Sponsorship changes (#4274)

Rotate sponsors on the top of the page:
- `topIcon` -> `topIconShowEvery`
- `Sponsors` becomes an interface with methods to get levels, pick sponsors etc
- A somewhat acceptable algorithm for generating a "fair choice" of sponsors given the constraints:
  - "show at least 1 in N times"
  - don't unfairly show one sponsor more than any other at the same level
 - Sponsor icons are loaded dynamically via a "bits" handler (introducing a short delay in them appearing), but this means the index.html doesn't change on every load, so it's still cacheable

etc/config/sponsors.yaml

@@ -1,4 +1,5 @@
 ---
+maxTopIcons: 3
 levels:
   - name: Corporate Sponsors
     description: 'Enormous thanks to our corporate sponsors. Please visit their websites below:'
@@ -9,7 +10,7 @@ levels:
         img: https://static.ce-cdn.net/SOLID+SANDS-LOGO-RGB-500px.png
         url: https://solidsands.com/
         priority: 100
-        topIcon: true
+        topIconShowEvery: 3
         statsId: solid_sands
       - name: Intel
         description: We engineer solutions for our customers’ greatest challenges with reliable, cloud to edge computing, inspired by Moore’s Law.
@@ -17,7 +18,7 @@ levels:
         img: https://static.ce-cdn.net/intel/logo-classicblue-3000px.png
         url: https://intel.com/
         priority: 400
-        topIcon: true
+        topIconShowEvery: 1
         sideBySide: true
         statsId: intel
       - name: Backtrace
@@ -29,7 +30,7 @@ levels:
         img: https://static.ce-cdn.net/bt/BT-logo (1).png
         url: https://backtrace.io/sign-up?utm_source=website&utm_medium=paiddisplay&utm_campaign=00O8Y000008JiuiUAC&utm_content=godboltbannerad
         priority: 500
-        topIcon: true
+        topIconShowEvery: 3
         sideBySide: true
         statsId: backtrace
   - name: Patreon Legends

lib/sponsors.interfaces.ts

@@ -31,7 +31,7 @@ export type Sponsor = {
     url?: string;
     onclick: string;
     priority: number;
-    topIcon: boolean;
+    topIconShowEvery: number;
     sideBySide: boolean;
     statsId?: string;
 };
@@ -43,7 +43,10 @@ export type Level = {
     sponsors: Sponsor[];
 };
 
-export type Sponsors = {
-    icons: Sponsor[];
-    levels: Level[];
-};
+export interface Sponsors {
+    getLevels(): Level[];
+
+    pickTopIcons(): Sponsor[];
+
+    getAllTopIcons(): Sponsor[];
+}

lib/sponsors.ts

@@ -24,7 +24,7 @@
 
 import yaml from 'yaml';
 
-import {Sponsor, Sponsors} from './sponsors.interfaces';
+import {Level, Sponsor, Sponsors} from './sponsors.interfaces';
 
 export function parse(mapOrString: Record<string, any> | string): Sponsor {
     if (typeof mapOrString == 'string') mapOrString = {name: mapOrString};
@@ -36,7 +36,7 @@ export function parse(mapOrString: Record<string, any> | string): Sponsor {
         img: mapOrString.img,
         icon: mapOrString.icon || mapOrString.img,
         icon_dark: mapOrString.icon_dark,
-        topIcon: !!mapOrString.topIcon,
+        topIconShowEvery: mapOrString.topIconShowEvery || 0,
         sideBySide: !!mapOrString.sideBySide,
         priority: mapOrString.priority || 0,
         statsId: mapOrString.statsId,
@@ -50,14 +50,113 @@ function compareSponsors(lhs: Sponsor, rhs: Sponsor): number {
     return lhs.name.localeCompare(rhs.name);
 }
 
+function calcMean(values: number[]): number {
+    return values.reduce((x, y) => x + y, 0) / values.length;
+}
+
+function squareSumFromMean(values: number[]): number {
+    const mean = calcMean(values);
+    return values.reduce((x, y) => x + (y - mean) * (y - mean), 0);
+}
+
+function standardDeviation(values: number[]): number {
+    return values.length < 2 ? 0 : Math.sqrt(squareSumFromMean(values) / (values.length - 1));
+}
+
+// A sponsor icon set is ok if:
+// - each sponsor is shown at least every "topIconShowEvery"
+// - the standard deviation for the number of showings between sponsors at the same "show every' is not too high: that
+//   is we fairly distribute showings of sponsors at the same level
+function sponsorIconSetsOk(
+    sponsorAppearanceCount: Map<Sponsor, number>,
+    totalAppearances: number,
+    maxStandardDeviation: number,
+): boolean {
+    const countsByShowEvery: Map<number, number[]> = new Map();
+    for (const [icon, count] of sponsorAppearanceCount.entries()) {
+        const seenEvery = count > 0 ? totalAppearances / count : Infinity;
+        if (seenEvery > icon.topIconShowEvery) {
+            return false;
+        }
+        const others = countsByShowEvery.get(icon.topIconShowEvery) || [];
+        others.push(seenEvery);
+        countsByShowEvery.set(icon.topIconShowEvery, others);
+    }
+    return Math.max(...[...countsByShowEvery.values()].map(standardDeviation)) <= maxStandardDeviation;
+}
+
+export function makeIconSets(
+    icons: Sponsor[],
+    maxIcons: number,
+    maxIters = 100,
+    maxStandardDeviation = 0.5,
+): Sponsor[][] {
+    const result: Sponsor[][] = [];
+    const sponsorAppearanceCount: Map<Sponsor, number> = new Map();
+    for (const icon of icons) sponsorAppearanceCount.set(icon, 0);
+    while (!sponsorIconSetsOk(sponsorAppearanceCount, result.length, maxStandardDeviation)) {
+        if (result.length > maxIters) {
+            throw new Error(`Unable to find a solution in ${maxIters}`);
+        }
+        const toPick = icons.map(icon => {
+            return {
+                icon: icon,
+                // Number of times we'd expect to see this, divided by number of times we saw it
+                error: result.length / icon.topIconShowEvery / (sponsorAppearanceCount.get(icon) || 0.00001),
+            };
+        });
+        toPick.sort((lhs, rhs) => rhs.error - lhs.error);
+        const chosen = toPick
+            .slice(0, maxIcons)
+            .map(x => x.icon)
+            .sort(compareSponsors);
+        for (const c of chosen) sponsorAppearanceCount.set(c, (sponsorAppearanceCount.get(c) || 0) + 1);
+        result.push(chosen);
+    }
+    return result;
+}
+
+class SponsorsImpl implements Sponsors {
+    private readonly _levels: Level[];
+    private readonly _icons: Sponsor[];
+    private readonly _iconSets: Sponsor[][];
+    private _nextSet: number;
+
+    constructor(levels: Level[], maxTopIcons) {
+        this._levels = levels;
+        this._icons = [];
+        for (const level of levels) {
+            this._icons.push(...level.sponsors.filter(sponsor => sponsor.topIconShowEvery && sponsor.icon));
+        }
+        this._iconSets = makeIconSets(this._icons, maxTopIcons);
+        this._nextSet = 0;
+    }
+
+    getLevels(): Level[] {
+        return this._levels;
+    }
+
+    getAllTopIcons(): Sponsor[] {
+        return this._icons;
+    }
+
+    pickTopIcons(): Sponsor[] {
+        const result = this._iconSets[this._nextSet];
+        this._nextSet = (this._nextSet + 1) % this._iconSets.length;
+        return result;
+    }
+}
+
+export function loadSponsorsFromLevels(levels: Level[], maxTopIcons: number): Sponsors {
+    return new SponsorsImpl(levels, maxTopIcons);
+}
+
 export function loadSponsorsFromString(stringConfig: string): Sponsors {
     const sponsorConfig = yaml.parse(stringConfig);
-    sponsorConfig.icons = [];
     for (const level of sponsorConfig.levels) {
         for (const required of ['name', 'description', 'sponsors'])
             if (!level[required]) throw new Error(`Level is missing '${required}'`);
         level.sponsors = level.sponsors.map(parse).sort(compareSponsors);
-        sponsorConfig.icons.push(...level.sponsors.filter(sponsor => sponsor.topIcon && sponsor.icon));
     }
-    return sponsorConfig;
+    return loadSponsorsFromLevels(sponsorConfig.levels, sponsorConfig.maxTopIcons || 3);
 }

static/main.js

@@ -196,6 +196,14 @@ function setupButtons(options, hub) {
         alertSystem.alert('Changelog', $(require('./generated/changelog.pug').default.text));
     });
 
+    $.get(window.location.origin + window.httpRoot + 'bits/icons.html')
+        .done(function (data) {
+            $('#ces .ces-icons').html(data);
+        })
+        .fail(function (err) {
+            Sentry.captureException(err);
+        });
+
     $('#ces').on('click', function () {
         $.get(window.location.origin + window.httpRoot + 'bits/sponsors.html')
             .done(function (data) {

test/sponsors-test.js

@@ -22,9 +22,11 @@
 // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 // POSSIBILITY OF SUCH DAMAGE.
 
-import {loadSponsorsFromString, parse} from '../lib/sponsors';
+import fs from 'fs';
 
-import {should} from './utils';
+import {loadSponsorsFromString, makeIconSets, parse} from '../lib/sponsors';
+
+import {resolvePathFromTestRoot, should} from './utils';
 
 describe('Sponsors', () => {
     it('should expand names to objects', () => {
@@ -41,7 +43,7 @@ describe('Sponsors', () => {
         should.equal(obj.img, undefined);
         should.equal(obj.icon, undefined);
         should.equal(obj.icon_dark, undefined);
-        obj.topIcon.should.be.false;
+        obj.topIconShowEvery.should.eq(0);
         obj.sideBySide.should.be.false;
         should.equal(obj.statsId, undefined);
     });
@@ -64,7 +66,7 @@ describe('Sponsors', () => {
         parse({name: 'bob', icon: 'icon', icon_dark: 'icon_dark'}).icon_dark.should.eq('icon_dark');
     });
     it('should handle topIcons', () => {
-        parse({name: 'bob', topIcon: true}).topIcon.should.be.true;
+        parse({name: 'bob', topIconShowEvery: 2}).topIconShowEvery.should.eq(2);
     });
     it('should handle clicks', () => {
         parse({
@@ -92,9 +94,10 @@ levels:
       - Yay
 `);
         sample.should.not.be.null;
-        sample.levels.length.should.eq(2);
-        sample.levels[0].name.should.eq('Patreon Legends');
-        sample.levels[1].name.should.eq('Patreons');
+        const levels = sample.getLevels();
+        levels.length.should.eq(2);
+        levels[0].name.should.eq('Patreon Legends');
+        levels[1].name.should.eq('Patreons');
     });
 
     it('should sort sponsors by name', () => {
@@ -108,7 +111,7 @@ levels:
     - C
     - A
     - B
-        `).levels[0].sponsors;
+        `).getLevels()[0].sponsors;
         peeps.map(sponsor => sponsor.name).should.deep.equals(['A', 'B', 'C', 'D']);
     });
     it('should sort sponsors by priority then name', () => {
@@ -124,7 +127,7 @@ levels:
       priority: 50
     - name: B
       priority: 50
-        `).levels[0].sponsors;
+        `).getLevels()[0].sponsors;
         peeps
             .map(sponsor => {
                 return {name: sponsor.name, priority: sponsor.priority};
@@ -136,7 +139,7 @@ levels:
             ]);
     });
 
-    it('should pick out the top level icons', () => {
+    it('should pick out all the top level icons', () => {
         const icons = loadSponsorsFromString(`
 ---
 levels:
@@ -145,7 +148,7 @@ levels:
     sponsors:
     - name: one
       img: pick_me
-      topIcon: true
+      topIconShowEvery: 1
     - name: two
       img: not_me
   - name: another level
@@ -153,13 +156,96 @@ levels:
     sponsors:
     - name: three
       img: not_me_either
-      topIcon: false
+      topIconShowEvery: 0
     - name: four
       img: pick_me_also
-      topIcon: true
+      topIconShowEvery: 2
     - name: five
-      topIcon: true
-        `).icons;
+      topIconShowEvery: 3
+        `).getAllTopIcons();
         icons.map(s => s.name).should.deep.equals(['one', 'four']);
     });
+
+    it('should pick icons appropriately when all required every 3', () => {
+        const sponsor1 = parse({name: 'Sponsor1', topIconShowEvery: 3, icon: '1'});
+        const sponsor2 = parse({name: 'Sponsor2', topIconShowEvery: 3, icon: '2'});
+        const sponsor3 = parse({name: 'Sponsor3', topIconShowEvery: 3, icon: '3'});
+        const icons = [sponsor1, sponsor2, sponsor3];
+        makeIconSets(icons, 10).should.deep.eq([icons]);
+        makeIconSets(icons, 3).should.deep.eq([icons]);
+        makeIconSets(icons, 2).should.deep.eq([
+            [sponsor1, sponsor2],
+            [sponsor1, sponsor3],
+            [sponsor2, sponsor3],
+        ]);
+        makeIconSets(icons, 1).should.deep.eq([[sponsor1], [sponsor2], [sponsor3]]);
+    });
+    it('should pick icons appropriately when not required on different schedules', () => {
+        const sponsor1 = parse({name: 'Sponsor1', topIconShowEvery: 1, icon: '1'});
+        const sponsor2 = parse({name: 'Sponsor2', topIconShowEvery: 2, icon: '2'});
+        const sponsor3 = parse({name: 'Sponsor3', topIconShowEvery: 3, icon: '3'});
+        const icons = [sponsor1, sponsor2, sponsor3];
+        makeIconSets(icons, 10).should.deep.eq([icons]);
+        makeIconSets(icons, 3).should.deep.eq([icons]);
+        makeIconSets(icons, 2).should.deep.eq([
+            [sponsor1, sponsor2],
+            [sponsor1, sponsor3],
+        ]);
+        (() => makeIconSets(icons, 1)).should.throw();
+    });
+    it('should pick icons appropriately with a lot of sponsors on representative schedules', () => {
+        const sponsor1 = parse({name: 'Sponsor1', topIconShowEvery: 1, icon: '1'});
+        const sponsor2 = parse({name: 'Sponsor2', topIconShowEvery: 3, icon: '2'});
+        const sponsor3 = parse({name: 'Sponsor3', topIconShowEvery: 3, icon: '3'});
+        const sponsor4 = parse({name: 'Sponsor4', topIconShowEvery: 3, icon: '3'});
+        const sponsor5 = parse({name: 'Sponsor5', topIconShowEvery: 3, icon: '3'});
+        const icons = [sponsor1, sponsor2, sponsor3, sponsor4, sponsor5];
+        makeIconSets(icons, 10).should.deep.eq([icons]);
+        makeIconSets(icons, 3).should.deep.eq([
+            [sponsor1, sponsor2, sponsor3],
+            [sponsor1, sponsor4, sponsor5],
+        ]);
+        (() => makeIconSets(icons, 1)).should.throw();
+    });
+    it('should handle alternating', () => {
+        const sponsor1 = parse({name: 'Sponsor1', topIconShowEvery: 1, icon: '1'});
+        const sponsor2 = parse({name: 'Sponsor2', topIconShowEvery: 1, icon: '2'});
+        const sponsor3 = parse({name: 'Sponsor3', topIconShowEvery: 2, icon: '3'});
+        const sponsor4 = parse({name: 'Sponsor4', topIconShowEvery: 2, icon: '4'});
+        const icons = [sponsor1, sponsor2, sponsor3, sponsor4];
+        makeIconSets(icons, 4).should.deep.eq([icons]);
+        makeIconSets(icons, 3).should.deep.eq([
+            [sponsor1, sponsor2, sponsor3],
+            [sponsor1, sponsor2, sponsor4],
+        ]);
+        (() => makeIconSets(icons, 2)).should.throw();
+    });
+});
+
+describe('Our specific sponsor file', () => {
+    const stringConfig = fs.readFileSync(resolvePathFromTestRoot('../etc/config/sponsors.yaml')).toString();
+    it('should parse the current config', () => {
+        loadSponsorsFromString(stringConfig);
+    });
+    it('should pick appropriate sponsor icons', () => {
+        const numLoads = 100;
+        const expectedNumIcons = 3;
+
+        const sponsors = loadSponsorsFromString(stringConfig);
+        const picks = [];
+        for (let load = 0; load < numLoads; ++load) {
+            picks.push(sponsors.pickTopIcons());
+        }
+        const countBySponsor = new Map();
+        for (const pick of picks) {
+            for (const sponsor of pick) {
+                countBySponsor.set(sponsor, (countBySponsor.get(sponsor) || 0) + 1);
+            }
+            pick.length.should.eq(expectedNumIcons);
+        }
+        for (const topIcon of sponsors.getAllTopIcons()) {
+            const appearsEvery = countBySponsor.get(topIcon) / numLoads;
+            appearsEvery.should.lte(topIcon.topIconShowEvery);
+        }
+    });
 });

views/bits/icons.pug

@@ -0,0 +1,6 @@
+each icon in sponsors.pickTopIcons()
+  if !icon.icon_dark || icon.icon === icon.icon_dark
+    img.ces-icon(src=icon.icon alt=icon.name data-statsid=icon.statsId)
+  else
+    img.ces-icon.theme-light-only(src=icon.icon alt=icon.name data-statsid=icon.statsId)
+    img.ces-icon.theme-dark-only(src=icon.icon_dark alt=icon.name data-statsid=icon.statsId)

views/bits/sponsors-content.pug

@@ -18,7 +18,7 @@ block content
       a(href="mailto:matt@godbolt.org") email Matt
       |  for corporate sponsorship.
     .mt-6
-      each level, index in sponsors.levels
+      each level, index in sponsors.getLevels()
         .ces-item-block(class=level.class id="ces_hop_" + index)
           h2.ces-item-name= level.name
           div.ces-item-description= level.description

views/bits/sponsors.pug

@@ -1,6 +1,6 @@
 div.ces-level-selectors.d-flex.justify-content-center.mt-3
   div.btn-group.btn-group
-    each level, index in sponsors.levels
+    each level, index in sponsors.getLevels()
       button.btn.btn-primary(onclick='document.getElementById("ces_hop_' + index + '").scrollIntoView({behavior:"smooth"});')=level.name
 
 block content

views/sponsor-icons.pug

@@ -1,12 +1,6 @@
 .ces-icons
-  each icon in sponsors.icons
-    if noscript
-      a(href=icon.url)
-        img.ces-icon(src=icon.icon alt=icon.name data-statsid=icon.statsId)
-      span  
-    else
-      if !icon.icon_dark || icon.icon === icon.icon_dark
-        img.ces-icon(src=icon.icon alt=icon.name data-statsid=icon.statsId)
-      else
-        img.ces-icon.theme-light-only(src=icon.icon alt=icon.name data-statsid=icon.statsId)
-        img.ces-icon.theme-dark-only(src=icon.icon_dark alt=icon.name data-statsid=icon.statsId)
+  if noscript
+    each icon in sponsors.pickTopIcons()
+        a(href=icon.url)
+          img.ces-icon(src=icon.icon alt=icon.name data-statsid=icon.statsId)
+        span