chained_token_credential_impl.hpp

// Copyright (c) Microsoft Corporation.
// Licensed under the MIT License.
 
#pragma once
 
#include "azure/identity/chained_token_credential.hpp"
 
#include <atomic>
#include <limits>
#include <mutex>
 
#if defined(_azure_TESTING_BUILD)
class DefaultAzureCredential_CachingCredential_Test;
#endif
 
namespace Azure { namespace Identity { namespace _detail {
 
  class ChainedTokenCredentialImpl final {
 
#if defined(_azure_TESTING_BUILD)
    //  make tests classes friends to validate caching
    friend class ::DefaultAzureCredential_CachingCredential_Test;
#endif
 
  public:
    ChainedTokenCredentialImpl(
        std::string const& credentialName,
        ChainedTokenCredential::Sources&& sources,
        bool reuseSuccessfulSource = false);
 
    Core::Credentials::AccessToken GetToken(
        std::string const& credentialName,
        Core::Credentials::TokenRequestContext const& tokenRequestContext,
        Core::Context const& context) const;
 
  private:
    ChainedTokenCredential::Sources m_sources;
    mutable std::mutex m_sourcesMutex;
    // Used as a sentinel value to indicate that the index of the source being used for future calls
    // hasn't been found yet.
    constexpr static std::size_t SuccessfulSourceNotSet = (std::numeric_limits<std::size_t>::max)();
    // This needs to be atomic so that sentinel comparison is thread safe.
    mutable std::atomic<std::size_t> m_successfulSourceIndex = {SuccessfulSourceNotSet};
    bool m_reuseSuccessfulSource;
  };
 
}}} // namespace Azure::Identity::_detail