Module graph

Inspect Graph

This module provides an abstraction over a Directed Graph on Inspect.

The graph has vertices and edges. Edges have an origin and destination vertex. Each vertex and edge can have a set of key value pairs of associated metadata.

The resulting graph has the following schema:

{ “fuchsia.inspect.Graph”: { “topology”: { “vertex-0”: { “meta”: { “key-1”: value, … “key-i”: value }, “relationships”: { “vertex-j”: { “meta”: { “key-1”: value, … “key-i”: value } }, … “vertex-k”: { “meta”: { … }, }, } }, … “vertex-i”: { “meta”: { … }, “relationships”: { … }, } } } }

The topology node contains all the vertices as children, each of the child names is the ID of the vertex provided through the API.

Each vertex has a metadata associated with it under the child meta. Each of the child names of meta is the key of the metadata field.

Each vertex also has a child relationships which contains all the outgoing edges of that vertex. Each edge is identified by an incremental ID assigned at runtime and contains a property @to which represents the vertex that has that incoming edge. Similar to vertices, it also has a meta containing metadata key value pairs.

Semantics

This API follows regular inspect semantics with the following important detail: Dropping a Vertex results in the deletion of all the associated metadata as well as all the associated outgoing and incoming edges from the Inspect VMO. This is especially important for Edges given that the program may still be holding an Edge struct, but if any of the nodes associated with that edge is dropped, the Edge data will be considered as removed from the Inspect VMO and operations on the Edge will be no-ops.

Overview of type structure

GraphMetadata is the key-value storage per inspect Node; the value’s type is MetadataProperty. VertexGraphMetadata and EdgeGraphMetadata each contain a field, inner, of type GraphMetadata.

Metadata is used as input specification but not storage. It holds key and value; the value is an InnerMetadata enum with internal types MetadataValue and boolean, or Nested.

Structs

Digraph

A directed graph on top of Inspect.

DigraphOpts

Options used to configure the Digraph.

Edge

An Edge in the graph.

Vertex

A vertex of the graph. When this is dropped, all the outgoing edges and metadata fields will removed from Inspect.

Traits

EdgeMetadata

VertexId

The ID of a vertex.

VertexMetadata

Trait implemented by types that hold a vertex metadata.