Bitcoin Core  27.99.0
P2P Digital Currency
txrequest.cpp
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1 // Copyright (c) 2020-2021 The Bitcoin Core developers
2 // Distributed under the MIT software license, see the accompanying
3 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
4 
5 #include <txrequest.h>
6 
7 #include <crypto/siphash.h>
8 #include <net.h>
10 #include <random.h>
11 #include <uint256.h>
12 
13 #include <boost/multi_index/indexed_by.hpp>
14 #include <boost/multi_index/ordered_index.hpp>
15 #include <boost/multi_index/sequenced_index.hpp>
16 #include <boost/multi_index/tag.hpp>
17 #include <boost/multi_index_container.hpp>
18 #include <boost/tuple/tuple.hpp>
19 
20 #include <chrono>
21 #include <unordered_map>
22 #include <utility>
23 
24 #include <assert.h>
25 
26 namespace {
27 
42 enum class State : uint8_t {
44  CANDIDATE_DELAYED,
46  CANDIDATE_READY,
50  CANDIDATE_BEST,
52  REQUESTED,
54  COMPLETED,
55 };
56 
58 using SequenceNumber = uint64_t;
59 
61 struct Announcement {
63  const uint256 m_txhash;
65  std::chrono::microseconds m_time;
67  const NodeId m_peer;
69  const SequenceNumber m_sequence : 59;
71  const bool m_preferred : 1;
73  const bool m_is_wtxid : 1;
74 
76  State m_state : 3 {State::CANDIDATE_DELAYED};
77  State GetState() const { return m_state; }
78  void SetState(State state) { m_state = state; }
79 
81  bool IsSelected() const
82  {
83  return GetState() == State::CANDIDATE_BEST || GetState() == State::REQUESTED;
84  }
85 
87  bool IsWaiting() const
88  {
89  return GetState() == State::REQUESTED || GetState() == State::CANDIDATE_DELAYED;
90  }
91 
93  bool IsSelectable() const
94  {
95  return GetState() == State::CANDIDATE_READY || GetState() == State::CANDIDATE_BEST;
96  }
97 
99  Announcement(const GenTxid& gtxid, NodeId peer, bool preferred, std::chrono::microseconds reqtime,
100  SequenceNumber sequence)
101  : m_txhash(gtxid.GetHash()), m_time(reqtime), m_peer(peer), m_sequence(sequence), m_preferred(preferred),
102  m_is_wtxid{gtxid.IsWtxid()} {}
103 };
104 
106 using Priority = uint64_t;
107 
112 class PriorityComputer {
113  const uint64_t m_k0, m_k1;
114 public:
115  explicit PriorityComputer(bool deterministic) :
116  m_k0{deterministic ? 0 : FastRandomContext().rand64()},
117  m_k1{deterministic ? 0 : FastRandomContext().rand64()} {}
118 
119  Priority operator()(const uint256& txhash, NodeId peer, bool preferred) const
120  {
121  uint64_t low_bits = CSipHasher(m_k0, m_k1).Write(txhash).Write(peer).Finalize() >> 1;
122  return low_bits | uint64_t{preferred} << 63;
123  }
124 
125  Priority operator()(const Announcement& ann) const
126  {
127  return operator()(ann.m_txhash, ann.m_peer, ann.m_preferred);
128  }
129 };
130 
131 // Definitions for the 3 indexes used in the main data structure.
132 //
133 // Each index has a By* type to identify it, a By*View data type to represent the view of announcement it is sorted
134 // by, and an By*ViewExtractor type to convert an announcement into the By*View type.
135 // See https://www.boost.org/doc/libs/1_58_0/libs/multi_index/doc/reference/key_extraction.html#key_extractors
136 // for more information about the key extraction concept.
137 
138 // The ByPeer index is sorted by (peer, state == CANDIDATE_BEST, txhash)
139 //
140 // Uses:
141 // * Looking up existing announcements by peer/txhash, by checking both (peer, false, txhash) and
142 // (peer, true, txhash).
143 // * Finding all CANDIDATE_BEST announcements for a given peer in GetRequestable.
144 struct ByPeer {};
145 using ByPeerView = std::tuple<NodeId, bool, const uint256&>;
146 struct ByPeerViewExtractor
147 {
148  using result_type = ByPeerView;
149  result_type operator()(const Announcement& ann) const
150  {
151  return ByPeerView{ann.m_peer, ann.GetState() == State::CANDIDATE_BEST, ann.m_txhash};
152  }
153 };
154 
155 // The ByTxHash index is sorted by (txhash, state, priority).
156 //
157 // Note: priority == 0 whenever state != CANDIDATE_READY.
158 //
159 // Uses:
160 // * Deleting all announcements with a given txhash in ForgetTxHash.
161 // * Finding the best CANDIDATE_READY to convert to CANDIDATE_BEST, when no other CANDIDATE_READY or REQUESTED
162 // announcement exists for that txhash.
163 // * Determining when no more non-COMPLETED announcements for a given txhash exist, so the COMPLETED ones can be
164 // deleted.
165 struct ByTxHash {};
166 using ByTxHashView = std::tuple<const uint256&, State, Priority>;
167 class ByTxHashViewExtractor {
168  const PriorityComputer& m_computer;
169 public:
170  explicit ByTxHashViewExtractor(const PriorityComputer& computer) : m_computer(computer) {}
171  using result_type = ByTxHashView;
172  result_type operator()(const Announcement& ann) const
173  {
174  const Priority prio = (ann.GetState() == State::CANDIDATE_READY) ? m_computer(ann) : 0;
175  return ByTxHashView{ann.m_txhash, ann.GetState(), prio};
176  }
177 };
178 
179 enum class WaitState {
181  FUTURE_EVENT,
183  NO_EVENT,
185  PAST_EVENT,
186 };
187 
188 WaitState GetWaitState(const Announcement& ann)
189 {
190  if (ann.IsWaiting()) return WaitState::FUTURE_EVENT;
191  if (ann.IsSelectable()) return WaitState::PAST_EVENT;
192  return WaitState::NO_EVENT;
193 }
194 
195 // The ByTime index is sorted by (wait_state, time).
196 //
197 // All announcements with a timestamp in the future can be found by iterating the index forward from the beginning.
198 // All announcements with a timestamp in the past can be found by iterating the index backwards from the end.
199 //
200 // Uses:
201 // * Finding CANDIDATE_DELAYED announcements whose reqtime has passed, and REQUESTED announcements whose expiry has
202 // passed.
203 // * Finding CANDIDATE_READY/BEST announcements whose reqtime is in the future (when the clock time went backwards).
204 struct ByTime {};
205 using ByTimeView = std::pair<WaitState, std::chrono::microseconds>;
206 struct ByTimeViewExtractor
207 {
208  using result_type = ByTimeView;
209  result_type operator()(const Announcement& ann) const
210  {
211  return ByTimeView{GetWaitState(ann), ann.m_time};
212  }
213 };
214 
216 using Index = boost::multi_index_container<
217  Announcement,
218  boost::multi_index::indexed_by<
219  boost::multi_index::ordered_unique<boost::multi_index::tag<ByPeer>, ByPeerViewExtractor>,
220  boost::multi_index::ordered_non_unique<boost::multi_index::tag<ByTxHash>, ByTxHashViewExtractor>,
221  boost::multi_index::ordered_non_unique<boost::multi_index::tag<ByTime>, ByTimeViewExtractor>
222  >
223 >;
224 
226 template<typename Tag>
227 using Iter = typename Index::index<Tag>::type::iterator;
228 
230 struct PeerInfo {
231  size_t m_total = 0;
232  size_t m_completed = 0;
233  size_t m_requested = 0;
234 };
235 
237 struct TxHashInfo
238 {
240  size_t m_candidate_delayed = 0;
242  size_t m_candidate_ready = 0;
244  size_t m_candidate_best = 0;
246  size_t m_requested = 0;
248  Priority m_priority_candidate_best = std::numeric_limits<Priority>::max();
250  Priority m_priority_best_candidate_ready = std::numeric_limits<Priority>::min();
252  std::vector<NodeId> m_peers;
253 };
254 
256 bool operator==(const PeerInfo& a, const PeerInfo& b)
257 {
258  return std::tie(a.m_total, a.m_completed, a.m_requested) ==
259  std::tie(b.m_total, b.m_completed, b.m_requested);
260 };
261 
263 std::unordered_map<NodeId, PeerInfo> RecomputePeerInfo(const Index& index)
264 {
265  std::unordered_map<NodeId, PeerInfo> ret;
266  for (const Announcement& ann : index) {
267  PeerInfo& info = ret[ann.m_peer];
268  ++info.m_total;
269  info.m_requested += (ann.GetState() == State::REQUESTED);
270  info.m_completed += (ann.GetState() == State::COMPLETED);
271  }
272  return ret;
273 }
274 
276 std::map<uint256, TxHashInfo> ComputeTxHashInfo(const Index& index, const PriorityComputer& computer)
277 {
278  std::map<uint256, TxHashInfo> ret;
279  for (const Announcement& ann : index) {
280  TxHashInfo& info = ret[ann.m_txhash];
281  // Classify how many announcements of each state we have for this txhash.
282  info.m_candidate_delayed += (ann.GetState() == State::CANDIDATE_DELAYED);
283  info.m_candidate_ready += (ann.GetState() == State::CANDIDATE_READY);
284  info.m_candidate_best += (ann.GetState() == State::CANDIDATE_BEST);
285  info.m_requested += (ann.GetState() == State::REQUESTED);
286  // And track the priority of the best CANDIDATE_READY/CANDIDATE_BEST announcements.
287  if (ann.GetState() == State::CANDIDATE_BEST) {
288  info.m_priority_candidate_best = computer(ann);
289  }
290  if (ann.GetState() == State::CANDIDATE_READY) {
291  info.m_priority_best_candidate_ready = std::max(info.m_priority_best_candidate_ready, computer(ann));
292  }
293  // Also keep track of which peers this txhash has an announcement for (so we can detect duplicates).
294  info.m_peers.push_back(ann.m_peer);
295  }
296  return ret;
297 }
298 
299 GenTxid ToGenTxid(const Announcement& ann)
300 {
301  return ann.m_is_wtxid ? GenTxid::Wtxid(ann.m_txhash) : GenTxid::Txid(ann.m_txhash);
302 }
303 
304 } // namespace
305 
310  SequenceNumber m_current_sequence{0};
311 
313  const PriorityComputer m_computer;
314 
316  Index m_index;
317 
319  std::unordered_map<NodeId, PeerInfo> m_peerinfo;
320 
321 public:
322  void SanityCheck() const
323  {
324  // Recompute m_peerdata from m_index. This verifies the data in it as it should just be caching statistics
325  // on m_index. It also verifies the invariant that no PeerInfo announcements with m_total==0 exist.
326  assert(m_peerinfo == RecomputePeerInfo(m_index));
327 
328  // Calculate per-txhash statistics from m_index, and validate invariants.
329  for (auto& item : ComputeTxHashInfo(m_index, m_computer)) {
330  TxHashInfo& info = item.second;
331 
332  // Cannot have only COMPLETED peer (txhash should have been forgotten already)
333  assert(info.m_candidate_delayed + info.m_candidate_ready + info.m_candidate_best + info.m_requested > 0);
334 
335  // Can have at most 1 CANDIDATE_BEST/REQUESTED peer
336  assert(info.m_candidate_best + info.m_requested <= 1);
337 
338  // If there are any CANDIDATE_READY announcements, there must be exactly one CANDIDATE_BEST or REQUESTED
339  // announcement.
340  if (info.m_candidate_ready > 0) {
341  assert(info.m_candidate_best + info.m_requested == 1);
342  }
343 
344  // If there is both a CANDIDATE_READY and a CANDIDATE_BEST announcement, the CANDIDATE_BEST one must be
345  // at least as good (equal or higher priority) as the best CANDIDATE_READY.
346  if (info.m_candidate_ready && info.m_candidate_best) {
347  assert(info.m_priority_candidate_best >= info.m_priority_best_candidate_ready);
348  }
349 
350  // No txhash can have been announced by the same peer twice.
351  std::sort(info.m_peers.begin(), info.m_peers.end());
352  assert(std::adjacent_find(info.m_peers.begin(), info.m_peers.end()) == info.m_peers.end());
353  }
354  }
355 
356  void PostGetRequestableSanityCheck(std::chrono::microseconds now) const
357  {
358  for (const Announcement& ann : m_index) {
359  if (ann.IsWaiting()) {
360  // REQUESTED and CANDIDATE_DELAYED must have a time in the future (they should have been converted
361  // to COMPLETED/CANDIDATE_READY respectively).
362  assert(ann.m_time > now);
363  } else if (ann.IsSelectable()) {
364  // CANDIDATE_READY and CANDIDATE_BEST cannot have a time in the future (they should have remained
365  // CANDIDATE_DELAYED, or should have been converted back to it if time went backwards).
366  assert(ann.m_time <= now);
367  }
368  }
369  }
370 
371 private:
373  template<typename Tag>
374  Iter<Tag> Erase(Iter<Tag> it)
375  {
376  auto peerit = m_peerinfo.find(it->m_peer);
377  peerit->second.m_completed -= it->GetState() == State::COMPLETED;
378  peerit->second.m_requested -= it->GetState() == State::REQUESTED;
379  if (--peerit->second.m_total == 0) m_peerinfo.erase(peerit);
380  return m_index.get<Tag>().erase(it);
381  }
382 
384  template<typename Tag, typename Modifier>
385  void Modify(Iter<Tag> it, Modifier modifier)
386  {
387  auto peerit = m_peerinfo.find(it->m_peer);
388  peerit->second.m_completed -= it->GetState() == State::COMPLETED;
389  peerit->second.m_requested -= it->GetState() == State::REQUESTED;
390  m_index.get<Tag>().modify(it, std::move(modifier));
391  peerit->second.m_completed += it->GetState() == State::COMPLETED;
392  peerit->second.m_requested += it->GetState() == State::REQUESTED;
393  }
394 
398  void PromoteCandidateReady(Iter<ByTxHash> it)
399  {
400  assert(it != m_index.get<ByTxHash>().end());
401  assert(it->GetState() == State::CANDIDATE_DELAYED);
402  // Convert CANDIDATE_DELAYED to CANDIDATE_READY first.
403  Modify<ByTxHash>(it, [](Announcement& ann){ ann.SetState(State::CANDIDATE_READY); });
404  // The following code relies on the fact that the ByTxHash is sorted by txhash, and then by state (first
405  // _DELAYED, then _READY, then _BEST/REQUESTED). Within the _READY announcements, the best one (highest
406  // priority) comes last. Thus, if an existing _BEST exists for the same txhash that this announcement may
407  // be preferred over, it must immediately follow the newly created _READY.
408  auto it_next = std::next(it);
409  if (it_next == m_index.get<ByTxHash>().end() || it_next->m_txhash != it->m_txhash ||
410  it_next->GetState() == State::COMPLETED) {
411  // This is the new best CANDIDATE_READY, and there is no IsSelected() announcement for this txhash
412  // already.
413  Modify<ByTxHash>(it, [](Announcement& ann){ ann.SetState(State::CANDIDATE_BEST); });
414  } else if (it_next->GetState() == State::CANDIDATE_BEST) {
415  Priority priority_old = m_computer(*it_next);
416  Priority priority_new = m_computer(*it);
417  if (priority_new > priority_old) {
418  // There is a CANDIDATE_BEST announcement already, but this one is better.
419  Modify<ByTxHash>(it_next, [](Announcement& ann){ ann.SetState(State::CANDIDATE_READY); });
420  Modify<ByTxHash>(it, [](Announcement& ann){ ann.SetState(State::CANDIDATE_BEST); });
421  }
422  }
423  }
424 
427  void ChangeAndReselect(Iter<ByTxHash> it, State new_state)
428  {
429  assert(new_state == State::COMPLETED || new_state == State::CANDIDATE_DELAYED);
430  assert(it != m_index.get<ByTxHash>().end());
431  if (it->IsSelected() && it != m_index.get<ByTxHash>().begin()) {
432  auto it_prev = std::prev(it);
433  // The next best CANDIDATE_READY, if any, immediately precedes the REQUESTED or CANDIDATE_BEST
434  // announcement in the ByTxHash index.
435  if (it_prev->m_txhash == it->m_txhash && it_prev->GetState() == State::CANDIDATE_READY) {
436  // If one such CANDIDATE_READY exists (for this txhash), convert it to CANDIDATE_BEST.
437  Modify<ByTxHash>(it_prev, [](Announcement& ann){ ann.SetState(State::CANDIDATE_BEST); });
438  }
439  }
440  Modify<ByTxHash>(it, [new_state](Announcement& ann){ ann.SetState(new_state); });
441  }
442 
444  bool IsOnlyNonCompleted(Iter<ByTxHash> it)
445  {
446  assert(it != m_index.get<ByTxHash>().end());
447  assert(it->GetState() != State::COMPLETED); // Not allowed to call this on COMPLETED announcements.
448 
449  // This announcement has a predecessor that belongs to the same txhash. Due to ordering, and the
450  // fact that 'it' is not COMPLETED, its predecessor cannot be COMPLETED here.
451  if (it != m_index.get<ByTxHash>().begin() && std::prev(it)->m_txhash == it->m_txhash) return false;
452 
453  // This announcement has a successor that belongs to the same txhash, and is not COMPLETED.
454  if (std::next(it) != m_index.get<ByTxHash>().end() && std::next(it)->m_txhash == it->m_txhash &&
455  std::next(it)->GetState() != State::COMPLETED) return false;
456 
457  return true;
458  }
459 
463  bool MakeCompleted(Iter<ByTxHash> it)
464  {
465  assert(it != m_index.get<ByTxHash>().end());
466 
467  // Nothing to be done if it's already COMPLETED.
468  if (it->GetState() == State::COMPLETED) return true;
469 
470  if (IsOnlyNonCompleted(it)) {
471  // This is the last non-COMPLETED announcement for this txhash. Delete all.
472  uint256 txhash = it->m_txhash;
473  do {
474  it = Erase<ByTxHash>(it);
475  } while (it != m_index.get<ByTxHash>().end() && it->m_txhash == txhash);
476  return false;
477  }
478 
479  // Mark the announcement COMPLETED, and select the next best announcement (the first CANDIDATE_READY) if
480  // needed.
481  ChangeAndReselect(it, State::COMPLETED);
482 
483  return true;
484  }
485 
490  void SetTimePoint(std::chrono::microseconds now, std::vector<std::pair<NodeId, GenTxid>>* expired)
491  {
492  if (expired) expired->clear();
493 
494  // Iterate over all CANDIDATE_DELAYED and REQUESTED from old to new, as long as they're in the past,
495  // and convert them to CANDIDATE_READY and COMPLETED respectively.
496  while (!m_index.empty()) {
497  auto it = m_index.get<ByTime>().begin();
498  if (it->GetState() == State::CANDIDATE_DELAYED && it->m_time <= now) {
499  PromoteCandidateReady(m_index.project<ByTxHash>(it));
500  } else if (it->GetState() == State::REQUESTED && it->m_time <= now) {
501  if (expired) expired->emplace_back(it->m_peer, ToGenTxid(*it));
502  MakeCompleted(m_index.project<ByTxHash>(it));
503  } else {
504  break;
505  }
506  }
507 
508  while (!m_index.empty()) {
509  // If time went backwards, we may need to demote CANDIDATE_BEST and CANDIDATE_READY announcements back
510  // to CANDIDATE_DELAYED. This is an unusual edge case, and unlikely to matter in production. However,
511  // it makes it much easier to specify and test TxRequestTracker::Impl's behaviour.
512  auto it = std::prev(m_index.get<ByTime>().end());
513  if (it->IsSelectable() && it->m_time > now) {
514  ChangeAndReselect(m_index.project<ByTxHash>(it), State::CANDIDATE_DELAYED);
515  } else {
516  break;
517  }
518  }
519  }
520 
521 public:
522  explicit Impl(bool deterministic) :
523  m_computer(deterministic),
524  // Explicitly initialize m_index as we need to pass a reference to m_computer to ByTxHashViewExtractor.
525  m_index(boost::make_tuple(
526  boost::make_tuple(ByPeerViewExtractor(), std::less<ByPeerView>()),
527  boost::make_tuple(ByTxHashViewExtractor(m_computer), std::less<ByTxHashView>()),
528  boost::make_tuple(ByTimeViewExtractor(), std::less<ByTimeView>())
529  )) {}
530 
531  // Disable copying and assigning (a default copy won't work due the stateful ByTxHashViewExtractor).
532  Impl(const Impl&) = delete;
533  Impl& operator=(const Impl&) = delete;
534 
536  {
537  auto& index = m_index.get<ByPeer>();
538  auto it = index.lower_bound(ByPeerView{peer, false, uint256::ZERO});
539  while (it != index.end() && it->m_peer == peer) {
540  // Check what to continue with after this iteration. 'it' will be deleted in what follows, so we need to
541  // decide what to continue with afterwards. There are a number of cases to consider:
542  // - std::next(it) is end() or belongs to a different peer. In that case, this is the last iteration
543  // of the loop (denote this by setting it_next to end()).
544  // - 'it' is not the only non-COMPLETED announcement for its txhash. This means it will be deleted, but
545  // no other Announcement objects will be modified. Continue with std::next(it) if it belongs to the
546  // same peer, but decide this ahead of time (as 'it' may change position in what follows).
547  // - 'it' is the only non-COMPLETED announcement for its txhash. This means it will be deleted along
548  // with all other announcements for the same txhash - which may include std::next(it). However, other
549  // than 'it', no announcements for the same peer can be affected (due to (peer, txhash) uniqueness).
550  // In other words, the situation where std::next(it) is deleted can only occur if std::next(it)
551  // belongs to a different peer but the same txhash as 'it'. This is covered by the first bulletpoint
552  // already, and we'll have set it_next to end().
553  auto it_next = (std::next(it) == index.end() || std::next(it)->m_peer != peer) ? index.end() :
554  std::next(it);
555  // If the announcement isn't already COMPLETED, first make it COMPLETED (which will mark other
556  // CANDIDATEs as CANDIDATE_BEST, or delete all of a txhash's announcements if no non-COMPLETED ones are
557  // left).
558  if (MakeCompleted(m_index.project<ByTxHash>(it))) {
559  // Then actually delete the announcement (unless it was already deleted by MakeCompleted).
560  Erase<ByPeer>(it);
561  }
562  it = it_next;
563  }
564  }
565 
566  void ForgetTxHash(const uint256& txhash)
567  {
568  auto it = m_index.get<ByTxHash>().lower_bound(ByTxHashView{txhash, State::CANDIDATE_DELAYED, 0});
569  while (it != m_index.get<ByTxHash>().end() && it->m_txhash == txhash) {
570  it = Erase<ByTxHash>(it);
571  }
572  }
573 
574  void ReceivedInv(NodeId peer, const GenTxid& gtxid, bool preferred,
575  std::chrono::microseconds reqtime)
576  {
577  // Bail out if we already have a CANDIDATE_BEST announcement for this (txhash, peer) combination. The case
578  // where there is a non-CANDIDATE_BEST announcement already will be caught by the uniqueness property of the
579  // ByPeer index when we try to emplace the new object below.
580  if (m_index.get<ByPeer>().count(ByPeerView{peer, true, gtxid.GetHash()})) return;
581 
582  // Try creating the announcement with CANDIDATE_DELAYED state (which will fail due to the uniqueness
583  // of the ByPeer index if a non-CANDIDATE_BEST announcement already exists with the same txhash and peer).
584  // Bail out in that case.
585  auto ret = m_index.get<ByPeer>().emplace(gtxid, peer, preferred, reqtime, m_current_sequence);
586  if (!ret.second) return;
587 
588  // Update accounting metadata.
589  ++m_peerinfo[peer].m_total;
591  }
592 
594  std::vector<GenTxid> GetRequestable(NodeId peer, std::chrono::microseconds now,
595  std::vector<std::pair<NodeId, GenTxid>>* expired)
596  {
597  // Move time.
598  SetTimePoint(now, expired);
599 
600  // Find all CANDIDATE_BEST announcements for this peer.
601  std::vector<const Announcement*> selected;
602  auto it_peer = m_index.get<ByPeer>().lower_bound(ByPeerView{peer, true, uint256::ZERO});
603  while (it_peer != m_index.get<ByPeer>().end() && it_peer->m_peer == peer &&
604  it_peer->GetState() == State::CANDIDATE_BEST) {
605  selected.emplace_back(&*it_peer);
606  ++it_peer;
607  }
608 
609  // Sort by sequence number.
610  std::sort(selected.begin(), selected.end(), [](const Announcement* a, const Announcement* b) {
611  return a->m_sequence < b->m_sequence;
612  });
613 
614  // Convert to GenTxid and return.
615  std::vector<GenTxid> ret;
616  ret.reserve(selected.size());
617  std::transform(selected.begin(), selected.end(), std::back_inserter(ret), [](const Announcement* ann) {
618  return ToGenTxid(*ann);
619  });
620  return ret;
621  }
622 
623  void RequestedTx(NodeId peer, const uint256& txhash, std::chrono::microseconds expiry)
624  {
625  auto it = m_index.get<ByPeer>().find(ByPeerView{peer, true, txhash});
626  if (it == m_index.get<ByPeer>().end()) {
627  // There is no CANDIDATE_BEST announcement, look for a _READY or _DELAYED instead. If the caller only
628  // ever invokes RequestedTx with the values returned by GetRequestable, and no other non-const functions
629  // other than ForgetTxHash and GetRequestable in between, this branch will never execute (as txhashes
630  // returned by GetRequestable always correspond to CANDIDATE_BEST announcements).
631 
632  it = m_index.get<ByPeer>().find(ByPeerView{peer, false, txhash});
633  if (it == m_index.get<ByPeer>().end() || (it->GetState() != State::CANDIDATE_DELAYED &&
634  it->GetState() != State::CANDIDATE_READY)) {
635  // There is no CANDIDATE announcement tracked for this peer, so we have nothing to do. Either this
636  // txhash wasn't tracked at all (and the caller should have called ReceivedInv), or it was already
637  // requested and/or completed for other reasons and this is just a superfluous RequestedTx call.
638  return;
639  }
640 
641  // Look for an existing CANDIDATE_BEST or REQUESTED with the same txhash. We only need to do this if the
642  // found announcement had a different state than CANDIDATE_BEST. If it did, invariants guarantee that no
643  // other CANDIDATE_BEST or REQUESTED can exist.
644  auto it_old = m_index.get<ByTxHash>().lower_bound(ByTxHashView{txhash, State::CANDIDATE_BEST, 0});
645  if (it_old != m_index.get<ByTxHash>().end() && it_old->m_txhash == txhash) {
646  if (it_old->GetState() == State::CANDIDATE_BEST) {
647  // The data structure's invariants require that there can be at most one CANDIDATE_BEST or one
648  // REQUESTED announcement per txhash (but not both simultaneously), so we have to convert any
649  // existing CANDIDATE_BEST to another CANDIDATE_* when constructing another REQUESTED.
650  // It doesn't matter whether we pick CANDIDATE_READY or _DELAYED here, as SetTimePoint()
651  // will correct it at GetRequestable() time. If time only goes forward, it will always be
652  // _READY, so pick that to avoid extra work in SetTimePoint().
653  Modify<ByTxHash>(it_old, [](Announcement& ann) { ann.SetState(State::CANDIDATE_READY); });
654  } else if (it_old->GetState() == State::REQUESTED) {
655  // As we're no longer waiting for a response to the previous REQUESTED announcement, convert it
656  // to COMPLETED. This also helps guaranteeing progress.
657  Modify<ByTxHash>(it_old, [](Announcement& ann) { ann.SetState(State::COMPLETED); });
658  }
659  }
660  }
661 
662  Modify<ByPeer>(it, [expiry](Announcement& ann) {
663  ann.SetState(State::REQUESTED);
664  ann.m_time = expiry;
665  });
666  }
667 
668  void ReceivedResponse(NodeId peer, const uint256& txhash)
669  {
670  // We need to search the ByPeer index for both (peer, false, txhash) and (peer, true, txhash).
671  auto it = m_index.get<ByPeer>().find(ByPeerView{peer, false, txhash});
672  if (it == m_index.get<ByPeer>().end()) {
673  it = m_index.get<ByPeer>().find(ByPeerView{peer, true, txhash});
674  }
675  if (it != m_index.get<ByPeer>().end()) MakeCompleted(m_index.project<ByTxHash>(it));
676  }
677 
678  size_t CountInFlight(NodeId peer) const
679  {
680  auto it = m_peerinfo.find(peer);
681  if (it != m_peerinfo.end()) return it->second.m_requested;
682  return 0;
683  }
684 
685  size_t CountCandidates(NodeId peer) const
686  {
687  auto it = m_peerinfo.find(peer);
688  if (it != m_peerinfo.end()) return it->second.m_total - it->second.m_requested - it->second.m_completed;
689  return 0;
690  }
691 
692  size_t Count(NodeId peer) const
693  {
694  auto it = m_peerinfo.find(peer);
695  if (it != m_peerinfo.end()) return it->second.m_total;
696  return 0;
697  }
698 
700  size_t Size() const { return m_index.size(); }
701 
702  uint64_t ComputePriority(const uint256& txhash, NodeId peer, bool preferred) const
703  {
704  // Return Priority as a uint64_t as Priority is internal.
705  return uint64_t{m_computer(txhash, peer, preferred)};
706  }
707 
708 };
709 
711  m_impl{std::make_unique<TxRequestTracker::Impl>(deterministic)} {}
712 
714 
715 void TxRequestTracker::ForgetTxHash(const uint256& txhash) { m_impl->ForgetTxHash(txhash); }
716 void TxRequestTracker::DisconnectedPeer(NodeId peer) { m_impl->DisconnectedPeer(peer); }
717 size_t TxRequestTracker::CountInFlight(NodeId peer) const { return m_impl->CountInFlight(peer); }
718 size_t TxRequestTracker::CountCandidates(NodeId peer) const { return m_impl->CountCandidates(peer); }
719 size_t TxRequestTracker::Count(NodeId peer) const { return m_impl->Count(peer); }
720 size_t TxRequestTracker::Size() const { return m_impl->Size(); }
721 void TxRequestTracker::SanityCheck() const { m_impl->SanityCheck(); }
722 
723 void TxRequestTracker::PostGetRequestableSanityCheck(std::chrono::microseconds now) const
724 {
725  m_impl->PostGetRequestableSanityCheck(now);
726 }
727 
728 void TxRequestTracker::ReceivedInv(NodeId peer, const GenTxid& gtxid, bool preferred,
729  std::chrono::microseconds reqtime)
730 {
731  m_impl->ReceivedInv(peer, gtxid, preferred, reqtime);
732 }
733 
734 void TxRequestTracker::RequestedTx(NodeId peer, const uint256& txhash, std::chrono::microseconds expiry)
735 {
736  m_impl->RequestedTx(peer, txhash, expiry);
737 }
738 
740 {
741  m_impl->ReceivedResponse(peer, txhash);
742 }
743 
744 std::vector<GenTxid> TxRequestTracker::GetRequestable(NodeId peer, std::chrono::microseconds now,
745  std::vector<std::pair<NodeId, GenTxid>>* expired)
746 {
747  return m_impl->GetRequestable(peer, now, expired);
748 }
749 
750 uint64_t TxRequestTracker::ComputePriority(const uint256& txhash, NodeId peer, bool preferred) const
751 {
752  return m_impl->ComputePriority(txhash, peer, preferred);
753 }
int ret
SipHash-2-4.
Definition: siphash.h:15
uint64_t Finalize() const
Compute the 64-bit SipHash-2-4 of the data written so far.
Definition: siphash.cpp:77
CSipHasher & Write(uint64_t data)
Hash a 64-bit integer worth of data It is treated as if this was the little-endian interpretation of ...
Definition: siphash.cpp:28
Fast randomness source.
Definition: random.h:377
A generic txid reference (txid or wtxid).
Definition: transaction.h:428
bool m_is_wtxid
Definition: transaction.h:429
static GenTxid Wtxid(const uint256 &hash)
Definition: transaction.h:435
Actual implementation for TxRequestTracker's data structure.
Definition: txrequest.cpp:307
const PriorityComputer m_computer
This tracker's priority computer.
Definition: txrequest.cpp:313
Iter< Tag > Erase(Iter< Tag > it)
Wrapper around Index::...::erase that keeps m_peerinfo up to date.
Definition: txrequest.cpp:374
void PromoteCandidateReady(Iter< ByTxHash > it)
Convert a CANDIDATE_DELAYED announcement into a CANDIDATE_READY.
Definition: txrequest.cpp:398
SequenceNumber m_current_sequence
The current sequence number.
Definition: txrequest.cpp:310
void ReceivedResponse(NodeId peer, const uint256 &txhash)
Definition: txrequest.cpp:668
size_t CountInFlight(NodeId peer) const
Definition: txrequest.cpp:678
std::vector< GenTxid > GetRequestable(NodeId peer, std::chrono::microseconds now, std::vector< std::pair< NodeId, GenTxid >> *expired)
Find the GenTxids to request now from peer.
Definition: txrequest.cpp:594
size_t Size() const
Count how many announcements are being tracked in total across all peers and transactions.
Definition: txrequest.cpp:700
void ReceivedInv(NodeId peer, const GenTxid &gtxid, bool preferred, std::chrono::microseconds reqtime)
Definition: txrequest.cpp:574
Impl(const Impl &)=delete
bool MakeCompleted(Iter< ByTxHash > it)
Convert any announcement to a COMPLETED one.
Definition: txrequest.cpp:463
void PostGetRequestableSanityCheck(std::chrono::microseconds now) const
Definition: txrequest.cpp:356
Index m_index
This tracker's main data structure. See SanityCheck() for the invariants that apply to it.
Definition: txrequest.cpp:316
bool IsOnlyNonCompleted(Iter< ByTxHash > it)
Check if 'it' is the only announcement for a given txhash that isn't COMPLETED.
Definition: txrequest.cpp:444
void SanityCheck() const
Definition: txrequest.cpp:322
Impl & operator=(const Impl &)=delete
void ForgetTxHash(const uint256 &txhash)
Definition: txrequest.cpp:566
uint64_t ComputePriority(const uint256 &txhash, NodeId peer, bool preferred) const
Definition: txrequest.cpp:702
std::unordered_map< NodeId, PeerInfo > m_peerinfo
Map with this tracker's per-peer statistics.
Definition: txrequest.cpp:319
Impl(bool deterministic)
Definition: txrequest.cpp:522
void RequestedTx(NodeId peer, const uint256 &txhash, std::chrono::microseconds expiry)
Definition: txrequest.cpp:623
void ChangeAndReselect(Iter< ByTxHash > it, State new_state)
Change the state of an announcement to something non-IsSelected().
Definition: txrequest.cpp:427
size_t CountCandidates(NodeId peer) const
Definition: txrequest.cpp:685
void SetTimePoint(std::chrono::microseconds now, std::vector< std::pair< NodeId, GenTxid >> *expired)
Make the data structure consistent with a given point in time:
Definition: txrequest.cpp:490
size_t Count(NodeId peer) const
Definition: txrequest.cpp:692
void Modify(Iter< Tag > it, Modifier modifier)
Wrapper around Index::...::modify that keeps m_peerinfo up to date.
Definition: txrequest.cpp:385
void DisconnectedPeer(NodeId peer)
Definition: txrequest.cpp:535
Data structure to keep track of, and schedule, transaction downloads from peers.
Definition: txrequest.h:96
void ReceivedInv(NodeId peer, const GenTxid &gtxid, bool preferred, std::chrono::microseconds reqtime)
Adds a new CANDIDATE announcement.
Definition: txrequest.cpp:728
void SanityCheck() const
Run internal consistency check (testing only).
Definition: txrequest.cpp:721
size_t CountInFlight(NodeId peer) const
Count how many REQUESTED announcements a peer has.
Definition: txrequest.cpp:717
size_t CountCandidates(NodeId peer) const
Count how many CANDIDATE announcements a peer has.
Definition: txrequest.cpp:718
TxRequestTracker(bool deterministic=false)
Construct a TxRequestTracker.
Definition: txrequest.cpp:710
const std::unique_ptr< Impl > m_impl
Definition: txrequest.h:98
void DisconnectedPeer(NodeId peer)
Deletes all announcements for a given peer.
Definition: txrequest.cpp:716
void ReceivedResponse(NodeId peer, const uint256 &txhash)
Converts a CANDIDATE or REQUESTED announcement to a COMPLETED one.
Definition: txrequest.cpp:739
uint64_t ComputePriority(const uint256 &txhash, NodeId peer, bool preferred) const
Access to the internal priority computation (testing only)
Definition: txrequest.cpp:750
void PostGetRequestableSanityCheck(std::chrono::microseconds now) const
Run a time-dependent internal consistency check (testing only).
Definition: txrequest.cpp:723
void RequestedTx(NodeId peer, const uint256 &txhash, std::chrono::microseconds expiry)
Marks a transaction as requested, with a specified expiry.
Definition: txrequest.cpp:734
size_t Count(NodeId peer) const
Count how many announcements a peer has (REQUESTED, CANDIDATE, and COMPLETED combined).
Definition: txrequest.cpp:719
size_t Size() const
Count how many announcements are being tracked in total across all peers and transaction hashes.
Definition: txrequest.cpp:720
std::vector< GenTxid > GetRequestable(NodeId peer, std::chrono::microseconds now, std::vector< std::pair< NodeId, GenTxid >> *expired=nullptr)
Find the txids to request now from peer.
Definition: txrequest.cpp:744
void ForgetTxHash(const uint256 &txhash)
Deletes all announcements for a given txhash (both txid and wtxid ones).
Definition: txrequest.cpp:715
256-bit opaque blob.
Definition: uint256.h:106
static const uint256 ZERO
Definition: uint256.h:111
uint64_t sequence
int64_t NodeId
Definition: net.h:97
bool operator==(const CNetAddr &a, const CNetAddr &b)
Definition: netaddress.cpp:607
GenTxid ToGenTxid(const CInv &inv)
Convert a TX/WITNESS_TX/WTX CInv to a GenTxid.
Definition: protocol.cpp:121
assert(!tx.IsCoinBase())