README.md

Module kotlinx-coroutines-core

Core primitives to work with coroutines available on all platforms.

Coroutine builder functions:

Name	Result	Scope	Description
launch	Job	CoroutineScope	Launches coroutine that does not have any result
async	Deferred	CoroutineScope	Returns a single value with the future result
produce	ReceiveChannel	ProducerScope	Produces a stream of elements
actor	SendChannel	ActorScope	Processes a stream of messages

Coroutine dispatchers implementing CoroutineDispatcher:

Name	Description
Dispatchers.Default	Confines coroutine execution to a shared pool of background threads
Dispatchers.Unconfined	Does not confine coroutine execution in any way
newSingleThreadContext	Creates a single-threaded coroutine context
newFixedThreadPoolContext	Creates a thread pool of a fixed size
Executor.asCoroutineDispatcher	Extension to convert any executor

More context elements:

Name	Description
NonCancellable	A non-cancelable job that is always active
CoroutineExceptionHandler	Handler for uncaught exception

Synchronization primitives for coroutines:

Name	Suspending functions	Description
Mutex	lock	Mutual exclusion
Channel	send, receive	Communication channel (aka queue or exchanger)

Top-level suspending functions:

Name	Description
delay	Non-blocking sleep
yield	Yields thread in single-threaded dispatchers
withContext	Switches to a different context
withTimeout	Set execution time-limit with exception on timeout
withTimeoutOrNull	Set execution time-limit will null result on timeout
awaitAll	Awaits for successful completion of all given jobs or exceptional completion of any
joinAll	Joins on all given jobs

Cancellation support for user-defined suspending functions is available with suspendCancellableCoroutine helper function. NonCancellable job object is provided to suppress cancellation with withContext(NonCancellable) {...} block of code.

Select expression waits for the result of multiple suspending functions simultaneously:

Receiver	Suspending function	Select clause	Non-suspending version
Job	join	onJoin	isCompleted
Deferred	await	onAwait	isCompleted
SendChannel	send	onSend	trySend
ReceiveChannel	receive	onReceive	tryReceive
ReceiveChannel	receiveCatching	onReceiveCatching	tryReceive
none	delay	onTimeout	none

This module provides debugging facilities for coroutines (run JVM with -ea or -Dkotlinx.coroutines.debug options) and newCoroutineContext function to write user-defined coroutine builders that work with these debugging facilities. See DEBUG_PROPERTY_NAME for more details.

This module provides a special CoroutineContext type TestCoroutineCoroutineContext that allows the writer of code that contains Coroutines with delays and timeouts to write non-flaky unit-tests for that code allowing these tests to terminate in near zero time. See the documentation for this class for more information.

Package kotlinx.coroutines

General-purpose coroutine builders, contexts, and helper functions.

Package kotlinx.coroutines.flow

Flow -- primitive to work with asynchronous and event-based streams of data.

Package kotlinx.coroutines.sync

Synchronization primitives (mutex).

Package kotlinx.coroutines.channels

Channels -- non-blocking primitives for communicating a stream of elements between coroutines.

Package kotlinx.coroutines.selects

Select expression to perform multiple suspending operations simultaneously until one of them succeeds.

Package kotlinx.coroutines.intrinsics

Low-level primitives for finer-grained control of coroutines.