com.browserup.bup.proxy.dns

Class NativeCacheManipulatingResolver

java.lang.Object

com.browserup.bup.proxy.dns.AbstractHostNameRemapper

com.browserup.bup.proxy.dns.NativeResolver

com.browserup.bup.proxy.dns.NativeCacheManipulatingResolver

All Implemented Interfaces:

AdvancedHostResolver, HostResolver

public class NativeCacheManipulatingResolver
extends NativeResolver

An AdvancedHostResolver that provides native JVM lookup using NativeResolver but also implements DNS cache manipulation functionality. Important note: The Oracle JVM does not provide any public facility to manipulate the JVM's DNS cache. This class uses reflection to forcibly manipulate the cache, which includes access to private class members that are not part of the published Java specification. As such, this implementation is brittle and may break in a future Java release, or may not work on non-Oracle JVMs. If this implementation cannot perform any of its operations due to a failure to find or set the relevant field using reflection, it will log a warning but will not throw an exception. You are using this class at your own risk! JVM cache manipulation does not work on Windows -- this class will behave exactly the same as NativeResolver on that platform.

Constructor Summary

Constructors

Constructor and Description
NativeCacheManipulatingResolver()

Method Summary

Modifier and Type	Method and Description
void	clearDNSCache() Clears both the positive (successful DNS lookups) and negative (failed DNS lookups) cache.
void	setNegativeDNSCacheTimeout(int timeout, java.util.concurrent.TimeUnit timeUnit) Sets the negative (failed DNS lookup) timeout when making DNS lookups.
void	setPositiveDNSCacheTimeout(int timeout, java.util.concurrent.TimeUnit timeUnit) Sets the positive (successful DNS lookup) timeout when making DNS lookups.

Methods inherited from class com.browserup.bup.proxy.dns.NativeResolver

resolveRemapped

Methods inherited from class com.browserup.bup.proxy.dns.AbstractHostNameRemapper

applyRemapping, clearHostRemappings, getHostRemappings, getOriginalHostnames, remapHost, remapHosts, removeHostRemapping, resolve

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.browserup.bup.proxy.dns.AdvancedHostResolver

clearHostRemappings, getHostRemappings, getOriginalHostnames, remapHost, remapHosts, removeHostRemapping

Methods inherited from interface com.browserup.bup.proxy.dns.HostResolver

resolve

Constructor Detail

NativeCacheManipulatingResolver

public NativeCacheManipulatingResolver()

Method Detail

clearDNSCache

public void clearDNSCache()

Description copied from interface: AdvancedHostResolver

Clears both the positive (successful DNS lookups) and negative (failed DNS lookups) cache.

Specified by:

clearDNSCache in interface AdvancedHostResolver

Overrides:

clearDNSCache in class NativeResolver

setPositiveDNSCacheTimeout

public void setPositiveDNSCacheTimeout(int timeout,
                                       java.util.concurrent.TimeUnit timeUnit)

Description copied from interface: AdvancedHostResolver

Sets the positive (successful DNS lookup) timeout when making DNS lookups. Note: The timeUnit parameter does not guarantee the specified precision; implementations may need to reduce precision, depending on the underlying DNS implementation. For example, the Oracle JVM's DNS cache only supports timeouts in whole seconds, so specifying a timeout of 1200ms will result in a timeout of 1 second.

Specified by:

setPositiveDNSCacheTimeout in interface AdvancedHostResolver

Overrides:

setPositiveDNSCacheTimeout in class NativeResolver

Parameters:

timeout - maximum lookup time

timeUnit - units of the timeout value

setNegativeDNSCacheTimeout

public void setNegativeDNSCacheTimeout(int timeout,
                                       java.util.concurrent.TimeUnit timeUnit)

Description copied from interface: AdvancedHostResolver

Sets the negative (failed DNS lookup) timeout when making DNS lookups. Note: The timeUnit parameter does not guarantee the specified precision; implementations may need to reduce precision, depending on the underlying DNS implementation. For example, the Oracle JVM's DNS cache only supports timeouts in whole seconds, so specifying a timeout of 1200ms will result in a timeout of 1 second.

Specified by:

setNegativeDNSCacheTimeout in interface AdvancedHostResolver

Overrides:

setNegativeDNSCacheTimeout in class NativeResolver

Parameters:

timeout - maximum lookup time

timeUnit - units of the timeout value