sampling_impl.h

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/*
 * Copyright 2025 Stanford University, NVIDIA Corporation
 * SPDX-License-Identifier: Apache-2.0
 *
 * 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.
 */
 
// sampling profiler implementation for Realm
 
#ifndef REALM_SAMPLING_IMPL_H
#define REALM_SAMPLING_IMPL_H
 
#include "realm/sampling.h"
#include "realm/threads.h"
 
namespace Realm {
 
  class SamplingProfilerImpl;
 
  class GaugeSampleBuffer {
  public:
    GaugeSampleBuffer(int _sampler_id);
    virtual ~GaugeSampleBuffer(void);
 
    virtual void write_data(int fd) = 0;
 
    int sampler_id;
    int compressed_len;
    int first_sample;
    int last_sample;
  };
 
  template <typename T>
  class GaugeSampleBufferImpl : public GaugeSampleBuffer {
  public:
    GaugeSampleBufferImpl(int _sampler_id, size_t _reserve);
 
    virtual void write_data(int fd);
 
    std::vector<typename T::Sample> samples;
    std::vector<unsigned short> run_lengths;
  };
 
  class GaugeSampler {
  public:
    GaugeSampler(int _sampler_id, SamplingProfilerImpl *_profiler);
    virtual ~GaugeSampler(void);
 
    virtual bool sample_gauge(int sample_index) = 0;
    virtual GaugeSampleBuffer *buffer_swap(size_t new_buffer_size,
                                           bool nonempty_only = false) = 0;
 
  protected:
    friend class ProfilingGauges::Gauge;
    friend class SamplingProfilerImpl;
 
    template <typename T>
    void perform_sample(ProfilingGauges::AbsoluteGauge<T> &gauge,
                        typename ProfilingGauges::AbsoluteGauge<T>::Sample &sample);
    template <typename T>
    void perform_sample(ProfilingGauges::AbsoluteRangeGauge<T> &gauge,
                        typename ProfilingGauges::AbsoluteRangeGauge<T>::Sample &sample);
    template <typename T>
    void perform_sample(ProfilingGauges::EventCounter<T> &gauge,
                        typename ProfilingGauges::EventCounter<T>::Sample &sample);
 
    int sampler_id;
    SamplingProfilerImpl *profiler;
    Mutex mutex; // prevents deletion of a gauge during sampling
    bool gauge_exists;
    GaugeSampler *next;
  };
 
  template <typename T>
  class GaugeSamplerImpl : public GaugeSampler {
  public:
    GaugeSamplerImpl(int _sampler_id, SamplingProfilerImpl *_profiler, T *_gauge,
                     SampleFile::PacketNewGauge *info);
 
    virtual bool sample_gauge(int sample_index);
    virtual GaugeSampleBuffer *buffer_swap(size_t new_buffer_size,
                                           bool nonempty_only = false);
 
  protected:
    T *gauge;
    size_t buffer_size;
    GaugeSampleBufferImpl<T> *buffer;
  };
 
  class DelayedGaugeAddition {
  public:
    DelayedGaugeAddition(ProfilingGauges::Gauge *_gauge, DelayedGaugeAddition *_next);
    virtual ~DelayedGaugeAddition(void);
 
    virtual GaugeSampler *create_sampler(int sampler_id, SamplingProfilerImpl *profiler,
                                         SampleFile::PacketNewGauge *info) = 0;
 
    ProfilingGauges::Gauge *gauge;
    DelayedGaugeAddition *next;
  };
 
  template <typename T>
  class DelayedGaugeAdditionImpl : public DelayedGaugeAddition {
  public:
    DelayedGaugeAdditionImpl(ProfilingGauges::Gauge *_gauge, DelayedGaugeAddition *_next);
 
    virtual GaugeSampler *create_sampler(int sampler_id, SamplingProfilerImpl *profiler,
                                         SampleFile::PacketNewGauge *info);
  };
 
  class SamplingProfilerImpl {
  protected:
    friend class SamplingProfiler;
 
    SamplingProfilerImpl(bool _is_default);
    ~SamplingProfilerImpl(void);
 
  public:
    void configure_from_cmdline(std::vector<std::string> &cmdline,
                                CoreReservationSet &crs);
 
    void flush_data(void);
    void shutdown(void);
 
    static SamplingProfiler &get_profiler(void);
 
    template <typename T>
    GaugeSampler *add_gauge(T *gauge);
 
    void remove_gauge(ProfilingGauges::Gauge *gauge, GaugeSampler *sampler);
 
    void sampler_loop(void);
 
  protected:
    bool parse_profile_pattern(const std::string &s);
 
    bool is_default;
    Mutex mutex;
    bool is_configured, is_shut_down;
    bool cfg_enabled;
    size_t cfg_sample_interval;
    size_t cfg_buffer_size;
    std::vector<std::string> cfg_patterns;
    atomic<int> next_sampler_id;
    atomic<int> next_sample_index;
 
    bool pattern_match(const std::string &name) const;
 
    // list of active samplers
    std::vector<SampleFile::PacketNewGauge *> new_sampler_infos;
    GaugeSampler *sampler_head;
    GaugeSampler **sampler_tail;
 
    // we don't create samplers until we're configured - defer any additions that
    //  come before that
    DelayedGaugeAddition *delayed_additions;
 
    CoreReservation *core_rsrv;
    Thread *sampling_thread;
    int output_fd;
    bool flush_requested;
    ProfilingGauges::AbsoluteGauge<long long> *sampling_start;
    ProfilingGauges::EventCounter<long long> *sampling_time;
  };
 
}; // namespace Realm
 
#endif