db: add options to configure block index database

There was a previous assumption that blockindex would be quite small. With addressindex
and spentindex enabled the blockindex is much larger and the amount of cache allocated for
it should also increase. Furthermore, enabling compression should decrease the amount of
disk space required and less data to write/read. The default leveldb max_open_files is set to
1000, for the blockindex the default is set to 1000 with compression. The 64 value that is
current is kept for the utxo database and does not enable compression. Two additional options
are added here to be able to configure the values for leveldb and the block index:

- `-dbmaxopenfiles` A number of files for leveldb to keep open
- `-dbcompression` Boolean 0 or 1 to enable snappy leveldb compression

Author: Braydon Fuller

src/dbwrapper.cpp

@@ -29,14 +29,14 @@ void HandleError(const leveldb::Status& status) throw(dbwrapper_error)
     throw dbwrapper_error("Unknown database error");
 }
 
-static leveldb::Options GetOptions(size_t nCacheSize)
+static leveldb::Options GetOptions(size_t nCacheSize, bool compression, int maxOpenFiles)
 {
     leveldb::Options options;
     options.block_cache = leveldb::NewLRUCache(nCacheSize / 2);
     options.write_buffer_size = nCacheSize / 4; // up to two write buffers may be held in memory simultaneously
     options.filter_policy = leveldb::NewBloomFilterPolicy(10);
-    options.compression = leveldb::kNoCompression;
-    options.max_open_files = 64;
+    options.compression = compression ? leveldb::kSnappyCompression : leveldb::kNoCompression;
+    options.max_open_files = maxOpenFiles;
     if (leveldb::kMajorVersion > 1 || (leveldb::kMajorVersion == 1 && leveldb::kMinorVersion >= 16)) {
         // LevelDB versions before 1.16 consider short writes to be corruption. Only trigger error
         // on corruption in later versions.
@@ -45,14 +45,14 @@ static leveldb::Options GetOptions(size_t nCacheSize)
     return options;
 }
 
-CDBWrapper::CDBWrapper(const boost::filesystem::path& path, size_t nCacheSize, bool fMemory, bool fWipe, bool obfuscate)
+CDBWrapper::CDBWrapper(const boost::filesystem::path& path, size_t nCacheSize, bool fMemory, bool fWipe, bool obfuscate, bool compression, int maxOpenFiles)
 {
     penv = NULL;
     readoptions.verify_checksums = true;
     iteroptions.verify_checksums = true;
     iteroptions.fill_cache = false;
     syncoptions.sync = true;
-    options = GetOptions(nCacheSize);
+    options = GetOptions(nCacheSize, compression, maxOpenFiles);
     options.create_if_missing = true;
     if (fMemory) {
         penv = leveldb::NewMemEnv(leveldb::Env::Default());

src/dbwrapper.h

@@ -169,14 +169,16 @@ class CDBWrapper
 
 public:
     /**
-     * @param[in] path        Location in the filesystem where leveldb data will be stored.
-     * @param[in] nCacheSize  Configures various leveldb cache settings.
-     * @param[in] fMemory     If true, use leveldb's memory environment.
-     * @param[in] fWipe       If true, remove all existing data.
-     * @param[in] obfuscate   If true, store data obfuscated via simple XOR. If false, XOR
-     *                        with a zero'd byte array.
+     * @param[in] path          Location in the filesystem where leveldb data will be stored.
+     * @param[in] nCacheSize    Configures various leveldb cache settings.
+     * @param[in] fMemory       If true, use leveldb's memory environment.
+     * @param[in] fWipe         If true, remove all existing data.
+     * @param[in] obfuscate     If true, store data obfuscated via simple XOR. If false, XOR
+     *                          with a zero'd byte array.
+     * @param[in] compression   Enable snappy compression for the database
+     * @param[in] maxOpenFiles  The maximum number of open files for the database
      */
-    CDBWrapper(const boost::filesystem::path& path, size_t nCacheSize, bool fMemory = false, bool fWipe = false, bool obfuscate = false);
+    CDBWrapper(const boost::filesystem::path& path, size_t nCacheSize, bool fMemory = false, bool fWipe = false, bool obfuscate = false, bool compression = false, int maxOpenFiles = 64);
     ~CDBWrapper();
 
     template <typename K, typename V>

src/init.cpp

@@ -1294,18 +1294,33 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
         }
     }
 
+    // block tree db settings
+    int dbMaxOpenFiles = GetArg("-dbmaxopenfiles", DEFAULT_DB_MAX_OPEN_FILES);
+    bool dbCompression = GetBoolArg("-dbcompression", DEFAULT_DB_COMPRESSION);
+
+    LogPrintf("Block index database configuration:\n");
+    LogPrintf("* Using %d max open files\n", dbMaxOpenFiles);
+    LogPrintf("* Compression is %s\n", dbCompression ? "enabled" : "disabled");
+
     // cache size calculations
     int64_t nTotalCache = (GetArg("-dbcache", nDefaultDbCache) << 20);
     nTotalCache = std::max(nTotalCache, nMinDbCache << 20); // total cache cannot be less than nMinDbCache
     nTotalCache = std::min(nTotalCache, nMaxDbCache << 20); // total cache cannot be greated than nMaxDbcache
     int64_t nBlockTreeDBCache = nTotalCache / 8;
-    if (nBlockTreeDBCache > (1 << 21) && !GetBoolArg("-txindex", DEFAULT_TXINDEX))
-        nBlockTreeDBCache = (1 << 21); // block tree db cache shouldn't be larger than 2 MiB
+    if (GetBoolArg("-addressindex", DEFAULT_ADDRESSINDEX) || GetBoolArg("-spentindex", DEFAULT_SPENTINDEX)) {
+        // enable 3/4 of the cache if addressindex and/or spentindex is enabled
+        nBlockTreeDBCache = nTotalCache * 3 / 4;
+    } else {
+        if (nBlockTreeDBCache > (1 << 21) && !GetBoolArg("-txindex", DEFAULT_TXINDEX)) {
+            nBlockTreeDBCache = (1 << 21); // block tree db cache shouldn't be larger than 2 MiB
+        }
+    }
     nTotalCache -= nBlockTreeDBCache;
     int64_t nCoinDBCache = std::min(nTotalCache / 2, (nTotalCache / 4) + (1 << 23)); // use 25%-50% of the remainder for disk cache
     nTotalCache -= nCoinDBCache;
     nCoinCacheUsage = nTotalCache; // the rest goes to in-memory cache
     LogPrintf("Cache configuration:\n");
+    LogPrintf("* Max cache setting possible %.1fMiB\n", nMaxDbCache);
     LogPrintf("* Using %.1fMiB for block index database\n", nBlockTreeDBCache * (1.0 / 1024 / 1024));
     LogPrintf("* Using %.1fMiB for chain state database\n", nCoinDBCache * (1.0 / 1024 / 1024));
     LogPrintf("* Using %.1fMiB for in-memory UTXO set\n", nCoinCacheUsage * (1.0 / 1024 / 1024));
@@ -1326,7 +1341,7 @@ bool AppInit2(boost::thread_group& threadGroup, CScheduler& scheduler)
                 delete pcoinscatcher;
                 delete pblocktree;
 
-                pblocktree = new CBlockTreeDB(nBlockTreeDBCache, false, fReindex);
+                pblocktree = new CBlockTreeDB(nBlockTreeDBCache, false, fReindex, dbCompression, dbMaxOpenFiles);
                 pcoinsdbview = new CCoinsViewDB(nCoinDBCache, false, fReindex);
                 pcoinscatcher = new CCoinsViewErrorCatcher(pcoinsdbview);
                 pcoinsTip = new CCoinsViewCache(pcoinscatcher);

src/main.h

@@ -115,6 +115,8 @@ static const bool DEFAULT_TXINDEX = false;
 static const bool DEFAULT_ADDRESSINDEX = false;
 static const bool DEFAULT_TIMESTAMPINDEX = false;
 static const bool DEFAULT_SPENTINDEX = false;
+static const unsigned int DEFAULT_DB_MAX_OPEN_FILES = 1000;
+static const bool DEFAULT_DB_COMPRESSION = true;
 static const unsigned int DEFAULT_BANSCORE_THRESHOLD = 100;
 
 static const bool DEFAULT_TESTSAFEMODE = false;

src/txdb.cpp

@@ -33,7 +33,7 @@ static const char DB_REINDEX_FLAG = 'R';
 static const char DB_LAST_BLOCK = 'l';
 
 
-CCoinsViewDB::CCoinsViewDB(size_t nCacheSize, bool fMemory, bool fWipe) : db(GetDataDir() / "chainstate", nCacheSize, fMemory, fWipe, true) 
+CCoinsViewDB::CCoinsViewDB(size_t nCacheSize, bool fMemory, bool fWipe) : db(GetDataDir() / "chainstate", nCacheSize, fMemory, fWipe, true, false, 64)
 {
 }
 
@@ -75,7 +75,7 @@ bool CCoinsViewDB::BatchWrite(CCoinsMap &mapCoins, const uint256 &hashBlock) {
     return db.WriteBatch(batch);
 }
 
-CBlockTreeDB::CBlockTreeDB(size_t nCacheSize, bool fMemory, bool fWipe) : CDBWrapper(GetDataDir() / "blocks" / "index", nCacheSize, fMemory, fWipe) {
+CBlockTreeDB::CBlockTreeDB(size_t nCacheSize, bool fMemory, bool fWipe, bool compression, int maxOpenFiles) : CDBWrapper(GetDataDir() / "blocks" / "index", nCacheSize, fMemory, fWipe, false, compression, maxOpenFiles) {
 }
 
 bool CBlockTreeDB::ReadBlockFileInfo(int nFile, CBlockFileInfo &info) {

src/txdb.h

@@ -54,7 +54,7 @@ class CCoinsViewDB : public CCoinsView
 class CBlockTreeDB : public CDBWrapper
 {
 public:
-    CBlockTreeDB(size_t nCacheSize, bool fMemory = false, bool fWipe = false);
+    CBlockTreeDB(size_t nCacheSize, bool fMemory = false, bool fWipe = false, bool compression = true, int maxOpenFiles = 1000);
 private:
     CBlockTreeDB(const CBlockTreeDB&);
     void operator=(const CBlockTreeDB&);