Apache HttpClient 5.3 · org.apache.hc.client5.http.impl.routing.DistributedProxySelector

A DistributedProxySelector is a custom ProxySelector implementation that delegates proxy selection to a list of underlying ProxySelectors in a distributed manner. It ensures that proxy selection is load-balanced across the available ProxySelectors, and provides thread safety by maintaining separate states for each thread.

The DistributedProxySelector class maintains a list of ProxySelectors, a ThreadLocal variable for the current ProxySelector, and an AtomicInteger to keep track of the shared index across all threads. When the select() method is called, it delegates the proxy selection to the current ProxySelector or the next available one in the list if the current one returns an empty proxy list. Any exceptions that occur during proxy selection are caught and ignored, and the next ProxySelector is tried.

The connectFailed() method notifies the active ProxySelector of a connection failure, allowing the underlying ProxySelector to handle connection failures according to its own logic.

Field Summary

Modifier and Type	Field and Description
private final ThreadLocal<ProxySelector>	currentSelector A `ThreadLocal` variable holding the current `ProxySelector` for each thread, ensuring thread safety when accessing the current `ProxySelector`.
private static final Logger	LOG
private final List<ProxySelector>	selectors A list of `ProxySelector` instances to be used by the DistributedProxySelector for selecting proxies.
private final AtomicInteger	sharedIndex An `AtomicInteger` representing the shared index across all threads for maintaining the current position in the list of ProxySelectors, ensuring proper distribution of `ProxySelector` usage.

Constructor Summary

Access	Constructor and Description
public	DistributedProxySelector(final List<ProxySelector> the list of ProxySelectors to use. selectors) Constructs a DistributedProxySelector with the given list of `ProxySelector`.

Method Summary

Modifier and Type	Method and Description
public void	connectFailed(final URI the `URI` that failed to connect. uri, final SocketAddress the `SocketAddress` of the proxy that failed to connect. sa, final IOException the `IOException` that resulted from the failed connection. ioe) Implements abstract java.net.ProxySelector.connectFailed. Notifies the active `ProxySelector` of a connection failure.
private ProxySelector	Returns: the next `ProxySelector` in the list. nextSelector() Retrieves the next available `ProxySelector` in the list of selectors, incrementing the shared index atomically to ensure proper distribution across different threads.
public List<Proxy>	Returns: a list of proxies for the given `URI`. select(final URI the `URI` to select a proxy for. uri) Implements abstract java.net.ProxySelector.select. Selects a list of proxies for the given `URI` by delegating to the current `ProxySelector` or the next available `ProxySelector` in the list if the current one returns an empty proxy list.

Inherited from java.net.ProxySelector:: getDefault of setDefault

Field Detail

currentSelector	back to summary
private final ThreadLocal<ProxySelector> currentSelector A `ThreadLocal` variable holding the current `ProxySelector` for each thread, ensuring thread safety when accessing the current `ProxySelector`.

LOG	back to summary
private static final Logger LOG

selectors	back to summary
private final List<ProxySelector> selectors A list of `ProxySelector` instances to be used by the DistributedProxySelector for selecting proxies.

sharedIndex	back to summary
private final AtomicInteger sharedIndex An `AtomicInteger` representing the shared index across all threads for maintaining the current position in the list of ProxySelectors, ensuring proper distribution of `ProxySelector` usage.

Constructor Detail

DistributedProxySelector back to summary

DistributedProxySelector	back to summary
public DistributedProxySelector(final List<ProxySelector> selectors) Constructs a DistributedProxySelector with the given list of `ProxySelector`. The constructor initializes the currentSelector as a `ThreadLocal`, and the sharedIndex as an `AtomicInteger`. Parameters selectors:List<ProxySelector> the list of ProxySelectors to use. Exceptions IllegalArgumentException: if the list is null or empty.

public DistributedProxySelector(final List<ProxySelector> selectors)

Constructs a DistributedProxySelector with the given list of ProxySelector. The constructor initializes the currentSelector as a ThreadLocal, and the sharedIndex as an AtomicInteger.

Parameters

selectors:List<ProxySelector>: the list of ProxySelectors to use.

Exceptions

IllegalArgumentException:: if the list is null or empty.

Method Detail

connectFailed back to summary

connectFailed	back to summary
public void connectFailed(final URI uri, final SocketAddress sa, final IOException ioe) Implements abstract java.net.ProxySelector.connectFailed. Notifies the active `ProxySelector` of a connection failure. This method retrieves the current `ProxySelector` from the `ThreadLocal` variable and delegates the handling of the connection failure to the underlying ProxySelector's connectFailed() method. After handling the connection failure, the current ProxySelector is removed from the `ThreadLocal` variable. Parameters uri:URI the `URI` that failed to connect. sa:SocketAddress the `SocketAddress` of the proxy that failed to connect. ioe:IOException the `IOException` that resulted from the failed connection. Annotations @Override

public void connectFailed(final URI uri, final SocketAddress sa, final IOException ioe)

Implements abstract java.net.ProxySelector.connectFailed.

Notifies the active ProxySelector of a connection failure. This method retrieves the current ProxySelector from the ThreadLocal variable and delegates the handling of the connection failure to the underlying ProxySelector's connectFailed() method. After handling the connection failure, the current ProxySelector is removed from the ThreadLocal variable.

Parameters

uri:URI: the URI that failed to connect.
sa:SocketAddress: the SocketAddress of the proxy that failed to connect.
ioe:IOException: the IOException that resulted from the failed connection.

Annotations

@Override

nextSelector back to summary

nextSelector	back to summary
private ProxySelector nextSelector() Retrieves the next available `ProxySelector` in the list of selectors, incrementing the shared index atomically to ensure proper distribution across different threads. Returns:ProxySelector the next `ProxySelector` in the list.

private ProxySelector nextSelector()

Retrieves the next available ProxySelector in the list of selectors, incrementing the shared index atomically to ensure proper distribution across different threads.

Returns:ProxySelector: the next ProxySelector in the list.

select back to summary

select	back to summary
public List<Proxy> select(final URI uri) Implements abstract java.net.ProxySelector.select. Selects a list of proxies for the given `URI` by delegating to the current `ProxySelector` or the next available `ProxySelector` in the list if the current one returns an empty proxy list. If an `Exception` occurs, it will be caught and ignored, and the next `ProxySelector` will be tried. Parameters uri:URI the `URI` to select a proxy for. Returns:List<Proxy> a list of proxies for the given `URI`. Annotations @Override

public List<Proxy> select(final URI uri)

Implements abstract java.net.ProxySelector.select.

Selects a list of proxies for the given URI by delegating to the current ProxySelector or the next available ProxySelector in the list if the current one returns an empty proxy list. If an Exception occurs, it will be caught and ignored, and the next ProxySelector will be tried.

Parameters

uri:URI: the URI to select a proxy for.

Returns:List<Proxy>

a list of proxies for the given URI.

Annotations

@Override

public Class DistributedProxySelector

Field Summary

Constructor Summary

Method Summary

Field Detail

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Method Detail