add tests around mbTile SQKM calculation

.eslintrc

@@ -1,3 +1,6 @@
 {
-  "extends": "eslint-config-unstyled"
+  "extends": "eslint-config-unstyled",
+  "parserOptions": {
+    "ecmaVersion": 9
+  }
 }

lib/mbtiles.js

@@ -11,6 +11,7 @@ var tiletype = require('@mapbox/tiletype');
 var ZXYStream = require('./zxystream');
 var queue = require('d3-queue').queue;
 var os = require('os');
+var utils = require('./utils.js');
 
 if (process.env.BRIDGE_LOG_MAX_VTILE_BYTES_COMPRESSED) {
     var stats = { max:0, total:0, count:0 };
@@ -192,6 +193,15 @@ MBTiles.prototype.getTile = function(z, x, y, callback) {
                 if (stats.max < tileDataLength) {
                     stats.max = tileDataLength;
                 }
+                var area = stats.hasOwnProperty(z)
+                    ? stats[z] + utils.calculateTileArea(z, x, y)
+                    : utils.calculateTileArea(z, x, y);
+
+                stats = {
+                    ...stats,
+                    [z]: area
+                };
+
             }
             return callback(null, row.tile_data, headers);
         }

lib/utils.js

@@ -0,0 +1,35 @@
+'use strict'
+
+var EARTH_RADIUS = 6371.0088;
+
+function degToRad(degrees) {
+    return degrees * (Math.PI / 180);
+}
+
+function tileToLon(tileX, zoom) {
+    return ((tileX / 2**zoom) * 360.0) - 180.0;
+}
+
+function tileToLat(tileY, zoom) {
+    var n = Math.PI - 2 * Math.PI * tileY / 2**zoom;
+    return (180.0 / Math.PI) * Math.atan(0.5 * (Math.exp(n) - Math.exp(-n)));
+}
+
+/**
+ *
+ * @param {Number} zoom
+ * @param {Number} tileX
+ * @param {Number} tileY
+ * @returns {Number} SqKM of a given tile
+ */
+function calculateTileArea(zoom, tileX, tileY) {
+    var left = degToRad(tileToLon(tileX, zoom));
+    var top = degToRad(tileToLat(tileY, zoom));
+    var right = degToRad(tileToLon(tileX + 1, zoom));
+    var bottom = degToRad(tileToLat(tileY + 1, zoom));
+    return (Math.PI / degToRad(180)) * EARTH_RADIUS**2 * Math.abs(Math.sin(top) - Math.sin(bottom)) * Math.abs(left - right);
+}
+
+module.exports = {
+    calculateTileArea
+};

package.json

@@ -36,6 +36,7 @@
   "devDependencies": {
     "eslint": "~5.16.0",
     "eslint-config-unstyled": "^1.1.0",
+    "sinon": "^9.0.2",
     "tape": "~4.10.1"
   },
   "engines": {

test/zztile.sqkm.test.js

@@ -0,0 +1,61 @@
+'use strict';
+require('sqlite3').verbose();
+var tape = require('tape');
+var fs = require('fs');
+var os = require('os');
+var sinon = require('sinon');
+
+var fixtures = {
+    plain_1: __dirname + '/fixtures/plain_1.mbtiles'
+};
+
+tape('[tile.sqkm] should log sqkm in a stats file', function (assert) {
+    delete require.cache[require.resolve('..')];
+    process.env.BRIDGE_LOG_MAX_VTILE_BYTES_COMPRESSED = 1;
+    var MBTiles = require('../lib/mbtiles');
+    sinon.stub(process, 'exit');
+    process.on('exit', function() {
+        var assert = require('assert');
+        var expectedStats = {
+            '0': 508164394.24620897,
+            max: 7072,
+            total: 7.072,
+            count: 1
+        };
+
+        var actualStats = JSON.parse(fs.readFileSync(os.tmpdir() + '/tilelive-bridge-stats.json').toString());
+        assert.deepEqual(expectedStats, actualStats, 'stats should match');
+        fs.unlinkSync(os.tmpdir() + '/tilelive-bridge-stats.json');
+        delete process.env.BRIDGE_LOG_MAX_VTILE_BYTES_COMPRESSED;
+    });
+    new Promise(function (resolve, reject) {
+        new MBTiles(fixtures.plain_1, function (err, mbTiles) {
+            if (err) reject(err);
+            resolve(mbTiles);
+        });
+    })
+        .then(function (mbTiles) {
+            return new Promise(function (resolve, reject) {
+                mbTiles.getTile(0, 0, 0, function (error, tile, headers) {
+                    if (error) {
+                        assert.ifErr(error, 'should be empty');
+                        reject(error);
+                    }
+                    assert.deepEqual(
+                        tile,
+                        fs.readFileSync(
+                            __dirname + '/fixtures/images/plain_1_0_0_0.png'
+                        )
+                    );
+                    resolve(null);
+                });
+            });
+        })
+        .catch(function (error) {
+            console.log(error);
+        })
+        .finally(function () {
+            assert.end();
+            process.exit();
+        });
+});

yarn.lock

@@ -28,6 +28,42 @@
   resolved "https://registry.yarnpkg.com/@mapbox/tiletype/-/tiletype-0.3.1.tgz#1a1498f6a1b777630e0b4d3a2fed9d94959560cc"
   integrity sha1-GhSY9qG3d2MOC006L+2dlJWVYMw=
 
+"@sinonjs/commons@^1", "@sinonjs/commons@^1.6.0", "@sinonjs/commons@^1.7.0", "@sinonjs/commons@^1.7.2":
+  version "1.8.0"
+  resolved "https://registry.yarnpkg.com/@sinonjs/commons/-/commons-1.8.0.tgz#c8d68821a854c555bba172f3b06959a0039b236d"
+  integrity sha512-wEj54PfsZ5jGSwMX68G8ZXFawcSglQSXqCftWX3ec8MDUzQdHgcKvw97awHbY0efQEL5iKUOAmmVtoYgmrSG4Q==
+  dependencies:
+    type-detect "4.0.8"
+
+"@sinonjs/fake-timers@^6.0.0", "@sinonjs/fake-timers@^6.0.1":
+  version "6.0.1"
+  resolved "https://registry.yarnpkg.com/@sinonjs/fake-timers/-/fake-timers-6.0.1.tgz#293674fccb3262ac782c7aadfdeca86b10c75c40"
+  integrity sha512-MZPUxrmFubI36XS1DI3qmI0YdN1gks62JtFZvxR67ljjSNCeK6U08Zx4msEWOXuofgqUt6zPHSi1H9fbjR/NRA==
+  dependencies:
+    "@sinonjs/commons" "^1.7.0"
+
+"@sinonjs/formatio@^5.0.1":
+  version "5.0.1"
+  resolved "https://registry.yarnpkg.com/@sinonjs/formatio/-/formatio-5.0.1.tgz#f13e713cb3313b1ab965901b01b0828ea6b77089"
+  integrity sha512-KaiQ5pBf1MpS09MuA0kp6KBQt2JUOQycqVG1NZXvzeaXe5LGFqAKueIS0bw4w0P9r7KuBSVdUk5QjXsUdu2CxQ==
+  dependencies:
+    "@sinonjs/commons" "^1"
+    "@sinonjs/samsam" "^5.0.2"
+
+"@sinonjs/samsam@^5.0.2", "@sinonjs/samsam@^5.0.3":
+  version "5.0.3"
+  resolved "https://registry.yarnpkg.com/@sinonjs/samsam/-/samsam-5.0.3.tgz#86f21bdb3d52480faf0892a480c9906aa5a52938"
+  integrity sha512-QucHkc2uMJ0pFGjJUDP3F9dq5dx8QIaqISl9QgwLOh6P9yv877uONPGXh/OH/0zmM3tW1JjuJltAZV2l7zU+uQ==
+  dependencies:
+    "@sinonjs/commons" "^1.6.0"
+    lodash.get "^4.4.2"
+    type-detect "^4.0.8"
+
+"@sinonjs/text-encoding@^0.7.1":
+  version "0.7.1"
+  resolved "https://registry.yarnpkg.com/@sinonjs/text-encoding/-/text-encoding-0.7.1.tgz#8da5c6530915653f3a1f38fd5f101d8c3f8079c5"
+  integrity sha512-+iTbntw2IZPb/anVDbypzfQa+ay64MW0Zo8aJ8gZPWMMK6/OubMVb6lUPMagqjOPnmtauXnFCACVl3O7ogjeqQ==
+
 abbrev@1:
   version "1.1.1"
   resolved "https://registry.yarnpkg.com/abbrev/-/abbrev-1.1.1.tgz#f8f2c887ad10bf67f634f005b6987fed3179aac8"
@@ -311,6 +347,11 @@ detect-libc@^1.0.2:
   resolved "https://registry.yarnpkg.com/detect-libc/-/detect-libc-1.0.3.tgz#fa137c4bd698edf55cd5cd02ac559f91a4c4ba9b"
   integrity sha1-+hN8S9aY7fVc1c0CrFWfkaTEups=
 
+diff@^4.0.2:
+  version "4.0.2"
+  resolved "https://registry.yarnpkg.com/diff/-/diff-4.0.2.tgz#60f3aecb89d5fae520c11aa19efc2bb982aade7d"
+  integrity sha512-58lmxKSA4BNyLz+HHMUzlOEpg09FV+ev6ZMe3vJihgdxzgcwZ8VoEEPmALCZG9LmqfVoNMMKpttIYTVG6uDY7A==
+
 doctrine@^3.0.0:
   version "3.0.0"
   resolved "https://registry.yarnpkg.com/doctrine/-/doctrine-3.0.0.tgz#addebead72a6574db783639dc87a121773973961"
@@ -655,6 +696,11 @@ has-flag@^3.0.0:
   resolved "https://registry.yarnpkg.com/has-flag/-/has-flag-3.0.0.tgz#b5d454dc2199ae225699f3467e5a07f3b955bafd"
   integrity sha1-tdRU3CGZriJWmfNGfloH87lVuv0=
 
+has-flag@^4.0.0:
+  version "4.0.0"
+  resolved "https://registry.yarnpkg.com/has-flag/-/has-flag-4.0.0.tgz#944771fd9c81c81265c4d6941860da06bb59479b"
+  integrity sha512-EykJT/Q1KjTWctppgIAgfSO0tKVuZUjhgMr17kqTumMl6Afv3EISleU7qZUzoXDFTAHTDC4NOoG/ZxU3EvlMPQ==
+
 has-symbols@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/has-symbols/-/has-symbols-1.0.0.tgz#ba1a8f1af2a0fc39650f5c850367704122063b44"
@@ -801,6 +847,11 @@ is-typedarray@~1.0.0:
   resolved "https://registry.yarnpkg.com/is-typedarray/-/is-typedarray-1.0.0.tgz#e479c80858df0c1b11ddda6940f96011fcda4a9a"
   integrity sha1-5HnICFjfDBsR3dppQPlgEfzaSpo=
 
+isarray@0.0.1:
+  version "0.0.1"
+  resolved "https://registry.yarnpkg.com/isarray/-/isarray-0.0.1.tgz#8a18acfca9a8f4177e09abfc6038939b05d1eedf"
+  integrity sha1-ihis/Kmo9Bd+Cav8YDiTmwXR7t8=
+
 isarray@~1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/isarray/-/isarray-1.0.0.tgz#bb935d48582cba168c06834957a54a3e07124f11"
@@ -864,6 +915,11 @@ jsprim@^1.2.2:
     json-schema "0.2.3"
     verror "1.10.0"
 
+just-extend@^4.0.2:
+  version "4.1.0"
+  resolved "https://registry.yarnpkg.com/just-extend/-/just-extend-4.1.0.tgz#7278a4027d889601640ee0ce0e5a00b992467da4"
+  integrity sha512-ApcjaOdVTJ7y4r08xI5wIqpvwS48Q0PBG4DJROcEkH1f8MdAiNFyFxz3xoL0LWAVwjrwPYZdVHHxhRHcx/uGLA==
+
 levn@^0.3.0, levn@~0.3.0:
   version "0.3.0"
   resolved "https://registry.yarnpkg.com/levn/-/levn-0.3.0.tgz#3b09924edf9f083c0490fdd4c0bc4421e04764ee"
@@ -872,6 +928,11 @@ levn@^0.3.0, levn@~0.3.0:
     prelude-ls "~1.1.2"
     type-check "~0.3.2"
 
+lodash.get@^4.4.2:
+  version "4.4.2"
+  resolved "https://registry.yarnpkg.com/lodash.get/-/lodash.get-4.4.2.tgz#2d177f652fa31e939b4438d5341499dfa3825e99"
+  integrity sha1-LRd/ZS+jHpObRDjVNBSZ36OCXpk=
+
 lodash@^4.17.11:
   version "4.17.15"
   resolved "https://registry.yarnpkg.com/lodash/-/lodash-4.17.15.tgz#b447f6670a0455bbfeedd11392eff330ea097548"
@@ -974,6 +1035,17 @@ nice-try@^1.0.4:
   resolved "https://registry.yarnpkg.com/nice-try/-/nice-try-1.0.5.tgz#a3378a7696ce7d223e88fc9b764bd7ef1089e366"
   integrity sha512-1nh45deeb5olNY7eX82BkPO7SSxR5SSYJiPTrTdFUVYwAl8CKMA5N9PjTYkHiRjisVcxcQ1HXdLhx2qxxJzLNQ==
 
+nise@^4.0.1:
+  version "4.0.4"
+  resolved "https://registry.yarnpkg.com/nise/-/nise-4.0.4.tgz#d73dea3e5731e6561992b8f570be9e363c4512dd"
+  integrity sha512-bTTRUNlemx6deJa+ZyoCUTRvH3liK5+N6VQZ4NIw90AgDXY6iPnsqplNFf6STcj+ePk0H/xqxnP75Lr0J0Fq3A==
+  dependencies:
+    "@sinonjs/commons" "^1.7.0"
+    "@sinonjs/fake-timers" "^6.0.0"
+    "@sinonjs/text-encoding" "^0.7.1"
+    just-extend "^4.0.2"
+    path-to-regexp "^1.7.0"
+
 node-addon-api@2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/node-addon-api/-/node-addon-api-2.0.0.tgz#f9afb8d777a91525244b01775ea0ddbe1125483b"
@@ -1147,6 +1219,13 @@ path-parse@^1.0.6:
   resolved "https://registry.yarnpkg.com/path-parse/-/path-parse-1.0.6.tgz#d62dbb5679405d72c4737ec58600e9ddcf06d24c"
   integrity sha512-GSmOT2EbHrINBf9SR7CDELwlJ8AENk3Qn7OikK4nFYAu3Ote2+JYNVvkpAEQm3/TLNEJFD/xZJjzyxg3KBWOzw==
 
+path-to-regexp@^1.7.0:
+  version "1.8.0"
+  resolved "https://registry.yarnpkg.com/path-to-regexp/-/path-to-regexp-1.8.0.tgz#887b3ba9d84393e87a0a0b9f4cb756198b53548a"
+  integrity sha512-n43JRhlUKUAlibEJhPeir1ncUID16QnEjNpwzNdO3Lm4ywrBpBZ5oLD0I6br9evr1Y9JTqwRtAh7JLoOzAQdVA==
+  dependencies:
+    isarray "0.0.1"
+
 performance-now@^2.1.0:
   version "2.1.0"
   resolved "https://registry.yarnpkg.com/performance-now/-/performance-now-2.1.0.tgz#6309f4e0e5fa913ec1c69307ae364b4b377c9e7b"
@@ -1343,6 +1422,19 @@ signal-exit@^3.0.0, signal-exit@^3.0.2:
   resolved "https://registry.yarnpkg.com/signal-exit/-/signal-exit-3.0.2.tgz#b5fdc08f1287ea1178628e415e25132b73646c6d"
   integrity sha1-tf3AjxKH6hF4Yo5BXiUTK3NkbG0=
 
+sinon@^9.0.2:
+  version "9.0.2"
+  resolved "https://registry.yarnpkg.com/sinon/-/sinon-9.0.2.tgz#b9017e24633f4b1c98dfb6e784a5f0509f5fd85d"
+  integrity sha512-0uF8Q/QHkizNUmbK3LRFqx5cpTttEVXudywY9Uwzy8bTfZUhljZ7ARzSxnRHWYWtVTeh4Cw+tTb3iU21FQVO9A==
+  dependencies:
+    "@sinonjs/commons" "^1.7.2"
+    "@sinonjs/fake-timers" "^6.0.1"
+    "@sinonjs/formatio" "^5.0.1"
+    "@sinonjs/samsam" "^5.0.3"
+    diff "^4.0.2"
+    nise "^4.0.1"
+    supports-color "^7.1.0"
+
 slice-ansi@^2.1.0:
   version "2.1.0"
   resolved "https://registry.yarnpkg.com/slice-ansi/-/slice-ansi-2.1.0.tgz#cacd7693461a637a5788d92a7dd4fba068e81636"
@@ -1457,6 +1549,13 @@ supports-color@^5.3.0:
   dependencies:
     has-flag "^3.0.0"
 
+supports-color@^7.1.0:
+  version "7.1.0"
+  resolved "https://registry.yarnpkg.com/supports-color/-/supports-color-7.1.0.tgz#68e32591df73e25ad1c4b49108a2ec507962bfd1"
+  integrity sha512-oRSIpR8pxT1Wr2FquTNnGet79b3BWljqOuoW/h4oBhxJ/HUbX5nX6JSruTkvXDCFMwDPvsaTTbvMLKZWSy0R5g==
+  dependencies:
+    has-flag "^4.0.0"
+
 table@^5.2.3:
   version "5.3.2"
   resolved "https://registry.yarnpkg.com/table/-/table-5.3.2.tgz#3aab56a41b2905bf66a6a006bd716fa1e78d4702"
@@ -1557,6 +1656,11 @@ type-check@~0.3.2:
   dependencies:
     prelude-ls "~1.1.2"
 
+type-detect@4.0.8, type-detect@^4.0.8:
+  version "4.0.8"
+  resolved "https://registry.yarnpkg.com/type-detect/-/type-detect-4.0.8.tgz#7646fb5f18871cfbb7749e69bd39a6388eb7450c"
+  integrity sha512-0fr/mIH1dlO+x7TlcMy+bIDqKPsw/70tVyeHW787goQjhmqaZe10uwLujubK9q9Lg6Fiho1KUKDYz0Z7k7g5/g==
+
 uri-js@^4.2.2:
   version "4.2.2"
   resolved "https://registry.yarnpkg.com/uri-js/-/uri-js-4.2.2.tgz#94c540e1ff772956e2299507c010aea6c8838eb0"