// Copyright (c) 2014 Baidu, Inc.
// 
// 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.

// Author: Ge,Jun (gejun@baidu.com)
// Date: 2014/09/22 11:57:43

#ifndef  BVAR_LATENCY_RECORDER_H
#define  BVAR_LATENCY_RECORDER_H

#include "bvar/recorder.h"
#include "bvar/reducer.h"
#include "bvar/passive_status.h"
#include "bvar/detail/percentile.h"

namespace bvar {
namespace detail {

class Percentile;
typedef Window<IntRecorder, SERIES_IN_SECOND> RecorderWindow;
typedef Window<Maxer<int64_t>, SERIES_IN_SECOND> MaxWindow;
typedef Window<Percentile, SERIES_IN_SECOND> PercentileWindow;

// NOTE: Always use int64_t in the interfaces no matter what the impl. is.

class CDF : public Variable {
public:
    explicit CDF(PercentileWindow* w);
    ~CDF();
    void describe(std::ostream& os, bool quote_string) const;
    int describe_series(std::ostream& os, const SeriesOptions& options) const;
private:
    PercentileWindow* _w; 
};

// For mimic constructor inheritance.
class LatencyRecorderBase {
public:
    explicit LatencyRecorderBase(time_t window_size);
    time_t window_size() const { return _latency_window.window_size(); }
protected:
    IntRecorder _latency;
    Maxer<int64_t> _max_latency;
    Percentile _latency_percentile;

    RecorderWindow _latency_window;
    MaxWindow _max_latency_window;
    PassiveStatus<int64_t> _count;
    PassiveStatus<int64_t> _qps;
    PercentileWindow _latency_percentile_window;
    PassiveStatus<int64_t> _latency_p1;
    PassiveStatus<int64_t> _latency_p2;
    PassiveStatus<int64_t> _latency_p3;
    PassiveStatus<int64_t> _latency_999;  // 99.9%
    PassiveStatus<int64_t> _latency_9999; // 99.99%
    CDF _latency_cdf;
    PassiveStatus<Vector<int64_t, 4> > _latency_percentiles;
};
} // namespace detail

// Specialized structure to record latency.
// It's not a Variable, but it contains multiple bvar inside.
class LatencyRecorder : public detail::LatencyRecorderBase {
    typedef detail::LatencyRecorderBase Base;
public:
    LatencyRecorder() : Base(-1) {}
    explicit LatencyRecorder(time_t window_size) : Base(window_size) {}
    explicit LatencyRecorder(const butil::StringPiece& prefix) : Base(-1) {
        expose(prefix);
    }
    LatencyRecorder(const butil::StringPiece& prefix,
                    time_t window_size) : Base(window_size) {
        expose(prefix);
    }
    LatencyRecorder(const butil::StringPiece& prefix1,
                    const butil::StringPiece& prefix2) : Base(-1) {
        expose(prefix1, prefix2);
    }
    LatencyRecorder(const butil::StringPiece& prefix1,
                    const butil::StringPiece& prefix2,
                    time_t window_size) : Base(window_size) {
        expose(prefix1, prefix2);
    }

    ~LatencyRecorder() { hide(); }

    // Record the latency.
    LatencyRecorder& operator<<(int64_t latency);
        
    // Expose all internal variables using `prefix' as prefix.
    // Returns 0 on success, -1 otherwise.
    // Example:
    //   LatencyRecorder rec;
    //   rec.expose("foo_bar_write");     // foo_bar_write_latency
    //                                    // foo_bar_write_max_latency
    //                                    // foo_bar_write_count
    //                                    // foo_bar_write_qps
    //   rec.expose("foo_bar", "read");   // foo_bar_read_latency
    //                                    // foo_bar_read_max_latency
    //                                    // foo_bar_read_count
    //                                    // foo_bar_read_qps
    int expose(const butil::StringPiece& prefix) {
        return expose(butil::StringPiece(), prefix);
    }
    int expose(const butil::StringPiece& prefix1,
               const butil::StringPiece& prefix2);
    
    // Hide all internal variables, called in dtor as well.
    void hide();

    // Get the average latency in recent |window_size| seconds
    // If |window_size| is absent, use the window_size to ctor.
    int64_t latency(time_t window_size) const
    { return _latency_window.get_value(window_size).get_average_int(); }
    int64_t latency() const
    { return _latency_window.get_value().get_average_int(); }

    // Get p1/p2/p3/99.9-ile latencies in recent window_size-to-ctor seconds.
    Vector<int64_t, 4> latency_percentiles() const;

    // Get the max latency in recent window_size-to-ctor seconds.
    int64_t max_latency() const { return _max_latency_window.get_value(); }

    // Get the total number of recorded latencies.
    int64_t count() const { return _latency.get_value().num; }

    // Get qps in recent |window_size| seconds. The `q' means latencies
    // recorded by operator<<().
    // If |window_size| is absent, use the window_size to ctor.
    int64_t qps(time_t window_size) const;
    int64_t qps() const { return _qps.get_value(); }

    // Get |ratio|-ile latency in recent |window_size| seconds
    // E.g. 0.99 means 99%-ile
    int64_t latency_percentile(double ratio) const;

    // Get name of a sub-bvar.
    const std::string& latency_name() const { return _latency_window.name(); }
    const std::string& latency_percentiles_name() const
    { return _latency_percentiles.name(); }
    const std::string& latency_cdf_name() const { return _latency_cdf.name(); }
    const std::string& max_latency_name() const
    { return _max_latency_window.name(); }
    const std::string& count_name() const { return _count.name(); }
    const std::string& qps_name() const { return _qps.name(); }
};

std::ostream& operator<<(std::ostream& os, const LatencyRecorder&);

}  // namespace bvar

#endif  //BVAR_LATENCY_RECORDER_H
