kv_store_logger.h

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/* Copyright (c) 2020, 2024, Oracle and/or its affiliates.
 
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/** @file storage/temptable/include/temptable/kv_store_logger.h
TempTable key-value store logger implementation. */
 
#ifndef TEMPTABLE_KV_STORE_LOGGER_H
#define TEMPTABLE_KV_STORE_LOGGER_H
 
#include <thread>
#include <vector>
 
#include "my_dbug.h"
#include "storage/temptable/include/temptable/kv_store_stats.h"
 
namespace temptable {
 
/** Default Key_value_store logging facility which turns to no-op in non-debug
 * builds.
 */
template <typename T, bool DebugBuild>
class Key_value_store_logger {
 protected:
  void log(Key_value_store_stats::Event /*event*/) {
    // no-op
  }
  void dbug_print() {
    // no-op
  }
};
 
/** Key_value_store logging facility debug builds only. */
template <typename T>
class Key_value_store_logger<T, true> {
  /** Container of stats that we will be collecting. */
  std::vector<Key_value_store_stats> m_stats;
 
 public:
  /** Returns a snapshot of stats collected. To keep up with the thread-safety
   * guarantee promise, snapshot must be made under the lock.
   *
   * @return Stats snapshot.
   * */
  std::vector<Key_value_store_stats> stats() {
    auto &kv_store_lock = static_cast<T &>(*this).m_lock;
    typename T::Exclusive_or_shared_lock lock(kv_store_lock);
    return m_stats;
  }
 
 protected:
  /** Appends a new entry to stats container with the given event.
   *
   * [in] event Type of event to be logged.
   * */
  void log(Key_value_store_stats::Event event) {
    const auto &kv_store = static_cast<T &>(*this).m_kv_store;
    m_stats.push_back({event, kv_store.size(), kv_store.bucket_count(),
                       kv_store.load_factor(), kv_store.max_load_factor(),
                       kv_store.max_bucket_count(),
                       std::this_thread::get_id()});
  }
 
  /** DBUG_PRINT's the stats of underlying key-value store implementation.
   * */
  void dbug_print() {
    const auto &kv_store = static_cast<T &>(*this).m_kv_store;
    DBUG_PRINT(
        "temptable_api_kv_store",
        ("this=%p size=%zu; bucket_count=%zu load_factor=%f "
         "max_load_factor=%f "
         "max_bucket_count=%zu",
         this, kv_store.size(), kv_store.bucket_count(), kv_store.load_factor(),
         kv_store.max_load_factor(), kv_store.max_bucket_count()));
  }
};
 
}  // namespace temptable
 
#endif /* TEMPTABLE_KV_STORE_LOGGER_H */