Block cache analyzer: Compute correlation of features and human readable trace file. (#5596)

Summary:
- Compute correlation between a few features and predictions, e.g., number of accesses since the last access vs number of accesses till the next access on a block.
- Output human readable trace file so python can consume it.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5596

Test Plan: make clean && USE_CLANG=1 make check -j32

Differential Revision: D16373200

Pulled By: HaoyuHuang

fbshipit-source-id: c848d26bc2e9210461f317d7dbee42d55be5a0cc

tools/block_cache_trace_analyzer.cc

@@ -7,11 +7,16 @@
 #ifdef GFLAGS
 #include "tools/block_cache_trace_analyzer.h"
 
+#include <algorithm>
 #include <cinttypes>
+#include <cstdio>
+#include <cstdlib>
 #include <fstream>
 #include <iomanip>
 #include <iostream>
+#include <random>
 #include <sstream>
+
 #include "monitoring/histogram.h"
 #include "util/gflags_compat.h"
 #include "util/string_util.h"
@@ -122,6 +127,20 @@ DEFINE_string(analyze_get_spatial_locality_labels, "",
               "Group data blocks using these labels.");
 DEFINE_string(analyze_get_spatial_locality_buckets, "",
               "Group data blocks by their statistics using these buckets.");
+DEFINE_bool(mrc_only, false,
+            "Evaluate alternative cache policies only. When this flag is true, "
+            "the analyzer does NOT maintain states of each block in memory for "
+            "analysis. It only feeds the accesses into the cache simulators.");
+DEFINE_string(
+    analyze_correlation_coefficients_labels, "",
+    "Analyze the correlation coefficients of features such as number of past "
+    "accesses with regard to the number of accesses till the next access.");
+DEFINE_int32(analyze_correlation_coefficients_max_number_of_values, 1000000,
+             "The maximum number of values for a feature. If the number of "
+             "values for a feature is larger than this max, it randomly "
+             "selects 'max' number of values.");
+DEFINE_string(human_readable_trace_file_path, "",
+              "The filt path that saves human readable access records.");
 
 namespace rocksdb {
 namespace {
@@ -143,7 +162,10 @@ const std::string kSupportedCacheNames =
     "ghost_lru_hybrid_no_insert_on_row_miss ";
 
 // The suffix for the generated csv files.
+const std::string kFileNameSuffixMissRatioTimeline = "miss_ratio_timeline";
+const std::string kFileNameSuffixMissTimeline = "miss_timeline";
 const std::string kFileNameSuffixAccessTimeline = "access_timeline";
+const std::string kFileNameSuffixCorrelation = "correlation_input";
 const std::string kFileNameSuffixAvgReuseIntervalNaccesses =
     "avg_reuse_interval_naccesses";
 const std::string kFileNameSuffixAvgReuseInterval = "avg_reuse_interval";
@@ -279,6 +301,18 @@ double percent(uint64_t numerator, uint64_t denomenator) {
   return static_cast<double>(numerator * 100.0 / denomenator);
 }
 
+std::map<uint64_t, uint64_t> adjust_time_unit(
+    const std::map<uint64_t, uint64_t>& time_stats, uint64_t time_unit) {
+  if (time_unit == 1) {
+    return time_stats;
+  }
+  std::map<uint64_t, uint64_t> adjusted_time_stats;
+  for (auto const& time : time_stats) {
+    adjusted_time_stats[static_cast<uint64_t>(time.first / time_unit)] +=
+        time.second;
+  }
+  return adjusted_time_stats;
+}
 }  // namespace
 
 void BlockCacheTraceAnalyzer::WriteMissRatioCurves() const {
@@ -288,8 +322,12 @@ void BlockCacheTraceAnalyzer::WriteMissRatioCurves() const {
   if (output_dir_.empty()) {
     return;
   }
+  uint64_t trace_duration =
+      trace_end_timestamp_in_seconds_ - trace_start_timestamp_in_seconds_;
+  uint64_t total_accesses = access_sequence_number_;
   const std::string output_miss_ratio_curve_path =
-      output_dir_ + "/" + kMissRatioCurveFileName;
+      output_dir_ + "/" + std::to_string(trace_duration) + "_" +
+      std::to_string(total_accesses) + "_" + kMissRatioCurveFileName;
   std::ofstream out(output_miss_ratio_curve_path);
   if (!out.is_open()) {
     return;
@@ -302,7 +340,8 @@ void BlockCacheTraceAnalyzer::WriteMissRatioCurves() const {
   for (auto const& config_caches : cache_simulator_->sim_caches()) {
     const CacheConfiguration& config = config_caches.first;
     for (uint32_t i = 0; i < config.cache_capacities.size(); i++) {
-      double miss_ratio = config_caches.second[i]->miss_ratio();
+      double miss_ratio =
+          config_caches.second[i]->miss_ratio_stats().miss_ratio();
       // Write the body.
       out << config.cache_name;
       out << ",";
@@ -314,13 +353,287 @@ void BlockCacheTraceAnalyzer::WriteMissRatioCurves() const {
       out << ",";
       out << std::fixed << std::setprecision(4) << miss_ratio;
       out << ",";
-      out << config_caches.second[i]->total_accesses();
+      out << config_caches.second[i]->miss_ratio_stats().total_accesses();
       out << std::endl;
     }
   }
   out.close();
 }
 
+void BlockCacheTraceAnalyzer::UpdateFeatureVectors(
+    const std::vector<uint64_t>& access_sequence_number_timeline,
+    const std::vector<uint64_t>& access_timeline, const std::string& label,
+    std::map<std::string, Features>* label_features,
+    std::map<std::string, Predictions>* label_predictions) const {
+  if (access_sequence_number_timeline.empty() || access_timeline.empty()) {
+    return;
+  }
+  assert(access_timeline.size() == access_sequence_number_timeline.size());
+  uint64_t prev_access_sequence_number = access_sequence_number_timeline[0];
+  uint64_t prev_access_timestamp = access_timeline[0];
+  for (uint32_t i = 0; i < access_sequence_number_timeline.size(); i++) {
+    uint64_t num_accesses_since_last_access =
+        access_sequence_number_timeline[i] - prev_access_sequence_number;
+    uint64_t elapsed_time_since_last_access =
+        access_timeline[i] - prev_access_timestamp;
+    prev_access_sequence_number = access_sequence_number_timeline[i];
+    prev_access_timestamp = access_timeline[i];
+    if (i < access_sequence_number_timeline.size() - 1) {
+      (*label_features)[label].num_accesses_since_last_access.push_back(
+          num_accesses_since_last_access);
+      (*label_features)[label].num_past_accesses.push_back(i);
+      (*label_features)[label].elapsed_time_since_last_access.push_back(
+          elapsed_time_since_last_access);
+    }
+    if (i >= 1) {
+      (*label_predictions)[label].num_accesses_till_next_access.push_back(
+          num_accesses_since_last_access);
+      (*label_predictions)[label].elapsed_time_till_next_access.push_back(
+          elapsed_time_since_last_access);
+    }
+  }
+}
+
+void BlockCacheTraceAnalyzer::WriteMissRatioTimeline(uint64_t time_unit) const {
+  if (!cache_simulator_ || output_dir_.empty()) {
+    return;
+  }
+  std::map<uint64_t, std::map<std::string, std::map<uint64_t, double>>>
+      cs_name_timeline;
+  uint64_t start_time = port::kMaxUint64;
+  uint64_t end_time = 0;
+  const std::map<uint64_t, uint64_t>& trace_num_misses =
+      adjust_time_unit(miss_ratio_stats_.num_misses_timeline(), time_unit);
+  const std::map<uint64_t, uint64_t>& trace_num_accesses =
+      adjust_time_unit(miss_ratio_stats_.num_accesses_timeline(), time_unit);
+  assert(trace_num_misses.size() == trace_num_accesses.size());
+  for (auto const& num_miss : trace_num_misses) {
+    uint64_t time = num_miss.first;
+    start_time = std::min(start_time, time);
+    end_time = std::max(end_time, time);
+    uint64_t miss = num_miss.second;
+    auto it = trace_num_accesses.find(time);
+    assert(it != trace_num_accesses.end());
+    uint64_t access = it->second;
+    cs_name_timeline[port::kMaxUint64]["trace"][time] = percent(miss, access);
+  }
+  for (auto const& config_caches : cache_simulator_->sim_caches()) {
+    const CacheConfiguration& config = config_caches.first;
+    std::string cache_label = config.cache_name + "-" +
+                              std::to_string(config.num_shard_bits) + "-" +
+                              std::to_string(config.ghost_cache_capacity);
+    for (uint32_t i = 0; i < config.cache_capacities.size(); i++) {
+      const std::map<uint64_t, uint64_t>& num_misses = adjust_time_unit(
+          config_caches.second[i]->miss_ratio_stats().num_misses_timeline(),
+          time_unit);
+      const std::map<uint64_t, uint64_t>& num_accesses = adjust_time_unit(
+          config_caches.second[i]->miss_ratio_stats().num_accesses_timeline(),
+          time_unit);
+      assert(num_misses.size() == num_accesses.size());
+      for (auto const& num_miss : num_misses) {
+        uint64_t time = num_miss.first;
+        start_time = std::min(start_time, time);
+        end_time = std::max(end_time, time);
+        uint64_t miss = num_miss.second;
+        auto it = num_accesses.find(time);
+        assert(it != num_accesses.end());
+        uint64_t access = it->second;
+        cs_name_timeline[config.cache_capacities[i]][cache_label][time] =
+            percent(miss, access);
+      }
+    }
+  }
+  for (auto const& it : cs_name_timeline) {
+    const std::string output_miss_ratio_timeline_path =
+        output_dir_ + "/" + std::to_string(it.first) + "_" +
+        std::to_string(time_unit) + "_" + kFileNameSuffixMissRatioTimeline;
+    std::ofstream out(output_miss_ratio_timeline_path);
+    if (!out.is_open()) {
+      return;
+    }
+    std::string header("time");
+    for (uint64_t now = start_time; now <= end_time; now++) {
+      header += ",";
+      header += std::to_string(now);
+    }
+    out << header << std::endl;
+    for (auto const& label : it.second) {
+      std::string row(label.first);
+      for (uint64_t now = start_time; now <= end_time; now++) {
+        auto misses = label.second.find(now);
+        row += ",";
+        if (misses != label.second.end()) {
+          row += std::to_string(misses->second);
+        } else {
+          row += "0";
+        }
+      }
+      out << row << std::endl;
+    }
+    out.close();
+  }
+}
+
+void BlockCacheTraceAnalyzer::WriteMissTimeline(uint64_t time_unit) const {
+  if (!cache_simulator_ || output_dir_.empty()) {
+    return;
+  }
+  std::map<uint64_t, std::map<std::string, std::map<uint64_t, uint64_t>>>
+      cs_name_timeline;
+  uint64_t start_time = port::kMaxUint64;
+  uint64_t end_time = 0;
+  const std::map<uint64_t, uint64_t>& trace_num_misses =
+      adjust_time_unit(miss_ratio_stats_.num_misses_timeline(), time_unit);
+  for (auto const& num_miss : trace_num_misses) {
+    uint64_t time = num_miss.first;
+    start_time = std::min(start_time, time);
+    end_time = std::max(end_time, time);
+    uint64_t miss = num_miss.second;
+    cs_name_timeline[port::kMaxUint64]["trace"][time] = miss;
+  }
+  for (auto const& config_caches : cache_simulator_->sim_caches()) {
+    const CacheConfiguration& config = config_caches.first;
+    std::string cache_label = config.cache_name + "-" +
+                              std::to_string(config.num_shard_bits) + "-" +
+                              std::to_string(config.ghost_cache_capacity);
+    for (uint32_t i = 0; i < config.cache_capacities.size(); i++) {
+      const std::map<uint64_t, uint64_t>& num_misses = adjust_time_unit(
+          config_caches.second[i]->miss_ratio_stats().num_misses_timeline(),
+          time_unit);
+      for (auto const& num_miss : num_misses) {
+        uint64_t time = num_miss.first;
+        start_time = std::min(start_time, time);
+        end_time = std::max(end_time, time);
+        uint64_t miss = num_miss.second;
+        cs_name_timeline[config.cache_capacities[i]][cache_label][time] = miss;
+      }
+    }
+  }
+  for (auto const& it : cs_name_timeline) {
+    const std::string output_miss_ratio_timeline_path =
+        output_dir_ + "/" + std::to_string(it.first) + "_" +
+        std::to_string(time_unit) + "_" + kFileNameSuffixMissTimeline;
+    std::ofstream out(output_miss_ratio_timeline_path);
+    if (!out.is_open()) {
+      return;
+    }
+    std::string header("time");
+    for (uint64_t now = start_time; now <= end_time; now++) {
+      header += ",";
+      header += std::to_string(now);
+    }
+    out << header << std::endl;
+    for (auto const& label : it.second) {
+      std::string row(label.first);
+      for (uint64_t now = start_time; now <= end_time; now++) {
+        auto misses = label.second.find(now);
+        row += ",";
+        if (misses != label.second.end()) {
+          row += std::to_string(misses->second);
+        } else {
+          row += "0";
+        }
+      }
+      out << row << std::endl;
+    }
+    out.close();
+  }
+}
+
+void BlockCacheTraceAnalyzer::WriteCorrelationFeatures(
+    const std::string& label_str, uint32_t max_number_of_values) const {
+  std::set<std::string> labels = ParseLabelStr(label_str);
+  std::map<std::string, Features> label_features;
+  std::map<std::string, Predictions> label_predictions;
+  auto block_callback =
+      [&](const std::string& cf_name, uint64_t fd, uint32_t level,
+          TraceType block_type, const std::string& /*block_key*/,
+          uint64_t /*block_key_id*/, const BlockAccessInfo& block) {
+        if (labels.find(kGroupbyCaller) != labels.end()) {
+          // Group by caller.
+          for (auto const& caller_map : block.caller_access_timeline) {
+            const std::string label =
+                BuildLabel(labels, cf_name, fd, level, block_type,
+                           caller_map.first, /*block_id=*/0);
+            auto it = block.caller_access_sequence__number_timeline.find(
+                caller_map.first);
+            assert(it != block.caller_access_sequence__number_timeline.end());
+            UpdateFeatureVectors(it->second, caller_map.second, label,
+                                 &label_features, &label_predictions);
+          }
+          return;
+        }
+        const std::string label = BuildLabel(
+            labels, cf_name, fd, level, block_type,
+            TableReaderCaller::kMaxBlockCacheLookupCaller, /*block_id=*/0);
+        UpdateFeatureVectors(block.access_sequence_number_timeline,
+                             block.access_timeline, label, &label_features,
+                             &label_predictions);
+      };
+  TraverseBlocks(block_callback);
+  WriteCorrelationFeaturesToFile(label_str, label_features, label_predictions,
+                                 max_number_of_values);
+}
+
+void BlockCacheTraceAnalyzer::WriteCorrelationFeaturesToFile(
+    const std::string& label,
+    const std::map<std::string, Features>& label_features,
+    const std::map<std::string, Predictions>& label_predictions,
+    uint32_t max_number_of_values) const {
+  std::default_random_engine rand_engine(env_->NowMicros());
+  for (auto const& label_feature_vectors : label_features) {
+    const Features& past = label_feature_vectors.second;
+    auto it = label_predictions.find(label_feature_vectors.first);
+    assert(it != label_predictions.end());
+    const Predictions& future = it->second;
+    const std::string output_path = output_dir_ + "/" + label + "_" +
+                                    label_feature_vectors.first + "_" +
+                                    kFileNameSuffixCorrelation;
+    std::ofstream out(output_path);
+    if (!out.is_open()) {
+      return;
+    }
+    std::string header(
+        "num_accesses_since_last_access,elapsed_time_since_last_access,num_"
+        "past_accesses,num_accesses_till_next_access,elapsed_time_till_next_"
+        "access");
+    out << header << std::endl;
+    std::vector<uint32_t> indexes;
+    for (uint32_t i = 0; i < past.num_accesses_since_last_access.size(); i++) {
+      indexes.push_back(i);
+    }
+    std::shuffle(indexes.begin(), indexes.end(), rand_engine);
+    for (uint32_t i = 0; i < max_number_of_values && i < indexes.size(); i++) {
+      uint32_t rand_index = indexes[i];
+      out << std::to_string(past.num_accesses_since_last_access[rand_index])
+          << ",";
+      out << std::to_string(past.elapsed_time_since_last_access[rand_index])
+          << ",";
+      out << std::to_string(past.num_past_accesses[rand_index]) << ",";
+      out << std::to_string(future.num_accesses_till_next_access[rand_index])
+          << ",";
+      out << std::to_string(future.elapsed_time_till_next_access[rand_index])
+          << std::endl;
+    }
+    out.close();
+  }
+}
+
+void BlockCacheTraceAnalyzer::WriteCorrelationFeaturesForGet(
+    uint32_t max_number_of_values) const {
+  std::string label = "GetKeyInfo";
+  std::map<std::string, Features> label_features;
+  std::map<std::string, Predictions> label_predictions;
+  for (auto const& get_info : get_key_info_map_) {
+    const GetKeyInfo& info = get_info.second;
+    UpdateFeatureVectors(info.access_sequence_number_timeline,
+                         info.access_timeline, label, &label_features,
+                         &label_predictions);
+  }
+  WriteCorrelationFeaturesToFile(label, label_features, label_predictions,
+                                 max_number_of_values);
+}
+
 std::set<std::string> BlockCacheTraceAnalyzer::ParseLabelStr(
     const std::string& label_str) const {
   std::stringstream ss(label_str);
@@ -371,7 +684,6 @@ void BlockCacheTraceAnalyzer::TraverseBlocks(
                        uint64_t /*block_key_id*/,
                        const BlockAccessInfo& /*block_access_info*/)>
         block_callback) const {
-  uint64_t block_id = 0;
   for (auto const& cf_aggregates : cf_aggregates_map_) {
     // Stats per column family.
     const std::string& cf_name = cf_aggregates.first;
@@ -387,8 +699,8 @@ void BlockCacheTraceAnalyzer::TraverseBlocks(
              block_type_aggregates.second.block_access_info_map) {
           // Stats per block.
           block_callback(cf_name, fd, level, type, block_access_info.first,
-                         block_id, block_access_info.second);
-          block_id++;
+                         block_access_info.second.block_id,
+                         block_access_info.second);
         }
       }
     }
@@ -1046,12 +1358,15 @@ void BlockCacheTraceAnalyzer::WriteAccessCountSummaryStats(
 
 BlockCacheTraceAnalyzer::BlockCacheTraceAnalyzer(
     const std::string& trace_file_path, const std::string& output_dir,
-    bool compute_reuse_distance,
+    const std::string& human_readable_trace_file_path,
+    bool compute_reuse_distance, bool mrc_only,
     std::unique_ptr<BlockCacheTraceSimulator>&& cache_simulator)
     : env_(rocksdb::Env::Default()),
       trace_file_path_(trace_file_path),
       output_dir_(output_dir),
+      human_readable_trace_file_path_(human_readable_trace_file_path),
       compute_reuse_distance_(compute_reuse_distance),
+      mrc_only_(mrc_only),
       cache_simulator_(std::move(cache_simulator)) {}
 
 void BlockCacheTraceAnalyzer::ComputeReuseDistance(
@@ -1072,7 +1387,29 @@ void BlockCacheTraceAnalyzer::ComputeReuseDistance(
   info->unique_blocks_since_last_access.clear();
 }
 
-void BlockCacheTraceAnalyzer::RecordAccess(
+Status BlockCacheTraceAnalyzer::WriteHumanReadableTraceRecord(
+    const BlockCacheTraceRecord& access, uint64_t block_id,
+    uint64_t get_key_id) {
+  if (!human_readable_trace_file_writer_) {
+    return Status::OK();
+  }
+  int ret = snprintf(
+      trace_record_buffer_, sizeof(trace_record_buffer_),
+      "%" PRIu64 ",%" PRIu64 ",%u,%" PRIu64 ",%" PRIu64 ",%" PRIu32 ",%" PRIu64
+      ""
+      ",%u,%u,%" PRIu64 ",%" PRIu64 ",%" PRIu64 ",%u\n",
+      access.access_timestamp, block_id, access.block_type, access.block_size,
+      access.cf_id, access.level, access.sst_fd_number, access.caller,
+      access.no_insert, access.get_id, get_key_id, access.referenced_data_size,
+      access.is_cache_hit);
+  if (ret < 0) {
+    return Status::IOError("failed to format the output");
+  }
+  std::string printout(trace_record_buffer_);
+  return human_readable_trace_file_writer_->Append(printout);
+}
+
+Status BlockCacheTraceAnalyzer::RecordAccess(
     const BlockCacheTraceRecord& access) {
   ColumnFamilyAccessInfoAggregate& cf_aggr = cf_aggregates_map_[access.cf_name];
   SSTFileAccessInfoAggregate& file_aggr =
@@ -1080,18 +1417,30 @@ void BlockCacheTraceAnalyzer::RecordAccess(
   file_aggr.level = access.level;
   BlockTypeAccessInfoAggregate& block_type_aggr =
       file_aggr.block_type_aggregates_map[access.block_type];
+  if (block_type_aggr.block_access_info_map.find(access.block_key) ==
+      block_type_aggr.block_access_info_map.end()) {
+    block_type_aggr.block_access_info_map[access.block_key].block_id =
+        unique_block_id_;
+    unique_block_id_++;
+  }
   BlockAccessInfo& block_access_info =
       block_type_aggr.block_access_info_map[access.block_key];
   if (compute_reuse_distance_) {
     ComputeReuseDistance(&block_access_info);
   }
-  block_access_info.AddAccess(access);
+  block_access_info.AddAccess(access, access_sequence_number_);
   block_info_map_[access.block_key] = &block_access_info;
-  if (trace_start_timestamp_in_seconds_ == 0) {
-    trace_start_timestamp_in_seconds_ =
-        access.access_timestamp / kMicrosInSecond;
+  uint64_t get_key_id = 0;
+  if (access.caller == TableReaderCaller::kUserGet &&
+      access.get_id != BlockCacheTraceHelper::kReservedGetId) {
+    std::string row_key = BlockCacheTraceHelper::ComputeRowKey(access);
+    if (get_key_info_map_.find(row_key) == get_key_info_map_.end()) {
+      get_key_info_map_[row_key].key_id = unique_get_key_id_;
+      get_key_id = unique_get_key_id_;
+      unique_get_key_id_++;
+    }
+    get_key_info_map_[row_key].AddAccess(access, access_sequence_number_);
   }
-  trace_end_timestamp_in_seconds_ = access.access_timestamp / kMicrosInSecond;
 
   if (compute_reuse_distance_) {
     // Add this block to all existing blocks.
@@ -1108,6 +1457,8 @@ void BlockCacheTraceAnalyzer::RecordAccess(
       }
     }
   }
+  return WriteHumanReadableTraceRecord(access, block_access_info.block_id,
+                                       get_key_id);
 }
 
 Status BlockCacheTraceAnalyzer::Analyze() {
@@ -1122,32 +1473,68 @@ Status BlockCacheTraceAnalyzer::Analyze() {
   if (!s.ok()) {
     return s;
   }
+  if (!human_readable_trace_file_path_.empty()) {
+    s = env_->NewWritableFile(human_readable_trace_file_path_,
+                              &human_readable_trace_file_writer_, EnvOptions());
+    if (!s.ok()) {
+      return s;
+    }
+  }
   uint64_t start = env_->NowMicros();
-  uint64_t processed_records = 0;
   uint64_t time_interval = 0;
   while (s.ok()) {
     BlockCacheTraceRecord access;
     s = reader.ReadAccess(&access);
     if (!s.ok()) {
-      return s;
+      break;
+    }
+    if (!mrc_only_) {
+      s = RecordAccess(access);
+      if (!s.ok()) {
+        break;
       }
-    RecordAccess(access);
+    }
+    if (trace_start_timestamp_in_seconds_ == 0) {
+      trace_start_timestamp_in_seconds_ =
+          access.access_timestamp / kMicrosInSecond;
+    }
+    trace_end_timestamp_in_seconds_ = access.access_timestamp / kMicrosInSecond;
+    miss_ratio_stats_.UpdateMetrics(access.access_timestamp,
+                                    is_user_access(access.caller),
+                                    access.is_cache_hit == Boolean::kFalse);
     if (cache_simulator_) {
       cache_simulator_->Access(access);
     }
-    processed_records++;
+    access_sequence_number_++;
     uint64_t now = env_->NowMicros();
     uint64_t duration = (now - start) / kMicrosInSecond;
     if (duration > 10 * time_interval) {
+      uint64_t trace_duration =
+          trace_end_timestamp_in_seconds_ - trace_start_timestamp_in_seconds_;
       fprintf(stdout,
               "Running for %" PRIu64 " seconds: Processed %" PRIu64
-              " records/second\n",
-              duration, processed_records / duration);
-      processed_records = 0;
+              " records/second. Trace duration %" PRIu64
+              " seconds. Observed miss ratio %.2f\n",
+              duration, duration > 0 ? access_sequence_number_ / duration : 0,
+              trace_duration, miss_ratio_stats_.miss_ratio());
       time_interval++;
     }
   }
-  return Status::OK();
+  if (human_readable_trace_file_writer_) {
+    human_readable_trace_file_writer_->Flush();
+    human_readable_trace_file_writer_->Close();
+  }
+  uint64_t now = env_->NowMicros();
+  uint64_t duration = (now - start) / kMicrosInSecond;
+  uint64_t trace_duration =
+      trace_end_timestamp_in_seconds_ - trace_start_timestamp_in_seconds_;
+  fprintf(stdout,
+          "Running for %" PRIu64 " seconds: Processed %" PRIu64
+          " records/second. Trace duration %" PRIu64
+          " seconds. Observed miss ratio %.2f\n",
+          duration, duration > 0 ? access_sequence_number_ / duration : 0,
+          trace_duration, miss_ratio_stats_.miss_ratio());
+  return s;
 }
 
 void BlockCacheTraceAnalyzer::PrintBlockSizeStats() const {
@@ -1321,15 +1708,6 @@ void BlockCacheTraceAnalyzer::PrintAccessCountStats(bool user_access_only,
               "Top %" PRIu32 " access count blocks access_count=%" PRIu64
               " %s\n",
               top_k, naccess_it->first, statistics.c_str());
-      // if (block->referenced_data_size > block->block_size) {
-      //   for (auto const& ref_key_it : block->key_num_access_map) {
-      //     ParsedInternalKey internal_key;
-      //     ParseInternalKey(ref_key_it.first, &internal_key);
-      //     printf("######%lu %lu %d %s\n", block->referenced_data_size,
-      //     block->block_size, internal_key.type,
-      //     internal_key.user_key.ToString().c_str());
-      //   }
-      // }
     }
   }
 
@@ -1696,16 +2074,32 @@ int block_cache_trace_analyzer_tool(int argc, char** argv) {
       exit(1);
     }
   }
-  BlockCacheTraceAnalyzer analyzer(
-      FLAGS_block_cache_trace_path, FLAGS_block_cache_analysis_result_dir,
-      !FLAGS_reuse_distance_labels.empty(), std::move(cache_simulator));
+  BlockCacheTraceAnalyzer analyzer(FLAGS_block_cache_trace_path,
+                                   FLAGS_block_cache_analysis_result_dir,
+                                   FLAGS_human_readable_trace_file_path,
+                                   !FLAGS_reuse_distance_labels.empty(),
+                                   FLAGS_mrc_only, std::move(cache_simulator));
   Status s = analyzer.Analyze();
-  if (!s.IsIncomplete()) {
+  if (!s.IsIncomplete() && !s.ok()) {
     // Read all traces.
     fprintf(stderr, "Cannot process the trace %s\n", s.ToString().c_str());
     exit(1);
   }
   fprintf(stdout, "Status: %s\n", s.ToString().c_str());
+  analyzer.WriteMissRatioCurves();
+  analyzer.WriteMissRatioTimeline(1);
+  analyzer.WriteMissRatioTimeline(kSecondInMinute);
+  analyzer.WriteMissRatioTimeline(kSecondInHour);
+  analyzer.WriteMissTimeline(1);
+  analyzer.WriteMissTimeline(kSecondInMinute);
+  analyzer.WriteMissTimeline(kSecondInHour);
+
+  if (FLAGS_mrc_only) {
+    fprintf(stdout,
+            "Skipping the analysis statistics since the user wants to compute "
+            "MRC only");
+    return 0;
+  }
 
   analyzer.PrintStatsSummary();
   if (FLAGS_print_access_count_stats) {
@@ -1727,7 +2121,6 @@ int block_cache_trace_analyzer_tool(int argc, char** argv) {
     analyzer.PrintDataBlockAccessStats();
   }
   print_break_lines(/*num_break_lines=*/3);
-  analyzer.WriteMissRatioCurves();
 
   if (!FLAGS_timeline_labels.empty()) {
     std::stringstream ss(FLAGS_timeline_labels);
@@ -1819,6 +2212,18 @@ int block_cache_trace_analyzer_tool(int argc, char** argv) {
       analyzer.WriteGetSpatialLocality(label, buckets);
     }
   }
+
+  if (!FLAGS_analyze_correlation_coefficients_labels.empty()) {
+    std::stringstream ss(FLAGS_analyze_correlation_coefficients_labels);
+    while (ss.good()) {
+      std::string label;
+      getline(ss, label, ',');
+      analyzer.WriteCorrelationFeatures(
+          label, FLAGS_analyze_correlation_coefficients_max_number_of_values);
+    }
+    analyzer.WriteCorrelationFeaturesForGet(
+        FLAGS_analyze_correlation_coefficients_max_number_of_values);
+  }
   return 0;
 }
 

tools/block_cache_trace_analyzer.h

@@ -16,8 +16,23 @@
 #include "utilities/simulator_cache/cache_simulator.h"
 
 namespace rocksdb {
+
+// Statistics of a key refereneced by a Get.
+struct GetKeyInfo {
+  uint64_t key_id = 0;
+  std::vector<uint64_t> access_sequence_number_timeline;
+  std::vector<uint64_t> access_timeline;
+
+  void AddAccess(const BlockCacheTraceRecord& access,
+                 uint64_t access_sequnce_number) {
+    access_sequence_number_timeline.push_back(access_sequnce_number);
+    access_timeline.push_back(access.access_timestamp);
+  }
+};
+
 // Statistics of a block.
 struct BlockAccessInfo {
+  uint64_t block_id = 0;
   uint64_t num_accesses = 0;
   uint64_t block_size = 0;
   uint64_t first_access_time = 0;
@@ -39,7 +54,16 @@ struct BlockAccessInfo {
   // Number of reuses grouped by reuse distance.
   std::map<uint64_t, uint64_t> reuse_distance_count;
 
-  void AddAccess(const BlockCacheTraceRecord& access) {
+  // The access sequence numbers of this block.
+  std::vector<uint64_t> access_sequence_number_timeline;
+  std::map<TableReaderCaller, std::vector<uint64_t>>
+      caller_access_sequence__number_timeline;
+  // The access timestamp in microseconds of this block.
+  std::vector<uint64_t> access_timeline;
+  std::map<TableReaderCaller, std::vector<uint64_t>> caller_access_timeline;
+
+  void AddAccess(const BlockCacheTraceRecord& access,
+                 uint64_t access_sequnce_number) {
     if (block_size != 0 && access.block_size != 0) {
       assert(block_size == access.block_size);
     }
@@ -57,6 +81,12 @@ struct BlockAccessInfo {
     const uint64_t timestamp_in_seconds =
         access.access_timestamp / kMicrosInSecond;
     caller_num_accesses_timeline[access.caller][timestamp_in_seconds] += 1;
+    // Populate the feature vectors.
+    access_sequence_number_timeline.push_back(access_sequnce_number);
+    caller_access_sequence__number_timeline[access.caller].push_back(
+        access_sequnce_number);
+    access_timeline.push_back(access.access_timestamp);
+    caller_access_timeline[access.caller].push_back(access.access_timestamp);
     if (BlockCacheTraceHelper::IsGetOrMultiGetOnDataBlock(access.block_type,
                                                           access.caller)) {
       num_keys = access.num_keys_in_block;
@@ -94,11 +124,23 @@ struct ColumnFamilyAccessInfoAggregate {
   std::map<uint64_t, SSTFileAccessInfoAggregate> fd_aggregates_map;
 };
 
+struct Features {
+  std::vector<uint64_t> elapsed_time_since_last_access;
+  std::vector<uint64_t> num_accesses_since_last_access;
+  std::vector<uint64_t> num_past_accesses;
+};
+
+struct Predictions {
+  std::vector<uint64_t> elapsed_time_till_next_access;
+  std::vector<uint64_t> num_accesses_till_next_access;
+};
+
 class BlockCacheTraceAnalyzer {
  public:
   BlockCacheTraceAnalyzer(
       const std::string& trace_file_path, const std::string& output_dir,
-      bool compute_reuse_distance,
+      const std::string& human_readable_trace_file_path,
+      bool compute_reuse_distance, bool mrc_only,
       std::unique_ptr<BlockCacheTraceSimulator>&& cache_simulator);
   ~BlockCacheTraceAnalyzer() = default;
   // No copy and move.
@@ -184,6 +226,24 @@ class BlockCacheTraceAnalyzer {
   // "cache_name,num_shard_bits,capacity,miss_ratio,total_accesses".
   void WriteMissRatioCurves() const;
 
+  // Write miss ratio timeline of simulated cache configurations into several
+  // csv files, one per cache capacity saved in 'output_dir'.
+  //
+  // The file format is
+  // "time,label_1_access_per_second,label_2_access_per_second,...,label_N_access_per_second"
+  // where N is the number of unique cache names
+  // (cache_name+num_shard_bits+ghost_capacity).
+  void WriteMissRatioTimeline(uint64_t time_unit) const;
+
+  // Write misses timeline of simulated cache configurations into several
+  // csv files, one per cache capacity saved in 'output_dir'.
+  //
+  // The file format is
+  // "time,label_1_access_per_second,label_2_access_per_second,...,label_N_access_per_second"
+  // where N is the number of unique cache names
+  // (cache_name+num_shard_bits+ghost_capacity).
+  void WriteMissTimeline(uint64_t time_unit) const;
+
   // Write the access timeline into a csv file saved in 'output_dir'.
   //
   // The file is named "label_access_timeline".The file format is
@@ -236,6 +296,11 @@ class BlockCacheTraceAnalyzer {
       const std::string& label_str,
       const std::vector<uint64_t>& percent_buckets) const;
 
+  void WriteCorrelationFeatures(const std::string& label_str,
+                                uint32_t max_number_of_values) const;
+
+  void WriteCorrelationFeaturesForGet(uint32_t max_number_of_values) const;
+
   const std::map<std::string, ColumnFamilyAccessInfoAggregate>&
   TEST_cf_aggregates_map() const {
     return cf_aggregates_map_;
@@ -251,7 +316,7 @@ class BlockCacheTraceAnalyzer {
 
   void ComputeReuseDistance(BlockAccessInfo* info) const;
 
-  void RecordAccess(const BlockCacheTraceRecord& access);
+  Status RecordAccess(const BlockCacheTraceRecord& access);
 
   void UpdateReuseIntervalStats(
       const std::string& label, const std::vector<uint64_t>& time_buckets,
@@ -278,17 +343,41 @@ class BlockCacheTraceAnalyzer {
                          const BlockAccessInfo& /*block_access_info*/)>
           block_callback) const;
 
+  void UpdateFeatureVectors(
+      const std::vector<uint64_t>& access_sequence_number_timeline,
+      const std::vector<uint64_t>& access_timeline, const std::string& label,
+      std::map<std::string, Features>* label_features,
+      std::map<std::string, Predictions>* label_predictions) const;
+
+  void WriteCorrelationFeaturesToFile(
+      const std::string& label,
+      const std::map<std::string, Features>& label_features,
+      const std::map<std::string, Predictions>& label_predictions,
+      uint32_t max_number_of_values) const;
+
+  Status WriteHumanReadableTraceRecord(const BlockCacheTraceRecord& access,
+                                       uint64_t block_id, uint64_t get_key_id);
+
   rocksdb::Env* env_;
   const std::string trace_file_path_;
   const std::string output_dir_;
+  std::string human_readable_trace_file_path_;
   const bool compute_reuse_distance_;
+  const bool mrc_only_;
 
   BlockCacheTraceHeader header_;
   std::unique_ptr<BlockCacheTraceSimulator> cache_simulator_;
   std::map<std::string, ColumnFamilyAccessInfoAggregate> cf_aggregates_map_;
   std::map<std::string, BlockAccessInfo*> block_info_map_;
+  std::unordered_map<std::string, GetKeyInfo> get_key_info_map_;
+  uint64_t access_sequence_number_ = 0;
   uint64_t trace_start_timestamp_in_seconds_ = 0;
   uint64_t trace_end_timestamp_in_seconds_ = 0;
+  MissRatioStats miss_ratio_stats_;
+  uint64_t unique_block_id_ = 1;
+  uint64_t unique_get_key_id_ = 1;
+  char trace_record_buffer_[1024 * 1024];
+  std::unique_ptr<rocksdb::WritableFile> human_readable_trace_file_writer_;
 };
 
 int block_cache_trace_analyzer_tool(int argc, char** argv);

tools/block_cache_trace_analyzer_test.cc

@@ -117,7 +117,8 @@ class BlockCacheTracerTest : public testing::Test {
       // Provide these fields for all block types.
       // The writer should only write these fields for data blocks and the
       // caller is either GET or MGET.
-      record.referenced_key = kRefKeyPrefix + std::to_string(key_id);
+      record.referenced_key =
+          kRefKeyPrefix + std::to_string(key_id) + std::string(8, 0);
       record.referenced_key_exist_in_block = Boolean::kTrue;
       record.num_keys_in_block = kNumKeysInBlock;
       ASSERT_OK(writer->WriteBlockAccess(
@@ -179,7 +180,8 @@ class BlockCacheTracerTest : public testing::Test {
         "-analyze_get_spatial_locality_labels=" +
             analyze_get_spatial_locality_labels_,
         "-analyze_get_spatial_locality_buckets=" +
-            analyze_get_spatial_locality_buckets_};
+            analyze_get_spatial_locality_buckets_,
+        "-analyze_correlation_coefficients_labels=all"};
     char arg_buffer[kArgBufferSize];
     char* argv[kMaxArgCount];
     int argc = 0;
@@ -236,9 +238,9 @@ TEST_F(BlockCacheTracerTest, BlockCacheAnalyzer) {
   RunBlockCacheTraceAnalyzer();
   {
     // Validate the cache miss ratios.
-    const std::vector<uint64_t> expected_capacities{1024, 1024 * 1024,
+    std::vector<uint64_t> expected_capacities{1024, 1024 * 1024,
                                               1024 * 1024 * 1024};
-    const std::string mrc_path = test_path_ + "/mrc";
+    const std::string mrc_path = test_path_ + "/49_50_mrc";
     std::ifstream infile(mrc_path);
     uint32_t config_index = 0;
     std::string line;
@@ -266,6 +268,68 @@ TEST_F(BlockCacheTracerTest, BlockCacheAnalyzer) {
     ASSERT_EQ(expected_capacities.size(), config_index);
     infile.close();
     ASSERT_OK(env_->DeleteFile(mrc_path));
+
+    const std::vector<std::string> time_units{"1", "60", "3600"};
+    expected_capacities.push_back(port::kMaxUint64);
+    for (auto const& expected_capacity : expected_capacities) {
+      for (auto const& time_unit : time_units) {
+        const std::string miss_ratio_timeline_path =
+            test_path_ + "/" + std::to_string(expected_capacity) + "_" +
+            time_unit + "_miss_ratio_timeline";
+        std::ifstream mrt_file(miss_ratio_timeline_path);
+        // Read header.
+        ASSERT_TRUE(getline(mrt_file, line));
+        ASSERT_TRUE(getline(mrt_file, line));
+        std::stringstream ss(line);
+        bool read_header = false;
+        while (ss.good()) {
+          std::string substr;
+          getline(ss, substr, ',');
+          if (!read_header) {
+            if (expected_capacity == port::kMaxUint64) {
+              ASSERT_EQ("trace", substr);
+            } else {
+              ASSERT_EQ("lru-1-0", substr);
+            }
+            read_header = true;
+            continue;
+          }
+          ASSERT_DOUBLE_EQ(100.0, ParseDouble(substr));
+        }
+        ASSERT_FALSE(getline(mrt_file, line));
+        mrt_file.close();
+        ASSERT_OK(env_->DeleteFile(miss_ratio_timeline_path));
+      }
+      for (auto const& time_unit : time_units) {
+        const std::string miss_timeline_path =
+            test_path_ + "/" + std::to_string(expected_capacity) + "_" +
+            time_unit + "_miss_timeline";
+        std::ifstream mt_file(miss_timeline_path);
+        // Read header.
+        ASSERT_TRUE(getline(mt_file, line));
+        ASSERT_TRUE(getline(mt_file, line));
+        std::stringstream ss(line);
+        uint32_t num_misses = 0;
+        while (ss.good()) {
+          std::string substr;
+          getline(ss, substr, ',');
+          if (num_misses == 0) {
+            if (expected_capacity == port::kMaxUint64) {
+              ASSERT_EQ("trace", substr);
+            } else {
+              ASSERT_EQ("lru-1-0", substr);
+            }
+            num_misses++;
+            continue;
+          }
+          num_misses += ParseInt(substr);
+        }
+        ASSERT_EQ(51, num_misses);
+        ASSERT_FALSE(getline(mt_file, line));
+        mt_file.close();
+        ASSERT_OK(env_->DeleteFile(miss_timeline_path));
+      }
+    }
   }
   {
     // Validate the timeline csv files.
@@ -543,7 +607,9 @@ TEST_F(BlockCacheTracerTest, MixedBlocks) {
     // Read blocks.
     BlockCacheTraceAnalyzer analyzer(trace_file_path_,
                                      /*output_miss_ratio_curve_path=*/"",
+                                     /*human_readable_trace_file_path=*/"",
                                      /*compute_reuse_distance=*/true,
+                                     /*mrc_only=*/false,
                                      /*simulator=*/nullptr);
     // The analyzer ends when it detects an incomplete access record.
     ASSERT_EQ(Status::Incomplete(""), analyzer.Analyze());

trace_replay/block_cache_tracer.cc

@@ -6,6 +6,7 @@
 #include "trace_replay/block_cache_tracer.h"
 
 #include "db/db_impl/db_impl.h"
+#include "db/dbformat.h"
 #include "rocksdb/slice.h"
 #include "util/coding.h"
 #include "util/hash.h"
@@ -54,6 +55,19 @@ bool BlockCacheTraceHelper::IsUserAccess(TableReaderCaller caller) {
          caller == TableReaderCaller::kUserVerifyChecksum;
 }
 
+std::string BlockCacheTraceHelper::ComputeRowKey(
+    const BlockCacheTraceRecord& access) {
+  if (!IsGetOrMultiGet(access.caller)) {
+    return "";
+  }
+  Slice key = ExtractUserKey(access.referenced_key);
+  uint64_t seq_no = access.get_from_user_specified_snapshot == Boolean::kFalse
+                        ? 0
+                        : 1 + GetInternalKeySeqno(access.referenced_key);
+  return std::to_string(access.sst_fd_number) + "_" + key.ToString() + "_" +
+         std::to_string(seq_no);
+}
+
 BlockCacheTraceWriter::BlockCacheTraceWriter(
     Env* env, const TraceOptions& trace_options,
     std::unique_ptr<TraceWriter>&& trace_writer)

trace_replay/block_cache_tracer.h

@@ -20,6 +20,7 @@ extern const uint64_t kMicrosInSecond;
 extern const uint64_t kSecondInMinute;
 extern const uint64_t kSecondInHour;
 
+struct BlockCacheTraceRecord;
 
 class BlockCacheTraceHelper {
  public:
@@ -27,7 +28,9 @@ class BlockCacheTraceHelper {
                                          TableReaderCaller caller);
   static bool IsGetOrMultiGet(TableReaderCaller caller);
   static bool IsUserAccess(TableReaderCaller caller);
-
+  // Row key is a concatenation of the access's fd_number and the referenced
+  // user key.
+  static std::string ComputeRowKey(const BlockCacheTraceRecord& access);
   static const std::string kUnknownColumnFamilyName;
   static const uint64_t kReservedGetId;
 };

utilities/simulator_cache/cache_simulator.cc

@@ -4,13 +4,14 @@
 //  (found in the LICENSE.Apache file in the root directory).
 
 #include "utilities/simulator_cache/cache_simulator.h"
+#include <algorithm>
 #include "db/dbformat.h"
 
 namespace rocksdb {
 
 namespace {
 const std::string kGhostCachePrefix = "ghost_";
-}
+}  // namespace
 
 GhostCache::GhostCache(std::shared_ptr<Cache> sim_cache)
     : sim_cache_(sim_cache) {}
@@ -22,7 +23,7 @@ bool GhostCache::Admit(const Slice& lookup_key) {
     return true;
   }
   sim_cache_->Insert(lookup_key, /*value=*/nullptr, lookup_key.size(),
-                     /*deleter=*/nullptr, /*handle=*/nullptr);
+                     /*deleter=*/nullptr);
   return false;
 }
 
@@ -43,18 +44,27 @@ void CacheSimulator::Access(const BlockCacheTraceRecord& access) {
     sim_cache_->Release(handle);
     is_cache_miss = false;
   } else {
-    if (access.no_insert == Boolean::kFalse && admit) {
+    if (access.no_insert == Boolean::kFalse && admit && access.block_size > 0) {
       sim_cache_->Insert(access.block_key, /*value=*/nullptr, access.block_size,
-                         /*deleter=*/nullptr, /*handle=*/nullptr);
+                         /*deleter=*/nullptr);
     }
   }
-  UpdateMetrics(is_user_access, is_cache_miss);
+  miss_ratio_stats_.UpdateMetrics(access.access_timestamp, is_user_access,
+                                  is_cache_miss);
 }
 
-void CacheSimulator::UpdateMetrics(bool is_user_access, bool is_cache_miss) {
+void MissRatioStats::UpdateMetrics(uint64_t timestamp_in_ms,
+                                   bool is_user_access, bool is_cache_miss) {
+  uint64_t timestamp_in_seconds = timestamp_in_ms / kMicrosInSecond;
+  num_accesses_timeline_[timestamp_in_seconds] += 1;
   num_accesses_ += 1;
+  if (num_misses_timeline_.find(timestamp_in_seconds) ==
+      num_misses_timeline_.end()) {
+    num_misses_timeline_[timestamp_in_seconds] = 0;
+  }
   if (is_cache_miss) {
     num_misses_ += 1;
+    num_misses_timeline_[timestamp_in_seconds] += 1;
   }
   if (is_user_access) {
     user_accesses_ += 1;
@@ -76,8 +86,8 @@ Cache::Priority PrioritizedCacheSimulator::ComputeBlockPriority(
 
 void PrioritizedCacheSimulator::AccessKVPair(
     const Slice& key, uint64_t value_size, Cache::Priority priority,
-    bool no_insert, bool is_user_access, bool* is_cache_miss, bool* admitted,
-    bool update_metrics) {
+    const BlockCacheTraceRecord& access, bool no_insert, bool is_user_access,
+    bool* is_cache_miss, bool* admitted, bool update_metrics) {
   assert(is_cache_miss);
   assert(admitted);
   *is_cache_miss = true;
@@ -90,11 +100,12 @@ void PrioritizedCacheSimulator::AccessKVPair(
     sim_cache_->Release(handle);
     *is_cache_miss = false;
   } else if (!no_insert && *admitted && value_size > 0) {
-    sim_cache_->Insert(key, /*value=*/nullptr, value_size,
-                       /*deleter=*/nullptr, /*handle=*/nullptr, priority);
+    sim_cache_->Insert(key, /*value=*/nullptr, value_size, /*deleter=*/nullptr,
+                       /*handle=*/nullptr, priority);
   }
   if (update_metrics) {
-    UpdateMetrics(is_user_access, *is_cache_miss);
+    miss_ratio_stats_.UpdateMetrics(access.access_timestamp, is_user_access,
+                                    *is_cache_miss);
   }
 }
 
@@ -102,38 +113,28 @@ void PrioritizedCacheSimulator::Access(const BlockCacheTraceRecord& access) {
   bool is_cache_miss = true;
   bool admitted = true;
   AccessKVPair(access.block_key, access.block_size,
-               ComputeBlockPriority(access), access.no_insert,
+               ComputeBlockPriority(access), access, access.no_insert,
                BlockCacheTraceHelper::IsUserAccess(access.caller),
                &is_cache_miss, &admitted, /*update_metrics=*/true);
 }
 
-std::string HybridRowBlockCacheSimulator::ComputeRowKey(
-    const BlockCacheTraceRecord& access) {
-  assert(access.get_id != BlockCacheTraceHelper::kReservedGetId);
-  Slice key = ExtractUserKey(access.referenced_key);
-  uint64_t seq_no = access.get_from_user_specified_snapshot == Boolean::kFalse
-                        ? 0
-                        : 1 + GetInternalKeySeqno(access.referenced_key);
-  return std::to_string(access.sst_fd_number) + "_" + key.ToString() + "_" +
-         std::to_string(seq_no);
-}
-
 void HybridRowBlockCacheSimulator::Access(const BlockCacheTraceRecord& access) {
-  bool is_cache_miss = true;
-  bool admitted = true;
   // TODO (haoyu): We only support Get for now. We need to extend the tracing
   // for MultiGet, i.e., non-data block accesses must log all keys in a
   // MultiGet.
+  bool is_cache_miss = false;
+  bool admitted = false;
   if (access.caller == TableReaderCaller::kUserGet &&
       access.get_id != BlockCacheTraceHelper::kReservedGetId) {
     // This is a Get/MultiGet request.
-    const std::string& row_key = ComputeRowKey(access);
+    const std::string& row_key = BlockCacheTraceHelper::ComputeRowKey(access);
     if (getid_getkeys_map_[access.get_id].find(row_key) ==
         getid_getkeys_map_[access.get_id].end()) {
       // This is the first time that this key is accessed. Look up the key-value
       // pair first. Do not update the miss/accesses metrics here since it will
       // be updated later.
       AccessKVPair(row_key, access.referenced_data_size, Cache::Priority::HIGH,
+                   access,
                    /*no_insert=*/false,
                    /*is_user_access=*/true, &is_cache_miss, &admitted,
                    /*update_metrics=*/false);
@@ -154,28 +155,31 @@ void HybridRowBlockCacheSimulator::Access(const BlockCacheTraceRecord& access) {
       // referenced key-value pair already. Thus, we treat these lookups as
       // hits. This is also to ensure the total number of accesses are the same
       // when comparing to other policies.
-      UpdateMetrics(/*is_user_access=*/true, /*is_cache_miss=*/false);
+      miss_ratio_stats_.UpdateMetrics(access.access_timestamp,
+                                      /*is_user_access=*/true,
+                                      /*is_cache_miss=*/false);
       return;
     }
     // The key-value pair observes a cache miss. We need to access its
     // index/filter/data blocks.
     AccessKVPair(
         access.block_key, access.block_type, ComputeBlockPriority(access),
+        access,
         /*no_insert=*/!insert_blocks_upon_row_kvpair_miss_ || access.no_insert,
         /*is_user_access=*/true, &is_cache_miss, &admitted,
         /*update_metrics=*/true);
     if (access.referenced_data_size > 0 &&
         miss_inserted.second == InsertResult::ADMITTED) {
-      sim_cache_->Insert(
-          row_key, /*value=*/nullptr, access.referenced_data_size,
-          /*deleter=*/nullptr, /*handle=*/nullptr, Cache::Priority::HIGH);
+      sim_cache_->Insert(row_key, /*value=*/nullptr,
+                         access.referenced_data_size, /*deleter=*/nullptr,
+                         /*handle=*/nullptr, Cache::Priority::HIGH);
       getid_getkeys_map_[access.get_id][row_key] =
           std::make_pair(true, InsertResult::INSERTED);
     }
     return;
   }
   AccessKVPair(access.block_key, access.block_size,
-               ComputeBlockPriority(access), access.no_insert,
+               ComputeBlockPriority(access), access, access.no_insert,
                BlockCacheTraceHelper::IsUserAccess(access.caller),
                &is_cache_miss, &admitted, /*update_metrics=*/true);
 }

utilities/simulator_cache/cache_simulator.h

@@ -5,6 +5,9 @@
 
 #pragma once
 
+#include <unordered_map>
+
+#include "cache/lru_cache.h"
 #include "trace_replay/block_cache_tracer.h"
 
 namespace rocksdb {
@@ -29,6 +32,51 @@ struct CacheConfiguration {
   }
 };
 
+class MissRatioStats {
+ public:
+  void reset_counter() {
+    num_misses_ = 0;
+    num_accesses_ = 0;
+    user_accesses_ = 0;
+    user_misses_ = 0;
+  }
+  double miss_ratio() const {
+    if (num_accesses_ == 0) {
+      return -1;
+    }
+    return static_cast<double>(num_misses_ * 100.0 / num_accesses_);
+  }
+  uint64_t total_accesses() const { return num_accesses_; }
+
+  const std::map<uint64_t, uint64_t>& num_accesses_timeline() const {
+    return num_accesses_timeline_;
+  }
+
+  const std::map<uint64_t, uint64_t>& num_misses_timeline() const {
+    return num_misses_timeline_;
+  }
+
+  double user_miss_ratio() const {
+    if (user_accesses_ == 0) {
+      return -1;
+    }
+    return static_cast<double>(user_misses_ * 100.0 / user_accesses_);
+  }
+  uint64_t user_accesses() const { return user_accesses_; }
+
+  void UpdateMetrics(uint64_t timestamp_in_ms, bool is_user_access,
+                     bool is_cache_miss);
+
+ private:
+  uint64_t num_accesses_ = 0;
+  uint64_t num_misses_ = 0;
+  uint64_t user_accesses_ = 0;
+  uint64_t user_misses_ = 0;
+
+  std::map<uint64_t, uint64_t> num_accesses_timeline_;
+  std::map<uint64_t, uint64_t> num_misses_timeline_;
+};
+
 // A ghost cache admits an entry on its second access.
 class GhostCache {
  public:
@@ -61,37 +109,15 @@ class CacheSimulator {
   CacheSimulator& operator=(CacheSimulator&&) = delete;
 
   virtual void Access(const BlockCacheTraceRecord& access);
-  void reset_counter() {
-    num_misses_ = 0;
-    num_accesses_ = 0;
-    user_accesses_ = 0;
-    user_misses_ = 0;
-  }
-  double miss_ratio() const {
-    if (num_accesses_ == 0) {
-      return -1;
-    }
-    return static_cast<double>(num_misses_ * 100.0 / num_accesses_);
-  }
-  uint64_t total_accesses() const { return num_accesses_; }
 
-  double user_miss_ratio() const {
-    if (user_accesses_ == 0) {
-      return -1;
-    }
-    return static_cast<double>(user_misses_ * 100.0 / user_accesses_);
-  }
-  uint64_t user_accesses() const { return user_accesses_; }
+  void reset_counter() { miss_ratio_stats_.reset_counter(); }
 
- protected:
-  void UpdateMetrics(bool is_user_access, bool is_cache_miss);
+  const MissRatioStats& miss_ratio_stats() const { return miss_ratio_stats_; }
 
+ protected:
+  MissRatioStats miss_ratio_stats_;
   std::unique_ptr<GhostCache> ghost_cache_;
   std::shared_ptr<Cache> sim_cache_;
-  uint64_t num_accesses_ = 0;
-  uint64_t num_misses_ = 0;
-  uint64_t user_accesses_ = 0;
-  uint64_t user_misses_ = 0;
 };
 
 // A prioritized cache simulator that runs against a block cache trace.
@@ -107,7 +133,8 @@ class PrioritizedCacheSimulator : public CacheSimulator {
  protected:
   // Access the key-value pair and returns true upon a cache miss.
   void AccessKVPair(const Slice& key, uint64_t value_size,
-                    Cache::Priority priority, bool no_insert,
+                    Cache::Priority priority,
+                    const BlockCacheTraceRecord& access, bool no_insert,
                     bool is_user_access, bool* is_cache_miss, bool* admitted,
                     bool update_metrics);
 
@@ -135,10 +162,6 @@ class HybridRowBlockCacheSimulator : public PrioritizedCacheSimulator {
   void Access(const BlockCacheTraceRecord& access) override;
 
  private:
-  // Row key is a concatenation of the access's fd_number and the referenced
-  // user key.
-  std::string ComputeRowKey(const BlockCacheTraceRecord& access);
-
   enum InsertResult : char {
     INSERTED,
     ADMITTED,

utilities/simulator_cache/cache_simulator_test.cc

@@ -94,21 +94,21 @@ TEST_F(CacheSimulatorTest, CacheSimulator) {
       new CacheSimulator(nullptr, sim_cache));
   cache_simulator->Access(access);
   cache_simulator->Access(access);
-  ASSERT_EQ(2, cache_simulator->total_accesses());
-  ASSERT_EQ(50, cache_simulator->miss_ratio());
-  ASSERT_EQ(2, cache_simulator->user_accesses());
-  ASSERT_EQ(50, cache_simulator->user_miss_ratio());
+  ASSERT_EQ(2, cache_simulator->miss_ratio_stats().total_accesses());
+  ASSERT_EQ(50, cache_simulator->miss_ratio_stats().miss_ratio());
+  ASSERT_EQ(2, cache_simulator->miss_ratio_stats().user_accesses());
+  ASSERT_EQ(50, cache_simulator->miss_ratio_stats().user_miss_ratio());
 
   cache_simulator->Access(compaction_access);
   cache_simulator->Access(compaction_access);
-  ASSERT_EQ(4, cache_simulator->total_accesses());
-  ASSERT_EQ(75, cache_simulator->miss_ratio());
-  ASSERT_EQ(2, cache_simulator->user_accesses());
-  ASSERT_EQ(50, cache_simulator->user_miss_ratio());
+  ASSERT_EQ(4, cache_simulator->miss_ratio_stats().total_accesses());
+  ASSERT_EQ(75, cache_simulator->miss_ratio_stats().miss_ratio());
+  ASSERT_EQ(2, cache_simulator->miss_ratio_stats().user_accesses());
+  ASSERT_EQ(50, cache_simulator->miss_ratio_stats().user_miss_ratio());
 
   cache_simulator->reset_counter();
-  ASSERT_EQ(0, cache_simulator->total_accesses());
-  ASSERT_EQ(-1, cache_simulator->miss_ratio());
+  ASSERT_EQ(0, cache_simulator->miss_ratio_stats().total_accesses());
+  ASSERT_EQ(-1, cache_simulator->miss_ratio_stats().miss_ratio());
   auto handle = sim_cache->Lookup(access.block_key);
   ASSERT_NE(nullptr, handle);
   sim_cache->Release(handle);
@@ -129,9 +129,9 @@ TEST_F(CacheSimulatorTest, GhostCacheSimulator) {
                   /*high_pri_pool_ratio=*/0)));
   cache_simulator->Access(access);
   cache_simulator->Access(access);
-  ASSERT_EQ(2, cache_simulator->total_accesses());
+  ASSERT_EQ(2, cache_simulator->miss_ratio_stats().total_accesses());
   // Both of them will be miss since we have a ghost cache.
-  ASSERT_EQ(100, cache_simulator->miss_ratio());
+  ASSERT_EQ(100, cache_simulator->miss_ratio_stats().miss_ratio());
 }
 
 TEST_F(CacheSimulatorTest, PrioritizedCacheSimulator) {
@@ -144,8 +144,8 @@ TEST_F(CacheSimulatorTest, PrioritizedCacheSimulator) {
       new PrioritizedCacheSimulator(nullptr, sim_cache));
   cache_simulator->Access(access);
   cache_simulator->Access(access);
-  ASSERT_EQ(2, cache_simulator->total_accesses());
-  ASSERT_EQ(50, cache_simulator->miss_ratio());
+  ASSERT_EQ(2, cache_simulator->miss_ratio_stats().total_accesses());
+  ASSERT_EQ(50, cache_simulator->miss_ratio_stats().miss_ratio());
 
   auto handle = sim_cache->Lookup(access.block_key);
   ASSERT_NE(nullptr, handle);
@@ -166,9 +166,9 @@ TEST_F(CacheSimulatorTest, GhostPrioritizedCacheSimulator) {
                       /*high_pri_pool_ratio=*/0)));
   cache_simulator->Access(access);
   cache_simulator->Access(access);
-  ASSERT_EQ(2, cache_simulator->total_accesses());
+  ASSERT_EQ(2, cache_simulator->miss_ratio_stats().total_accesses());
   // Both of them will be miss since we have a ghost cache.
-  ASSERT_EQ(100, cache_simulator->miss_ratio());
+  ASSERT_EQ(100, cache_simulator->miss_ratio_stats().miss_ratio());
 }
 
 TEST_F(CacheSimulatorTest, HybridRowBlockCacheSimulator) {
@@ -200,10 +200,11 @@ TEST_F(CacheSimulatorTest, HybridRowBlockCacheSimulator) {
     cache_simulator->Access(first_get);
     block_id++;
   }
-  ASSERT_EQ(10, cache_simulator->total_accesses());
-  ASSERT_EQ(100, cache_simulator->miss_ratio());
-  ASSERT_EQ(10, cache_simulator->user_accesses());
-  ASSERT_EQ(100, cache_simulator->user_miss_ratio());
+
+  ASSERT_EQ(10, cache_simulator->miss_ratio_stats().total_accesses());
+  ASSERT_EQ(100, cache_simulator->miss_ratio_stats().miss_ratio());
+  ASSERT_EQ(10, cache_simulator->miss_ratio_stats().user_accesses());
+  ASSERT_EQ(100, cache_simulator->miss_ratio_stats().user_miss_ratio());
   auto handle = sim_cache->Lookup(
       std::to_string(first_get.sst_fd_number) + "_" +
       ExtractUserKey(first_get.referenced_key).ToString() + "_" +
@@ -225,10 +226,12 @@ TEST_F(CacheSimulatorTest, HybridRowBlockCacheSimulator) {
     cache_simulator->Access(second_get);
     block_id++;
   }
-  ASSERT_EQ(15, cache_simulator->total_accesses());
-  ASSERT_EQ(66, static_cast<uint64_t>(cache_simulator->miss_ratio()));
-  ASSERT_EQ(15, cache_simulator->user_accesses());
-  ASSERT_EQ(66, static_cast<uint64_t>(cache_simulator->user_miss_ratio()));
+  ASSERT_EQ(15, cache_simulator->miss_ratio_stats().total_accesses());
+  ASSERT_EQ(66, static_cast<uint64_t>(
+                    cache_simulator->miss_ratio_stats().miss_ratio()));
+  ASSERT_EQ(15, cache_simulator->miss_ratio_stats().user_accesses());
+  ASSERT_EQ(66, static_cast<uint64_t>(
+                    cache_simulator->miss_ratio_stats().user_miss_ratio()));
   handle = sim_cache->Lookup(
       std::to_string(second_get.sst_fd_number) + "_" +
       ExtractUserKey(second_get.referenced_key).ToString() + "_" +
@@ -252,10 +255,12 @@ TEST_F(CacheSimulatorTest, HybridRowBlockCacheSimulator) {
     cache_simulator->Access(third_get);
     block_id++;
   }
-  ASSERT_EQ(20, cache_simulator->total_accesses());
-  ASSERT_EQ(75, static_cast<uint64_t>(cache_simulator->miss_ratio()));
-  ASSERT_EQ(20, cache_simulator->user_accesses());
-  ASSERT_EQ(75, static_cast<uint64_t>(cache_simulator->user_miss_ratio()));
+  ASSERT_EQ(20, cache_simulator->miss_ratio_stats().total_accesses());
+  ASSERT_EQ(75, static_cast<uint64_t>(
+                    cache_simulator->miss_ratio_stats().miss_ratio()));
+  ASSERT_EQ(20, cache_simulator->miss_ratio_stats().user_accesses());
+  ASSERT_EQ(75, static_cast<uint64_t>(
+                    cache_simulator->miss_ratio_stats().user_miss_ratio()));
   // Assert that the third key is not inserted into the cache.
   handle = sim_cache->Lookup(std::to_string(third_get.sst_fd_number) + "_" +
                              third_get.referenced_key);
@@ -318,19 +323,21 @@ TEST_F(CacheSimulatorTest, GhostHybridRowBlockCacheSimulator) {
   // Two get requests access the same key.
   cache_simulator->Access(first_get);
   cache_simulator->Access(second_get);
-  ASSERT_EQ(2, cache_simulator->total_accesses());
-  ASSERT_EQ(100, cache_simulator->miss_ratio());
-  ASSERT_EQ(2, cache_simulator->user_accesses());
-  ASSERT_EQ(100, cache_simulator->user_miss_ratio());
+  ASSERT_EQ(2, cache_simulator->miss_ratio_stats().total_accesses());
+  ASSERT_EQ(100, cache_simulator->miss_ratio_stats().miss_ratio());
+  ASSERT_EQ(2, cache_simulator->miss_ratio_stats().user_accesses());
+  ASSERT_EQ(100, cache_simulator->miss_ratio_stats().user_miss_ratio());
   // We insert the key-value pair upon the second get request. A third get
   // request should observe a hit.
   for (uint32_t i = 0; i < 10; i++) {
     cache_simulator->Access(third_get);
   }
-  ASSERT_EQ(12, cache_simulator->total_accesses());
-  ASSERT_EQ(16, static_cast<uint64_t>(cache_simulator->miss_ratio()));
-  ASSERT_EQ(12, cache_simulator->user_accesses());
-  ASSERT_EQ(16, static_cast<uint64_t>(cache_simulator->user_miss_ratio()));
+  ASSERT_EQ(12, cache_simulator->miss_ratio_stats().total_accesses());
+  ASSERT_EQ(16, static_cast<uint64_t>(
+                    cache_simulator->miss_ratio_stats().miss_ratio()));
+  ASSERT_EQ(12, cache_simulator->miss_ratio_stats().user_accesses());
+  ASSERT_EQ(16, static_cast<uint64_t>(
+                    cache_simulator->miss_ratio_stats().user_miss_ratio()));
 }
 
 }  // namespace rocksdb