Introducing ledger shards and new ledger syncing logic. (#247)

- The ledgers are stored in a sqlite database in ledger file system.
- Ledgers are organized in shards inside primary folder.
- Raw inputs are saved as shards inside blob folder. No input files are created if neither inputs nor outputs are available.
- Both last primary shard hash and last blob shard hashes are subjected to consensus and necessary sync operations are performed if out of sync.
- Hpfs sync support setting single sync targets from both ends of the list. (Targets set from front are prioritized).
- Contract and ledger syncs and serving are performed independently.

src/util/util.cpp

@@ -410,4 +410,35 @@ namespace util
         lock.l_type = F_UNLCK;
         return fcntl(fd, F_SETLKW, &lock);
     }
+
+    /**
+     * Convert given little endian byte stream to uint64_t.
+     * @param data Byte stream to be converted.
+     * @return Returns converted uint64_t.
+    */
+    uint64_t uint64_from_bytes(const uint8_t *data)
+    {
+        return ((uint64_t)data[0] << 56) +
+               ((uint64_t)data[1] << 48) +
+               ((uint64_t)data[2] << 40) +
+               ((uint64_t)data[3] << 32) +
+               ((uint64_t)data[4] << 24) +
+               ((uint64_t)data[5] << 16) +
+               ((uint64_t)data[6] << 8) +
+               ((uint64_t)data[7]);
+    }
+
+    /**
+     * Convert given uint64_t to little endian byte stream.
+     * @param dest Byte stream to be populated.
+     * @param x uint64_t to be converted.
+    */
+    void uint64_to_bytes(uint8_t *dest, uint64_t x)
+    {
+        for (int j = 0; j < 8; j++)
+        {
+            *(dest + (7 - j)) = x & 0xff;
+            x >>= 8;
+        }
+    }
 } // namespace util