Diagrams as text tools for databases and distributed systems

ophistory lets you write a simple text file of operations starting and ending in order, and renders them like so:¹

This tool is used to make diagrams for showing concurrent operations, modeled after those seen in Linearizability: A correctness condition for concurrent objects.

It may be invoked as ophistory.py [--embed] <input_file> -o <output_file.svg>.

By default, the SVG uses the ch and em units to scale with the text size of the document. This does not work well with any viewers or tools other than a webbrowser, so --embed causes only px to be used as units, and the font size fixed to 12px so that lines match up with text.

The input file follows a similar syntax as the paper as well. Each line has three parts:

<ACTOR> [:.]? <OPERATION> [KEY]

Where <> is required and [] is optional.

The ACTOR exists to group spans together. It should either be the object being operated upon, on the entity performing the operations. OPERATION is the text that will be displayed above a span. If the text has spaces, but double quotes around it. KEY can be any identifier, and the first time that a key is seen on a line, the line is interpreted as the start of the span. The next line with the same KEY denotes the end of the span, and then the KEY is forgotten.

The operation END is special, and not displayed. The span will be shown with just one operation text centered over the span instead. If an operation starts and immediately finishes, you may omit the KEY. This is semantically equivalent to writing an immediately following line with an END operation.

The operation EVENT is special, and will display a dot along the operation line that the given point. This can be used to signify when the operation atomically occurred between its start and end, if needed.

To reproduce the four FIFO queue histories from S1.2 Motivation:

A: E(x) a B: E(y) A: END a B: D(x) A: D(y) A: E(z)
A: E(x) B: E(y) a A: D(y) a B: END a A: END a
A: E(x) a B: D(x) A: END a
A: E(x) a B: E(y) a A: END a B: END a A: D(y) a C: D(x) a A: END a C: END a