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using System;
using System.Buffers;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.EntityFrameworkCore;
namespace Jellyfin.Database.Implementations;
/// <summary>
/// Contains helpers to partition EFCore queries.
/// </summary>
public static class QueryPartitionHelpers
{
/// <summary>
/// Adds a callback to any directly following calls of Partition for every partition thats been invoked.
/// </summary>
/// <typeparam name="TEntity">The entity to load.</typeparam>
/// <param name="query">The source query.</param>
/// <param name="beginPartition">The callback invoked for partition before enumerating items.</param>
/// <param name="endPartition">The callback invoked for partition after enumerating items.</param>
/// <returns>A queryable that can be used to partition.</returns>
public static ProgressablePartitionReporting<TEntity> WithPartitionProgress<TEntity>(this IOrderedQueryable<TEntity> query, Action<int>? beginPartition = null, Action<int, TimeSpan>? endPartition = null)
{
var progressable = new ProgressablePartitionReporting<TEntity>(query);
progressable.OnBeginPartition = beginPartition;
progressable.OnEndPartition = endPartition;
return progressable;
}
/// <summary>
/// Adds a callback to any directly following calls of Partition for every item thats been invoked.
/// </summary>
/// <typeparam name="TEntity">The entity to load.</typeparam>
/// <param name="query">The source query.</param>
/// <param name="beginItem">The callback invoked for each item before processing.</param>
/// <param name="endItem">The callback invoked for each item after processing.</param>
/// <returns>A queryable that can be used to partition.</returns>
public static ProgressablePartitionReporting<TEntity> WithItemProgress<TEntity>(this IOrderedQueryable<TEntity> query, Action<TEntity, int, int>? beginItem = null, Action<TEntity, int, int, TimeSpan>? endItem = null)
{
var progressable = new ProgressablePartitionReporting<TEntity>(query);
progressable.OnBeginItem = beginItem;
progressable.OnEndItem = endItem;
return progressable;
}
/// <summary>
/// Adds a callback to any directly following calls of Partition for every partition thats been invoked.
/// </summary>
/// <typeparam name="TEntity">The entity to load.</typeparam>
/// <param name="progressable">The source query.</param>
/// <param name="beginPartition">The callback invoked for partition before enumerating items.</param>
/// <param name="endPartition">The callback invoked for partition after enumerating items.</param>
/// <returns>A queryable that can be used to partition.</returns>
public static ProgressablePartitionReporting<TEntity> WithPartitionProgress<TEntity>(this ProgressablePartitionReporting<TEntity> progressable, Action<int>? beginPartition = null, Action<int, TimeSpan>? endPartition = null)
{
progressable.OnBeginPartition = beginPartition;
progressable.OnEndPartition = endPartition;
return progressable;
}
/// <summary>
/// Adds a callback to any directly following calls of Partition for every item thats been invoked.
/// </summary>
/// <typeparam name="TEntity">The entity to load.</typeparam>
/// <param name="progressable">The source query.</param>
/// <param name="beginItem">The callback invoked for each item before processing.</param>
/// <param name="endItem">The callback invoked for each item after processing.</param>
/// <returns>A queryable that can be used to partition.</returns>
public static ProgressablePartitionReporting<TEntity> WithItemProgress<TEntity>(this ProgressablePartitionReporting<TEntity> progressable, Action<TEntity, int, int>? beginItem = null, Action<TEntity, int, int, TimeSpan>? endItem = null)
{
progressable.OnBeginItem = beginItem;
progressable.OnEndItem = endItem;
return progressable;
}
/// <summary>
/// Enumerates the source query by loading the entities in partitions in a lazy manner reading each item from the database as its requested.
/// </summary>
/// <typeparam name="TEntity">The entity to load.</typeparam>
/// <param name="partitionInfo">The source query.</param>
/// <param name="partitionSize">The number of elements to load per partition.</param>
/// <param name="cancellationToken">The cancelation token.</param>
/// <returns>A enumerable representing the whole of the query.</returns>
public static async IAsyncEnumerable<TEntity> PartitionAsync<TEntity>(this ProgressablePartitionReporting<TEntity> partitionInfo, int partitionSize, [EnumeratorCancellation] CancellationToken cancellationToken = default)
{
await foreach (var item in partitionInfo.Source.PartitionAsync(partitionSize, partitionInfo, cancellationToken).ConfigureAwait(false))
{
yield return item;
}
}
/// <summary>
/// Enumerates the source query by loading the entities in partitions directly into memory.
/// </summary>
/// <typeparam name="TEntity">The entity to load.</typeparam>
/// <param name="partitionInfo">The source query.</param>
/// <param name="partitionSize">The number of elements to load per partition.</param>
/// <param name="cancellationToken">The cancelation token.</param>
/// <returns>A enumerable representing the whole of the query.</returns>
public static async IAsyncEnumerable<TEntity> PartitionEagerAsync<TEntity>(this ProgressablePartitionReporting<TEntity> partitionInfo, int partitionSize, [EnumeratorCancellation] CancellationToken cancellationToken = default)
{
await foreach (var item in partitionInfo.Source.PartitionEagerAsync(partitionSize, partitionInfo, cancellationToken).ConfigureAwait(false))
{
yield return item;
}
}
/// <summary>
/// Enumerates the source query by loading the entities in partitions in a lazy manner reading each item from the database as its requested.
/// </summary>
/// <typeparam name="TEntity">The entity to load.</typeparam>
/// <param name="query">The source query.</param>
/// <param name="partitionSize">The number of elements to load per partition.</param>
/// <param name="progressablePartition">Reporting helper.</param>
/// <param name="cancellationToken">The cancelation token.</param>
/// <returns>A enumerable representing the whole of the query.</returns>
public static async IAsyncEnumerable<TEntity> PartitionAsync<TEntity>(
this IOrderedQueryable<TEntity> query,
int partitionSize,
ProgressablePartitionReporting<TEntity>? progressablePartition = null,
[EnumeratorCancellation] CancellationToken cancellationToken = default)
{
var iterator = 0;
int itemCounter;
do
{
progressablePartition?.BeginPartition(iterator);
itemCounter = 0;
await foreach (var item in query
.Skip(partitionSize * iterator)
.Take(partitionSize)
.AsAsyncEnumerable()
.WithCancellation(cancellationToken)
.ConfigureAwait(false))
{
progressablePartition?.BeginItem(item, iterator, itemCounter);
yield return item;
progressablePartition?.EndItem(item, iterator, itemCounter);
itemCounter++;
}
progressablePartition?.EndPartition(iterator);
iterator++;
} while (itemCounter == partitionSize && !cancellationToken.IsCancellationRequested);
}
/// <summary>
/// Enumerates the source query by loading the entities in partitions directly into memory.
/// </summary>
/// <typeparam name="TEntity">The entity to load.</typeparam>
/// <param name="query">The source query.</param>
/// <param name="partitionSize">The number of elements to load per partition.</param>
/// <param name="progressablePartition">Reporting helper.</param>
/// <param name="cancellationToken">The cancelation token.</param>
/// <returns>A enumerable representing the whole of the query.</returns>
public static async IAsyncEnumerable<TEntity> PartitionEagerAsync<TEntity>(
this IOrderedQueryable<TEntity> query,
int partitionSize,
ProgressablePartitionReporting<TEntity>? progressablePartition = null,
[EnumeratorCancellation] CancellationToken cancellationToken = default)
{
var iterator = 0;
int itemCounter;
var items = ArrayPool<TEntity>.Shared.Rent(partitionSize);
try
{
do
{
progressablePartition?.BeginPartition(iterator);
itemCounter = 0;
await foreach (var item in query
.Skip(partitionSize * iterator)
.Take(partitionSize)
.AsAsyncEnumerable()
.WithCancellation(cancellationToken)
.ConfigureAwait(false))
{
items[itemCounter++] = item;
}
for (int i = 0; i < itemCounter; i++)
{
progressablePartition?.BeginItem(items[i], iterator, itemCounter);
yield return items[i];
progressablePartition?.EndItem(items[i], iterator, itemCounter);
}
progressablePartition?.EndPartition(iterator);
iterator++;
} while (itemCounter == partitionSize && !cancellationToken.IsCancellationRequested);
}
finally
{
ArrayPool<TEntity>.Shared.Return(items);
}
}
/// <summary>
/// Adds an Index to the enumeration of the async enumerable.
/// </summary>
/// <typeparam name="TEntity">The entity to load.</typeparam>
/// <param name="query">The source query.</param>
/// <returns>The source list with an index added.</returns>
public static async IAsyncEnumerable<(TEntity Item, int Index)> WithIndex<TEntity>(this IAsyncEnumerable<TEntity> query)
{
var index = 0;
await foreach (var item in query.ConfigureAwait(false))
{
yield return (item, index++);
}
}
}
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