Module progress 

How far a long operation has come, one step at a time, so a host can draw a bar for it instead of a bare spinner (api.md E1).

Structs

Progress

How far an operation has come: the step it is on, and how many of that step’s units are done out of its total. Each step names its unit. Steps arrive in the order the operation runs them, and within a step done only grows and never passes total, which never shrinks.

ProgressChannel

Where an owner reports each run of one kind of operation, such as a store’s open, for the host watching it. Each run reports into it afresh.

ProgressReport

Reports one operation’s progress into a watch. A step’s beginning and its last unit are always reported; between them, a report waits until REPORT_INTERVAL has passed since the one before. Reporting stores the newest value and writes nothing to a database.

ProgressWatch

Hears the progress an owner’s operation reports into its ProgressChannel, for a host that draws it.

RecordingClock

A clock that keeps every value reported into one watch, for a test that checks steps a host reading the watch could miss. A report reads its clock just before it sends, so what the watch holds at each reading, with what it holds at the end, is every value sent, in order. Time and waits are clock’s.

Constants

REPORT_INTERVAL

The least time between two reports within one step: a host redraws a few times a second, never once per row.

Functions

forward

Run work to its end, calling report on this task with the progress it reports into progress. A host that redraws more slowly than work reports sees the newest value, never an older one after it; a report made just before work ends is still delivered, and none twice. What the watch held before progress subscribed belongs to an earlier operation and is never delivered.