1 files changed, 128 insertions, 0 deletions
diff --git a/vendor/go.opentelemetry.io/otel/sdk/metric/view.go b/vendor/go.opentelemetry.io/otel/sdk/metric/view.go
new file mode 100644
index 000000000..65f243bef
--- /dev/null
+++ b/vendor/go.opentelemetry.io/otel/sdk/metric/view.go
@@ -0,0 +1,128 @@
+// Copyright The OpenTelemetry Authors
+//
+// 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 metric // import "go.opentelemetry.io/otel/sdk/metric"
+
+import (
+	"errors"
+	"regexp"
+	"strings"
+
+	"go.opentelemetry.io/otel/internal/global"
+)
+
+var (
+	errMultiInst = errors.New("name replacement for multiple instruments")
+	errEmptyView = errors.New("no criteria provided for view")
+
+	emptyView = func(Instrument) (Stream, bool) { return Stream{}, false }
+)
+
+// View is an override to the default behavior of the SDK. It defines how data
+// should be collected for certain instruments. It returns true and the exact
+// Stream to use for matching Instruments. Otherwise, if the view does not
+// match, false is returned.
+type View func(Instrument) (Stream, bool)
+
+// NewView returns a View that applies the Stream mask for all instruments that
+// match criteria. The returned View will only apply mask if all non-zero-value
+// fields of criteria match the corresponding Instrument passed to the view. If
+// no criteria are provided, all field of criteria are their zero-values, a
+// view that matches no instruments is returned. If you need to match a
+// zero-value field, create a View directly.
+//
+// The Name field of criteria supports wildcard pattern matching. The "*"
+// wildcard is recognized as matching zero or more characters, and "?" is
+// recognized as matching exactly one character. For example, a pattern of "*"
+// matches all instrument names.
+//
+// The Stream mask only applies updates for non-zero-value fields. By default,
+// the Instrument the View matches against will be use for the Name,
+// Description, and Unit of the returned Stream and no Aggregation or
+// AttributeFilter are set. All non-zero-value fields of mask are used instead
+// of the default. If you need to zero out an Stream field returned from a
+// View, create a View directly.
+func NewView(criteria Instrument, mask Stream) View {
+	if criteria.empty() {
+		global.Error(
+			errEmptyView, "dropping view",
+			"mask", mask,
+		)
+		return emptyView
+	}
+
+	var matchFunc func(Instrument) bool
+	if strings.ContainsAny(criteria.Name, "*?") {
+		if mask.Name != "" {
+			global.Error(
+				errMultiInst, "dropping view",
+				"criteria", criteria,
+				"mask", mask,
+			)
+			return emptyView
+		}
+
+		// Handle branching here in NewView instead of criteria.matches so
+		// criteria.matches remains inlinable for the simple case.
+		pattern := regexp.QuoteMeta(criteria.Name)
+		pattern = "^" + pattern + "$"
+		pattern = strings.ReplaceAll(pattern, `\?`, ".")
+		pattern = strings.ReplaceAll(pattern, `\*`, ".*")
+		re := regexp.MustCompile(pattern)
+		matchFunc = func(i Instrument) bool {
+			return re.MatchString(i.Name) &&
+				criteria.matchesDescription(i) &&
+				criteria.matchesKind(i) &&
+				criteria.matchesUnit(i) &&
+				criteria.matchesScope(i)
+		}
+	} else {
+		matchFunc = criteria.matches
+	}
+
+	var agg Aggregation
+	if mask.Aggregation != nil {
+		agg = mask.Aggregation.copy()
+		if err := agg.err(); err != nil {
+			global.Error(
+				err, "not using aggregation with view",
+				"criteria", criteria,
+				"mask", mask,
+			)
+			agg = nil
+		}
+	}
+
+	return func(i Instrument) (Stream, bool) {
+		if matchFunc(i) {
+			return Stream{
+				Name:            nonZero(mask.Name, i.Name),
+				Description:     nonZero(mask.Description, i.Description),
+				Unit:            nonZero(mask.Unit, i.Unit),
+				Aggregation:     agg,
+				AttributeFilter: mask.AttributeFilter,
+			}, true
+		}
+		return Stream{}, false
+	}
+}
+
+// nonZero returns v if it is non-zero-valued, otherwise alt.
+func nonZero[T comparable](v, alt T) T {
+	var zero T
+	if v != zero {
+		return v
+	}
+	return alt
+}