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authorGregory Maxwell <greg@xiph.org>2013-08-18 20:21:06 -0700
committerGregory Maxwell <greg@xiph.org>2013-08-20 02:27:26 -0700
commit37c6389c5a0ca63ae3573440ecdfe95d28ad8f07 (patch)
tree51ef4367b16dc75bd60d4de0da261b65cebf4f2d /src/bloom.cpp
parent4bc9a192696273c88966c39debf8d17f16ebe471 (diff)
Performance optimization for bloom filters.
This reduces a peer's ability to attack network resources by using a full bloom filter, but without reducing the usability of bloom filters. It sets a default match everything filter for peers and it generalizes a prior optimization to cover more cases.
Diffstat (limited to 'src/bloom.cpp')
-rw-r--r--src/bloom.cpp26
1 files changed, 24 insertions, 2 deletions
diff --git a/src/bloom.cpp b/src/bloom.cpp
index b6799e143d..8e8d8fa06b 100644
--- a/src/bloom.cpp
+++ b/src/bloom.cpp
@@ -23,6 +23,8 @@ vData(min((unsigned int)(-1 / LN2SQUARED * nElements * log(nFPRate)), MAX_BLOOM
// The ideal number of hash functions is filter size * ln(2) / number of elements
// Again, we ignore filter parameters which will create a bloom filter with more hash functions than the protocol limits
// See http://en.wikipedia.org/wiki/Bloom_filter for an explanation of these formulas
+isFull(false),
+isEmpty(false),
nHashFuncs(min((unsigned int)(vData.size() * 8 / nElements * LN2), MAX_HASH_FUNCS)),
nTweak(nTweakIn),
nFlags(nFlagsIn)
@@ -37,7 +39,7 @@ inline unsigned int CBloomFilter::Hash(unsigned int nHashNum, const std::vector<
void CBloomFilter::insert(const vector<unsigned char>& vKey)
{
- if (vData.size() == 1 && vData[0] == 0xff)
+ if (isFull)
return;
for (unsigned int i = 0; i < nHashFuncs; i++)
{
@@ -45,6 +47,7 @@ void CBloomFilter::insert(const vector<unsigned char>& vKey)
// Sets bit nIndex of vData
vData[nIndex >> 3] |= bit_mask[7 & nIndex];
}
+ isEmpty = false;
}
void CBloomFilter::insert(const COutPoint& outpoint)
@@ -63,8 +66,10 @@ void CBloomFilter::insert(const uint256& hash)
bool CBloomFilter::contains(const vector<unsigned char>& vKey) const
{
- if (vData.size() == 1 && vData[0] == 0xff)
+ if (isFull)
return true;
+ if (isEmpty)
+ return false;
for (unsigned int i = 0; i < nHashFuncs; i++)
{
unsigned int nIndex = Hash(i, vKey);
@@ -99,6 +104,10 @@ bool CBloomFilter::IsRelevantAndUpdate(const CTransaction& tx, const uint256& ha
bool fFound = false;
// Match if the filter contains the hash of tx
// for finding tx when they appear in a block
+ if (isFull)
+ return true;
+ if (isEmpty)
+ return false;
if (contains(hash))
fFound = true;
@@ -158,3 +167,16 @@ bool CBloomFilter::IsRelevantAndUpdate(const CTransaction& tx, const uint256& ha
return false;
}
+
+void CBloomFilter::UpdateEmptyFull()
+{
+ bool full = true;
+ bool empty = true;
+ for (unsigned int i = 0; i < vData.size(); i++)
+ {
+ full &= vData[i] == 0xff;
+ empty &= vData[i] == 0;
+ }
+ isFull = full;
+ isEmpty = empty;
+}