Create a monitoring task that counts how many blocks have been found in the last four hours. If very few or too many have been found, an alert is triggered. "Very few" and "too many" are set based on a false positive rate of once every fifty years of constant running with constant hashing power, which works out to getting 5 or fewer or 48 or more blocks in four hours (instead of the average of 24). Only one alert per day is triggered, so if you get disconnected from the network (or are being Sybil'ed) -alertnotify will be triggered after 3.5 hours but you won't get another -alertnotify for 24 hours. Tested with a new unit test and by running on the main network with -debug=partitioncheck Run test/test_bitcoin --log_level=message to see the alert messages: WARNING: check your network connection, 3 blocks received in the last 4 hours (24 expected) WARNING: abnormally high number of blocks generated, 60 blocks received in the last 4 hours (24 expected) The -debug=partitioncheck debug.log messages look like: ThreadPartitionCheck : Found 22 blocks in the last 4 hours ThreadPartitionCheck : likelihood: 0.0777702
Notes
The sources in this directory are unit test cases. Boost includes a unit testing framework, and since bitcoin 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 setup to compile an executable called "test_bitcoin" that runs all of the unit tests. The main source file is called test_bitcoin.cpp, which simply includes other files that contain the actual unit tests (outside of a couple required preprocessor directives). 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 examples of this pattern, examine uint160_tests.cpp and uint256_tests.cpp.
For further reading, I found the following website to be helpful in explaining how the boost unit test framework works: http://www.alittlemadness.com/2009/03/31/c-unit-testing-with-boosttest/.