prometheus-net.AspNetCore 2.0.0-pre-003523-49de0a3

* 2.0.0 - Targeting .NET Standard 2.0 as minimum version (.NET Framework 4.6.1, .NET Core 2.0 and Mono 5.4) - Added ASP.NET Core middlware - Added possibility to signal a failed scrape from on-demand collectors - Removed dependency on Reactive Extensions - Minor breaking changes to API - Performance improvements for hot-path code - Removed mostly obsolete PerfCounterCollector class - Fixed NuGet package contents to remove assemblies from dependencies - Various minor fixes (see issues on GitHub for details) * 1.3.4 - Added support for .NET 4.5 using System.Reactive 3.1.1. - .NET 4.0 support continues to target Rx 2.5 * 1.2.4: - Fixed MetricPusher not flushing metrics when stopped * 1.2.3: - Fixed label values escaping for ASCII formatter * 1.2.2: - PushGateway support - Various internal improvements (replaced locks with Interlocked operations) * 1.1.4: - Fixed some metrics not updating, added process ID metric - Replaced lock statements in Counter and Gauge with CAS * 1.1.3: - optionally use https in MetricServer * 1.1.2: - using UTF-8 in text formatter - catching exceptions in MetricServer http loop * 1.1.1: - disposing of MetricServer loop on Stop() * 1.1.0: - Renamed some metric names to be in-line with prometheus guidelines (breaking change as far as the exported metrics are concerned) * 1.0.0: - Add CPU, num handles, start time, num threads metrics to dot net stats collector - Made DotNetStatsCollector default (previously it was PerfCounterCollector) * 0.0.11: - Summary metric ported from go * 0.0.10: - Fix header writing order * 0.0.9: - Generalise scraping so it can be called externally without using the embedded http handler * 0.0.8: - Introduced interfaces for all the metrics to make unlabelled collectors and their children polymorph * 0.0.7: - Added the notion of OnDemandCollectors + a DotNetStatsCollector to avoid having to use .net perf counters * 0.0.6: - Do not create unlabelled metric if label names are specified * 0.0.5: - Allow specifying hostname in URL - Fix null ref exception if 'Accept' header is not specified * 0.0.3 - initial version