Initial QSfera import

Server/vendor/github.com/prometheus/alertmanager/featurecontrol/featurecontrol.go

@@ -0,0 +1,178 @@
+// Copyright 2023 Prometheus Team
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package featurecontrol
+
+import (
+	"errors"
+	"fmt"
+	"log/slog"
+	"strings"
+)
+
+const (
+	FeatureAlertNamesInMetrics   = "alert-names-in-metrics"
+	FeatureReceiverNameInMetrics = "receiver-name-in-metrics"
+	FeatureClassicMode           = "classic-mode"
+	FeatureUTF8StrictMode        = "utf8-strict-mode"
+	FeatureAutoGOMEMLIMIT        = "auto-gomemlimit"
+	FeatureAutoGOMAXPROCS        = "auto-gomaxprocs"
+)
+
+var AllowedFlags = []string{
+	FeatureAlertNamesInMetrics,
+	FeatureReceiverNameInMetrics,
+	FeatureClassicMode,
+	FeatureUTF8StrictMode,
+	FeatureAutoGOMEMLIMIT,
+	FeatureAutoGOMAXPROCS,
+}
+
+type Flagger interface {
+	EnableAlertNamesInMetrics() bool
+	EnableReceiverNamesInMetrics() bool
+	ClassicMode() bool
+	UTF8StrictMode() bool
+	EnableAutoGOMEMLIMIT() bool
+	EnableAutoGOMAXPROCS() bool
+}
+
+type Flags struct {
+	logger                       *slog.Logger
+	enableAlertNamesInMetrics    bool
+	enableReceiverNamesInMetrics bool
+	classicMode                  bool
+	utf8StrictMode               bool
+	enableAutoGOMEMLIMIT         bool
+	enableAutoGOMAXPROCS         bool
+}
+
+func (f *Flags) EnableAlertNamesInMetrics() bool {
+	return f.enableAlertNamesInMetrics
+}
+
+func (f *Flags) EnableReceiverNamesInMetrics() bool {
+	return f.enableReceiverNamesInMetrics
+}
+
+func (f *Flags) ClassicMode() bool {
+	return f.classicMode
+}
+
+func (f *Flags) UTF8StrictMode() bool {
+	return f.utf8StrictMode
+}
+
+func (f *Flags) EnableAutoGOMEMLIMIT() bool {
+	return f.enableAutoGOMEMLIMIT
+}
+
+func (f *Flags) EnableAutoGOMAXPROCS() bool {
+	return f.enableAutoGOMAXPROCS
+}
+
+type flagOption func(flags *Flags)
+
+func enableReceiverNameInMetrics() flagOption {
+	return func(configs *Flags) {
+		configs.enableReceiverNamesInMetrics = true
+	}
+}
+
+func enableClassicMode() flagOption {
+	return func(configs *Flags) {
+		configs.classicMode = true
+	}
+}
+
+func enableUTF8StrictMode() flagOption {
+	return func(configs *Flags) {
+		configs.utf8StrictMode = true
+	}
+}
+
+func enableAutoGOMEMLIMIT() flagOption {
+	return func(configs *Flags) {
+		configs.enableAutoGOMEMLIMIT = true
+	}
+}
+
+func enableAutoGOMAXPROCS() flagOption {
+	return func(configs *Flags) {
+		configs.enableAutoGOMAXPROCS = true
+	}
+}
+
+func enableAlertNamesInMetrics() flagOption {
+	return func(configs *Flags) {
+		configs.enableAlertNamesInMetrics = true
+	}
+}
+
+func NewFlags(logger *slog.Logger, features string) (Flagger, error) {
+	fc := &Flags{logger: logger}
+	opts := []flagOption{}
+
+	if len(features) == 0 {
+		return NoopFlags{}, nil
+	}
+
+	for feature := range strings.SplitSeq(features, ",") {
+		switch feature {
+		case FeatureAlertNamesInMetrics:
+			opts = append(opts, enableAlertNamesInMetrics())
+			logger.Warn("Alert names in metrics enabled")
+		case FeatureReceiverNameInMetrics:
+			opts = append(opts, enableReceiverNameInMetrics())
+			logger.Warn("Experimental receiver name in metrics enabled")
+		case FeatureClassicMode:
+			opts = append(opts, enableClassicMode())
+			logger.Warn("Classic mode enabled")
+		case FeatureUTF8StrictMode:
+			opts = append(opts, enableUTF8StrictMode())
+			logger.Warn("UTF-8 strict mode enabled")
+		case FeatureAutoGOMEMLIMIT:
+			opts = append(opts, enableAutoGOMEMLIMIT())
+			logger.Warn("Automatically set GOMEMLIMIT to match the Linux container or system memory limit.")
+		case FeatureAutoGOMAXPROCS:
+			opts = append(opts, enableAutoGOMAXPROCS())
+			logger.Warn("Automatically set GOMAXPROCS to match Linux container CPU quota")
+		default:
+			return nil, fmt.Errorf("unknown option '%s' for --enable-feature", feature)
+		}
+	}
+
+	for _, opt := range opts {
+		opt(fc)
+	}
+
+	if fc.classicMode && fc.utf8StrictMode {
+		return nil, errors.New("cannot have both classic and UTF-8 modes enabled")
+	}
+
+	return fc, nil
+}
+
+type NoopFlags struct{}
+
+func (n NoopFlags) EnableAlertNamesInMetrics() bool { return false }
+
+func (n NoopFlags) EnableReceiverNamesInMetrics() bool { return false }
+
+func (n NoopFlags) ClassicMode() bool { return false }
+
+func (n NoopFlags) UTF8StrictMode() bool { return false }
+
+func (n NoopFlags) EnableAutoGOMEMLIMIT() bool { return false }
+
+func (n NoopFlags) EnableAutoGOMAXPROCS() bool { return false }