Class CacheConfig
- All Implemented Interfaces:
Cloneable
Java Beans-style configuration for caching HttpClient
.
Any class in the caching module that has configuration options should take a
CacheConfig
argument in one of its constructors. A
CacheConfig
instance has sane and conservative defaults, so the
easiest way to specify options is to get an instance and then set just
the options you want to modify from their defaults.
N.B. This class is only for caching-specific configuration; to
configure the behavior of the rest of the client, configure the
HttpClient
used as the "backend"
for the CachingHttpClient
.
Cache configuration can be grouped into the following categories:
Cache size. If the backend storage supports these limits, you
can specify the maximum number of
cache entries
as well as the getMaxObjectSize()
maximum cacheable response body size}.
Public/private caching. By default, the caching module considers
itself to be a shared (public) cache, and will not, for example, cache
responses to requests with Authorization
headers or responses
marked with Cache-Control: private
. If, however, the cache
is only going to be used by one logical "user" (behaving similarly to a
browser cache), then you will want to isSharedCache()
turn off the shared cache setting}.
303 caching. RFC2616 explicitly disallows caching 303 responses;
however, the HTTPbis working group says they can be cached
if explicitly indicated in the response headers and permitted by the request method.
(They also indicate that disallowing 303 caching is actually an unintended
spec error in RFC2616).
This behavior is off by default, to err on the side of a conservative
adherence to the existing standard, but you may want to
enable it
.
Weak ETags on PUT/DELETE If-Match requests. RFC2616 explicitly
prohibits the use of weak validators in non-GET requests, however, the
HTTPbis working group says while the limitation for weak validators on ranged
requests makes sense, weak ETag validation is useful on full non-GET
requests; e.g., PUT with If-Match. This behavior is off by default, to err on
the side of a conservative adherence to the existing standard, but you may
want to enable it
.
Heuristic caching. Per RFC2616, a cache may cache certain cache
entries even if no explicit cache control headers are set by the origin.
This behavior is off by default, but you may want to turn this on if you
are working with an origin that doesn't set proper headers but where you
still want to cache the responses. You will want to isHeuristicCachingEnabled()
enable heuristic caching},
then specify either a default freshness lifetime
and/or a fraction of the time since
the resource was last modified
. See Sections
13.2.2 and
13.2.4 of the HTTP/1.1 RFC for more details on heuristic caching.
Background validation. The cache module supports the
stale-while-revalidate
directive of
RFC5861, which allows
certain cache entry revalidations to happen in the background. Asynchronous
validation is enabled by default but it could be disabled by setting the number
of re-validation workers to 0
with getAsynchronousWorkers()
parameter
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Nested Class Summary
Nested Classes -
Field Summary
FieldsModifier and TypeFieldDescriptionprivate final boolean
private final int
static final CacheConfig
static final boolean
Default setting for 303 cachingstatic final int
Default number of worker threads to allow for background revalidations resulting from the stale-while-revalidate directive.static final boolean
Default setting for heuristic cachingstatic final float
Default coefficient used to heuristically determine freshness lifetime from the Last-Modified time of a cache entry.static final org.apache.hc.core5.util.TimeValue
Default lifetime to be assumed when we cannot calculate freshness heuristically.static final int
Default setting for the maximum number of cache entries that will be retained.static final int
Default setting for the maximum object size that will be cached, in bytes.static final int
Default setting for the number of retries on a failed cache processChallengestatic final boolean
Default setting to allow weak tags on PUT/DELETE methodsprivate final boolean
private final boolean
private final float
private final org.apache.hc.core5.util.TimeValue
private final int
private final long
private final int
private final boolean
private final boolean
private final boolean
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Constructor Summary
ConstructorsConstructorDescriptionCacheConfig
(long maxObjectSize, int maxCacheEntries, int maxUpdateRetries, boolean allow303Caching, boolean weakETagOnPutDeleteAllowed, boolean heuristicCachingEnabled, float heuristicCoefficient, org.apache.hc.core5.util.TimeValue heuristicDefaultLifetime, boolean sharedCache, boolean freshnessCheckEnabled, int asynchronousWorkers, boolean neverCacheHTTP10ResponsesWithQuery) -
Method Summary
Modifier and TypeMethodDescriptionprotected CacheConfig
clone()
static CacheConfig.Builder
copy
(CacheConfig config) static CacheConfig.Builder
custom()
int
Returns the maximum number of threads to allow for background revalidations due to thestale-while-revalidate
directive.float
Returns lifetime coefficient used in heuristic freshness caching.org.apache.hc.core5.util.TimeValue
Get the default lifetime to be used if heuristic freshness calculation is not possible.int
Returns the maximum number of cache entries the cache will retain.long
Returns the current maximum response body size that will be cached.int
Returns the number of times to retry a cache processChallenge on failureboolean
Returns whether 303 caching is enabled.boolean
Returns whether the cache will perform an extra cache entry freshness check upon cache update in case of a cache missboolean
Returns whether heuristic caching is enabled.boolean
Returns whether the cache will never cache HTTP 1.0 responses with a query string or not.boolean
Returns whether the cache will behave as a shared cache or not.boolean
Returns whether weak etags is allowed with PUT/DELETE methods.toString()
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Field Details
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DEFAULT_MAX_OBJECT_SIZE_BYTES
public static final int DEFAULT_MAX_OBJECT_SIZE_BYTESDefault setting for the maximum object size that will be cached, in bytes.- See Also:
-
DEFAULT_MAX_CACHE_ENTRIES
public static final int DEFAULT_MAX_CACHE_ENTRIESDefault setting for the maximum number of cache entries that will be retained.- See Also:
-
DEFAULT_MAX_UPDATE_RETRIES
public static final int DEFAULT_MAX_UPDATE_RETRIESDefault setting for the number of retries on a failed cache processChallenge- See Also:
-
DEFAULT_303_CACHING_ENABLED
public static final boolean DEFAULT_303_CACHING_ENABLEDDefault setting for 303 caching- See Also:
-
DEFAULT_WEAK_ETAG_ON_PUTDELETE_ALLOWED
public static final boolean DEFAULT_WEAK_ETAG_ON_PUTDELETE_ALLOWEDDefault setting to allow weak tags on PUT/DELETE methods- See Also:
-
DEFAULT_HEURISTIC_CACHING_ENABLED
public static final boolean DEFAULT_HEURISTIC_CACHING_ENABLEDDefault setting for heuristic caching- See Also:
-
DEFAULT_HEURISTIC_COEFFICIENT
public static final float DEFAULT_HEURISTIC_COEFFICIENTDefault coefficient used to heuristically determine freshness lifetime from the Last-Modified time of a cache entry.- See Also:
-
DEFAULT_HEURISTIC_LIFETIME
public static final org.apache.hc.core5.util.TimeValue DEFAULT_HEURISTIC_LIFETIMEDefault lifetime to be assumed when we cannot calculate freshness heuristically. -
DEFAULT_ASYNCHRONOUS_WORKERS
public static final int DEFAULT_ASYNCHRONOUS_WORKERSDefault number of worker threads to allow for background revalidations resulting from the stale-while-revalidate directive.- See Also:
-
DEFAULT
-
maxObjectSize
private final long maxObjectSize -
maxCacheEntries
private final int maxCacheEntries -
maxUpdateRetries
private final int maxUpdateRetries -
allow303Caching
private final boolean allow303Caching -
weakETagOnPutDeleteAllowed
private final boolean weakETagOnPutDeleteAllowed -
heuristicCachingEnabled
private final boolean heuristicCachingEnabled -
heuristicCoefficient
private final float heuristicCoefficient -
heuristicDefaultLifetime
private final org.apache.hc.core5.util.TimeValue heuristicDefaultLifetime -
freshnessCheckEnabled
private final boolean freshnessCheckEnabled -
asynchronousWorkers
private final int asynchronousWorkers -
neverCacheHTTP10ResponsesWithQuery
private final boolean neverCacheHTTP10ResponsesWithQuery
-
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Constructor Details
-
CacheConfig
CacheConfig(long maxObjectSize, int maxCacheEntries, int maxUpdateRetries, boolean allow303Caching, boolean weakETagOnPutDeleteAllowed, boolean heuristicCachingEnabled, float heuristicCoefficient, org.apache.hc.core5.util.TimeValue heuristicDefaultLifetime, boolean sharedCache, boolean freshnessCheckEnabled, int asynchronousWorkers, boolean neverCacheHTTP10ResponsesWithQuery)
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Method Details
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getMaxObjectSize
public long getMaxObjectSize()Returns the current maximum response body size that will be cached.- Returns:
- size in bytes
- Since:
- 4.2
-
isNeverCacheHTTP10ResponsesWithQuery
public boolean isNeverCacheHTTP10ResponsesWithQuery()Returns whether the cache will never cache HTTP 1.0 responses with a query string or not.- Returns:
true
to not cache query string responses,false
to cache if explicit cache headers are found
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getMaxCacheEntries
public int getMaxCacheEntries()Returns the maximum number of cache entries the cache will retain. -
getMaxUpdateRetries
public int getMaxUpdateRetries()Returns the number of times to retry a cache processChallenge on failure -
is303CachingEnabled
public boolean is303CachingEnabled()Returns whether 303 caching is enabled.- Returns:
true
if it is enabled.
-
isWeakETagOnPutDeleteAllowed
public boolean isWeakETagOnPutDeleteAllowed()Returns whether weak etags is allowed with PUT/DELETE methods.- Returns:
true
if it is allowed.
-
isHeuristicCachingEnabled
public boolean isHeuristicCachingEnabled()Returns whether heuristic caching is enabled.- Returns:
true
if it is enabled.
-
getHeuristicCoefficient
public float getHeuristicCoefficient()Returns lifetime coefficient used in heuristic freshness caching. -
getHeuristicDefaultLifetime
public org.apache.hc.core5.util.TimeValue getHeuristicDefaultLifetime()Get the default lifetime to be used if heuristic freshness calculation is not possible. -
isFreshnessCheckEnabled
public boolean isFreshnessCheckEnabled()Returns whether the cache will perform an extra cache entry freshness check upon cache update in case of a cache miss- Since:
- 5.0
-
getAsynchronousWorkers
public int getAsynchronousWorkers()Returns the maximum number of threads to allow for background revalidations due to thestale-while-revalidate
directive. A value of 0 means background revalidations are disabled. -
clone
- Overrides:
clone
in classObject
- Throws:
CloneNotSupportedException
-
custom
-
copy
-
toString
-