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#pragma once
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#include "envoy/stats/stats.h"

            

        

            

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#include "source/common/stats/metric_impl.h"

            

        

            

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namespace Envoy {

            

        

            

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namespace Stats {

            

        

            

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/**

            

        

            

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 * Null text readout implementation.

            

        

            

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 * No-ops on all calls and requires no underlying metric or data.

            

        

            

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 */

            

        

            

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class NullTextReadoutImpl : public MetricImpl<TextReadout> {

            

        

            

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public:

            

        

            

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  explicit NullTextReadoutImpl(SymbolTable& symbol_table)

            

        

            

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      : MetricImpl<TextReadout>(symbol_table), symbol_table_(symbol_table) {}

            

        

            

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  ~NullTextReadoutImpl() override {

            

        

            

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    // MetricImpl must be explicitly cleared() before destruction, otherwise it

            

        

            

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    // will not be able to access the SymbolTable& to free the symbols. An RAII

            

        

            

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    // alternative would be to store the SymbolTable reference in the

            

        

            

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    // MetricImpl, costing 8 bytes per stat.

            

        

            

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    MetricImpl::clear(symbol_table_);

            

        

            

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  }

            

        

            

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  void set(absl::string_view) override {}

            

        

            

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  std::string value() const override { return {}; }

            

        

            

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  // Metric

            

        

            

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  bool used() const override { return false; }

            

        

            

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  void markUnused() override {}

            

        

            

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  bool hidden() const override { return false; }

            

        

            

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  SymbolTable& symbolTable() override { return symbol_table_; }

            

        

            

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  // RefcountInterface

            

        

            

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  void incRefCount() override { refcount_helper_.incRefCount(); }

            

        

            

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  bool decRefCount() override { return refcount_helper_.decRefCount(); }

            

        

            

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  uint32_t use_count() const override { return refcount_helper_.use_count(); }

            

        

            

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private:

            

        

            

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  RefcountHelper refcount_helper_;

            

        

            

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  SymbolTable& symbol_table_;

            

        

            

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};

            

        

            

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} // namespace Stats

            

        

            

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} // namespace Envoy