path: root/src/rpcmining.cpp

// Copyright (c) 2010 Satoshi Nakamoto
// Copyright (c) 2009-2013 The Bitcoin developers
// Distributed under the MIT/X11 software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include "rpcserver.h"
#include "chainparams.h"
#include "init.h"
#include "net.h"
#include "main.h"
#include "miner.h"
#include "pow.h"
#include "core_io.h"
#ifdef ENABLE_WALLET
#include "db.h"
#include "wallet.h"
#endif

#include <stdint.h>

#include <boost/assign/list_of.hpp>

#include "json/json_spirit_utils.h"
#include "json/json_spirit_value.h"

using namespace json_spirit;
using namespace std;

// Return average network hashes per second based on the last 'lookup' blocks,
// or from the last difficulty change if 'lookup' is nonpositive.
// If 'height' is nonnegative, compute the estimate at the time when a given block was found.
Value GetNetworkHashPS(int lookup, int height) {
    CBlockIndex *pb = chainActive.Tip();

    if (height >= 0 && height < chainActive.Height())
        pb = chainActive[height];

    if (pb == NULL || !pb->nHeight)
        return 0;

    // If lookup is -1, then use blocks since last difficulty change.
    if (lookup <= 0)
        lookup = pb->nHeight % 2016 + 1;

    // If lookup is larger than chain, then set it to chain length.
    if (lookup > pb->nHeight)
        lookup = pb->nHeight;

    CBlockIndex *pb0 = pb;
    int64_t minTime = pb0->GetBlockTime();
    int64_t maxTime = minTime;
    for (int i = 0; i < lookup; i++) {
        pb0 = pb0->pprev;
        int64_t time = pb0->GetBlockTime();
        minTime = std::min(time, minTime);
        maxTime = std::max(time, maxTime);
    }

    // In case there's a situation where minTime == maxTime, we don't want a divide by zero exception.
    if (minTime == maxTime)
        return 0;

    uint256 workDiff = pb->nChainWork - pb0->nChainWork;
    int64_t timeDiff = maxTime - minTime;

    return (int64_t)(workDiff.getdouble() / timeDiff);
}

Value getnetworkhashps(const Array& params, bool fHelp)
{
    if (fHelp || params.size() > 2)
        throw runtime_error(
            "getnetworkhashps ( blocks height )\n"
            "\nReturns the estimated network hashes per second based on the last n blocks.\n"
            "Pass in [blocks] to override # of blocks, -1 specifies since last difficulty change.\n"
            "Pass in [height] to estimate the network speed at the time when a certain block was found.\n"
            "\nArguments:\n"
            "1. blocks     (numeric, optional, default=120) The number of blocks, or -1 for blocks since last difficulty change.\n"
            "2. height     (numeric, optional, default=-1) To estimate at the time of the given height.\n"
            "\nResult:\n"
            "x             (numeric) Hashes per second estimated\n"
            "\nExamples:\n"
            + HelpExampleCli("getnetworkhashps", "")
            + HelpExampleRpc("getnetworkhashps", "")
       );

    return GetNetworkHashPS(params.size() > 0 ? params[0].get_int() : 120, params.size() > 1 ? params[1].get_int() : -1);
}

#ifdef ENABLE_WALLET
Value getgenerate(const Array& params, bool fHelp)
{
    if (fHelp || params.size() != 0)
        throw runtime_error(
            "getgenerate\n"
            "\nReturn if the server is set to generate coins or not. The default is false.\n"
            "It is set with the command line argument -gen (or bitcoin.conf setting gen)\n"
            "It can also be set with the setgenerate call.\n"
            "\nResult\n"
            "true|false      (boolean) If the server is set to generate coins or not\n"
            "\nExamples:\n"
            + HelpExampleCli("getgenerate", "")
            + HelpExampleRpc("getgenerate", "")
        );

    return GetBoolArg("-gen", false);
}


Value setgenerate(const Array& params, bool fHelp)
{
    if (fHelp || params.size() < 1 || params.size() > 2)
        throw runtime_error(
            "setgenerate generate ( genproclimit )\n"
            "\nSet 'generate' true or false to turn generation on or off.\n"
            "Generation is limited to 'genproclimit' processors, -1 is unlimited.\n"
            "See the getgenerate call for the current setting.\n"
            "\nArguments:\n"
            "1. generate         (boolean, required) Set to true to turn on generation, off to turn off.\n"
            "2. genproclimit     (numeric, optional) Set the processor limit for when generation is on. Can be -1 for unlimited.\n"
            "                    Note: in -regtest mode, genproclimit controls how many blocks are generated immediately.\n"
            "\nExamples:\n"
            "\nSet the generation on with a limit of one processor\n"
            + HelpExampleCli("setgenerate", "true 1") +
            "\nCheck the setting\n"
            + HelpExampleCli("getgenerate", "") +
            "\nTurn off generation\n"
            + HelpExampleCli("setgenerate", "false") +
            "\nUsing json rpc\n"
            + HelpExampleRpc("setgenerate", "true, 1")
        );

    if (pwalletMain == NULL)
        throw JSONRPCError(RPC_METHOD_NOT_FOUND, "Method not found (disabled)");

    bool fGenerate = true;
    if (params.size() > 0)
        fGenerate = params[0].get_bool();

    int nGenProcLimit = -1;
    if (params.size() > 1)
    {
        nGenProcLimit = params[1].get_int();
        if (nGenProcLimit == 0)
            fGenerate = false;
    }

    // -regtest mode: don't return until nGenProcLimit blocks are generated
    if (fGenerate && Params().MineBlocksOnDemand())
    {
        int nHeightStart = 0;
        int nHeightEnd = 0;
        int nHeight = 0;
        int nGenerate = (nGenProcLimit > 0 ? nGenProcLimit : 1);
        {   // Don't keep cs_main locked
            LOCK(cs_main);
            nHeightStart = chainActive.Height();
            nHeight = nHeightStart;
            nHeightEnd = nHeightStart+nGenerate;
        }
        int nHeightLast = -1;
        while (nHeight < nHeightEnd)
        {
            if (nHeightLast != nHeight)
            {
                nHeightLast = nHeight;
                GenerateBitcoins(fGenerate, pwalletMain, 1);
            }
            MilliSleep(1);
            {   // Don't keep cs_main locked
                LOCK(cs_main);
                nHeight = chainActive.Height();
            }
        }
    }
    else // Not -regtest: start generate thread, return immediately
    {
        mapArgs["-gen"] = (fGenerate ? "1" : "0");
        mapArgs ["-genproclimit"] = itostr(nGenProcLimit);
        GenerateBitcoins(fGenerate, pwalletMain, nGenProcLimit);
    }

    return Value::null;
}

Value gethashespersec(const Array& params, bool fHelp)
{
    if (fHelp || params.size() != 0)
        throw runtime_error(
            "gethashespersec\n"
            "\nReturns a recent hashes per second performance measurement while generating.\n"
            "See the getgenerate and setgenerate calls to turn generation on and off.\n"
            "\nResult:\n"
            "n            (numeric) The recent hashes per second when generation is on (will return 0 if generation is off)\n"
            "\nExamples:\n"
            + HelpExampleCli("gethashespersec", "")
            + HelpExampleRpc("gethashespersec", "")
        );

    if (GetTimeMillis() - nHPSTimerStart > 8000)
        return (int64_t)0;
    return (int64_t)dHashesPerSec;
}
#endif


Value getmininginfo(const Array& params, bool fHelp)
{
    if (fHelp || params.size() != 0)
        throw runtime_error(
            "getmininginfo\n"
            "\nReturns a json object containing mining-related information."
            "\nResult:\n"
            "{\n"
            "  \"blocks\": nnn,             (numeric) The current block\n"
            "  \"currentblocksize\": nnn,   (numeric) The last block size\n"
            "  \"currentblocktx\": nnn,     (numeric) The last block transaction\n"
            "  \"difficulty\": xxx.xxxxx    (numeric) The current difficulty\n"
            "  \"errors\": \"...\"          (string) Current errors\n"
            "  \"generate\": true|false     (boolean) If the generation is on or off (see getgenerate or setgenerate calls)\n"
            "  \"genproclimit\": n          (numeric) The processor limit for generation. -1 if no generation. (see getgenerate or setgenerate calls)\n"
            "  \"hashespersec\": n          (numeric) The hashes per second of the generation, or 0 if no generation.\n"
            "  \"pooledtx\": n              (numeric) The size of the mem pool\n"
            "  \"testnet\": true|false      (boolean) If using testnet or not\n"
            "  \"chain\": \"xxxx\",         (string) current network name as defined in BIP70 (main, test, regtest)\n"
            "}\n"
            "\nExamples:\n"
            + HelpExampleCli("getmininginfo", "")
            + HelpExampleRpc("getmininginfo", "")
        );

    Object obj;
    obj.push_back(Pair("blocks",           (int)chainActive.Height()));
    obj.push_back(Pair("currentblocksize", (uint64_t)nLastBlockSize));
    obj.push_back(Pair("currentblocktx",   (uint64_t)nLastBlockTx));
    obj.push_back(Pair("difficulty",       (double)GetDifficulty()));
    obj.push_back(Pair("errors",           GetWarnings("statusbar")));
    obj.push_back(Pair("genproclimit",     (int)GetArg("-genproclimit", -1)));
    obj.push_back(Pair("networkhashps",    getnetworkhashps(params, false)));
    obj.push_back(Pair("pooledtx",         (uint64_t)mempool.size()));
    obj.push_back(Pair("testnet",          Params().NetworkID() == CBaseChainParams::TESTNET));
    obj.push_back(Pair("chain",            Params().NetworkIDString()));
#ifdef ENABLE_WALLET
    obj.push_back(Pair("generate",         getgenerate(params, false)));
    obj.push_back(Pair("hashespersec",     gethashespersec(params, false)));
#endif
    return obj;
}


Value prioritisetransaction(const Array& params, bool fHelp)
{
    if (fHelp || params.size() != 3)
        throw runtime_error(
            "prioritisetransaction <txid> <priority delta> <fee delta>\n"
            "Accepts the transaction into mined blocks at a higher (or lower) priority\n"
            "\nArguments:\n"
            "1. \"txid\"       (string, required) The transaction id.\n"
            "2. priority delta (numeric, required) The priority to add or subtract.\n"
            "                  The transaction selection algorithm considers the tx as it would have a higher priority.\n"
            "                  (priority of a transaction is calculated: coinage * value_in_satoshis / txsize) \n"
            "3. fee delta      (numeric, required) The absolute fee value to add or subtract in bitcoin.\n"
            "                  The fee is not actually paid, only the algorithm for selecting transactions into a block\n"
            "                  considers the transaction as it would have paid a higher (or lower) fee.\n"
            "\nResult\n"
            "true              (boolean) Returns true\n"
            "\nExamples:\n"
            + HelpExampleCli("prioritisetransaction", "\"txid\" 0.0 0.00010000")
            + HelpExampleRpc("prioritisetransaction", "\"txid\", 0.0, 0.00010000")
        );

    uint256 hash;
    hash.SetHex(params[0].get_str());

    int64_t nAmount = 0;
    if (params[2].get_real() != 0.0)
        nAmount = AmountFromValue(params[2]);

    mempool.PrioritiseTransaction(hash, params[0].get_str(), params[1].get_real(), nAmount);
    return true;
}


Value getblocktemplate(const Array& params, bool fHelp)
{
    if (fHelp || params.size() > 1)
        throw runtime_error(
            "getblocktemplate ( \"jsonrequestobject\" )\n"
            "\nIf the request parameters include a 'mode' key, that is used to explicitly select between the default 'template' request or a 'proposal'.\n"
            "It returns data needed to construct a block to work on.\n"
            "See https://en.bitcoin.it/wiki/BIP_0022 for full specification.\n"

            "\nArguments:\n"
            "1. \"jsonrequestobject\"       (string, optional) A json object in the following spec\n"
            "     {\n"
            "       \"mode\":\"template\"    (string, optional) This must be set to \"template\" or omitted\n"
            "       \"capabilities\":[       (array, optional) A list of strings\n"
            "           \"support\"           (string) client side supported feature, 'longpoll', 'coinbasetxn', 'coinbasevalue', 'proposal', 'serverlist', 'workid'\n"
            "           ,...\n"
            "         ]\n"
            "     }\n"
            "\n"

            "\nResult:\n"
            "{\n"
            "  \"version\" : n,                    (numeric) The block version\n"
            "  \"previousblockhash\" : \"xxxx\",    (string) The hash of current highest block\n"
            "  \"transactions\" : [                (array) contents of non-coinbase transactions that should be included in the next block\n"
            "      {\n"
            "         \"data\" : \"xxxx\",          (string) transaction data encoded in hexadecimal (byte-for-byte)\n"
            "         \"hash\" : \"xxxx\",          (string) hash/id encoded in little-endian hexadecimal\n"
            "         \"depends\" : [              (array) array of numbers \n"
            "             n                        (numeric) transactions before this one (by 1-based index in 'transactions' list) that must be present in the final block if this one is\n"
            "             ,...\n"
            "         ],\n"
            "         \"fee\": n,                   (numeric) difference in value between transaction inputs and outputs (in Satoshis); for coinbase transactions, this is a negative Number of the total collected block fees (ie, not including the block subsidy); if key is not present, fee is unknown and clients MUST NOT assume there isn't one\n"
            "         \"sigops\" : n,               (numeric) total number of SigOps, as counted for purposes of block limits; if key is not present, sigop count is unknown and clients MUST NOT assume there aren't any\n"
            "         \"required\" : true|false     (boolean) if provided and true, this transaction must be in the final block\n"
            "      }\n"
            "      ,...\n"
            "  ],\n"
            "  \"coinbaseaux\" : {                  (json object) data that should be included in the coinbase's scriptSig content\n"
            "      \"flags\" : \"flags\"            (string) \n"
            "  },\n"
            "  \"coinbasevalue\" : n,               (numeric) maximum allowable input to coinbase transaction, including the generation award and transaction fees (in Satoshis)\n"
            "  \"coinbasetxn\" : { ... },           (json object) information for coinbase transaction\n"
            "  \"target\" : \"xxxx\",               (string) The hash target\n"
            "  \"mintime\" : xxx,                   (numeric) The minimum timestamp appropriate for next block time in seconds since epoch (Jan 1 1970 GMT)\n"
            "  \"mutable\" : [                      (array of string) list of ways the block template may be changed \n"
            "     \"value\"                         (string) A way the block template may be changed, e.g. 'time', 'transactions', 'prevblock'\n"
            "     ,...\n"
            "  ],\n"
            "  \"noncerange\" : \"00000000ffffffff\",   (string) A range of valid nonces\n"
            "  \"sigoplimit\" : n,                 (numeric) limit of sigops in blocks\n"
            "  \"sizelimit\" : n,                  (numeric) limit of block size\n"
            "  \"curtime\" : ttt,                  (numeric) current timestamp in seconds since epoch (Jan 1 1970 GMT)\n"
            "  \"bits\" : \"xxx\",                 (string) compressed target of next block\n"
            "  \"height\" : n                      (numeric) The height of the next block\n"
            "}\n"

            "\nExamples:\n"
            + HelpExampleCli("getblocktemplate", "")
            + HelpExampleRpc("getblocktemplate", "")
         );

    std::string strMode = "template";
    Value lpval = Value::null;
    if (params.size() > 0)
    {
        const Object& oparam = params[0].get_obj();
        const Value& modeval = find_value(oparam, "mode");
        if (modeval.type() == str_type)
            strMode = modeval.get_str();
        else if (modeval.type() == null_type)
        {
            /* Do nothing */
        }
        else
            throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid mode");
        lpval = find_value(oparam, "longpollid");
    }

    if (strMode != "template")
        throw JSONRPCError(RPC_INVALID_PARAMETER, "Invalid mode");

    if (vNodes.empty())
        throw JSONRPCError(RPC_CLIENT_NOT_CONNECTED, "Bitcoin is not connected!");

    if (IsInitialBlockDownload())
        throw JSONRPCError(RPC_CLIENT_IN_INITIAL_DOWNLOAD, "Bitcoin is downloading blocks...");

    static unsigned int nTransactionsUpdatedLast;

    if (lpval.type() != null_type)
    {
        // Wait to respond until either the best block changes, OR a minute has passed and there are more transactions
        uint256 hashWatchedChain;
        boost::system_time checktxtime;
        unsigned int nTransactionsUpdatedLastLP;

        if (lpval.type() == str_type)
        {
            // Format: <hashBestChain><nTransactionsUpdatedLast>
            std::string lpstr = lpval.get_str();

            hashWatchedChain.SetHex(lpstr.substr(0, 64));
            nTransactionsUpdatedLastLP = atoi64(lpstr.substr(64));
        }
        else
        {
            // NOTE: Spec does not specify behaviour for non-string longpollid, but this makes testing easier
            hashWatchedChain = chainActive.Tip()->GetBlockHash();
            nTransactionsUpdatedLastLP = nTransactionsUpdatedLast;
        }

        // Release the wallet and main lock while waiting
#ifdef ENABLE_WALLET
        if(pwalletMain)
            LEAVE_CRITICAL_SECTION(pwalletMain->cs_wallet);
#endif
        LEAVE_CRITICAL_SECTION(cs_main);
        {
            checktxtime = boost::get_system_time() + boost::posix_time::minutes(1);

            boost::unique_lock<boost::mutex> lock(csBestBlock);
            while (chainActive.Tip()->GetBlockHash() == hashWatchedChain && IsRPCRunning())
            {
                if (!cvBlockChange.timed_wait(lock, checktxtime))
                {
                    // Timeout: Check transactions for update
                    if (mempool.GetTransactionsUpdated() != nTransactionsUpdatedLastLP)
                        break;
                    checktxtime += boost::posix_time::seconds(10);
                }
            }
        }
        ENTER_CRITICAL_SECTION(cs_main);
#ifdef ENABLE_WALLET
        if(pwalletMain)
            ENTER_CRITICAL_SECTION(pwalletMain->cs_wallet);
#endif

        if (!IsRPCRunning())
            throw JSONRPCError(RPC_CLIENT_NOT_CONNECTED, "Shutting down");
        // TODO: Maybe recheck connections/IBD and (if something wrong) send an expires-immediately template to stop miners?
    }

    // Update block
    static CBlockIndex* pindexPrev;
    static int64_t nStart;
    static CBlockTemplate* pblocktemplate;
    if (pindexPrev != chainActive.Tip() ||
        (mempool.GetTransactionsUpdated() != nTransactionsUpdatedLast && GetTime() - nStart > 5))
    {
        // Clear pindexPrev so future calls make a new block, despite any failures from here on
        pindexPrev = NULL;

        // Store the pindexBest used before CreateNewBlock, to avoid races
        nTransactionsUpdatedLast = mempool.GetTransactionsUpdated();
        CBlockIndex* pindexPrevNew = chainActive.Tip();
        nStart = GetTime();

        // Create new block
        if(pblocktemplate)
        {
            delete pblocktemplate;
            pblocktemplate = NULL;
        }
        CScript scriptDummy = CScript() << OP_TRUE;
        pblocktemplate = CreateNewBlock(scriptDummy);
        if (!pblocktemplate)
            throw JSONRPCError(RPC_OUT_OF_MEMORY, "Out of memory");

        // Need to update only after we know CreateNewBlock succeeded
        pindexPrev = pindexPrevNew;
    }
    CBlock* pblock = &pblocktemplate->block; // pointer for convenience

    // Update nTime
    UpdateTime(pblock, pindexPrev);
    pblock->nNonce = 0;

    Array transactions;
    map<uint256, int64_t> setTxIndex;
    int i = 0;
    BOOST_FOREACH (CTransaction& tx, pblock->vtx)
    {
        uint256 txHash = tx.GetHash();
        setTxIndex[txHash] = i++;

        if (tx.IsCoinBase())
            continue;

        Object entry;

        entry.push_back(Pair("data", EncodeHexTx(tx)));

        entry.push_back(Pair("hash", txHash.GetHex()));

        Array deps;
        BOOST_FOREACH (const CTxIn &in, tx.vin)
        {
            if (setTxIndex.count(in.prevout.hash))
                deps.push_back(setTxIndex[in.prevout.hash]);
        }
        entry.push_back(Pair("depends", deps));

        int index_in_template = i - 1;
        entry.push_back(Pair("fee", pblocktemplate->vTxFees[index_in_template]));
        entry.push_back(Pair("sigops", pblocktemplate->vTxSigOps[index_in_template]));

        transactions.push_back(entry);
    }

    Object aux;
    aux.push_back(Pair("flags", HexStr(COINBASE_FLAGS.begin(), COINBASE_FLAGS.end())));

    uint256 hashTarget = uint256().SetCompact(pblock->nBits);

    static Array aMutable;
    if (aMutable.empty())
    {
        aMutable.push_back("time");
        aMutable.push_back("transactions");
        aMutable.push_back("prevblock");
    }

    Object result;
    result.push_back(Pair("version", pblock->nVersion));
    result.push_back(Pair("previousblockhash", pblock->hashPrevBlock.GetHex()));
    result.push_back(Pair("transactions", transactions));
    result.push_back(Pair("coinbaseaux", aux));
    result.push_back(Pair("coinbasevalue", (int64_t)pblock->vtx[0].vout[0].nValue));
    result.push_back(Pair("longpollid", chainActive.Tip()->GetBlockHash().GetHex() + i64tostr(nTransactionsUpdatedLast)));
    result.push_back(Pair("target", hashTarget.GetHex()));
    result.push_back(Pair("mintime", (int64_t)pindexPrev->GetMedianTimePast()+1));
    result.push_back(Pair("mutable", aMutable));
    result.push_back(Pair("noncerange", "00000000ffffffff"));
    result.push_back(Pair("sigoplimit", (int64_t)MAX_BLOCK_SIGOPS));
    result.push_back(Pair("sizelimit", (int64_t)MAX_BLOCK_SIZE));
    result.push_back(Pair("curtime", pblock->GetBlockTime()));
    result.push_back(Pair("bits", strprintf("%08x", pblock->nBits)));
    result.push_back(Pair("height", (int64_t)(pindexPrev->nHeight+1)));

    return result;
}

Value submitblock(const Array& params, bool fHelp)
{
    if (fHelp || params.size() < 1 || params.size() > 2)
        throw runtime_error(
            "submitblock \"hexdata\" ( \"jsonparametersobject\" )\n"
            "\nAttempts to submit new block to network.\n"
            "The 'jsonparametersobject' parameter is currently ignored.\n"
            "See https://en.bitcoin.it/wiki/BIP_0022 for full specification.\n"

            "\nArguments\n"
            "1. \"hexdata\"    (string, required) the hex-encoded block data to submit\n"
            "2. \"jsonparametersobject\"     (string, optional) object of optional parameters\n"
            "    {\n"
            "      \"workid\" : \"id\"    (string, optional) if the server provided a workid, it MUST be included with submissions\n"
            "    }\n"
            "\nResult:\n"
            "\nExamples:\n"
            + HelpExampleCli("submitblock", "\"mydata\"")
            + HelpExampleRpc("submitblock", "\"mydata\"")
        );

    vector<unsigned char> blockData(ParseHex(params[0].get_str()));
    CDataStream ssBlock(blockData, SER_NETWORK, PROTOCOL_VERSION);
    CBlock pblock;
    try {
        ssBlock >> pblock;
    }
    catch (std::exception &e) {
        throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "Block decode failed");
    }

    CValidationState state;
    bool fAccepted = ProcessBlock(state, NULL, &pblock);
    if (!fAccepted)
        return "rejected"; // TODO: report validation state

    return Value::null;
}

Value estimatefee(const Array& params, bool fHelp)
{
    if (fHelp || params.size() != 1)
        throw runtime_error(
            "estimatefee nblocks\n"
            "\nEstimates the approximate fee per kilobyte\n"
            "needed for a transaction to get confirmed\n"
            "within nblocks blocks.\n"
            "\nArguments:\n"
            "1. nblocks     (numeric)\n"
            "\nResult:\n"
            "n :    (numeric) estimated fee-per-kilobyte\n"
            "\n"
            "-1.0 is returned if not enough transactions and\n"
            "blocks have been observed to make an estimate.\n"
            "\nExample:\n"
            + HelpExampleCli("estimatefee", "6")
            );

    RPCTypeCheck(params, boost::assign::list_of(int_type));

    int nBlocks = params[0].get_int();
    if (nBlocks < 1)
        nBlocks = 1;

    CFeeRate feeRate = mempool.estimateFee(nBlocks);
    if (feeRate == CFeeRate(0))
        return -1.0;

    return ValueFromAmount(feeRate.GetFeePerK());
}

Value estimatepriority(const Array& params, bool fHelp)
{
    if (fHelp || params.size() != 1)
        throw runtime_error(
            "estimatepriority nblocks\n"
            "\nEstimates the approximate priority\n"
            "a zero-fee transaction needs to get confirmed\n"
            "within nblocks blocks.\n"
            "\nArguments:\n"
            "1. nblocks     (numeric)\n"
            "\nResult:\n"
            "n :    (numeric) estimated priority\n"
            "\n"
            "-1.0 is returned if not enough transactions and\n"
            "blocks have been observed to make an estimate.\n"
            "\nExample:\n"
            + HelpExampleCli("estimatepriority", "6")
            );

    RPCTypeCheck(params, boost::assign::list_of(int_type));

    int nBlocks = params[0].get_int();
    if (nBlocks < 1)
        nBlocks = 1;

    return mempool.estimatePriority(nBlocks);
}