/// <summary>
/// Loads all tag definitions for the specified historian.
/// </summary>
/// <param name="historian">The historian.</param>
/// <param name="callback">A callback function that is invoked every time a tag definition is loaded from Redis.</param>
/// <param name="cancellationToken">The cancellation token for the request.</param>
/// <returns>
/// A task that will load all tags into the historian.
/// </returns>
internal static async Task LoadAll(RedisHistorian historian, Action <RedisTagDefinition> callback, CancellationToken cancellationToken)
{
var key = historian.GetKeyForTagIdsList();
const int pageSize = 100;
var page = 0;
bool @continue;
// Load tag definitions 100 at a time.
do
{
@continue = false;
++page;
long start = (page - 1) * pageSize;
long end = start + pageSize - 1; // -1 because right-most item is included when getting the list range.
var tagIds = await historian.Connection.GetDatabase().ListRangeAsync(key, start, end).ConfigureAwait(false);
@continue = tagIds.Length == pageSize;
if (tagIds.Length == 0)
{
continue;
}
var tasks = tagIds.Select(x => Task.Run(async() => {
var tag = await Load(historian, x, cancellationToken).ConfigureAwait(false);
callback(tag);
})).ToArray();
await Task.WhenAny(Task.WhenAll(tasks), Task.Delay(-1, cancellationToken)).ConfigureAwait(false);
cancellationToken.ThrowIfCancellationRequested();
} while (@continue);
}
/// <summary>
/// Deletes the tag definition and raises the <see cref="TagDefinition.Deleted"/> event.
/// </summary>
/// <param name="cancellationToken">The cancellation token for the request.</param>
/// <returns>
/// A task that will delete the tag.
/// </returns>
internal async Task Delete(CancellationToken cancellationToken)
{
var tasks = new List <Task>();
var db = _historian.Connection.GetDatabase();
// Delete the tag definition.
tasks.Add(db.KeyDeleteAsync(_tagDefinitionKey));
// Delete the snapshot value.
tasks.Add(db.KeyDeleteAsync(_snapshotKey));
// Delete the raw values.
tasks.Add(db.KeyDeleteAsync(_archiveKey));
// Delete the archive candidate value.
tasks.Add(db.KeyDeleteAsync(_archiveCandidateKey));
// Remove the tag ID from the list of defined tag IDs.
var tagIdListKey = _historian.GetKeyForTagIdsList();
tasks.Add(_historian.Connection.GetDatabase().ListRemoveAsync(tagIdListKey, Id));
try {
await Task.WhenAny(Task.WhenAll(tasks), Task.Delay(-1, cancellationToken)).ConfigureAwait(false);
cancellationToken.ThrowIfCancellationRequested();
}
finally {
Updated -= TagUpdated;
OnDeleted();
}
}
/// <summary>
/// Creates a new <see cref="RedisTagDefinition"/>.
/// </summary>
/// <param name="historian">The historian for the tag.</param>
/// <param name="settings">The tag settings.</param>
/// <param name="creator">The tag's creator.</param>
/// <param name="cancellationToken">The cancellation token for the request.</param>
/// <returns>
/// A task that will create a new <see cref="RedisTagDefinition"/> and save it to the
/// historian's Redis server.
/// </returns>
internal static async Task <RedisTagDefinition> Create(RedisHistorian historian, TagSettings settings, ClaimsPrincipal creator, CancellationToken cancellationToken)
{
var now = DateTime.UtcNow;
var result = new RedisTagDefinition(historian, null, settings, new TagMetadata(DateTime.UtcNow, creator?.Identity.Name), null, new[] { TagChangeHistoryEntry.Created(creator) });
var key = historian.GetKeyForTagIdsList();
await Task.WhenAny(Task.WhenAll(result.Save(cancellationToken), historian.Connection.GetDatabase().ListRightPushAsync(key, result.Id)), Task.Delay(-1, cancellationToken)).ConfigureAwait(false);
cancellationToken.ThrowIfCancellationRequested();
return(result);
}
