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 | offer |
| ReceiveChannel | receive | onReceive | poll |
| ReceiveChannel | receiveOrNull | onReceiveOrNull | poll |
| Mutex | lock | onLock | tryLock |
| 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.
General-purpose coroutine builders, contexts, and helper functions.
Flow -- primitive to work with asynchronous and event-based streams of data.
Synchronization primitives (mutex).
Channels -- non-blocking primitives for communicating a stream of elements between coroutines.
Select expression to perform multiple suspending operations simultaneously until one of them succeeds.
Low-level primitives for finer-grained control of coroutines.