ClickHouse/src/Functions/uptime.cpp

#include <Functions/IFunctionImpl.h>
#include <Functions/FunctionFactory.h>
#include <DataTypes/DataTypesNumber.h>
#include <Interpreters/Context.h>


namespace DB
{

/** Returns server uptime in seconds.
  */
class FunctionUptime : public IFunction
{
public:
    static constexpr auto name = "uptime";
    static FunctionPtr create(const Context & context)
    {
        return std::make_shared<FunctionUptime>(context.getUptimeSeconds());
    }

    explicit FunctionUptime(time_t uptime_) : uptime(uptime_)
    {
    }

    String getName() const override
    {
        return name;
    }

    size_t getNumberOfArguments() const override
    {
        return 0;
    }

    DataTypePtr getReturnTypeImpl(const DataTypes & /*arguments*/) const override
    {
        return std::make_shared<DataTypeUInt32>();
    }

    bool isDeterministic() const override { return false; }

    void executeImpl(Block & block, const ColumnNumbers &, size_t result, size_t input_rows_count) override
    {
        block.getByPosition(result).column = DataTypeUInt32().createColumnConst(input_rows_count, static_cast<UInt64>(uptime));
    }

private:
    time_t uptime;
};


void registerFunctionUptime(FunctionFactory & factory)
{
    factory.registerFunction<FunctionUptime>();
}

}