jdk.util.concurrent.Executors — clojure-interop/java.util.concurrent 1.0.0

Factory and utility methods for Executor, ExecutorService, ScheduledExecutorService, ThreadFactory, and Callable classes defined in this package. This class supports the following kinds of methods:

Methods that create and return an ExecutorService set up with commonly useful configuration settings. Methods that create and return a ScheduledExecutorService set up with commonly useful configuration settings. Methods that create and return a wrapped ExecutorService, that disables reconfiguration by making implementation-specific methods inaccessible. Methods that create and return a ThreadFactory that sets newly created threads to a known state. Methods that create and return a Callable out of other closure-like forms, so they can be used in execution methods requiring Callable.

*callable clj

(*callable task)

(*callable task result)

Returns a Callable object that, when called, runs the given task and returns the given result. This can be useful when applying methods requiring a Callable to an otherwise resultless action.

task - the task to run - java.lang.Runnable result - the result to return - T

returns: a callable object - <T> java.util.concurrent.Callable<T>

throws: java.lang.NullPointerException - if task null

*default-thread-factory clj

(*default-thread-factory)

Returns a default thread factory used to create new threads. This factory creates all new threads used by an Executor in the same ThreadGroup. If there is a SecurityManager, it uses the group of System.getSecurityManager(), else the group of the thread invoking this defaultThreadFactory method. Each new thread is created as a non-daemon thread with priority set to the smaller of Thread.NORM_PRIORITY and the maximum priority permitted in the thread group. New threads have names accessible via Thread.getName() of pool-N-thread-M, where N is the sequence number of this factory, and M is the sequence number of the thread created by this factory.

returns: a thread factory - java.util.concurrent.ThreadFactory

*new-cached-thread-pool clj

(*new-cached-thread-pool)

(*new-cached-thread-pool thread-factory)

Creates a thread pool that creates new threads as needed, but will reuse previously constructed threads when they are available, and uses the provided ThreadFactory to create new threads when needed.

thread-factory - the factory to use when creating new threads - java.util.concurrent.ThreadFactory

returns: the newly created thread pool - java.util.concurrent.ExecutorService

throws: java.lang.NullPointerException - if threadFactory is null

*new-fixed-thread-pool clj

(*new-fixed-thread-pool n-threads)

(*new-fixed-thread-pool n-threads thread-factory)

Creates a thread pool that reuses a fixed number of threads operating off a shared unbounded queue, using the provided ThreadFactory to create new threads when needed. At any point, at most nThreads threads will be active processing tasks. If additional tasks are submitted when all threads are active, they will wait in the queue until a thread is available. If any thread terminates due to a failure during execution prior to shutdown, a new one will take its place if needed to execute subsequent tasks. The threads in the pool will exist until it is explicitly shutdown.

n-threads - the number of threads in the pool - int thread-factory - the factory to use when creating new threads - java.util.concurrent.ThreadFactory

returns: the newly created thread pool - java.util.concurrent.ExecutorService

throws: java.lang.NullPointerException - if threadFactory is null

*new-scheduled-thread-pool clj

(*new-scheduled-thread-pool core-pool-size)

(*new-scheduled-thread-pool core-pool-size thread-factory)

Creates a thread pool that can schedule commands to run after a given delay, or to execute periodically.

core-pool-size - the number of threads to keep in the pool, even if they are idle - int thread-factory - the factory to use when the executor creates a new thread - java.util.concurrent.ThreadFactory

returns: a newly created scheduled thread pool - java.util.concurrent.ScheduledExecutorService

throws: java.lang.IllegalArgumentException - if corePoolSize < 0

*new-single-thread-executor clj

(*new-single-thread-executor)

(*new-single-thread-executor thread-factory)

Creates an Executor that uses a single worker thread operating off an unbounded queue, and uses the provided ThreadFactory to create a new thread when needed. Unlike the otherwise equivalent newFixedThreadPool(1, threadFactory) the returned executor is guaranteed not to be reconfigurable to use additional threads.

thread-factory - the factory to use when creating new threads - java.util.concurrent.ThreadFactory

returns: the newly created single-threaded Executor - java.util.concurrent.ExecutorService

throws: java.lang.NullPointerException - if threadFactory is null

*new-single-thread-scheduled-executor clj

(*new-single-thread-scheduled-executor)

(*new-single-thread-scheduled-executor thread-factory)

Creates a single-threaded executor that can schedule commands to run after a given delay, or to execute periodically. (Note however that if this single thread terminates due to a failure during execution prior to shutdown, a new one will take its place if needed to execute subsequent tasks.) Tasks are guaranteed to execute sequentially, and no more than one task will be active at any given time. Unlike the otherwise equivalent newScheduledThreadPool(1, threadFactory) the returned executor is guaranteed not to be reconfigurable to use additional threads.

thread-factory - the factory to use when creating new threads - java.util.concurrent.ThreadFactory

returns: a newly created scheduled executor - java.util.concurrent.ScheduledExecutorService

throws: java.lang.NullPointerException - if threadFactory is null

*new-work-stealing-pool clj

(*new-work-stealing-pool)

(*new-work-stealing-pool parallelism)

Creates a thread pool that maintains enough threads to support the given parallelism level, and may use multiple queues to reduce contention. The parallelism level corresponds to the maximum number of threads actively engaged in, or available to engage in, task processing. The actual number of threads may grow and shrink dynamically. A work-stealing pool makes no guarantees about the order in which submitted tasks are executed.

parallelism - the targeted parallelism level - int

returns: the newly created thread pool - java.util.concurrent.ExecutorService

throws: java.lang.IllegalArgumentException - if parallelism <= 0

*privileged-callable clj

(*privileged-callable callable)

Returns a Callable object that will, when called, execute the given callable under the current access control context. This method should normally be invoked within an AccessController.doPrivileged action to create callables that will, if possible, execute under the selected permission settings holding within that action; or if not possible, throw an associated AccessControlException.

callable - the underlying task - java.util.concurrent.Callable<T>

returns: a callable object - <T> java.util.concurrent.Callable<T>

throws: java.lang.NullPointerException - if callable null

*privileged-callable-using-current-class-loader clj

(*privileged-callable-using-current-class-loader callable)

Returns a Callable object that will, when called, execute the given callable under the current access control context, with the current context class loader as the context class loader. This method should normally be invoked within an AccessController.doPrivileged action to create callables that will, if possible, execute under the selected permission settings holding within that action; or if not possible, throw an associated AccessControlException.

callable - the underlying task - java.util.concurrent.Callable<T>

returns: a callable object - <T> java.util.concurrent.Callable<T>

throws: java.lang.NullPointerException - if callable null

*privileged-thread-factory clj

(*privileged-thread-factory)

Returns a thread factory used to create new threads that have the same permissions as the current thread. This factory creates threads with the same settings as defaultThreadFactory(), additionally setting the AccessControlContext and contextClassLoader of new threads to be the same as the thread invoking this privilegedThreadFactory method. A new privilegedThreadFactory can be created within an AccessController.doPrivileged action setting the current thread's access control context to create threads with the selected permission settings holding within that action.

Note that while tasks running within such threads will have the same access control and class loader settings as the current thread, they need not have the same ThreadLocal or InheritableThreadLocal values. If necessary, particular values of thread locals can be set or reset before any task runs in ThreadPoolExecutor subclasses using ThreadPoolExecutor.beforeExecute(Thread, Runnable). Also, if it is necessary to initialize worker threads to have the same InheritableThreadLocal settings as some other designated thread, you can create a custom ThreadFactory in which that thread waits for and services requests to create others that will inherit its values.

returns: a thread factory - java.util.concurrent.ThreadFactory

throws: java.security.AccessControlException - if the current access control context does not have permission to both get and set context class loader

*unconfigurable-executor-service clj

(*unconfigurable-executor-service executor)

Returns an object that delegates all defined ExecutorService methods to the given executor, but not any other methods that might otherwise be accessible using casts. This provides a way to safely freeze configuration and disallow tuning of a given concrete implementation.

executor - the underlying implementation - java.util.concurrent.ExecutorService

returns: an ExecutorService instance - java.util.concurrent.ExecutorService

throws: java.lang.NullPointerException - if executor null

*unconfigurable-scheduled-executor-service clj

(*unconfigurable-scheduled-executor-service executor)

Returns an object that delegates all defined ScheduledExecutorService methods to the given executor, but not any other methods that might otherwise be accessible using casts. This provides a way to safely freeze configuration and disallow tuning of a given concrete implementation.

executor - the underlying implementation - java.util.concurrent.ScheduledExecutorService

returns: a ScheduledExecutorService instance - java.util.concurrent.ScheduledExecutorService

throws: java.lang.NullPointerException - if executor null