Class SplitDbBuilder

Namespace

VpnHood.Core.Filtering.Sqlite

Assembly

VpnHood.Core.Filtering.Sqlite.dll

Provides the build of a split database: a SQLite file of include, exclude and block sets, which a filter of this package reads.

public abstract class SplitDbBuilder

Inheritance

object

SplitDbBuilder

Derived

SplitDomainDbBuilder

SplitIpDbBuilder

Inherited Members

object.Equals(object)

object.Equals(object, object)

object.GetHashCode()

object.GetType()

object.MemberwiseClone()

object.ReferenceEquals(object, object)

object.ToString()

Remarks

Derive from SplitIpDbBuilder or SplitDomainDbBuilder, which give the schema. A build writes a new file beside the target, its path plus .tmp, with no journal: the rows in one transaction, the indexes after them, and the mark that the file is complete last. It then deletes the target and moves the new file to its path, so a crash never leaves a half-built database there.

The target must not be open while it is replaced: give a changed source a new file name, from GetSourceSignature(), so a running filter keeps the old file until it swaps.

Methods

BuildAsync(string, CancellationToken)

Builds the database at a path, replacing the file there.

public Task BuildAsync(string dbPath, CancellationToken cancellationToken)

Parameters

dbPath string

The database's path; its folder is made if missing.

cancellationToken CancellationToken

The token to monitor for cancellation requests.

Returns

Task

A task that represents the asynchronous operation.

Remarks

The target's -wal, -shm and -journal files are deleted with it. A build that fails before its new file is complete leaves the target as it was, and the new file, which the next build deletes; as the target is deleted before the new file is moved to its path, a failure between the two leaves neither there.

Exceptions

ArgumentException

dbPath has no parent folder.

SqliteException

SQLite refused a row of the build.

OperationCanceledException

cancellationToken was canceled.

EnsureAsync(string, CancellationToken)

Builds the database at a path, unless the file there is complete, of this builder's schema version, and from the same source signature.

public Task EnsureAsync(string dbPath, CancellationToken cancellationToken)

Parameters

dbPath string

The database's path.

cancellationToken CancellationToken

The token to monitor for cancellation requests.

Returns

Task

A task that represents the asynchronous operation.

Remarks

A file that cannot be opened or read counts as out of date. With an unchanged source, it reads the database's own record of its build and nothing of the source.

Exceptions

ArgumentException

dbPath has no parent folder.

SqliteException

SQLite refused a row of the build.

OperationCanceledException

cancellationToken was canceled.

GetSourceSignature()

Gets the identity of the source of the sets, which a build stores in the database: it must change exactly when the sets would.

public abstract string GetSourceSignature()

Returns

string

The identity, compared as a string.

Remarks

EnsureAsync(string, CancellationToken) calls it every time, so keep it cheap: hashes and file sizes and times, never a parse of the source.