com.android.volley

Class RequestQueue

java.lang.Object

com.android.volley.RequestQueue

public class RequestQueue
extends java.lang.Object

A request dispatch queue with a thread pool of dispatchers. Calling add(Request) will enqueue the given Request for dispatch, resolving from either cache or network on a worker thread, and then delivering a parsed response on the main thread.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	RequestQueue.RequestFilter A simple predicate or filter interface for Requests, for use by cancelAll(com.android.volley.RequestQueue.RequestFilter).

Field Summary

Fields

Modifier and Type	Field and Description
private static int	DEFAULT_NETWORK_THREAD_POOL_SIZE Number of network request dispatcher threads to start.
private Cache	mCache Cache interface for retrieving and storing responses.
private CacheDispatcher	mCacheDispatcher The cache dispatcher.
private java.util.concurrent.PriorityBlockingQueue<Request<?>>	mCacheQueue The cache triage queue.
private java.util.Set<Request<?>>	mCurrentRequests The set of all requests currently being processed by this RequestQueue.
private ResponseDelivery	mDelivery Response delivery mechanism.
private NetworkDispatcher[]	mDispatchers The network dispatchers.
private Network	mNetwork Network interface for performing requests.
private java.util.concurrent.PriorityBlockingQueue<Request<?>>	mNetworkQueue The queue of requests that are actually going out to the network.
private java.util.concurrent.atomic.AtomicInteger	mSequenceGenerator Used for generating monotonically-increasing sequence numbers for requests.
private java.util.Map<java.lang.String,java.util.Queue<Request<?>>>	mWaitingRequests Staging area for requests that already have a duplicate request in flight.

Constructor Summary

Constructors

Constructor and Description
RequestQueue(Cache cache, Network network) Creates the worker pool.
RequestQueue(Cache cache, Network network, int threadPoolSize) Creates the worker pool.
RequestQueue(Cache cache, Network network, int threadPoolSize, ResponseDelivery delivery) Creates the worker pool.

Method Summary

Modifier and Type	Method and Description
<T> Request<T>	add(Request<T> request) Adds a Request to the dispatch queue.
void	cancelAll(java.lang.Object tag) Cancels all requests in this queue with the given tag.
void	cancelAll(RequestQueue.RequestFilter filter) Cancels all requests in this queue for which the given filter applies.
(package private) void	finish(Request<?> request) Called from Request.finish(String), indicating that processing of the given request has finished.
Cache	getCache() Gets the Cache instance being used.
int	getSequenceNumber() Gets a sequence number.
void	start() Starts the dispatchers in this queue.
void	stop() Stops the cache and network dispatchers.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

mSequenceGenerator

private java.util.concurrent.atomic.AtomicInteger mSequenceGenerator

Used for generating monotonically-increasing sequence numbers for requests.

mWaitingRequests

private final java.util.Map<java.lang.String,java.util.Queue<Request<?>>> mWaitingRequests

Staging area for requests that already have a duplicate request in flight.

• containsKey(cacheKey) indicates that there is a request in flight for the given cache key.
• get(cacheKey) returns waiting requests for the given cache key. The in flight request is not contained in that list. Is null if no requests are staged.

mCurrentRequests

private final java.util.Set<Request<?>> mCurrentRequests

The set of all requests currently being processed by this RequestQueue. A Request will be in this set if it is waiting in any queue or currently being processed by any dispatcher.

mCacheQueue

private final java.util.concurrent.PriorityBlockingQueue<Request<?>> mCacheQueue

The cache triage queue.

mNetworkQueue

private final java.util.concurrent.PriorityBlockingQueue<Request<?>> mNetworkQueue

The queue of requests that are actually going out to the network.

DEFAULT_NETWORK_THREAD_POOL_SIZE

private static final int DEFAULT_NETWORK_THREAD_POOL_SIZE

Number of network request dispatcher threads to start.

See Also:

Constant Field Values

mCache

private final Cache mCache

Cache interface for retrieving and storing responses.

mNetwork

private final Network mNetwork

Network interface for performing requests.

mDelivery

private final ResponseDelivery mDelivery

Response delivery mechanism.

mDispatchers

private NetworkDispatcher[] mDispatchers

The network dispatchers.

mCacheDispatcher

private CacheDispatcher mCacheDispatcher

The cache dispatcher.

Constructor Detail

RequestQueue

public RequestQueue(Cache cache,
                    Network network,
                    int threadPoolSize,
                    ResponseDelivery delivery)

Creates the worker pool. Processing will not begin until start() is called.

Parameters:

cache - A Cache to use for persisting responses to disk

network - A Network interface for performing HTTP requests

threadPoolSize - Number of network dispatcher threads to create

delivery - A ResponseDelivery interface for posting responses and errors

RequestQueue

public RequestQueue(Cache cache,
                    Network network,
                    int threadPoolSize)

Creates the worker pool. Processing will not begin until start() is called.

Parameters:

cache - A Cache to use for persisting responses to disk

network - A Network interface for performing HTTP requests

threadPoolSize - Number of network dispatcher threads to create

RequestQueue

public RequestQueue(Cache cache,
                    Network network)

Creates the worker pool. Processing will not begin until start() is called.

Parameters:

cache - A Cache to use for persisting responses to disk

network - A Network interface for performing HTTP requests

Method Detail

start

public void start()

Starts the dispatchers in this queue.

stop

public void stop()

Stops the cache and network dispatchers.

getSequenceNumber

public int getSequenceNumber()

Gets a sequence number.

getCache

public Cache getCache()

Gets the Cache instance being used.

cancelAll

public void cancelAll(RequestQueue.RequestFilter filter)

Cancels all requests in this queue for which the given filter applies.

Parameters:

filter - The filtering function to use

cancelAll

public void cancelAll(java.lang.Object tag)

Cancels all requests in this queue with the given tag. Tag must be non-null and equality is by identity.

add

public <T> Request<T> add(Request<T> request)

Adds a Request to the dispatch queue.

Parameters:

request - The request to service

Returns:

The passed-in request

finish

void finish(Request<?> request)

Called from Request.finish(String), indicating that processing of the given request has finished.

Releases waiting requests for request.getCacheKey() if request.shouldCache().