sharded_kv_store_logger.h

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/** @file storage/temptable/include/temptable/sharded_kv_store_logger.h
TempTable sharded key-value store logger implementation. */
 
#ifndef TEMPTABLE_SHARDED_KV_STORE_LOGGER_H
#define TEMPTABLE_SHARDED_KV_STORE_LOGGER_H
 
#include <algorithm>
#include <string>
#include <thread>
 
#include "my_dbug.h"
#include "storage/temptable/include/temptable/kv_store_stats.h"
 
namespace temptable {
 
/** Default Sharded_key_value_store logging facility which turns to no-op in
 * non-debug builds. */
template <typename T, bool DebugBuild>
struct Sharded_key_value_store_logger {
  void dbug_print() {
    // no-op
  }
};
 
/** Sharded_key_value_store logging facility debug builds only. */
template <typename T>
struct Sharded_key_value_store_logger<T, true> {
  /** DBUG_PRINT's the stats of each shard and additionally some further stats
   * which are deduced from it, e.g. ratio between insertions and removals.
   * */
  void dbug_print() {
    // As representation of std::thread::id is implementation defined, we have
    // to convert it to a string first before passing it over to DBUG_PRINT
    // machinery. Conversion to string can be done with the overloaded
    // std::thread::id::operator<< which is part of the library
    // implementation.
    auto std_thread_id_to_str = [](const std::thread::id &id) {
      std::stringstream ss;
      ss << id;
      return ss.str();
    };
 
    auto &kv_store_shards = static_cast<T &>(*this).m_kv_store_shard;
    uint32_t shard_id [[maybe_unused]] = 0;
    for (auto &kv : kv_store_shards) {
      auto kv_shard_stats = kv.shard.stats();
      size_t nr_of_emplace_events = std::count_if(
          kv_shard_stats.begin(), kv_shard_stats.end(), [](auto &stat) {
            return stat.event == Key_value_store_stats::Event::EMPLACE;
          });
 
      // Silence the -Wunused-variable false-positive warning (bug) from clang.
      // MY_COMPILER_CLANG_WORKAROUND_FALSE_POSITIVE_UNUSED_VARIABLE_WARNING
      // documentation contains more details (e.g. specific bug-number from LLVM
      // Bugzilla)
      MY_COMPILER_DIAGNOSTIC_PUSH()
      MY_COMPILER_CLANG_WORKAROUND_FALSE_POSITIVE_UNUSED_VARIABLE_WARNING()
      size_t nr_of_erase_events = kv_shard_stats.size() - nr_of_emplace_events;
      MY_COMPILER_DIAGNOSTIC_POP()
 
      DBUG_PRINT("temptable_api_sharded_kv_store",
                 ("shard_id=%u insertions=%zu removals=%zu", shard_id,
                  nr_of_emplace_events, nr_of_erase_events));
      for (auto &stat : kv_shard_stats) {
        DBUG_PRINT(
            "temptable_api_sharded_kv_store_debug",
            ("shard_id=%u event=%d size=%zu bucket_count=%zu load_factor=%f "
             "max_load_factor=%f "
             "max_bucket_count=%zu thread_id=%s",
             shard_id, static_cast<int>(stat.event), stat.size,
             stat.bucket_count, stat.load_factor, stat.max_load_factor,
             stat.max_bucket_count,
             std_thread_id_to_str(stat.thread_id).c_str()));
      }
      shard_id++;
    }
  }
};
 
}  // namespace temptable
 
#endif /* TEMPTABLE_SHARDED_KV_STORE_LOGGER_H */