Large Area Processing

Database tables

The lapRun table defines and groups the reprocessing of a single projection cell

name	type	note
lap_id	int
seq_id	int
tess_id	string
projection_cell	string
filter	string
state	string	'new' if still running, 'full' if complete
registered	date	date lapRun was defined
fault	int
label	string
quick_sass_id	int	stackAssociation id of the quickstack for this run
final_sass_id	int	stackAssociation id of the final stack for this run
dist_group	string	distribution group to give to all dependents

The lapExp table defines the pool of exposures, and associates them with the lapRuns that use them

name	type	note
lap_id	int
exp_id	int
chip_id	int	chip_id of the processing of exp_id used in this run
pair_id	int	chip_id of the companion exposure for a pairwise diff
private	bool	this exp_id/chip_id set is only available to this run
pairwise	bool	this chip_id will be pairwise diffed against pair_id
active	bool	this exp_id/chip_id is currently in use by this run
data_state	string

The lapSequence table groups a set of lapRuns together into a complete sample of the sky.

name	type	note
seq_id	integer
description	string

Processing Steps

Sequence definition

A lapSequence is defined by calling

laptool -definesequence -name "unique name" -description "long description explaining what this sequence is"

laptool -listsequence prints the information about sequences in the metadata format.

Run definition

A new lapRun is defined by calling

laptool -definerun -seq_id S -projection_cell PC_NAME -ra RA_CENTER -decl DEC_CENTER -radius R -filter F -label L

This adds a row to lapRun, and then creates a row in lapExp for each exposure that falls within the area on the sky defined by the -ra/-decl/-radius options. If these exposures have been previously processed (and therefore have a row in lapExp associated with a different lapRun), the chip_id for the new lapExp is copied from that previous entry, provided that the private flag is not true.

Chip-Warp processing

Defining the run does not queue chipRuns for those exposures that have not been processed previously. This is done by

lap_science.pl --chip_mode --lap_id LAP

This script calls laptool -pendingexp -lap_id LAP which returns a list of all the exposures included in this lapRun. Each exposure is checked, and a chipRun queued if the chip_id entry is blank.

This stage also defines the pairs for differencing, using the object and comment fields to organize the pairs as is done in nightly science. If a pair is found, the associated pair_id fields point at the chip_id of the companion exposure, and the pairwise flag is set to true. If a pair is not found, pair_id is left as NULL, pairwise is set to false, and private is set to true. This ensures that the difference against the quickstack will not be used by other lapRuns. After queuing the chipRuns, lapRun.state is set to run to signal that processing has begun, but has not yet finished.

Once all the chips have been queued, the state of the lapRun will be polled using the

lap_science.pl --monitor_mode --lap_id LAP

This calls laptool -exposures -lap_id LAP which returns the status of each exposure at the chip, camera, fake, warp, diff, and magic stages. In addition to gauging completion, exposure pairs are checked against each other to confirm that no faults have occurred. If one member of a pair has an unrecoverable fault, that entry is marked with data_state = 'drop', and is no longer used. The companion of that unrecoverable exposure is set to be private so it will be diffed against the quickstack.

Setting the lapExp to private "steals" this processing run away from any other lapRun that may want to use it. If lap_science.pl detects that another lapExp with this exp_id/chip_id set has private = true, then it will requeue a chipRun for that exp_id, and record the new chip_id for itself, and set private = true.

The script will also check the status of any stacks via the laptool -stacks -lap_id LAP which returns the status of all associated stacks for this lapRun. This information is used to set a pair of flags for both the quick and final stacks: the defined_flag notes that stacks have been queued, and the have_ flag notes that the stacks have completed (or attempted and failed with a fault) and may be used.

Using the information about the exposures and stacks for this lapRun, lap_science.pl will decide what the next step of the processing will be. After all exposures have a warpRun.state of full (or have been dropped due to quality), lap_science.pl checks which step is most appropriate:

Quick stacks

If any lapExp has private = true, then a quickstack is needed. If defined_quick is false, the quickstack is queued, and the appropriate stackAssociation.sass_id is recorded as lapRun.quick_sass_id.

Diffs

If all lapExp have completed the warp stage (or been dropped along the way), diffs may be queued. If no lapExp has private = true, then the pairwise diffs are performed. If a lapExp is set to be private, and the have_quick = true (marking that the quickstack has finished), then the private lapExps are diffed against the quickstack, and the others diffed as a pair.

Final stacks

Once the diffs have completed, the regular stdscience/distribution tools will be used to process all data through the magic and destreak steps. Once these have completed, the warpRun.magicked value is used to determine if a lapExp is ready for the final stacking stage. If all lapExps have a non-zero magicked value, or have a data_state = 'drop', and defined_final is false, then the final stack is queued, and the appropriate stackAssociation.sass_id is recorded as lapRun.final_sass_id.

Cleanup

Once the final stacks have completed, the lapRun is also complete. If have_final is true, then lapRun.state is set to 'full', and all lapExp.active is set to false. Periodically, lap_science.pl --cleanup_mode will poll all lapExp, and if all lapExp with a given chip_id have active = false, then the products of all stages generated from that chip_id will be marked for cleanup (STAGE.label = 'goto_cleaned', STAGE.state = 'goto_cleaned').

Proposed Changes

Update

Even after cleanup, lapExp still records whether an exposure has been fully processed previously. Therefore, instead of queuing a new chipRun for this exposure, the data products may be updated instead. This will be faster than starting from scratch. Implementing this is not significantly difficult, as it requires only relaxing the state restriction in laptool -definerun and having lap_science.pl know how to update a lapExp with STAGE.state = 'cleaned'.

Complete Private diffs

If an unpaired lapExp spans multiple projection_cells, then if we make the requirement that the quickstacks associated with all of the projection_cells are complete before diffing, then we do not need to make that lapExp private. The difference can then be done across the entire image, instead of only over the overlapping area. This will reduce the amount of processing required, but will likely increase the mask fraction for that lapExp.

Command Reference

Define a new sequence of lapRuns.

 laptool -definesequence -name "unique name" -description "long description explaining what this sequence is"

List the currently defined sequences.

 laptool -listsequence

Define a new lapRun for a given projection_cell/filter. By default selects exposures that match an obs_mode of 3PI. A future script will allow the definition of large areas, and execute the appropriate -definerun commands to queue all the lapRuns that make up that large area.

 laptool -definerun -seq_id SEQ_ID -projection_cell PROJECTION_CELL -tess_id TESS_ID -ra RA -decl DEC -radius R -filter FILTER -label label -dist_group dist_group

List runs that are defined, but have not been queued.

 laptool -pendingrun -state new

List runs that are processing.

 laptool -pendingrun -state run

List runs that have completed.

 laptool -pendingrun -state full

List the exposures that comprise this lapRun with details needed for queuing chipRuns.

 laptool -pendingexp -lap_id LAP_ID

List the exposures that comprise this lapRun with details about the state of their processing.

 laptool -exposures -lap_id LAP_ID

List the stacks that are created from this lapRun.

 laptool -stacks -lap_id LAP_ID

List the exposures that comprise this lapRun with details about whether they are still in use.

 laptool -inactiveexp

Queue chipRuns for a lapRun with state = new.

  lap_science.pl --chip_mode --lap_id LAP_ID

"Do the right thing" for a lapRun with state = run.

  lap_science.pl --monitor_mode --lap_id LAP_ID

See if any exposures can be cleaned for a lapRun with state = full.

  lap_science.pl --cleanup_mode --lap_id LAP_ID