How mehit Works

Here is a step-by-step explanation of how mehitabel works. This may be useful if you’re trying to recover from a disaster and want to know what mehitabel was doing at a certain point.

When mehitabel first starts up, it reads the Config file to find out where the MESSAGES file can be found. It then opens the MESSAGES file to find out where MSGHDR and MSGTXT are.

At this point, if you are holding down the mouse button, mehitabel branches to its “configuration” mode. Otherwise…

mehitabel draws an “in progress” dialog on the screen, starts its timer going and reads its STR  resources. If you’ve told it to write to the Tabby Log, it writes a “program starting” entry.

If you’ve specified Normal or Kill After backup options, mehit proceeds to copy MESSAGES, MSGHDR and MSGTXT, writing the results as MESSAGES.Bak, MSGHDR.Bak (analyzing MSGHDR as it copies) and MSGTXT.Bak wherever you’ve designated. If you haven’t asked mehitabel to back up anything, then mehit just analyzes the MSGHDR file, getting a count of active and deleted messages in each section.

Now comes the work part: mehitabel checks the message section counts against its configuration, and notes whether any sections are over their limits. In the following steps, mehit uses a single 125-entry buffer for the MSGHDR file and a 50K buffer for the MSGTXT file. It fills the respective buffers from the source files, marks messages for deletion as necessary, purges deleted messages and relocates the survivors in a continuous sequence. (If you’ve asked mehit to archive deleted messages, this is done now, too.) When the buffers are processed, they’re written out to the files and refilled, until the file has been completely processed. This “in place” backup method minimizes space requirements on your disk and allows flexible backup options.

When this is finished, mehitabel adjusts the MESSAGES file to reflect new low and high message numbers, along with the new figure for the length of the MSGTXT file.

If you’ve asked mehit to kill the backups after processing, that happens next.

If mehit has been asked to trim text files within a maximum length, this happens now.

If you’ve selected the Big Report option, mehitabel now writes a Big Report. Brief Report comes next.

If you’ve asked mehit to write to the Tabby Log, mehit now writes a “program ending” entry.

Finally, mehit checks out its status in the Tabby chain, dumps its in-progress dialog and either launches the next Tabby application or quits to the Desktop, depending on the contents (or lack of contents) of the launch.next file.