jdk.util.concurrent.BlockingDeque — clojure-interop/java.util.concurrent 1.0.5

A Deque that additionally supports blocking operations that wait for the deque to become non-empty when retrieving an element, and wait for space to become available in the deque when storing an element.

BlockingDeque methods come in four forms, with different ways of handling operations that cannot be satisfied immediately, but may be satisfied at some point in the future: one throws an exception, the second returns a special value (either null or false, depending on the operation), the third blocks the current thread indefinitely until the operation can succeed, and the fourth blocks for only a given maximum time limit before giving up. These methods are summarized in the following table:

Summary of BlockingDeque methods

First Element (Head)

Throws exception Special value Blocks Times out

Insert addFirst(e) offerFirst(e) putFirst(e) offerFirst(e, time, unit)

Remove removeFirst() pollFirst() takeFirst() pollFirst(time, unit)

Examine getFirst() peekFirst() not applicable not applicable

Last Element (Tail)

Throws exception Special value Blocks Times out

Insert addLast(e) offerLast(e) putLast(e) offerLast(e, time, unit)

Remove removeLast() pollLast() takeLast() pollLast(time, unit)

Examine getLast() peekLast() not applicable not applicable

Like any BlockingQueue, a BlockingDeque is thread safe, does not permit null elements, and may (or may not) be capacity-constrained.

A BlockingDeque implementation may be used directly as a FIFO BlockingQueue. The methods inherited from the BlockingQueue interface are precisely equivalent to BlockingDeque methods as indicated in the following table:

Comparison of BlockingQueue and BlockingDeque methods

BlockingQueue Method
Equivalent BlockingDeque Method


Insert

add(e) addLast(e)

offer(e) offerLast(e)

put(e) putLast(e)

offer(e, time, unit) offerLast(e, time, unit)

Remove

remove() removeFirst()

poll() pollFirst()

take() takeFirst()

poll(time, unit) pollFirst(time, unit)

Examine

element() getFirst()

peek() peekFirst()

Memory consistency effects: As with other concurrent collections, actions in a thread prior to placing an object into a BlockingDeque happen-before actions subsequent to the access or removal of that element from the BlockingDeque in another thread.

This interface is a member of the

Java Collections Framework.

add clj

(add this e)

Inserts the specified element into the queue represented by this deque (in other words, at the tail of this deque) if it is possible to do so immediately without violating capacity restrictions, returning true upon success and throwing an IllegalStateException if no space is currently available. When using a capacity-restricted deque, it is generally preferable to use offer.

This method is equivalent to addLast.

e - the element to add - E

returns: true (as specified by Collection.add(E)) - boolean

throws: java.lang.IllegalStateException - if the element cannot be added at this time due to capacity restrictions

add-first clj

(add-first this e)

Inserts the specified element at the front of this deque if it is possible to do so immediately without violating capacity restrictions, throwing an IllegalStateException if no space is currently available. When using a capacity-restricted deque, it is generally preferable to use offerFirst.

e - the element to add - E

throws: java.lang.IllegalStateException - if the element cannot be added at this time due to capacity restrictions

add-last clj

(add-last this e)

Inserts the specified element at the end of this deque if it is possible to do so immediately without violating capacity restrictions, throwing an IllegalStateException if no space is currently available. When using a capacity-restricted deque, it is generally preferable to use offerLast.

e - the element to add - E

throws: java.lang.IllegalStateException - if the element cannot be added at this time due to capacity restrictions

contains clj

(contains this o)

Returns true if this deque contains the specified element. More formally, returns true if and only if this deque contains at least one element e such that o.equals(e).

o - object to be checked for containment in this deque - java.lang.Object

returns: true if this deque contains the specified element - boolean

throws: java.lang.ClassCastException - if the class of the specified element is incompatible with this deque (optional)

element clj

(element this)

Retrieves, but does not remove, the head of the queue represented by this deque (in other words, the first element of this deque). This method differs from peek only in that it throws an exception if this deque is empty.

This method is equivalent to getFirst.

returns: the head of this deque - E

throws: java.util.NoSuchElementException - if this deque is empty

iterator clj

(iterator this)

Returns an iterator over the elements in this deque in proper sequence. The elements will be returned in order from first (head) to last (tail).

returns: an iterator over the elements in this deque in proper sequence - java.util.Iterator<E>

offer clj

(offer this e)

(offer this e timeout unit)

Inserts the specified element into the queue represented by this deque (in other words, at the tail of this deque), waiting up to the specified wait time if necessary for space to become available.

This method is equivalent to offerLast.

e - the element to add - E timeout - how long to wait before giving up, in units of unit - long unit - a TimeUnit determining how to interpret the timeout parameter - java.util.concurrent.TimeUnit

returns: true if the element was added to this deque, else false - boolean

throws: java.lang.InterruptedException - if interrupted while waiting

offer-first clj

(offer-first this e)

(offer-first this e timeout unit)

Inserts the specified element at the front of this deque, waiting up to the specified wait time if necessary for space to become available.

e - the element to add - E timeout - how long to wait before giving up, in units of unit - long unit - a TimeUnit determining how to interpret the timeout parameter - java.util.concurrent.TimeUnit

returns: true if successful, or false if the specified waiting time elapses before space is available - boolean

throws: java.lang.InterruptedException - if interrupted while waiting

offer-last clj

(offer-last this e)

(offer-last this e timeout unit)

Inserts the specified element at the end of this deque, waiting up to the specified wait time if necessary for space to become available.

e - the element to add - E timeout - how long to wait before giving up, in units of unit - long unit - a TimeUnit determining how to interpret the timeout parameter - java.util.concurrent.TimeUnit

returns: true if successful, or false if the specified waiting time elapses before space is available - boolean

throws: java.lang.InterruptedException - if interrupted while waiting

peek clj

(peek this)

Retrieves, but does not remove, the head of the queue represented by this deque (in other words, the first element of this deque), or returns null if this deque is empty.

This method is equivalent to peekFirst.

returns: the head of this deque, or null if this deque is empty - E

poll clj

(poll this)

(poll this timeout unit)

Retrieves and removes the head of the queue represented by this deque (in other words, the first element of this deque), waiting up to the specified wait time if necessary for an element to become available.

This method is equivalent to pollFirst.

timeout - how long to wait before giving up, in units of unit - long unit - a TimeUnit determining how to interpret the timeout parameter - java.util.concurrent.TimeUnit

returns: the head of this deque, or null if the specified waiting time elapses before an element is available - E

throws: java.lang.InterruptedException - if interrupted while waiting

poll-first clj

(poll-first this timeout unit)

Retrieves and removes the first element of this deque, waiting up to the specified wait time if necessary for an element to become available.

timeout - how long to wait before giving up, in units of unit - long unit - a TimeUnit determining how to interpret the timeout parameter - java.util.concurrent.TimeUnit

returns: the head of this deque, or null if the specified waiting time elapses before an element is available - E

throws: java.lang.InterruptedException - if interrupted while waiting

poll-last clj

(poll-last this timeout unit)

Retrieves and removes the last element of this deque, waiting up to the specified wait time if necessary for an element to become available.

timeout - how long to wait before giving up, in units of unit - long unit - a TimeUnit determining how to interpret the timeout parameter - java.util.concurrent.TimeUnit

returns: the tail of this deque, or null if the specified waiting time elapses before an element is available - E

throws: java.lang.InterruptedException - if interrupted while waiting

push clj

(push this e)

Pushes an element onto the stack represented by this deque (in other words, at the head of this deque) if it is possible to do so immediately without violating capacity restrictions, throwing an IllegalStateException if no space is currently available.

This method is equivalent to addFirst.

e - the element to push - E

throws: java.lang.IllegalStateException - if the element cannot be added at this time due to capacity restrictions

put clj

(put this e)

Inserts the specified element into the queue represented by this deque (in other words, at the tail of this deque), waiting if necessary for space to become available.

This method is equivalent to putLast.

e - the element to add - E

throws: java.lang.InterruptedException - if interrupted while waiting

put-first clj

(put-first this e)

Inserts the specified element at the front of this deque, waiting if necessary for space to become available.

e - the element to add - E

throws: java.lang.InterruptedException - if interrupted while waiting

put-last clj

(put-last this e)

Inserts the specified element at the end of this deque, waiting if necessary for space to become available.

e - the element to add - E

throws: java.lang.InterruptedException - if interrupted while waiting

remove clj

(remove this)

(remove this o)

Removes the first occurrence of the specified element from this deque. If the deque does not contain the element, it is unchanged. More formally, removes the first element e such that o.equals(e) (if such an element exists). Returns true if this deque contained the specified element (or equivalently, if this deque changed as a result of the call).

This method is equivalent to removeFirstOccurrence.

o - element to be removed from this deque, if present - java.lang.Object

returns: true if this deque changed as a result of the call - boolean

throws: java.lang.ClassCastException - if the class of the specified element is incompatible with this deque (optional)

remove-first-occurrence clj

(remove-first-occurrence this o)

Removes the first occurrence of the specified element from this deque. If the deque does not contain the element, it is unchanged. More formally, removes the first element e such that o.equals(e) (if such an element exists). Returns true if this deque contained the specified element (or equivalently, if this deque changed as a result of the call).

o - element to be removed from this deque, if present - java.lang.Object

returns: true if an element was removed as a result of this call - boolean

throws: java.lang.ClassCastException - if the class of the specified element is incompatible with this deque (optional)

remove-last-occurrence clj

(remove-last-occurrence this o)

Removes the last occurrence of the specified element from this deque. If the deque does not contain the element, it is unchanged. More formally, removes the last element e such that o.equals(e) (if such an element exists). Returns true if this deque contained the specified element (or equivalently, if this deque changed as a result of the call).

o - element to be removed from this deque, if present - java.lang.Object

returns: true if an element was removed as a result of this call - boolean

throws: java.lang.ClassCastException - if the class of the specified element is incompatible with this deque (optional)

size clj

(size this)

Returns the number of elements in this deque.

returns: the number of elements in this deque - int

take clj

(take this)

Retrieves and removes the head of the queue represented by this deque (in other words, the first element of this deque), waiting if necessary until an element becomes available.

This method is equivalent to takeFirst.

returns: the head of this deque - E

throws: java.lang.InterruptedException - if interrupted while waiting

take-first clj

(take-first this)

Retrieves and removes the first element of this deque, waiting if necessary until an element becomes available.

returns: the head of this deque - E

throws: java.lang.InterruptedException - if interrupted while waiting

take-last clj

(take-last this)

Retrieves and removes the last element of this deque, waiting if necessary until an element becomes available.

returns: the tail of this deque - E

throws: java.lang.InterruptedException - if interrupted while waiting