Files
bitcoin/src/test
Andrew Chow 5aa0c82ccd Merge bitcoin/bitcoin#25325: Add pool based memory resource
9f947fc3d4 Use PoolAllocator for CCoinsMap (Martin Leitner-Ankerl)
5e4ac5abf5 Call ReallocateCache() on each Flush() (Martin Leitner-Ankerl)
1afca6b663 Add PoolResource fuzzer (Martin Leitner-Ankerl)
e19943f049 Calculate memory usage correctly for unordered_maps that use PoolAllocator (Martin Leitner-Ankerl)
b8401c3281 Add pool based memory resource & allocator (Martin Leitner-Ankerl)

Pull request description:

  A memory resource similar to `std::pmr::unsynchronized_pool_resource`, but optimized for node-based containers. The goal is to be able to cache more coins with the same memory usage, and allocate/deallocate faster.

  This is a reimplementation of #22702. The goal was to implement it in a way that is simpler to review & test

  * There is now a generic `PoolResource` for allocating/deallocating memory. This has practically the same API as `std::pmr::memory_resource`. (Unfortunately I cannot use std::pmr because libc++ simply doesn't implement that API).
  * Thanks to sipa there is now a fuzzer for PoolResource! On a fast machine I ran it for ~770 million executions without finding any issue.

  * The estimation of the correct node size is now gone, PoolResource now has multiple pools and just needs to be created large enough to have space for the unordered_map nodes.

  I ran benchmarks with #22702, mergebase, and this PR. Frequency locked Intel i7-8700, clang++ 13.0.1 to reindex up to block 690000.

  ```sh
  bitcoind -dbcache=5000 -assumevalid=00000000000000000002a23d6df20eecec15b21d32c75833cce28f113de888b7 -reindex-chainstate -printtoconsole=0 -stopatheight=690000
  ```

  The performance is practically identical with #22702, just 0.4% slower. It's ~21% faster than master:

  ![Progress in Million Transactions over Time(2)](https://user-images.githubusercontent.com/14386/173288685-91952ade-f304-4825-8bfb-0725a71ca17b.png)

  ![Size of Cache in MiB over Time](https://user-images.githubusercontent.com/14386/173291421-e6b410be-ac77-479b-ad24-5fafcebf81eb.png)
  Note that on cache drops mergebase's memory doesnt go so far down because it does not free the `CCoinsMap` bucket array.

  ![Size of Cache in Million tx over Time(1)](https://user-images.githubusercontent.com/14386/173288703-a80c9c9e-93c8-4a16-9df8-610c89c61cc4.png)

ACKs for top commit:
  LarryRuane:
    ACK 9f947fc3d4
  achow101:
    re-ACK 9f947fc3d4
  john-moffett:
    ACK 9f947fc3d4
  jonatack:
    re-ACK 9f947fc3d4

Tree-SHA512: 48caf57d1775875a612b54388ef64c53952cd48741cacfe20d89049f2fb35301b5c28e69264b7d659a3ca33d4c714d47bafad6fd547c4075f08b45acc87c0f45
2023-04-20 16:20:15 -04:00
..
2023-03-23 12:55:18 +01:00
2022-12-24 23:49:50 +00:00
2023-01-12 13:42:44 +00:00
2023-01-18 12:24:06 +00:00

Unit tests

The sources in this directory are unit test cases. Boost includes a unit testing framework, and since Bitcoin Core already uses Boost, it makes sense to simply use this framework rather than require developers to configure some other framework (we want as few impediments to creating unit tests as possible).

The build system is set up to compile an executable called test_bitcoin that runs all of the unit tests. The main source file for the test library is found in util/setup_common.cpp.

Compiling/running unit tests

Unit tests will be automatically compiled if dependencies were met in ./configure and tests weren't explicitly disabled.

After configuring, they can be run with make check.

To run the unit tests manually, launch src/test/test_bitcoin. To recompile after a test file was modified, run make and then run the test again. If you modify a non-test file, use make -C src/test to recompile only what's needed to run the unit tests.

To add more unit tests, add BOOST_AUTO_TEST_CASE functions to the existing .cpp files in the test/ directory or add new .cpp files that implement new BOOST_AUTO_TEST_SUITE sections.

To run the GUI unit tests manually, launch src/qt/test/test_bitcoin-qt

To add more GUI unit tests, add them to the src/qt/test/ directory and the src/qt/test/test_main.cpp file.

Running individual tests

test_bitcoin accepts the command line arguments from the boost framework. For example, to run just the getarg_tests suite of tests:

test_bitcoin --log_level=all --run_test=getarg_tests

log_level controls the verbosity of the test framework, which logs when a test case is entered, for example. test_bitcoin also accepts the command line arguments accepted by bitcoind. Use -- to separate both types of arguments:

test_bitcoin --log_level=all --run_test=getarg_tests -- -printtoconsole=1

The -printtoconsole=1 after the two dashes redirects the debug log, which would normally go to a file in the test datadir (BasicTestingSetup::m_path_root), to the standard terminal output.

... or to run just the doubledash test:

test_bitcoin --run_test=getarg_tests/doubledash

Run test_bitcoin --help for the full list.

Adding test cases

To add a new unit test file to our test suite you need to add the file to src/Makefile.test.include. The pattern is to create one test file for each class or source file for which you want to create unit tests. The file naming convention is <source_filename>_tests.cpp and such files should wrap their tests in a test suite called <source_filename>_tests. For an example of this pattern, see uint256_tests.cpp.

Logging and debugging in unit tests

make check will write to a log file foo_tests.cpp.log and display this file on failure. For running individual tests verbosely, refer to the section above.

To write to logs from unit tests you need to use specific message methods provided by Boost. The simplest is BOOST_TEST_MESSAGE.

For debugging you can launch the test_bitcoin executable with gdb or lldb and start debugging, just like you would with any other program:

gdb src/test/test_bitcoin

Segmentation faults

If you hit a segmentation fault during a test run, you can diagnose where the fault is happening by running gdb ./src/test/test_bitcoin and then using the bt command within gdb.

Another tool that can be used to resolve segmentation faults is valgrind.

If for whatever reason you want to produce a core dump file for this fault, you can do that as well. By default, the boost test runner will intercept system errors and not produce a core file. To bypass this, add --catch_system_errors=no to the test_bitcoin arguments and ensure that your ulimits are set properly (e.g. ulimit -c unlimited).

Running the tests and hitting a segmentation fault should now produce a file called core (on Linux platforms, the file name will likely depend on the contents of /proc/sys/kernel/core_pattern).

You can then explore the core dump using

gdb src/test/test_bitcoin core

(gbd) bt  # produce a backtrace for where a segfault occurred