76 lines
3.1 KiB
Go
76 lines
3.1 KiB
Go
// Copyright 2025, Google Inc.
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// All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// met:
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//
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// distribution.
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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package gax
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import (
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"os"
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"strings"
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"sync"
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)
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var (
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// featureEnabledOnce caches results for IsFeatureEnabled.
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featureEnabledOnce sync.Once
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featureEnabledStore map[string]bool
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)
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// IsFeatureEnabled checks if an experimental feature is enabled via
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// environment variable. The environment variable must be prefixed with
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// "GOOGLE_SDK_GO_EXPERIMENTAL_". The feature name passed to this
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// function must be the suffix (e.g., "FOO" for "GOOGLE_SDK_GO_EXPERIMENTAL_FOO").
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// To enable the feature, the environment variable's value must be "true",
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// case-insensitive. The result for each name is cached on the first call.
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func IsFeatureEnabled(name string) bool {
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featureEnabledOnce.Do(func() {
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featureEnabledStore = make(map[string]bool)
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for _, env := range os.Environ() {
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if strings.HasPrefix(env, "GOOGLE_SDK_GO_EXPERIMENTAL_") {
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// Parse "KEY=VALUE"
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kv := strings.SplitN(env, "=", 2)
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if len(kv) == 2 && strings.ToLower(kv[1]) == "true" {
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key := strings.TrimPrefix(kv[0], "GOOGLE_SDK_GO_EXPERIMENTAL_")
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featureEnabledStore[key] = true
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}
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}
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}
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})
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return featureEnabledStore[name]
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}
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// TestOnlyResetIsFeatureEnabled is for testing purposes only. It resets the cached
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// feature flags, allowing environment variables to be re-read on the next call to IsFeatureEnabled.
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// This function is not thread-safe; if another goroutine reads a feature after this
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// function is called but before the `featureEnabledOnce` is re-initialized by IsFeatureEnabled,
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// it may see an inconsistent state.
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func TestOnlyResetIsFeatureEnabled() {
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featureEnabledOnce = sync.Once{}
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featureEnabledStore = nil
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}
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