Interface IDatasetMetadataCache

Namespace

EncDotNet.S100.Core.Metadata

Assembly

EncDotNet.S100.Core.dll

A cross-session cache of DatasetMetadata keyed by a dataset's source file identity, letting a host recover a dataset's cheap "peek" facts (spec, extent, CRS, display-scale window, temporal coverage) without re-parsing the dataset — including after a process restart (issue #467 WS3).

public interface IDatasetMetadataCache

Remarks

The cache is the enabler for the relaxed parse-once rule: a persisted metadata entry is what makes "cheap metadata parse now, full render parse later" pay off, and it is the primary enabler of loose-dataset lazy registration. A hit means zero parse on subsequent sessions.

Correctness rests on the key: an entry is valid only while the source file's last-write time and length are unchanged. Any mismatch — or a serialization-format bump, or a corrupt entry — is a miss, and a miss must never break loading (the producer still runs).

Properties

Hits

Number of reads served from a valid cached entry.

long Hits { get; }

Property Value

long

Misses

Number of lookups (via either GetOrRead(string, Func<string, DatasetMetadata>) or TryGet(string, out DatasetMetadata)) not served from a valid cached entry. In GetOrRead(string, Func<string, DatasetMetadata>) such a miss is where the producer runs; in TryGet(string, out DatasetMetadata) it simply returns false.

long Misses { get; }

Property Value

long

Methods

GetOrRead(string, Func<string, DatasetMetadata>)

Returns the cached metadata for sourcePath when a valid entry exists (source unchanged since it was written), otherwise invokes producer, persists its result, and returns it. A cache failure never propagates: the freshly produced value is still returned.

DatasetMetadata GetOrRead(string sourcePath, Func<string, DatasetMetadata> producer)

Parameters

sourcePath string

Absolute path to the dataset file whose metadata is cached. Its last-write time and length form the validity key.

producer Func<string, DatasetMetadata>

Cold path invoked on a miss to parse the metadata from sourcePath. Receives the same path.

Returns

DatasetMetadata

The cached or freshly produced metadata.

TryGet(string, out DatasetMetadata)

Attempts to read a valid cached entry for sourcePath without producing on a miss. Useful for a pure "is it already known?" probe.

bool TryGet(string sourcePath, out DatasetMetadata metadata)

Parameters

sourcePath string

Absolute path to the dataset file.

metadata DatasetMetadata

The cached metadata when the method returns true.

Returns

bool

true on a valid hit; otherwise false.