Switching from std::map to std::unordered_map and using the same approach
of storing iterators to this map in reverse map for additional bookkeeping
is incorrect and leads to undefined behaviour.
Documentation on std::unordered_map::insert() method reads:
If rehashing occurs due to the insertion, all iterators are invalidated.
Otherwise iterators are not affected. References are not invalidated.
Rehashing occurs only if the new number of elements is greater than
max_load_factor()*bucket_count()
Documentation on std::unordered_map::unordered_map() constructor mentions
that minimal bucket count is implementation dependent if not specified.
As the map is created without specifying minimum bucket count,
it can be rehashed after any insertion, invalidating all iterators
stored in reverse map and causing undefined behaviour.
This is not just a theoretical problem: it causes assertion failures in
test_dash utility if built with GCC 9.2 using _GLIBCXX_DEBUG define.
Fortunately, the new approach of pruning the map's contents in batches
using a sorted vector of iterators makes reverse map completely unnecessary.
This change eliminates the reverse map completely, thus fixing undefined
behaviour caused by invalidated iterators stored there.
Signed-off-by: Oleg Girko <ol@infoserver.lv>
64fb0ac Declare single-argument (non-converting) constructors "explicit" (practicalswift)
Pull request description:
Declare single-argument (non-converting) constructors `explicit`.
In order to avoid unintended implicit conversions.
For a more thorough discussion, see ["C.46: By default, declare single-argument constructors explicit"](http://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#c46-by-default-declare-single-argument-constructors-explicit) in the C++ Core Guidelines (Stroustrup & Sutter).
Tree-SHA512: e0c6922e56b11fa402621a38656d8b1122d16dd8f160e78626385373cf184ac7f26cb4c1851eca47e9b0dbd5e924e39a85c3cbdcb627a05ee3a655ecf5f7a0f1
* Merge #13176: Improve CRollingBloomFilter performance: replace modulus with FastMod
9aac9f90d5e56752cc6cbfac48063ad29a01143c replace modulus with FastMod (Martin Ankerl)
Pull request description:
Not sure if this is optimization is necessary, but anyway I have some spare time so here it is. This replaces the slow modulo operation with a much faster 64bit multiplication & shift. This works when the hash is uniformly distributed between 0 and 2^32-1. This speeds up the benchmark by a factor of about 1.3:
```
RollingBloom, 5, 1500000, 3.73733, 4.97569e-07, 4.99002e-07, 4.98372e-07 # before
RollingBloom, 5, 1500000, 2.86842, 3.81630e-07, 3.83730e-07, 3.82473e-07 # FastMod
```
Be aware that this changes the internal data of the filter, so this should probably
not be used for CBloomFilter because of interoperability problems.
Tree-SHA512: 04104f3fb09f56c9d14458a6aad919aeb0a5af944e8ee6a31f00e93c753e22004648c1cd65bf36752b6addec528d19fb665c27b955ce1666a85a928e17afa47a
* Use unordered_map in CSporkManager
In one of my profiling sessions with many InstantSend transactions
happening, calls into CSporkManager added up to about 1% of total CPU time.
This is easily avoidable by using unordered maps.
* Use std::unordered_map instead of std::map in limitedmap
* Use unordered_set for CNode::setAskFor
* Add serialization support for unordered maps and sets
* Use unordered_map for mapArgs and mapMultiArgs
* Let limitedmap prune in batches and use unordered_multimap
Due to the batched pruning, there is no need to maintain an ordered map
of values anymore. Only when nPruneAfterSize, there is a need to create
a temporary ordered vector of values to figure out what can be removed.
* Instead of using a multimap for mapAskFor, use a vector which we sort on demand
CNode::AskFor will now push entries into an initially unordered vector
instead of an ordered multimap. Only when we later want to use vecAskFor in
SendMessages, we sort the vector.
The vector will actually be mostly sorted in most cases as insertion order
usually mimics the desired ordering. Only the last few entries might need
some shuffling around. Doing the sort on-demand should be less wasteful
then trying to maintain correct order all the time.
* Fix compilation of tests
* Fix limitedmap tests
* Rename limitedmap to unordered_limitedmap to ensure backports conflict
This ensures that future backports that depends on limitedmap's ordering
conflict so that we are made aware of needed action.
* Fix compilation error on Travis
c784086 use std::map::emplace() instead of std::map::insert() (whythat)
5e187e7 use c++11 std::unique_ptr instead of boost::shared_ptr (whythat)
947913f use std::map::erase(const_iterator, const_iterator) to get non-constant iterator (whythat)
- ensures a consistent usage in header files
- also add a blank line after the copyright header where missing
- also remove orphan new-lines at the end of some files
Use misc methods of avoiding unnecesary header includes.
Replace int typedefs with int##_t from stdint.h.
Replace PRI64[xdu] with PRI[xdu]64 from inttypes.h.
Normalize QT_VERSION ifs where possible.
Resolve some indirect dependencies as direct ones.
Remove extern declarations from .cpp files.
