Make sigcache faster and more efficient

This commit is contained in:
Pieter Wuille 2015-10-30 23:14:38 +01:00
parent 48b5b84ee5
commit 830e3f3d02
3 changed files with 55 additions and 38 deletions

View File

@ -25,6 +25,7 @@
#include "policy/policy.h" #include "policy/policy.h"
#include "rpcserver.h" #include "rpcserver.h"
#include "script/standard.h" #include "script/standard.h"
#include "script/sigcache.h"
#include "scheduler.h" #include "scheduler.h"
#include "txdb.h" #include "txdb.h"
#include "txmempool.h" #include "txmempool.h"
@ -434,7 +435,7 @@ std::string HelpMessage(HelpMessageMode mode)
strUsage += HelpMessageOpt("-logtimemicros", strprintf("Add microsecond precision to debug timestamps (default: %u)", DEFAULT_LOGTIMEMICROS)); strUsage += HelpMessageOpt("-logtimemicros", strprintf("Add microsecond precision to debug timestamps (default: %u)", DEFAULT_LOGTIMEMICROS));
strUsage += HelpMessageOpt("-limitfreerelay=<n>", strprintf("Continuously rate-limit free transactions to <n>*1000 bytes per minute (default: %u)", 15)); strUsage += HelpMessageOpt("-limitfreerelay=<n>", strprintf("Continuously rate-limit free transactions to <n>*1000 bytes per minute (default: %u)", 15));
strUsage += HelpMessageOpt("-relaypriority", strprintf("Require high priority for relaying free or low-fee transactions (default: %u)", 1)); strUsage += HelpMessageOpt("-relaypriority", strprintf("Require high priority for relaying free or low-fee transactions (default: %u)", 1));
strUsage += HelpMessageOpt("-maxsigcachesize=<n>", strprintf("Limit size of signature cache to <n> entries (default: %u)", 50000)); strUsage += HelpMessageOpt("-maxsigcachesize=<n>", strprintf("Limit size of signature cache to <n> MiB (default: %u)", DEFAULT_MAX_SIG_CACHE_SIZE));
} }
strUsage += HelpMessageOpt("-minrelaytxfee=<amt>", strprintf(_("Fees (in %s/kB) smaller than this are considered zero fee for relaying (default: %s)"), strUsage += HelpMessageOpt("-minrelaytxfee=<amt>", strprintf(_("Fees (in %s/kB) smaller than this are considered zero fee for relaying (default: %s)"),
CURRENCY_UNIT, FormatMoney(::minRelayTxFee.GetFeePerK()))); CURRENCY_UNIT, FormatMoney(::minRelayTxFee.GetFeePerK())));

View File

@ -5,16 +5,29 @@
#include "sigcache.h" #include "sigcache.h"
#include "memusage.h"
#include "pubkey.h" #include "pubkey.h"
#include "random.h" #include "random.h"
#include "uint256.h" #include "uint256.h"
#include "util.h" #include "util.h"
#include <boost/thread.hpp> #include <boost/thread.hpp>
#include <boost/tuple/tuple_comparison.hpp> #include <boost/unordered_set.hpp>
namespace { namespace {
/**
* We're hashing a nonce into the entries themselves, so we don't need extra
* blinding in the set hash computation.
*/
class CSignatureCacheHasher
{
public:
size_t operator()(const uint256& key) const {
return key.GetCheapHash();
}
};
/** /**
* Valid signature cache, to avoid doing expensive ECDSA signature checking * Valid signature cache, to avoid doing expensive ECDSA signature checking
* twice for every transaction (once when accepted into memory pool, and * twice for every transaction (once when accepted into memory pool, and
@ -23,52 +36,48 @@ namespace {
class CSignatureCache class CSignatureCache
{ {
private: private:
//! sigdata_type is (signature hash, signature, public key): //! Entries are SHA256(nonce || signature hash || public key || signature):
typedef boost::tuple<uint256, std::vector<unsigned char>, CPubKey> sigdata_type; uint256 nonce;
std::set< sigdata_type> setValid; typedef boost::unordered_set<uint256, CSignatureCacheHasher> map_type;
map_type setValid;
boost::shared_mutex cs_sigcache; boost::shared_mutex cs_sigcache;
public:
bool
Get(const uint256 &hash, const std::vector<unsigned char>& vchSig, const CPubKey& pubKey)
{
boost::shared_lock<boost::shared_mutex> lock(cs_sigcache);
sigdata_type k(hash, vchSig, pubKey); public:
std::set<sigdata_type>::iterator mi = setValid.find(k); CSignatureCache()
if (mi != setValid.end()) {
return true; GetRandBytes(nonce.begin(), 32);
return false;
} }
void Set(const uint256 &hash, const std::vector<unsigned char>& vchSig, const CPubKey& pubKey) void
ComputeEntry(uint256& entry, const uint256 &hash, const std::vector<unsigned char>& vchSig, const CPubKey& pubkey)
{ {
// DoS prevention: limit cache size to less than 10MB CSHA256().Write(nonce.begin(), 32).Write(hash.begin(), 32).Write(&pubkey[0], pubkey.size()).Write(&vchSig[0], vchSig.size()).Finalize(entry.begin());
// (~200 bytes per cache entry times 50,000 entries) }
// Since there are a maximum of 20,000 signature operations per block
// 50,000 is a reasonable default. bool
int64_t nMaxCacheSize = GetArg("-maxsigcachesize", 50000); Get(const uint256& entry)
{
boost::shared_lock<boost::shared_mutex> lock(cs_sigcache);
return setValid.count(entry);
}
void Set(const uint256& entry)
{
size_t nMaxCacheSize = GetArg("-maxsigcachesize", DEFAULT_MAX_SIG_CACHE_SIZE) * ((size_t) 1 << 20);
if (nMaxCacheSize <= 0) return; if (nMaxCacheSize <= 0) return;
boost::unique_lock<boost::shared_mutex> lock(cs_sigcache); boost::unique_lock<boost::shared_mutex> lock(cs_sigcache);
while (memusage::DynamicUsage(setValid) > nMaxCacheSize)
while (static_cast<int64_t>(setValid.size()) > nMaxCacheSize)
{ {
// Evict a random entry. Random because that helps map_type::size_type s = GetRand(setValid.bucket_count());
// foil would-be DoS attackers who might try to pre-generate map_type::local_iterator it = setValid.begin(s);
// and re-use a set of valid signatures just-slightly-greater if (it != setValid.end(s)) {
// than our cache size. setValid.erase(*it);
uint256 randomHash = GetRandHash(); }
std::vector<unsigned char> unused;
std::set<sigdata_type>::iterator it =
setValid.lower_bound(sigdata_type(randomHash, unused, unused));
if (it == setValid.end())
it = setValid.begin();
setValid.erase(*it);
} }
sigdata_type k(hash, vchSig, pubKey); setValid.insert(entry);
setValid.insert(k);
} }
}; };
@ -78,13 +87,16 @@ bool CachingTransactionSignatureChecker::VerifySignature(const std::vector<unsig
{ {
static CSignatureCache signatureCache; static CSignatureCache signatureCache;
if (signatureCache.Get(sighash, vchSig, pubkey)) uint256 entry;
signatureCache.ComputeEntry(entry, sighash, vchSig, pubkey);
if (signatureCache.Get(entry))
return true; return true;
if (!TransactionSignatureChecker::VerifySignature(vchSig, pubkey, sighash)) if (!TransactionSignatureChecker::VerifySignature(vchSig, pubkey, sighash))
return false; return false;
if (store) if (store)
signatureCache.Set(sighash, vchSig, pubkey); signatureCache.Set(entry);
return true; return true;
} }

View File

@ -10,6 +10,10 @@
#include <vector> #include <vector>
// DoS prevention: limit cache size to less than 40MB (over 500000
// entries on 64-bit systems).
static const unsigned int DEFAULT_MAX_SIG_CACHE_SIZE = 40;
class CPubKey; class CPubKey;
class CachingTransactionSignatureChecker : public TransactionSignatureChecker class CachingTransactionSignatureChecker : public TransactionSignatureChecker