feat: initial tracing support (#1623)

vendor/google.golang.org/grpc/internal/envconfig/envconfig.go

@@ -0,0 +1,62 @@
+/*
+ *
+ * Copyright 2018 gRPC 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 envconfig contains grpc settings configured by environment variables.
+package envconfig
+
+import (
+	"os"
+	"strconv"
+	"strings"
+)
+
+var (
+	// TXTErrIgnore is set if TXT errors should be ignored ("GRPC_GO_IGNORE_TXT_ERRORS" is not "false").
+	TXTErrIgnore = boolFromEnv("GRPC_GO_IGNORE_TXT_ERRORS", true)
+	// AdvertiseCompressors is set if registered compressor should be advertised
+	// ("GRPC_GO_ADVERTISE_COMPRESSORS" is not "false").
+	AdvertiseCompressors = boolFromEnv("GRPC_GO_ADVERTISE_COMPRESSORS", true)
+	// RingHashCap indicates the maximum ring size which defaults to 4096
+	// entries but may be overridden by setting the environment variable
+	// "GRPC_RING_HASH_CAP".  This does not override the default bounds
+	// checking which NACKs configs specifying ring sizes > 8*1024*1024 (~8M).
+	RingHashCap = uint64FromEnv("GRPC_RING_HASH_CAP", 4096, 1, 8*1024*1024)
+)
+
+func boolFromEnv(envVar string, def bool) bool {
+	if def {
+		// The default is true; return true unless the variable is "false".
+		return !strings.EqualFold(os.Getenv(envVar), "false")
+	}
+	// The default is false; return false unless the variable is "true".
+	return strings.EqualFold(os.Getenv(envVar), "true")
+}
+
+func uint64FromEnv(envVar string, def, min, max uint64) uint64 {
+	v, err := strconv.ParseUint(os.Getenv(envVar), 10, 64)
+	if err != nil {
+		return def
+	}
+	if v < min {
+		return min
+	}
+	if v > max {
+		return max
+	}
+	return v
+}