package bisect_ppx

This module provides runtime support for Bisect. Instrumented programs should hence be linked with this module.

Each instrumented file creates an array of counters, one for each point in that file. It then registers the array with this runtime module. Upon program exit (using at_exit), this module dumps the accumulated counts from all the arrays into an output file.

The default base name for the output file is bisect in the current directory, but another base name can be specified using the BISECT_FILE environment variable. The actual file name is the first non-existing <base><n>.out file where base is the base name and n a natural number value padded with zeroes to 4 digits (i.e. "0001", "0002", and so on).

Another environment variable can be used to customize the behaviour of Bisect: BISECT_SILENT. If this variable is set to YES or ON (ignoring case), then Bisect will not output any message. Otherwise, Bisect will output a message in two situations:

• when the output file cannot be created at program termination;
• when the data cannot be written at program termination. If BISECT_SILENT is set to ERR (ignoring case), these error messages are routed to stderr, otherwise BISECT_SILENT is used to determine a filename for this output. The default value is bisect.log.

Because instrumented modules refer to Bisect, one is advised to link this module as one of the first ones of the program.

Since the counts output file and log file are, by default, relative to the current working directory, an instrumented process should be careful about changing its working directory, or else BISECT_FILE and BISECT_SILENT should be specified with absolute paths.