scan_for_files skips file count

[ghost]

I set up a text_file_backend to rotate log files with a counter appended to the target file name

auto backend = boost::make_shared<sinks::text_file_backend>(
  keywords::file_name = "foo.log",
  keywords::target_file_name = "foo.log.%N",
  keywords::rotation_size = 10,	// small size for testing
  keywords::open_mode = std::ios_base::out | std::ios_base::app
);
using file_sink = sinks::asynchronous_sink<sinks::text_file_backend>;
auto sink = boost::make_shared<file_sink>(backend);

sink->locked_backend()->set_file_collector(
  boost::log::sinks::file::make_collector(
    keywords::target = log_dir,
    keywords::max_files = 10
  )
);

sink->locked_backend()->scan_for_files();
logging::core::get()->add_sink(sink);

If I set up a program to log 3 entries during one run of the program. After two runs, the logs look like:

$ ls foo.log*
foo.log  foo.log.1  foo.log.2  foo.log.4  foo.log.5

The rotation works except foo.log.3 was skipped. If instead I log 2 entries (the second one to cause a file rotation) during one run of the program, and run it 6 times I get:

$ ls foo.log*
foo.log    foo.log.11  foo.log.5  foo.log.9
foo.log.1  foo.log.3   foo.log.7

We get only odd numbers because one count was skipped at each start of the program (at scan_for_files)

I tried making the rotation_size bigger, putting the counter elsewhere (e.g. in the middle of the file name), not opening the file in append mode, but to no avail.

I am using Boost 1.73

[Lastique]

Thanks for the report, should be fixed now in develop.