SharpOSRM

⚠️ Disclaimer: This project is entirely vibe coded.

A .NET 8 wrapper for OSRM (Open Source Routing Machine) using native C interop. SharpOSRM exposes OSRM's routing engine and data pipeline as idiomatic C# APIs, distributed as a cross-platform NuGet package that bundles the native libsharposrm shared library for Linux (x64), macOS (x64/arm64), and Windows (x64).

⚠️ TBB malloc proxy notice: The native library links TBB's tbbmalloc_proxy, which replaces the process's malloc/free/realloc with TBB's scalable allocator globally. This improves OSRM's routing performance but can cause crashes and memory corruption in other native libraries (e.g. SQLite, custom native dependencies) loaded in the same process. If your application uses other native libraries that are incompatible with a replaced malloc, build from source with -DSTRIP_TBBMALLOC=ON to disable the proxy at the cost of reduced routing performance.

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What it does

OSRM is a high-performance routing engine that operates on OpenStreetMap data. SharpOSRM gives you:

1. Data pipeline — prepare raw OSM data (.osm.pbf) into a routable dataset using the four OSRM pipeline stages: Extract, Partition, Customize (MLD), Contract (CH).
2. Routing engine — load a prepared dataset and issue routing queries in-process without any HTTP server.
3. Seven routing services — Route, Table, Nearest, Match, Trip, Tile, and a FlatBuffers variant of each.

All native calls cross a thin C bridge (libsharposrm) that wraps the OSRM C++ API. The C# side uses LibraryImport P/Invoke with SafeHandle-based lifetime management. All blocking OSRM calls have corresponding *Async overloads that offload to the thread pool.

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Requirements

• .NET 8
• The Sharposrm NuGet package (includes native libraries for all supported platforms — no separate OSRM installation needed)

For building from source, see CI/CD and Testing Guide.

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Installation

dotnet add package Sharposrm

The NuGet package includes prebuilt native libraries for:

Runtime ID	Library	Platform
linux-x64	libsharposrm.so	Ubuntu 22.04+
osx-x64	libsharposrm.dylib	macOS 13+ (Intel)
osx-arm64	libsharposrm.dylib	macOS 15+ (Apple Silicon)
win-x64	sharposrm.dll	Windows Server 2025

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Quick start

1. Prepare your data

OSRM cannot route until OSM data has been processed through the pipeline. You need an .osm.pbf file (download from Geofabrik or OSM extracts) and a routing profile Lua file.

Contraction Hierarchies (CH) — faster queries, longer upfront processing:

using Sharposrm;
using Sharposrm.Pipeline;

// Extract
OsrmPipeline.Extract(new ExtractorConfig
{
    InputPath  = "/data/monaco.osm.pbf",
    ProfilePath = "/profiles/car.lua",
    OutputPath  = "/data/monaco",        // base path, OSRM appends extensions
    RequestedThreads = 4,
});

// Contract (CH)
// Note: run on a thread with a large stack — OSRM's contractor is deeply recursive.
var thread = new Thread(() =>
{
    OsrmPipeline.Contract(new ContractorConfig
    {
        BasePath         = "/data/monaco",
        RequestedThreads = 4,
    });
}, maxStackSize: 8 * 1024 * 1024);
thread.Start();
thread.Join();

Multi-Level Dijkstra (MLD) — more flexible, faster preprocessing:

OsrmPipeline.Extract(new ExtractorConfig
{
    InputPath        = "/data/monaco.osm.pbf",
    ProfilePath      = "/profiles/car.lua",
    OutputPath       = "/data/monaco-mld",
    RequestedThreads = 4,
});

OsrmPipeline.Partition(new PartitionerConfig
{
    BasePath         = "/data/monaco-mld",
    RequestedThreads = 4,
});

OsrmPipeline.Customize(new CustomizerConfig
{
    BasePath         = "/data/monaco-mld",
    RequestedThreads = 4,
});

Important: All pipeline RequestedThreads must be ≥ 1. Setting 0 crashes OSRM's TBB backend.

2. Create an engine

await using var engine = await OsrmEngine.CreateAsync(new EngineConfig
{
    StoragePath = "/data/monaco",    // base path produced by the pipeline
    Algorithm   = Algorithm.CH,      // or Algorithm.MLD
});

OsrmEngine is IAsyncDisposable. Engine creation loads the dataset into memory — for large datasets this can take several seconds. CreateAsync offloads this to the thread pool so it doesn't block an async context.

3. Call routing services

Route

Compute a route between two or more waypoints:

using Sharposrm.Route;

var response = engine.Route(new RouteParameters
{
    Coordinates = new[]
    {
        (7.41337, 43.72956),   // (longitude, latitude)
        (7.41983, 43.73115),
    },
    Steps       = true,
    Annotations = true,
    AnnotationTypes = AnnotationsType.Duration | AnnotationsType.Speed,
    Geometries  = GeometriesType.Polyline,
    Overview    = OverviewType.Simplified,
    Alternatives = false,
    GenerateHints = true,
});

Console.WriteLine($"Distance: {response.Routes![0].Distance}m");
Console.WriteLine($"Duration: {response.Routes[0].Duration}s");

Table

Compute a duration/distance matrix between multiple origins and destinations:

using Sharposrm.Table;

var response = engine.Table(new TableParameters
{
    Coordinates = new[]
    {
        (7.41337, 43.72956),
        (7.41983, 43.73115),
        (7.42500, 43.73500),
    },
    // Optional: separate Sources/Destinations index lists for one-to-many queries
});

// Durations[i][j] is null when the pair cannot be routed
double? duration = response.Durations![0][1];

Nearest

Snap a coordinate to the nearest road network node:

using Sharposrm.Nearest;

var response = engine.Nearest(new NearestParameters
{
    Coordinates = new[] { (7.41337, 43.72956) },
    Number = 3,    // return 3 nearest snapping candidates
});

Match

Map-match a GPS trace to the road network:

using Sharposrm.Match;

var response = engine.Match(new MatchParameters
{
    Coordinates = gpsTrace,       // IReadOnlyList<(double, double)>
    Timestamps  = timestamps,     // optional, Unix epoch seconds
    Radiuses    = radiuses,       // optional, per-point search radius in metres
});

Trip

Solve a Travelling Salesman Problem (shortest round trip through all waypoints):

using Sharposrm.Trip;

var response = engine.Trip(new TripParameters
{
    Coordinates  = waypoints,
    RoundTrip    = true,
    Source       = TripSourceType.First,
    Destination  = TripDestinationType.Last,
});

Tile

Fetch a Mapbox Vector Tile for a given tile coordinate (returns raw MVT bytes):

using Sharposrm.Tile;

byte[] mvtData = engine.Tile(new TileParameters
{
    X    = 33660,
    Y    = 22961,
    Zoom = 15,
});

FlatBuffers variants

Every service except Tile has a *Flatbuffers() method that returns raw byte[] instead of a deserialized response object, for use cases where you need the FlatBuffers wire format directly:

byte[] fbBytes = engine.RouteFlatbuffers(routeParameters);
byte[] fbBytes = engine.TableFlatbuffers(tableParameters);
// etc.

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EngineConfig reference

Property	Type	Default	Description
StoragePath	string	(required)	Base path to the prepared .osrm dataset
Algorithm	Algorithm	CH	CH or MLD
UseSharedMemory	bool	false	Load from shared memory (requires osrm-datastore)
UseMmap	bool	true	Use memory-mapped file I/O
MaxLocationsTrip	int	-1 (unlimited)	Per-engine cap for Trip service
MaxLocationsViaroute	int	-1	Per-engine cap for Route service
MaxLocationsDistanceTable	int	-1	Per-engine cap for Table service
MaxLocationsMapMatching	int	-1	Per-engine cap for Match service
MaxResultsNearest	int	-1	Per-engine cap for Nearest service
MaxAlternatives	int	3	Maximum alternative routes
DisableRouteSteps	bool	false	Strip step data from all responses
DisableRouteGeometry	bool	false	Strip geometry from all responses

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Error handling

All routing services throw OsrmException on failure. The exception message contains OSRM's error code and message (e.g. "OSRM error: NoRoute — No route found between input coordinates").

try
{
    var response = engine.Route(parameters);
}
catch (OsrmException ex)
{
    Console.WriteLine(ex.Message);
}

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Threading

• OsrmEngine instances are not thread-safe. Use one engine per thread, or synchronise externally.
• Each *Async method calls Task.Run(...) — it offloads the blocking native call to the thread pool.
• OSRM's CH contraction is deeply recursive. Always run OsrmPipeline.Contract on a thread with a stack of at least 8 MB (see example above).

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License

SharpOSRM is licensed under the MIT License.

This package statically links OSRM, which is licensed under the BSD 2-Clause License. See THIRD-PARTY-NOTICES.txt for the full OSRM copyright notice.