1 files changed, 56 insertions, 52 deletions

diff --git a/src/script/sigcache.cpp b/src/script/sigcache.cpp
index 5580a5933..9638b12f9 100644
--- a/src/script/sigcache.cpp
+++ b/src/script/sigcache.cpp
@@ -1,20 +1,20 @@
 // Copyright (c) 2009-2010 Satoshi Nakamoto
-// Copyright (c) 2009-2014 The Bitcoin developers
+// Copyright (c) 2009-2017 The Bitcoin Core developers
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#include "sigcache.h"
+#include <script/sigcache.h>
 
-#include "pubkey.h"
-#include "random.h"
-#include "uint256.h"
-#include "util.h"
+#include <memusage.h>
+#include <pubkey.h>
+#include <random.h>
+#include <uint256.h>
+#include <util.h>
 
+#include <cuckoocache.h>
 #include <boost/thread.hpp>
-#include <boost/tuple/tuple_comparison.hpp>
 
 namespace {
-
 /**
  * Valid signature cache, to avoid doing expensive ECDSA signature checking
  * twice for every transaction (once when accepted into memory pool, and
@@ -23,68 +23,72 @@ namespace {
 class CSignatureCache
 {
 private:
-     //! sigdata_type is (signature hash, signature, public key):
-    typedef boost::tuple<uint256, std::vector<unsigned char>, CPubKey> sigdata_type;
-    std::set< sigdata_type> setValid;
+     //! Entries are SHA256(nonce || signature hash || public key || signature):
+    uint256 nonce;
+    typedef CuckooCache::cache<uint256, SignatureCacheHasher> map_type;
+    map_type setValid;
     boost::shared_mutex cs_sigcache;
 
 public:
-    bool
-    Get(const uint256 &hash, const std::vector<unsigned char>& vchSig, const CPubKey& pubKey)
+    CSignatureCache()
     {
-        boost::shared_lock<boost::shared_mutex> lock(cs_sigcache);
+        GetRandBytes(nonce.begin(), 32);
+    }
 
-        sigdata_type k(hash, vchSig, pubKey);
-        std::set<sigdata_type>::iterator mi = setValid.find(k);
-        if (mi != setValid.end())
-            return true;
-        return false;
+    void
+    ComputeEntry(uint256& entry, const uint256 &hash, const std::vector<unsigned char>& vchSig, const CPubKey& pubkey)
+    {
+        CSHA256().Write(nonce.begin(), 32).Write(hash.begin(), 32).Write(&pubkey[0], pubkey.size()).Write(&vchSig[0], vchSig.size()).Finalize(entry.begin());
     }
 
-    void Set(const uint256 &hash, const std::vector<unsigned char>& vchSig, const CPubKey& pubKey)
+    bool
+    Get(const uint256& entry, const bool erase)
     {
-        // DoS prevention: limit cache size to less than 10MB
-        // (~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.
-        int64_t nMaxCacheSize = GetArg("-maxsigcachesize", 50000);
-        if (nMaxCacheSize <= 0) return;
+        boost::shared_lock<boost::shared_mutex> lock(cs_sigcache);
+        return setValid.contains(entry, erase);
+    }
 
+    void Set(uint256& entry)
+    {
         boost::unique_lock<boost::shared_mutex> lock(cs_sigcache);
-
-        while (static_cast<int64_t>(setValid.size()) > nMaxCacheSize)
-        {
-            // Evict a random entry. Random because that helps
-            // foil would-be DoS attackers who might try to pre-generate
-            // and re-use a set of valid signatures just-slightly-greater
-            // than our cache size.
-            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(k);
+        setValid.insert(entry);
+    }
+    uint32_t setup_bytes(size_t n)
+    {
+        return setValid.setup_bytes(n);
     }
 };
 
+/* In previous versions of this code, signatureCache was a local static variable
+ * in CachingTransactionSignatureChecker::VerifySignature.  We initialize
+ * signatureCache outside of VerifySignature to avoid the atomic operation per
+ * call overhead associated with local static variables even though
+ * signatureCache could be made local to VerifySignature.
+*/
+static CSignatureCache signatureCache;
+} // namespace
+
+// To be called once in AppInitMain/BasicTestingSetup to initialize the
+// signatureCache.
+void InitSignatureCache()
+{
+    // nMaxCacheSize is unsigned. If -maxsigcachesize is set to zero,
+    // setup_bytes creates the minimum possible cache (2 elements).
+    size_t nMaxCacheSize = std::min(std::max((int64_t)0, gArgs.GetArg("-maxsigcachesize", DEFAULT_MAX_SIG_CACHE_SIZE) / 2), MAX_MAX_SIG_CACHE_SIZE) * ((size_t) 1 << 20);
+    size_t nElems = signatureCache.setup_bytes(nMaxCacheSize);
+    LogPrintf("Using %zu MiB out of %zu/2 requested for signature cache, able to store %zu elements\n",
+            (nElems*sizeof(uint256)) >>20, (nMaxCacheSize*2)>>20, nElems);
 }
 
-bool CachingSignatureChecker::VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash) const
+bool CachingTransactionSignatureChecker::VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash) const
 {
-    static CSignatureCache signatureCache;
-
-    if (signatureCache.Get(sighash, vchSig, pubkey))
+    uint256 entry;
+    signatureCache.ComputeEntry(entry, sighash, vchSig, pubkey);
+    if (signatureCache.Get(entry, !store))
         return true;
-
-    if (!SignatureChecker::VerifySignature(vchSig, pubkey, sighash))
+    if (!TransactionSignatureChecker::VerifySignature(vchSig, pubkey, sighash))
         return false;
-
     if (store)
-        signatureCache.Set(sighash, vchSig, pubkey);
+        signatureCache.Set(entry);
     return true;
 }