diff options
| -rw-r--r-- | src/Makefile.test.include | 1 | ||||
| -rw-r--r-- | src/cuckoocache.h | 457 | ||||
| -rw-r--r-- | src/init.cpp | 2 | ||||
| -rw-r--r-- | src/script/sigcache.cpp | 77 | ||||
| -rw-r--r-- | src/script/sigcache.h | 9 | ||||
| -rw-r--r-- | src/test/cuckoocache_tests.cpp | 394 | ||||
| -rw-r--r-- | src/test/test_bitcoin.cpp | 2 |
7 files changed, 901 insertions, 41 deletions
diff --git a/src/Makefile.test.include b/src/Makefile.test.include index a14adc7876..60fd13c90d 100644 --- a/src/Makefile.test.include +++ b/src/Makefile.test.include @@ -53,6 +53,7 @@ BITCOIN_TESTS =\ test/coins_tests.cpp \ test/compress_tests.cpp \ test/crypto_tests.cpp \ + test/cuckoocache_tests.cpp \ test/DoS_tests.cpp \ test/getarg_tests.cpp \ test/hash_tests.cpp \ diff --git a/src/cuckoocache.h b/src/cuckoocache.h new file mode 100644 index 0000000000..efd6a820b5 --- /dev/null +++ b/src/cuckoocache.h @@ -0,0 +1,457 @@ +// Copyright (c) 2016 Jeremy Rubin +// Distributed under the MIT software license, see the accompanying +// file COPYING or http://www.opensource.org/licenses/mit-license.php. + +#ifndef _BITCOIN_CUCKOOCACHE_H_ +#define _BITCOIN_CUCKOOCACHE_H_ + +#include <array> +#include <algorithm> +#include <atomic> +#include <cstring> +#include <cmath> +#include <memory> +#include <vector> + + +/** namespace CuckooCache provides high performance cache primitives + * + * Summary: + * + * 1) bit_packed_atomic_flags is bit-packed atomic flags for garbage collection + * + * 2) cache is a cache which is performant in memory usage and lookup speed. It + * is lockfree for erase operations. Elements are lazily erased on the next + * insert. + */ +namespace CuckooCache +{ +/** bit_packed_atomic_flags implements a container for garbage collection flags + * that is only thread unsafe on calls to setup. This class bit-packs collection + * flags for memory efficiency. + * + * All operations are std::memory_order_relaxed so external mechanisms must + * ensure that writes and reads are properly synchronized. + * + * On setup(n), all bits up to n are marked as collected. + * + * Under the hood, because it is an 8-bit type, it makes sense to use a multiple + * of 8 for setup, but it will be safe if that is not the case as well. + * + */ +class bit_packed_atomic_flags +{ + std::unique_ptr<std::atomic<uint8_t>[]> mem; + +public: + /** No default constructor as there must be some size */ + bit_packed_atomic_flags() = delete; + + /** + * bit_packed_atomic_flags constructor creates memory to sufficiently + * keep track of garbage collection information for size entries. + * + * @param size the number of elements to allocate space for + * + * @post bit_set, bit_unset, and bit_is_set function properly forall x. x < + * size + * @post All calls to bit_is_set (without subsequent bit_unset) will return + * true. + */ + bit_packed_atomic_flags(uint32_t size) + { + // pad out the size if needed + size = (size + 7) / 8; + mem.reset(new std::atomic<uint8_t>[size]); + for (uint32_t i = 0; i < size; ++i) + mem[i].store(0xFF); + }; + + /** setup marks all entries and ensures that bit_packed_atomic_flags can store + * at least size entries + * + * @param b the number of elements to allocate space for + * @post bit_set, bit_unset, and bit_is_set function properly forall x. x < + * b + * @post All calls to bit_is_set (without subsequent bit_unset) will return + * true. + */ + inline void setup(uint32_t b) + { + bit_packed_atomic_flags d(b); + std::swap(mem, d.mem); + } + + /** bit_set sets an entry as discardable. + * + * @param s the index of the entry to bit_set. + * @post immediately subsequent call (assuming proper external memory + * ordering) to bit_is_set(s) == true. + * + */ + inline void bit_set(uint32_t s) + { + mem[s >> 3].fetch_or(1 << (s & 7), std::memory_order_relaxed); + } + + /** bit_unset marks an entry as something that should not be overwritten + * + * @param s the index of the entry to bit_unset. + * @post immediately subsequent call (assuming proper external memory + * ordering) to bit_is_set(s) == false. + */ + inline void bit_unset(uint32_t s) + { + mem[s >> 3].fetch_and(~(1 << (s & 7)), std::memory_order_relaxed); + } + + /** bit_is_set queries the table for discardability at s + * + * @param s the index of the entry to read. + * @returns if the bit at index s was set. + * */ + inline bool bit_is_set(uint32_t s) const + { + return (1 << (s & 7)) & mem[s >> 3].load(std::memory_order_relaxed); + } +}; + +/** cache implements a cache with properties similar to a cuckoo-set + * + * The cache is able to hold up to (~(uint32_t)0) - 1 elements. + * + * Read Operations: + * - contains(*, false) + * + * Read+Erase Operations: + * - contains(*, true) + * + * Erase Operations: + * - allow_erase() + * + * Write Operations: + * - setup() + * - setup_bytes() + * - insert() + * - please_keep() + * + * Synchronization Free Operations: + * - invalid() + * - compute_hashes() + * + * User Must Guarantee: + * + * 1) Write Requires synchronized access (e.g., a lock) + * 2) Read Requires no concurrent Write, synchronized with the last insert. + * 3) Erase requires no concurrent Write, synchronized with last insert. + * 4) An Erase caller must release all memory before allowing a new Writer. + * + * + * Note on function names: + * - The name "allow_erase" is used because the real discard happens later. + * - The name "please_keep" is used because elements may be erased anyways on insert. + * + * @tparam Element should be a movable and copyable type + * @tparam Hash should be a function/callable which takes a template parameter + * hash_select and an Element and extracts a hash from it. Should return + * high-entropy hashes for `Hash h; h<0>(e) ... h<7>(e)`. + */ +template <typename Element, typename Hash> +class cache +{ +private: + /** table stores all the elements */ + std::vector<Element> table; + + /** size stores the total available slots in the hash table */ + uint32_t size; + + /** The bit_packed_atomic_flags array is marked mutable because we want + * garbage collection to be allowed to occur from const methods */ + mutable bit_packed_atomic_flags collection_flags; + + /** epoch_flags tracks how recently an element was inserted into + * the cache. true denotes recent, false denotes not-recent. See insert() + * method for full semantics. + */ + mutable std::vector<bool> epoch_flags; + + /** epoch_heuristic_counter is used to determine when a epoch might be aged + * & an expensive scan should be done. epoch_heuristic_counter is + * decremented on insert and reset to the new number of inserts which would + * cause the epoch to reach epoch_size when it reaches zero. + */ + uint32_t epoch_heuristic_counter; + + /** epoch_size is set to be the number of elements supposed to be in a + * epoch. When the number of non-erased elements in a epoch + * exceeds epoch_size, a new epoch should be started and all + * current entries demoted. epoch_size is set to be 45% of size because + * we want to keep load around 90%, and we support 3 epochs at once -- + * one "dead" which has been erased, one "dying" which has been marked to be + * erased next, and one "living" which new inserts add to. + */ + uint32_t epoch_size; + + /** hash_mask should be set to appropriately mask out a hash such that every + * masked hash is [0,size), eg, if floor(log2(size)) == 20, then hash_mask + * should be (1<<20)-1 + */ + uint32_t hash_mask; + + /** depth_limit determines how many elements insert should try to replace. + * Should be set to log2(n)*/ + uint8_t depth_limit; + + /** hash_function is a const instance of the hash function. It cannot be + * static or initialized at call time as it may have internal state (such as + * a nonce). + * */ + const Hash hash_function; + + /** compute_hashes is convenience for not having to write out this + * expression everywhere we use the hash values of an Element. + * + * @param e the element whose hashes will be returned + * @returns std::array<uint32_t, 8> of deterministic hashes derived from e + */ + inline std::array<uint32_t, 8> compute_hashes(const Element& e) const + { + return {{hash_function.template operator()<0>(e) & hash_mask, + hash_function.template operator()<1>(e) & hash_mask, + hash_function.template operator()<2>(e) & hash_mask, + hash_function.template operator()<3>(e) & hash_mask, + hash_function.template operator()<4>(e) & hash_mask, + hash_function.template operator()<5>(e) & hash_mask, + hash_function.template operator()<6>(e) & hash_mask, + hash_function.template operator()<7>(e) & hash_mask}}; + } + + /* end + * @returns a constexpr index that can never be inserted to */ + constexpr uint32_t invalid() const + { + return ~(uint32_t)0; + } + + /** allow_erase marks the element at index n as discardable. Threadsafe + * without any concurrent insert. + * @param n the index to allow erasure of + */ + inline void allow_erase(uint32_t n) const + { + collection_flags.bit_set(n); + } + + /** please_keep marks the element at index n as an entry that should be kept. + * Threadsafe without any concurrent insert. + * @param n the index to prioritize keeping + */ + inline void please_keep(uint32_t n) const + { + collection_flags.bit_unset(n); + } + + /** epoch_check handles the changing of epochs for elements stored in the + * cache. epoch_check should be run before every insert. + * + * First, epoch_check decrements and checks the cheap heuristic, and then does + * a more expensive scan if the cheap heuristic runs out. If the expensive + * scan suceeds, the epochs are aged and old elements are allow_erased. The + * cheap heuristic is reset to retrigger after the worst case growth of the + * current epoch's elements would exceed the epoch_size. + */ + void epoch_check() + { + if (epoch_heuristic_counter != 0) { + --epoch_heuristic_counter; + return; + } + // count the number of elements from the latest epoch which + // have not been erased. + uint32_t epoch_unused_count = 0; + for (uint32_t i = 0; i < size; ++i) + epoch_unused_count += epoch_flags[i] && + !collection_flags.bit_is_set(i); + // If there are more non-deleted entries in the current epoch than the + // epoch size, then allow_erase on all elements in the old epoch (marked + // false) and move all elements in the current epoch to the old epoch + // but do not call allow_erase on their indices. + if (epoch_unused_count >= epoch_size) { + for (uint32_t i = 0; i < size; ++i) + if (epoch_flags[i]) + epoch_flags[i] = false; + else + allow_erase(i); + epoch_heuristic_counter = epoch_size; + } else + // reset the epoch_heuristic_counter to next do a scan when worst + // case behavior (no intermittent erases) would exceed epoch size, + // with a reasonable minimum scan size. + // Ordinarily, we would have to sanity check std::min(epoch_size, + // epoch_unused_count), but we already know that `epoch_unused_count + // < epoch_size` in this branch + epoch_heuristic_counter = std::max(1u, std::max(epoch_size / 16, + epoch_size - epoch_unused_count)); + } + +public: + /** You must always construct a cache with some elements via a subsequent + * call to setup or setup_bytes, otherwise operations may segfault. + */ + cache() : table(), size(), collection_flags(0), epoch_flags(), + epoch_heuristic_counter(), epoch_size(), depth_limit(0), hash_function() + { + } + + /** setup initializes the container to store no more than new_size + * elements. setup rounds down to a power of two size. + * + * setup should only be called once. + * + * @param new_size the desired number of elements to store + * @returns the maximum number of elements storable + **/ + uint32_t setup(uint32_t new_size) + { + // depth_limit must be at least one otherwise errors can occur. + depth_limit = static_cast<uint8_t>(std::log2(static_cast<float>(std::max((uint32_t)2, new_size)))); + size = 1 << depth_limit; + hash_mask = size-1; + table.resize(size); + collection_flags.setup(size); + epoch_flags.resize(size); + // Set to 45% as described above + epoch_size = std::max((uint32_t)1, (45 * size) / 100); + // Initially set to wait for a whole epoch + epoch_heuristic_counter = epoch_size; + return size; + } + + /** setup_bytes is a convenience function which accounts for internal memory + * usage when deciding how many elements to store. It isn't perfect because + * it doesn't account for any overhead (struct size, MallocUsage, collection + * and epoch flags). This was done to simplify selecting a power of two + * size. In the expected use case, an extra two bits per entry should be + * negligible compared to the size of the elements. + * + * @param bytes the approximate number of bytes to use for this data + * structure. + * @returns the maximum number of elements storable (see setup() + * documentation for more detail) + */ + uint32_t setup_bytes(size_t bytes) + { + return setup(bytes/sizeof(Element)); + } + + /** insert loops at most depth_limit times trying to insert a hash + * at various locations in the table via a variant of the Cuckoo Algorithm + * with eight hash locations. + * + * It drops the last tried element if it runs out of depth before + * encountering an open slot. + * + * Thus + * + * insert(x); + * return contains(x, false); + * + * is not guaranteed to return true. + * + * @param e the element to insert + * @post one of the following: All previously inserted elements and e are + * now in the table, one previously inserted element is evicted from the + * table, the entry attempted to be inserted is evicted. + * + */ + inline void insert(Element e) + { + epoch_check(); + uint32_t last_loc = invalid(); + bool last_epoch = true; + std::array<uint32_t, 8> locs = compute_hashes(e); + // Make sure we have not already inserted this element + // If we have, make sure that it does not get deleted + for (uint32_t loc : locs) + if (table[loc] == e) { + please_keep(loc); + epoch_flags[loc] = last_epoch; + return; + } + for (uint8_t depth = 0; depth < depth_limit; ++depth) { + // First try to insert to an empty slot, if one exists + for (uint32_t loc : locs) { + if (!collection_flags.bit_is_set(loc)) + continue; + table[loc] = std::move(e); + please_keep(loc); + epoch_flags[loc] = last_epoch; + return; + } + /** Swap with the element at the location that was + * not the last one looked at. Example: + * + * 1) On first iteration, last_loc == invalid(), find returns last, so + * last_loc defaults to locs[0]. + * 2) On further iterations, where last_loc == locs[k], last_loc will + * go to locs[k+1 % 8], i.e., next of the 8 indicies wrapping around + * to 0 if needed. + * + * This prevents moving the element we just put in. + * + * The swap is not a move -- we must switch onto the evicted element + * for the next iteration. + */ + last_loc = locs[(1 + (std::find(locs.begin(), locs.end(), last_loc) - locs.begin())) & 7]; + std::swap(table[last_loc], e); + // Can't std::swap a std::vector<bool>::reference and a bool&. + bool epoch = last_epoch; + last_epoch = epoch_flags[last_loc]; + epoch_flags[last_loc] = epoch; + + // Recompute the locs -- unfortunately happens one too many times! + locs = compute_hashes(e); + } + } + + /* contains iterates through the hash locations for a given element + * and checks to see if it is present. + * + * contains does not check garbage collected state (in other words, + * garbage is only collected when the space is needed), so: + * + * insert(x); + * if (contains(x, true)) + * return contains(x, false); + * else + * return true; + * + * executed on a single thread will always return true! + * + * This is a great property for re-org performance for example. + * + * contains returns a bool set true if the element was found. + * + * @param e the element to check + * @param erase + * + * @post if erase is true and the element is found, then the garbage collect + * flag is set + * @returns true if the element is found, false otherwise + */ + inline bool contains(const Element& e, const bool erase) const + { + std::array<uint32_t, 8> locs = compute_hashes(e); + for (uint32_t loc : locs) + if (table[loc] == e) { + if (erase) + allow_erase(loc); + return true; + } + return false; + } +}; +} // namespace CuckooCache + +#endif diff --git a/src/init.cpp b/src/init.cpp index 71971a7642..73f885a1bb 100644 --- a/src/init.cpp +++ b/src/init.cpp @@ -1103,6 +1103,8 @@ bool AppInitMain(boost::thread_group& threadGroup, CScheduler& scheduler) LogPrintf("Using config file %s\n", GetConfigFile(GetArg("-conf", BITCOIN_CONF_FILENAME)).string()); LogPrintf("Using at most %i connections (%i file descriptors available)\n", nMaxConnections, nFD); + InitSignatureCache(); + LogPrintf("Using %u threads for script verification\n", nScriptCheckThreads); if (nScriptCheckThreads) { for (int i=0; i<nScriptCheckThreads-1; i++) diff --git a/src/script/sigcache.cpp b/src/script/sigcache.cpp index bdc0bfdc1c..b78d7b607f 100644 --- a/src/script/sigcache.cpp +++ b/src/script/sigcache.cpp @@ -11,20 +11,29 @@ #include "uint256.h" #include "util.h" +#include "cuckoocache.h" #include <boost/thread.hpp> -#include <boost/unordered_set.hpp> namespace { /** * We're hashing a nonce into the entries themselves, so we don't need extra * blinding in the set hash computation. + * + * This may exhibit platform endian dependent behavior but because these are + * nonced hashes (random) and this state is only ever used locally it is safe. + * All that matters is local consistency. */ -class CSignatureCacheHasher +class SignatureCacheHasher { public: - size_t operator()(const uint256& key) const { - return key.GetCheapHash(); + template <uint8_t hash_select> + uint32_t operator()(const uint256& key) const + { + static_assert(hash_select <8, "SignatureCacheHasher only has 8 hashes available."); + uint32_t u; + std::memcpy(&u, key.begin()+4*hash_select, 4); + return u; } }; @@ -38,11 +47,10 @@ class CSignatureCache private: //! Entries are SHA256(nonce || signature hash || public key || signature): uint256 nonce; - typedef boost::unordered_set<uint256, CSignatureCacheHasher> map_type; + typedef CuckooCache::cache<uint256, SignatureCacheHasher> map_type; map_type setValid; boost::shared_mutex cs_sigcache; - public: CSignatureCache() { @@ -56,58 +64,51 @@ public: } bool - Get(const uint256& entry) + Get(const uint256& entry, const bool erase) { boost::shared_lock<boost::shared_mutex> lock(cs_sigcache); - return setValid.count(entry); + return setValid.contains(entry, erase); } - void Erase(const uint256& entry) + void Set(uint256& entry) { boost::unique_lock<boost::shared_mutex> lock(cs_sigcache); - setValid.erase(entry); + setValid.insert(entry); } - - void Set(const uint256& entry) + uint32_t setup_bytes(size_t n) { - size_t nMaxCacheSize = GetArg("-maxsigcachesize", DEFAULT_MAX_SIG_CACHE_SIZE) * ((size_t) 1 << 20); - if (nMaxCacheSize <= 0) return; - - boost::unique_lock<boost::shared_mutex> lock(cs_sigcache); - while (memusage::DynamicUsage(setValid) > nMaxCacheSize) - { - map_type::size_type s = GetRand(setValid.bucket_count()); - map_type::local_iterator it = setValid.begin(s); - if (it != setValid.end(s)) { - setValid.erase(*it); - } - } - - setValid.insert(entry); + 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; } -bool CachingTransactionSignatureChecker::VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash) const +// To be called once in AppInit2/TestingSetup to initialize the signatureCache +void InitSignatureCache() { - static CSignatureCache signatureCache; + size_t nMaxCacheSize = GetArg("-maxsigcachesize", DEFAULT_MAX_SIG_CACHE_SIZE) * ((size_t) 1 << 20); + if (nMaxCacheSize <= 0) return; + size_t nElems = signatureCache.setup_bytes(nMaxCacheSize); + LogPrintf("Using %zu MiB out of %zu requested for signature cache, able to store %zu elements\n", + (nElems*sizeof(uint256)) >>20, nMaxCacheSize>>20, nElems); +} +bool CachingTransactionSignatureChecker::VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& pubkey, const uint256& sighash) const +{ uint256 entry; signatureCache.ComputeEntry(entry, sighash, vchSig, pubkey); - - if (signatureCache.Get(entry)) { - if (!store) { - signatureCache.Erase(entry); - } + if (signatureCache.Get(entry, !store)) return true; - } - if (!TransactionSignatureChecker::VerifySignature(vchSig, pubkey, sighash)) return false; - - if (store) { + if (store) signatureCache.Set(entry); - } return true; } diff --git a/src/script/sigcache.h b/src/script/sigcache.h index 44551ec2bc..5243fc0a42 100644 --- a/src/script/sigcache.h +++ b/src/script/sigcache.h @@ -10,9 +10,10 @@ #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; +// DoS prevention: limit cache size to 32MB (over 1000000 entries on 64-bit +// systems). Due to how we count cache size, actual memory usage is slightly +// more (~32.25 MB) +static const unsigned int DEFAULT_MAX_SIG_CACHE_SIZE = 32; class CPubKey; @@ -27,4 +28,6 @@ public: bool VerifySignature(const std::vector<unsigned char>& vchSig, const CPubKey& vchPubKey, const uint256& sighash) const; }; +void InitSignatureCache(); + #endif // BITCOIN_SCRIPT_SIGCACHE_H diff --git a/src/test/cuckoocache_tests.cpp b/src/test/cuckoocache_tests.cpp new file mode 100644 index 0000000000..1bc50d5ea9 --- /dev/null +++ b/src/test/cuckoocache_tests.cpp @@ -0,0 +1,394 @@ +// Copyright (c) 2012-2016 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 <boost/test/unit_test.hpp> +#include "cuckoocache.h" +#include "test/test_bitcoin.h" +#include "random.h" +#include <thread> +#include <boost/thread.hpp> + + +/** Test Suite for CuckooCache + * + * 1) All tests should have a deterministic result (using insecure rand + * with deterministic seeds) + * 2) Some test methods are templated to allow for easier testing + * against new versions / comparing + * 3) Results should be treated as a regression test, ie, did the behavior + * change significantly from what was expected. This can be OK, depending on + * the nature of the change, but requires updating the tests to reflect the new + * expected behavior. For example improving the hit rate may cause some tests + * using BOOST_CHECK_CLOSE to fail. + * + */ +FastRandomContext insecure_rand(true); + +BOOST_AUTO_TEST_SUITE(cuckoocache_tests); + + +/** insecure_GetRandHash fills in a uint256 from insecure_rand + */ +void insecure_GetRandHash(uint256& t) +{ + uint32_t* ptr = (uint32_t*)t.begin(); + for (uint8_t j = 0; j < 8; ++j) + *(ptr++) = insecure_rand.rand32(); +} + +/** Definition copied from /src/script/sigcache.cpp + */ +class uint256Hasher +{ +public: + template <uint8_t hash_select> + uint32_t operator()(const uint256& key) const + { + static_assert(hash_select <8, "SignatureCacheHasher only has 8 hashes available."); + uint32_t u; + std::memcpy(&u, key.begin() + 4 * hash_select, 4); + return u; + } +}; + + +/* Test that no values not inserted into the cache are read out of it. + * + * There are no repeats in the first 200000 insecure_GetRandHash calls + */ +BOOST_AUTO_TEST_CASE(test_cuckoocache_no_fakes) +{ + insecure_rand = FastRandomContext(true); + CuckooCache::cache<uint256, uint256Hasher> cc{}; + cc.setup_bytes(32 << 20); + uint256 v; + for (int x = 0; x < 100000; ++x) { + insecure_GetRandHash(v); + cc.insert(v); + } + for (int x = 0; x < 100000; ++x) { + insecure_GetRandHash(v); + BOOST_CHECK(!cc.contains(v, false)); + } +}; + +/** This helper returns the hit rate when megabytes*load worth of entries are + * inserted into a megabytes sized cache + */ +template <typename Cache> +double test_cache(size_t megabytes, double load) +{ + insecure_rand = FastRandomContext(true); + std::vector<uint256> hashes; + Cache set{}; + size_t bytes = megabytes * (1 << 20); + set.setup_bytes(bytes); + uint32_t n_insert = static_cast<uint32_t>(load * (bytes / sizeof(uint256))); + hashes.resize(n_insert); + for (uint32_t i = 0; i < n_insert; ++i) { + uint32_t* ptr = (uint32_t*)hashes[i].begin(); + for (uint8_t j = 0; j < 8; ++j) + *(ptr++) = insecure_rand.rand32(); + } + /** We make a copy of the hashes because future optimizations of the + * cuckoocache may overwrite the inserted element, so the test is + * "future proofed". + */ + std::vector<uint256> hashes_insert_copy = hashes; + /** Do the insert */ + for (uint256& h : hashes_insert_copy) + set.insert(h); + /** Count the hits */ + uint32_t count = 0; + for (uint256& h : hashes) + count += set.contains(h, false); + double hit_rate = ((double)count) / ((double)n_insert); + return hit_rate; +} + +/** The normalized hit rate for a given load. + * + * The semantics are a little confusing, so please see the below + * explanation. + * + * Examples: + * + * 1) at load 0.5, we expect a perfect hit rate, so we multiply by + * 1.0 + * 2) at load 2.0, we expect to see half the entries, so a perfect hit rate + * would be 0.5. Therefore, if we see a hit rate of 0.4, 0.4*2.0 = 0.8 is the + * normalized hit rate. + * + * This is basically the right semantics, but has a bit of a glitch depending on + * how you measure around load 1.0 as after load 1.0 your normalized hit rate + * becomes effectively perfect, ignoring freshness. + */ +double normalize_hit_rate(double hits, double load) +{ + return hits * std::max(load, 1.0); +} + +/** Check the hit rate on loads ranging from 0.1 to 2.0 */ +BOOST_AUTO_TEST_CASE(cuckoocache_hit_rate_ok) +{ + /** Arbitrarily selected Hit Rate threshold that happens to work for this test + * as a lower bound on performance. + */ + double HitRateThresh = 0.98; + size_t megabytes = 32; + for (double load = 0.1; load < 2; load *= 2) { + double hits = test_cache<CuckooCache::cache<uint256, uint256Hasher>>(megabytes, load); + BOOST_CHECK(normalize_hit_rate(hits, load) > HitRateThresh); + } +} + + +/** This helper checks that erased elements are preferentially inserted onto and + * that the hit rate of "fresher" keys is reasonable*/ +template <typename Cache> +void test_cache_erase(size_t megabytes) +{ + double load = 1; + insecure_rand = FastRandomContext(true); + std::vector<uint256> hashes; + Cache set{}; + size_t bytes = megabytes * (1 << 20); + set.setup_bytes(bytes); + uint32_t n_insert = static_cast<uint32_t>(load * (bytes / sizeof(uint256))); + hashes.resize(n_insert); + for (uint32_t i = 0; i < n_insert; ++i) { + uint32_t* ptr = (uint32_t*)hashes[i].begin(); + for (uint8_t j = 0; j < 8; ++j) + *(ptr++) = insecure_rand.rand32(); + } + /** We make a copy of the hashes because future optimizations of the + * cuckoocache may overwrite the inserted element, so the test is + * "future proofed". + */ + std::vector<uint256> hashes_insert_copy = hashes; + + /** Insert the first half */ + for (uint32_t i = 0; i < (n_insert / 2); ++i) + set.insert(hashes_insert_copy[i]); + /** Erase the first quarter */ + for (uint32_t i = 0; i < (n_insert / 4); ++i) + set.contains(hashes[i], true); + /** Insert the second half */ + for (uint32_t i = (n_insert / 2); i < n_insert; ++i) + set.insert(hashes_insert_copy[i]); + + /** elements that we marked erased but that are still there */ + size_t count_erased_but_contained = 0; + /** elements that we did not erase but are older */ + size_t count_stale = 0; + /** elements that were most recently inserted */ + size_t count_fresh = 0; + + for (uint32_t i = 0; i < (n_insert / 4); ++i) + count_erased_but_contained += set.contains(hashes[i], false); + for (uint32_t i = (n_insert / 4); i < (n_insert / 2); ++i) + count_stale += set.contains(hashes[i], false); + for (uint32_t i = (n_insert / 2); i < n_insert; ++i) + count_fresh += set.contains(hashes[i], false); + + double hit_rate_erased_but_contained = double(count_erased_but_contained) / (double(n_insert) / 4.0); + double hit_rate_stale = double(count_stale) / (double(n_insert) / 4.0); + double hit_rate_fresh = double(count_fresh) / (double(n_insert) / 2.0); + + // Check that our hit_rate_fresh is perfect + BOOST_CHECK_EQUAL(hit_rate_fresh, 1.0); + // Check that we have a more than 2x better hit rate on stale elements than + // erased elements. + BOOST_CHECK(hit_rate_stale > 2 * hit_rate_erased_but_contained); +} + +BOOST_AUTO_TEST_CASE(cuckoocache_erase_ok) +{ + size_t megabytes = 32; + test_cache_erase<CuckooCache::cache<uint256, uint256Hasher>>(megabytes); +} + +template <typename Cache> +void test_cache_erase_parallel(size_t megabytes) +{ + double load = 1; + insecure_rand = FastRandomContext(true); + std::vector<uint256> hashes; + Cache set{}; + size_t bytes = megabytes * (1 << 20); + set.setup_bytes(bytes); + uint32_t n_insert = static_cast<uint32_t>(load * (bytes / sizeof(uint256))); + hashes.resize(n_insert); + for (uint32_t i = 0; i < n_insert; ++i) { + uint32_t* ptr = (uint32_t*)hashes[i].begin(); + for (uint8_t j = 0; j < 8; ++j) + *(ptr++) = insecure_rand.rand32(); + } + /** We make a copy of the hashes because future optimizations of the + * cuckoocache may overwrite the inserted element, so the test is + * "future proofed". + */ + std::vector<uint256> hashes_insert_copy = hashes; + boost::shared_mutex mtx; + + { + /** Grab lock to make sure we release inserts */ + boost::unique_lock<boost::shared_mutex> l(mtx); + /** Insert the first half */ + for (uint32_t i = 0; i < (n_insert / 2); ++i) + set.insert(hashes_insert_copy[i]); + } + + /** Spin up 3 threads to run contains with erase. + */ + std::vector<std::thread> threads; + /** Erase the first quarter */ + for (uint32_t x = 0; x < 3; ++x) + /** Each thread is emplaced with x copy-by-value + */ + threads.emplace_back([&, x] { + boost::shared_lock<boost::shared_mutex> l(mtx); + size_t ntodo = (n_insert/4)/3; + size_t start = ntodo*x; + size_t end = ntodo*(x+1); + for (uint32_t i = start; i < end; ++i) + set.contains(hashes[i], true); + }); + + /** Wait for all threads to finish + */ + for (std::thread& t : threads) + t.join(); + /** Grab lock to make sure we observe erases */ + boost::unique_lock<boost::shared_mutex> l(mtx); + /** Insert the second half */ + for (uint32_t i = (n_insert / 2); i < n_insert; ++i) + set.insert(hashes_insert_copy[i]); + + /** elements that we marked erased but that are still there */ + size_t count_erased_but_contained = 0; + /** elements that we did not erase but are older */ + size_t count_stale = 0; + /** elements that were most recently inserted */ + size_t count_fresh = 0; + + for (uint32_t i = 0; i < (n_insert / 4); ++i) + count_erased_but_contained += set.contains(hashes[i], false); + for (uint32_t i = (n_insert / 4); i < (n_insert / 2); ++i) + count_stale += set.contains(hashes[i], false); + for (uint32_t i = (n_insert / 2); i < n_insert; ++i) + count_fresh += set.contains(hashes[i], false); + + double hit_rate_erased_but_contained = double(count_erased_but_contained) / (double(n_insert) / 4.0); + double hit_rate_stale = double(count_stale) / (double(n_insert) / 4.0); + double hit_rate_fresh = double(count_fresh) / (double(n_insert) / 2.0); + + // Check that our hit_rate_fresh is perfect + BOOST_CHECK_EQUAL(hit_rate_fresh, 1.0); + // Check that we have a more than 2x better hit rate on stale elements than + // erased elements. + BOOST_CHECK(hit_rate_stale > 2 * hit_rate_erased_but_contained); +} +BOOST_AUTO_TEST_CASE(cuckoocache_erase_parallel_ok) +{ + size_t megabytes = 32; + test_cache_erase_parallel<CuckooCache::cache<uint256, uint256Hasher>>(megabytes); +} + + +template <typename Cache> +void test_cache_generations() +{ + // This test checks that for a simulation of network activity, the fresh hit + // rate is never below 99%, and the number of times that it is worse than + // 99.9% are less than 1% of the time. + double min_hit_rate = 0.99; + double tight_hit_rate = 0.999; + double max_rate_less_than_tight_hit_rate = 0.01; + // A cache that meets this specification is therefore shown to have a hit + // rate of at least tight_hit_rate * (1 - max_rate_less_than_tight_hit_rate) + + // min_hit_rate*max_rate_less_than_tight_hit_rate = 0.999*99%+0.99*1% == 99.89% + // hit rate with low variance. + + // We use deterministic values, but this test has also passed on many + // iterations with non-deterministic values, so it isn't "overfit" to the + // specific entropy in FastRandomContext(true) and implementation of the + // cache. + insecure_rand = FastRandomContext(true); + + // block_activity models a chunk of network activity. n_insert elements are + // adde to the cache. The first and last n/4 are stored for removal later + // and the middle n/2 are not stored. This models a network which uses half + // the signatures of recently (since the last block) added transactions + // immediately and never uses the other half. + struct block_activity { + std::vector<uint256> reads; + block_activity(uint32_t n_insert, Cache& c) : reads() + { + std::vector<uint256> inserts; + inserts.resize(n_insert); + reads.reserve(n_insert / 2); + for (uint32_t i = 0; i < n_insert; ++i) { + uint32_t* ptr = (uint32_t*)inserts[i].begin(); + for (uint8_t j = 0; j < 8; ++j) + *(ptr++) = insecure_rand.rand32(); + } + for (uint32_t i = 0; i < n_insert / 4; ++i) + reads.push_back(inserts[i]); + for (uint32_t i = n_insert - (n_insert / 4); i < n_insert; ++i) + reads.push_back(inserts[i]); + for (auto h : inserts) + c.insert(h); + } + }; + + const uint32_t BLOCK_SIZE = 10000; + // We expect window size 60 to perform reasonably given that each epoch + // stores 45% of the cache size (~472k). + const uint32_t WINDOW_SIZE = 60; + const uint32_t POP_AMOUNT = (BLOCK_SIZE / WINDOW_SIZE) / 2; + const double load = 10; + const size_t megabytes = 32; + const size_t bytes = megabytes * (1 << 20); + const uint32_t n_insert = static_cast<uint32_t>(load * (bytes / sizeof(uint256))); + + std::vector<block_activity> hashes; + Cache set{}; + set.setup_bytes(bytes); + hashes.reserve(n_insert / BLOCK_SIZE); + std::deque<block_activity> last_few; + uint32_t out_of_tight_tolerance = 0; + uint32_t total = n_insert / BLOCK_SIZE; + // we use the deque last_few to model a sliding window of blocks. at each + // step, each of the last WINDOW_SIZE block_activities checks the cache for + // POP_AMOUNT of the hashes that they inserted, and marks these erased. + for (uint32_t i = 0; i < total; ++i) { + if (last_few.size() == WINDOW_SIZE) + last_few.pop_front(); + last_few.emplace_back(BLOCK_SIZE, set); + uint32_t count = 0; + for (auto& act : last_few) + for (uint32_t k = 0; k < POP_AMOUNT; ++k) { + count += set.contains(act.reads.back(), true); + act.reads.pop_back(); + } + // We use last_few.size() rather than WINDOW_SIZE for the correct + // behavior on the first WINDOW_SIZE iterations where the deque is not + // full yet. + double hit = (double(count)) / (last_few.size() * POP_AMOUNT); + // Loose Check that hit rate is above min_hit_rate + BOOST_CHECK(hit > min_hit_rate); + // Tighter check, count number of times we are less than tight_hit_rate + // (and implicityly, greater than min_hit_rate) + out_of_tight_tolerance += hit < tight_hit_rate; + } + // Check that being out of tolerance happens less than + // max_rate_less_than_tight_hit_rate of the time + BOOST_CHECK(double(out_of_tight_tolerance) / double(total) < max_rate_less_than_tight_hit_rate); +} +BOOST_AUTO_TEST_CASE(cuckoocache_generations) +{ + test_cache_generations<CuckooCache::cache<uint256, uint256Hasher>>(); +} + +BOOST_AUTO_TEST_SUITE_END(); diff --git a/src/test/test_bitcoin.cpp b/src/test/test_bitcoin.cpp index dc459bed0d..2a5a78de02 100644 --- a/src/test/test_bitcoin.cpp +++ b/src/test/test_bitcoin.cpp @@ -20,6 +20,7 @@ #include "ui_interface.h" #include "rpc/server.h" #include "rpc/register.h" +#include "script/sigcache.h" #include "test/testutil.h" @@ -40,6 +41,7 @@ BasicTestingSetup::BasicTestingSetup(const std::string& chainName) ECC_Start(); SetupEnvironment(); SetupNetworking(); + InitSignatureCache(); fPrintToDebugLog = false; // don't want to write to debug.log file fCheckBlockIndex = true; SelectParams(chainName); |