README.md

Open.ChannelExtensions

A set of extensions for optimizing/simplifying System.Threading.Channels usage.

Click here for detailed documentation.

Highlights

Read & Write

With optional concurrency levels.

• Reading all entries in a channel.
• Writing all entries from a source to a channel.
• Piping (consuming) all entries to a buffer (channel).
• .AsAsyncEnumerable() (IAsyncEnumerable) support for .NET Standard 2.1+ and .NET Core 3+

Special ChannelReader Operations

• Filter: reads from the channel until a match is found.
• Transform: applies a transform function upon successfully reading an item from the channel.
• Batch: attempts to group items into a List<T> (or a Queue<T>) before being available for reading.
• Join: combines batches into a single channel.

---

Installation

Install-Package Open.ChannelExtensions

---

Examples

Being able to define an asynchronous pipeline with best practice usage using simple expressive syntax:

await Channel
    .CreateBounded<T>(10)
    .SourceAsync(source /* IEnumerable<Task<T>> */)
    .PipeAsync(
        maxConcurrency: 2,
        capacity: 5,
        transform: asyncTransform01)
    .Pipe(transform02, /* capacity */ 3)
    .ReadAllAsync(finalTransformedValue => {
        // Do something async with each final value.
    });

await source /* IEnumerable<T> */
    .ToChannel(boundedSize: 10, singleReader: true)
    .PipeAsync(asyncTransform01, /* capacity */ 5)
    .Pipe(
        maxConcurrency: 2,
        capacity: 3,
        transform: transform02)
    .ReadAll(finalTransformedValue => {
        // Do something with each final value.
    });

Reading (until the channel is closed)

One by one read each entry from the channel

await channel.ReadAll(
    entry => { /* Processing Code */ });

await channel.ReadAll(
    (entry, index) => { /* Processing Code */ });

await channel.ReadAllAsync(
    async entry => { await /* Processing Code */ });

await channel.ReadAllAsync(
    async (entry, index) => { await /* Processing Code */ });

Read concurrently each entry from the channel

await channel.ReadAllConcurrently(
    maxConcurrency,
    entry => { /* Processing Code */ });

await channel.ReadAllConcurrentlyAsync(
    maxConcurrency,
    async entry => { await /* Processing Code */ });

Writing

If complete is true, the channel will be closed when the source is empty.

Dump a source enumeration into the channel

// source can be any IEnumerable<T>.
await channel.WriteAll(source, complete: true);

// source can be any IEnumerable<Task<T>> or IEnumerable<ValueTask<T>>.
await channel.WriteAllAsync(source, complete: true);

Synchronize reading from the source and process the results concurrently

// source can be any IEnumerable<Task<T>> or IEnumerable<ValueTask<T>>.
await channel.WriteAllConcurrentlyAsync(
    maxConcurrency, source, complete: true);

Filter & Transform

Both of these extensions operate synchronously after an item is read from the channel.

Any predicate or selector function must trap errors of the downstream read will fail and data may not be recoverable.

// Filter and transform when reading.
channel.Reader
    .Filter(predicate) // .Where()
    .Transform(selector) // .Select()
    .ReadAllAsync(async value => {/*...*/});

Batching

values.Reader
    .Batch(10 /*batch size*/) // Groups into List<T>.
    .WithTimeout(1000) // Any non-empty batches are flushed every second.
    .ReadAllAsync(async batch => {/*...*/});

Joining

The inverse of batching.

batches.Reader
    .Join() // Combines the batches into a single channel.
    .ReadAllAsync(async value => {/*...*/});

Pipelining / Transforming

Transform and buffer entries

// Transform values in a source channel to new unbounded channel.
var transformed = channel.Pipe(
    async value => /* transformation */);

// Transform values in a source channel to new unbounded channel with a max concurrency of X.
const int X = 4;
var transformed = channel.Pipe(
    X, async value => /* transformation */);

// Transform values in a source channel to new bounded channel bound of N entries.
const int N = 5;
var transformed = channel.Pipe(
    async value => /* transformation */, N);

// Transform values in a source channel to new bounded channel bound of N entries with a max concurrency of X.
const int X = 4;
const int N = 5;
var transformed = channel.Pipe(
    X, async value => /* transformation */, N);

// or
transformed = channel.Pipe(
    maxConcurrency: X,
    capacity: N,
    transform: async value => /* transformation */);