBlocks;
+		long long worldVolumeMapped = (m_xMax-m_xMin+1) * (m_zMax-m_zMin+1) * (m_YMaxMapped-m_YMinMapped+1);
+
+		if (verboseStatistics >= 4) {
+			std::cout << std::fixed << std::setprecision(2);
+			std::cout << "disable-blocklist-prefetch statistics:" << std::endl
+				<< "    World size (1M Blocks):          " << m_worldBlocks / 1000.0 / 1000
+					<< "  (" << MIN_NOPREFETCH_VOLUME / 1000.0 / 1000 << " .. "
+					<< MAX_NOPREFETCH_VOLUME / 1000.0 / 1000 << ")" << std::endl
+				<< "    Fraction of world blocks mapped: "
+					<< 100 * blocksFractionMapped << "%  (limit: 10%)" << std::endl
+				<< "    Volume mapped:                   "
+					<< worldVolumeMapped / 10000.0 << "%  (" << worldVolumeMapped << ")" << std::endl;
+		}
+
+		if (!(m_silenceSuggestions & SUGGESTION_PREFETCH)
+			&& m_worldBlocks >= MIN_NOPREFETCH_VOLUME
+			&& blocksFractionMapped < 0.1
+			&& worldVolumeMapped < MAX_NOPREFETCH_VOLUME) {
+			std::cout << "NOTE: Mapping speed may improve using the option --disable-blocklist-prefetch,"
+				<< " combined with vertical limits (" << m_YMinMapped * 16 << " .. " << m_YMaxMapped*16+15 << ")" << std::endl;
+			if (m_backend == "leveldb") {
+				std::cout << "      The option --database-format=" << (m_recommendedDatabaseFormat != "" ? m_recommendedDatabaseFormat : "mixed")
+					<< " is also required for the (current) leveldb backend." << std::endl
+					<< "      Use --verbose=2 or --database-format=query for details" << std::endl;
+			}
+		}
+	}
 }
 
 Color TileGenerator::computeMapHeightColor(int height)

TileGenerator.h

@@ -55,6 +55,7 @@
 #define HEIGHTSCALESIZE			60
 
 #define SUGGESTION_ALL			0xffffffff
+#define SUGGESTION_PREFETCH		0x00000001
 
 class TileGenerator
 {

doc/manual.rst

@@ -282,7 +282,7 @@ Feedback / information options:
     * ``--version`` :					Print version ID of minetestmapper
     * ``--verbose[=<n>]`` :				Report world and map statistics (size, dimensions, number of blocks)
     * ``--verbose-search-colors[=n]`` :			Report which colors files are used and/or which locations are searched
-    * ``--silence-suggestions all`` :			Do not bother doing suggestions
+    * ``--silence-suggestions all,prefetch`` :		Do not bother doing suggestions
     * ``--progress`` :					Show a progress indicator while generating the map
 
 Miscellaneous options
@@ -1056,7 +1056,7 @@ Detailed Description of Options
 	.. image:: images/drawscale-both.png
 	.. image:: images/sidescale-interval.png
 
-``--silence-suggestions all``
+``--silence-suggestions all,prefetch``
 ......................................
 	Do not print usage suggestions of the specified types.
 
@@ -1064,6 +1064,8 @@ Detailed Description of Options
 	if that may be advantageous. This option disables such messages.
 
 	    :all:	Silence all existing (and future) suggestions there may be.
+	    :prefetch:	Do not make suggestions a about the use of --disable-blocklist-prefetch,
+			and adjustment of --min-y and --max-y when using --disable-blocklist-prefetch.
 
 ``--sqlite-cacheworldrow``
 ..........................
@@ -1775,7 +1777,7 @@ More information is available:
 .. _--origincolor: `--origincolor <color>`_
 .. _--output: `--output <output_image.png>`_
 .. _--playercolor: `--playercolor <color>`_
-.. _--silence-suggestions: `--silence-suggestions all`_
+.. _--silence-suggestions: `--silence-suggestions all,prefetch`_
 .. _--scalecolor: `--scalecolor <color>`_
 .. _--scalefactor: `--scalefactor 1:<n>`_
 .. _--height-level-0: `--height-level-0 <level>`_

mapper.cpp

@@ -125,7 +125,7 @@ void usage()
 			"  --tilecenter <x>,<y>|world|map\n"
 			"  --scalefactor 1:<n>\n"
 			"  --chunksize <size>\n"
-			"  --silence-suggestions all\n"
+			"  --silence-suggestions all,prefetch\n"
 			"  --verbose[=n]\n"
 			"  --verbose-search-colors[=n]\n"
 			"  --progress\n"
@@ -883,6 +883,8 @@ int main(int argc, char *argv[])
 							}
 							else if (flag == "all")
 								generator.setSilenceSuggestion(SUGGESTION_ALL);
+							else if (flag == "prefetch")
+								generator.setSilenceSuggestion(SUGGESTION_PREFETCH);
 							else {
 								std::cerr << "Invalid flag to '" << long_options[option_index].name << "': '" << flag << "'" << std::endl;
 								usage();