MCOL-4713 Analyze table implementation.

utils/common/statistics.h

@@ -0,0 +1,122 @@
+/* Copyright (C) 2021 MariaDB Corporation
+
+   This program is free software; you can redistribute it and/or
+   modify it under the terms of the GNU General Public License
+   as published by the Free Software Foundation; version 2 of
+   the License.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+   MA 02110-1301, USA. */
+
+#ifndef STATISTICS_H
+#define STATISTICS_H
+
+#include "rowgroup.h"
+#include "logger.h"
+#include "hasher.h"
+#include "IDBPolicy.h"
+
+#include <map>
+#include <unordered_set>
+#include <mutex>
+
+// Represents a commands for `ExeMgr`.
+#define ANALYZE_TABLE_EXECUTE 6
+#define ANALYZE_TABLE_REC_STATS 7
+#define ANALYZE_TABLE_NEED_STATS 8
+#define ANALYZE_TABLE_SUCCESS 9
+// #define DEBUG_STATISTICS
+
+using namespace idbdatafile;
+
+namespace statistics
+{
+
+// Represents a column key type:
+// PK - primary key.
+// FK - foreign key.
+enum class KeyType : uint32_t
+{
+    PK,
+    FK
+};
+
+// Rerpresents types of statistics CS supports.
+enum class StatisticsType : uint32_t
+{
+    // A special statistics type, made to solve circular inner join problem.
+    PK_FK
+};
+
+// Represetns a header for the statistics file.
+struct StatisticsFileHeader
+{
+    uint64_t version;
+    uint64_t epoch;
+    uint64_t dataHash;
+    uint64_t dataSize;
+    uint8_t offset[1024];
+};
+
+// This class is responsible for processing and storing statistics.
+// On each `analyze table` iteration it increases an epoch and stores
+// the updated statistics into the special file.
+class StatisticsManager
+{
+  public:
+    // Returns the instance of this class, static initialization happens only once.
+    static StatisticsManager* instance();
+    // Analyzes the given `rowGroup` by processing it row by row and searching for foreign key.
+    void analyzeColumnKeyTypes(const rowgroup::RowGroup& rowGroup, bool trace);
+    // Ouputs stats to out stream.
+    void output(StatisticsType statisticsType = StatisticsType::PK_FK);
+    // Saves stats to the file.
+    void saveToFile();
+    // Loads stats from the file.
+    void loadFromFile();
+    void incEpoch() { ++epoch; }
+    // Serialize stats to the given `bs`.
+    void serialize(messageqcpp::ByteStream& bs);
+    // Unserialize stats from the given `bs`.
+    void unserialize(messageqcpp::ByteStream& bs);
+    // Computes hash from the current statistics data.
+    uint64_t computeHashFromStats();
+
+  private:
+    std::map<uint32_t, KeyType> keyTypes;
+    StatisticsManager() : epoch(0), version(1) { IDBPolicy::init(true, false, "", 0); }
+    std::unique_ptr<char[]> convertStatsToDataStream(uint64_t& dataStreamSize);
+
+    std::mutex mut;
+    uint32_t epoch;
+    uint32_t version;
+    std::string statsFile = "/var/lib/columnstore/local/statistics";
+};
+
+// This class is responsible for distributing the statistics across all `ExeMgr` in a cluster.
+class StatisticsDistributor
+{
+  public:
+    // Returns the instance of this class, static initialization happens only once.
+    static StatisticsDistributor* instance();
+
+    // Distribute stats across all `ExeMgr` in cluster by connecting to them using config file.
+    void distributeStatistics();
+
+  private:
+    StatisticsDistributor() : clientsCount(0) {}
+    // Count the number of clients by reading config file and evaluating `ExeMgr` fields.
+    void countClients();
+    uint32_t clientsCount;
+    std::mutex mut;
+};
+
+} // namespace statistics
+#endif