Add shared statistics and Prometheus metrics

tests/TypesTest.cpp

@@ -1,5 +1,7 @@
 #include "Types.h"
+#include "Metrics.h"
 
+#include <QTemporaryDir>
 #include <QTest>
 
 using namespace Qt::StringLiterals;
@@ -11,6 +13,7 @@ class TypesTest final : public QObject {
     void parsesShareUrl();
     void rejectsNonShareUrl();
     void plansByChecksum();
+    void persistsStatisticsAcrossInstances();
 };
 
 void TypesTest::parsesShareUrl()
@@ -46,5 +49,30 @@ void TypesTest::plansByChecksum()
     QCOMPARE(plan.rightToLeft.front().id, u"5"_s);
 }
 
+void TypesTest::persistsStatisticsAcrossInstances()
+{
+    QTemporaryDir directory;
+    QVERIFY(directory.isValid());
+    const QString path = directory.filePath(u"stats.json"_s);
+
+    Metrics first{path};
+    first.synchronizationStarted();
+    first.assetFinished(u"IMAGE"_s, true, 1'024);
+    first.synchronizationFinished(true);
+
+    Metrics second{path};
+    second.assetFinished(u"VIDEO"_s, true, 2'048);
+    second.assetFinished(u"IMAGE"_s, false, 512);
+
+    const QJsonObject statistics = first.statistics();
+    QCOMPARE(statistics.value(u"syncs"_s).toInteger(), 1);
+    QCOMPARE(statistics.value(u"assets"_s).toInteger(), 2);
+    QCOMPARE(statistics.value(u"images"_s).toInteger(), 1);
+    QCOMPARE(statistics.value(u"videos"_s).toInteger(), 1);
+    QCOMPARE(statistics.value(u"other"_s).toInteger(), 0);
+    QCOMPARE(statistics.value(u"bytes"_s).toInteger(), 3'072);
+    QVERIFY(second.prometheus().contains("immich_sync_lifetime_synchronizations_total 1"));
+}
+
 QTEST_MAIN(TypesTest)
 #include "TypesTest.moc"