Currently route results are annotated with additional path information,
such as geometries, turn-by-turn steps and other metadata.
These annotations are generated if they are not requested or returned
in the response.
Datasets needed to generate these annotations are loaded and available
to the OSRM process even when unused.
This commit is a first step towards making the loading of these datasets
optional. We refactor the code so that route annotations are only
generated if explicitly requested and needed in the response.
Specifically, we change the following annotations to be lazily generated:
- Turn-by-turn steps
- Route Overview geometry
- Route segment metadata
For example. a /route/v1 request with
steps=false&overview=false&annotations=false
would no longer call the following data facade methods:
- GetOSMNodeIDOfNode
- GetTurnInstructionForEdgeID
- GetNameIndex
- GetNameForID
- GetRefForID
- GetTurnInstructionForEdgeID
- GetClassData
- IsLeftHandDriving
- GetTravelMode
- IsSegregated
- PreTurnBearing
- PostTurnBearing
- HasLaneData
- GetLaneData
- GetEntryClass
Requests that include segment metadata and/or overview geometry
but not turn-by-turn instructions will also benefit from this,
although there is some interdependency with the step instructions
- a call to GetTurnInstructionForEdgeID is still required.
Requests for OSM annotations will understandably still need to
call GetOSMNodeIDOfNode.
Making these changes unlocks the optional loading of data contained in
the following OSRM files:
- osrm.names
- osrm.icd
- osrm.nbg_nodes (partial)
- osrm.ebg_nodes (partial)
- osrm.edges
Currently supports duration and distance for each coordinate.
This is particularly useful in map-matching, comparing how
a trip progresses compared to a real GPS trace that is
map-matched.
