Introduce generic flatdb implementation

src/Makefile.am

@@ -187,6 +187,7 @@ BITCOIN_CORE_H = \
   evo/evonotificationinterface.h \
   evo/providertx.h \
   evo/specialtx_validation.h \
+  flatdb.h \
   llmq/quorums_blockprocessor.h \
   llmq/quorums_commitment.h \
   llmq/quorums_init.h \

src/flatdb.h

@@ -0,0 +1,181 @@
+// Copyright (c) 2014-2020 The Dash Core developers
+// Copyright (c) 2021 The PIVX Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or https://www.opensource.org/licenses/mit-license.php.
+
+#ifndef PIVX_FLAT_DATABASE_H
+#define PIVX_FLAT_DATABASE_H
+
+#include "chainparams.h"
+#include "clientversion.h"
+#include "fs.h"
+#include "hash.h"
+#include "logging.h"
+#include "streams.h"
+#include "utiltime.h"
+#include "util/system.h"
+
+/**
+*   Generic Dumping and Loading
+*   ---------------------------
+*/
+
+template<typename T>
+class CFlatDB
+{
+private:
+    fs::path pathDB;
+    std::string strFilename;
+    std::string strMagicMessage;
+
+    enum ReadResult {
+        Ok,
+        FileError,
+        HashReadError,
+        IncorrectHash,
+        IncorrectMagicMessage,
+        IncorrectMagicNumber,
+        IncorrectFormat
+    };
+
+    bool Write(T& objToSave)
+    {
+        int64_t nStart = GetTimeMillis();
+
+        // serialize, checksum data up to that point, then append checksum
+        CDataStream ssObj(SER_DISK, CLIENT_VERSION);
+        ssObj << strMagicMessage; // specific magic message for this type of object
+        ssObj << Params().MessageStart(); // network specific magic number
+        ssObj << objToSave;
+        const uint256& hash = Hash(ssObj.begin(), ssObj.end());
+        ssObj << hash;
+
+        // open output file, and associate with CAutoFile
+        FILE* file = fopen(pathDB.string().c_str(), "wb");
+        CAutoFile fileout(file, SER_DISK, CLIENT_VERSION);
+        if (fileout.IsNull())
+            return error("%s: Failed to open file %s", __func__, pathDB.string());
+
+        // Write and commit header, data
+        try {
+            fileout << ssObj;
+        }
+        catch (std::exception &e) {
+            return error("%s: Serialize or I/O error - %s", __func__, e.what());
+        }
+        fileout.fclose();
+
+        LogPrintf("Written info to %s  %dms\n", strFilename, GetTimeMillis() - nStart);
+        LogPrintf("     %s\n", objToSave.ToString());
+        return true;
+    }
+
+    ReadResult Read(T& objToLoad)
+    {
+        int64_t nStart = GetTimeMillis();
+        // open input file, and associate with CAutoFile
+        FILE* file = fopen(pathDB.string().c_str(), "rb");
+        CAutoFile filein(file, SER_DISK, CLIENT_VERSION);
+        if (filein.IsNull()) {
+            error("%s: Failed to open file %s", __func__, pathDB.string());
+            return FileError;
+        }
+
+        // use file size to size memory buffer
+        int fileSize = fs::file_size(pathDB);
+        int dataSize = fileSize - sizeof(uint256);
+        // Don't try to resize to a negative number if file is small
+        if (dataSize < 0) dataSize = 0;
+        std::vector<unsigned char> vchData;
+        vchData.resize(dataSize);
+        uint256 hashIn;
+
+        // read data and checksum from file
+        try {
+            filein.read((char *)vchData.data(), dataSize);
+            filein >> hashIn;
+        } catch (std::exception &e) {
+            error("%s: Deserialize or I/O error - %s", __func__, e.what());
+            return HashReadError;
+        }
+        filein.fclose();
+
+        CDataStream ssObj(vchData, SER_DISK, CLIENT_VERSION);
+
+        // verify stored checksum matches input data
+        uint256 hashTmp = Hash(ssObj.begin(), ssObj.end());
+        if (hashIn != hashTmp) {
+            error("%s: Checksum mismatch, data corrupted", __func__);
+            return IncorrectHash;
+        }
+
+        unsigned char pchMsgTmp[4];
+        std::string strMagicMessageTmp;
+        try {
+            // de-serialize file header (file specific magic message) and ..
+            ssObj >> strMagicMessageTmp;
+
+            // ... verify the message matches predefined one
+            if (strMagicMessage != strMagicMessageTmp) {
+                error("%s: Invalid magic message", __func__);
+                return IncorrectMagicMessage;
+            }
+
+            // de-serialize file header (network specific magic number) and ..
+            ssObj >> pchMsgTmp;
+
+            // ... verify the network matches ours
+            if (memcmp(pchMsgTmp, Params().MessageStart(), sizeof(pchMsgTmp))) {
+                error("%s: Invalid network magic number", __func__);
+                return IncorrectMagicNumber;
+            }
+
+            // de-serialize data into T object
+            ssObj >> objToLoad;
+        } catch (std::exception &e) {
+            objToLoad.Clear();
+            error("%s: Deserialize or I/O error - %s", __func__, e.what());
+            return IncorrectFormat;
+        }
+
+        LogPrintf("Loaded info from %s  %dms\n", strFilename, GetTimeMillis() - nStart);
+        LogPrintf("     %s\n", objToLoad.ToString());
+        return Ok;
+    }
+public:
+    CFlatDB(const std::string& strFilenameIn,
+            const std::string& strMagicMessageIn) :
+            pathDB(GetDataDir() / strFilenameIn), strFilename(strFilenameIn),
+            strMagicMessage(strMagicMessageIn) {}
+
+    bool Load(T& objToLoad)
+    {
+        LogPrintf("Reading info from %s...\n", strFilename);
+        ReadResult readResult = Read(objToLoad);
+        if (readResult == FileError) {
+            LogPrintf("Missing file %s, will try to recreate\n", strFilename);
+        } else if (readResult != Ok) {
+            LogPrintf("Error reading %s: ", strFilename);
+            if (readResult == IncorrectFormat) {
+                LogPrintf("%s: Magic is ok but data has invalid format, will try to recreate\n", __func__);
+            } else {
+                LogPrintf("%s: File format is unknown or invalid, please fix it manually\n", __func__);
+                // program should exit with an error
+                return false;
+            }
+        }
+        return true;
+    }
+
+    bool Dump(T& objToSave)
+    {
+        int64_t nStart = GetTimeMillis();
+        LogPrintf("Writing info to %s...\n", strFilename);
+        Write(objToSave);
+        LogPrintf("%s dump finished  %dms\n", strFilename, GetTimeMillis() - nStart);
+        return true;
+    }
+};
+
+
+#endif // PIVX_FLAT_DATABASE_H