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HTTPCLIENT-990: Allow heuristic freshness caching 

Contributed by Michajlo Matijkiw <michajlo_matijkiw at comcast.com>


git-svn-id: https://svn.apache.org/repos/asf/httpcomponents/httpclient/trunk@1024393 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Oleg Kalnichevski 2010-10-19 20:17:16 +00:00
parent de7daf36de
commit 6b539c8c86
5 changed files with 200 additions and 1 deletions
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68
httpclient-cache/src/main/java/org/apache/http/impl/client/cache/CacheConfig.java vendored
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@ -47,10 +47,25 @@ public class CacheConfig {
*/
public final static int DEFAULT_MAX_UPDATE_RETRIES = 1;
/** Default setting for heuristic caching
*/
public final static boolean DEFAULT_HEURISTIC_CACHING_ENABLED = false;
/** Default coefficient used to heuristically determine freshness lifetime from
* cache entry.
*/
public final static float DEFAULT_HEURISTIC_COEFFICIENT = 0.1f;
/** Default lifetime to be assumed when we cannot calculate freshness heuristically
*/
public final static long DEFAULT_HEURISTIC_LIFETIME = 0;
private int maxObjectSizeBytes = DEFAULT_MAX_OBJECT_SIZE_BYTES;
private int maxCacheEntries = DEFAULT_MAX_CACHE_ENTRIES;
private int maxUpdateRetries = DEFAULT_MAX_UPDATE_RETRIES;
private boolean heuristicCachingEnabled = false;
private float heuristicCoefficient = DEFAULT_HEURISTIC_COEFFICIENT;
private long heuristicDefaultLifetime = DEFAULT_HEURISTIC_LIFETIME;
private boolean isSharedCache = true;
/**
@ -118,4 +133,55 @@ public class CacheConfig {
public void setMaxUpdateRetries(int maxUpdateRetries){
this.maxUpdateRetries = maxUpdateRetries;
}
/**
* Returns if heuristic freshness caching is in enabled
* @return
*/
public boolean isHeuristicCachingEnabled() {
return heuristicCachingEnabled;
}
/**
* Set if heuristic freshness caching is enabled
* @param heursiticCachingEnabled
*/
public void setHeuristicCachingEnabled(boolean heuristicCachingEnabled) {
this.heuristicCachingEnabled = heuristicCachingEnabled;
}
/**
* Returns coefficient used in heuristic freshness caching
* @return
*/
public float getHeuristicCoefficient() {
return heuristicCoefficient;
}
/**
* Set coefficient to be used in heuristic freshness caching
* @param heuristicCoefficient
*/
public void setHeuristicCoefficient(float heuristicCoefficient) {
this.heuristicCoefficient = heuristicCoefficient;
}
/**
* Get the default lifetime to be used if heuristic freshness calculation is
* not possible
* @return
*/
public long getHeuristicDefaultLifetime() {
return heuristicDefaultLifetime;
}
/**
* Set default lifetime to be used if heuristic freshness calculation is not possible
* @param heuristicDefaultLifetime
*/
public void setHeuristicDefaultLifetime(long heuristicDefaultLifetime) {
this.heuristicDefaultLifetime = heuristicDefaultLifetime;
}
}

45
httpclient-cache/src/main/java/org/apache/http/impl/client/cache/CacheValidityPolicy.java vendored
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@ -73,6 +73,39 @@ class CacheValidityPolicy {
return (getCurrentAgeSecs(entry, now) < getFreshnessLifetimeSecs(entry));
}
/**
* Decides if this response is fresh enough based Last-Modified and Date, if available.
* This entry is meant to be used when isResponseFresh returns false. The algorithm is as follows:
*
* if last-modified and date are defined, freshness lifetime is coefficient*(date-lastModified),
* else freshness lifetime is defaultLifetime
*
* @param entry
* @param now
* @param coefficient
* @param defaultLifetime
* @return
*/
public boolean isResponseHeuristicallyFresh(final HttpCacheEntry entry,
Date now, float coefficient, long defaultLifetime) {
return (getCurrentAgeSecs(entry, now) < getHeuristicFreshnessLifetimeSecs(entry, coefficient, defaultLifetime));
}
public long getHeuristicFreshnessLifetimeSecs(HttpCacheEntry entry,
float coefficient, long defaultLifetime) {
Date dateValue = getDateValue(entry);
Date lastModifiedValue = getLastModifiedValue(entry);
if (dateValue != null && lastModifiedValue != null) {
long diff = dateValue.getTime() - lastModifiedValue.getTime();
if (diff < 0)
return 0;
return (long)(coefficient * (diff / 1000));
}
return defaultLifetime;
}
public boolean isRevalidatable(final HttpCacheEntry entry) {
return entry.getFirstHeader(HeaderConstants.ETAG) != null
|| entry.getFirstHeader(HeaderConstants.LAST_MODIFIED) != null;
@ -98,6 +131,18 @@ class CacheValidityPolicy {
return null;
}
protected Date getLastModifiedValue(final HttpCacheEntry entry) {
Header dateHdr = entry.getFirstHeader(HeaderConstants.LAST_MODIFIED);
if (dateHdr == null)
return null;
try {
return DateUtils.parseDate(dateHdr.getValue());
} catch (DateParseException dpe) {
// ignore malformed date
}
return null;
}
protected long getContentLengthValue(final HttpCacheEntry entry) {
Header cl = entry.getFirstHeader(HTTP.CONTENT_LEN);
if (cl == null)

9
httpclient-cache/src/main/java/org/apache/http/impl/client/cache/CachedResponseSuitabilityChecker.java vendored
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@ -52,6 +52,9 @@ class CachedResponseSuitabilityChecker {
private final Log log = LogFactory.getLog(getClass());
private final boolean sharedCache;
private final boolean useHeuristicCaching;
private final float heuristicCoefficient;
private final long heuristicDefaultLifetime;
private final CacheValidityPolicy validityStrategy;
CachedResponseSuitabilityChecker(final CacheValidityPolicy validityStrategy,
@ -59,6 +62,9 @@ class CachedResponseSuitabilityChecker {
super();
this.validityStrategy = validityStrategy;
this.sharedCache = config.isSharedCache();
this.useHeuristicCaching = config.isHeuristicCachingEnabled();
this.heuristicCoefficient = config.getHeuristicCoefficient();
this.heuristicDefaultLifetime = config.getHeuristicDefaultLifetime();
}
CachedResponseSuitabilityChecker(CacheConfig config) {
@ -67,6 +73,9 @@ class CachedResponseSuitabilityChecker {
private boolean isFreshEnough(HttpCacheEntry entry, HttpRequest request, Date now) {
if (validityStrategy.isResponseFresh(entry, now)) return true;
if (useHeuristicCaching &&
validityStrategy.isResponseHeuristicallyFresh(entry, now, heuristicCoefficient, heuristicDefaultLifetime))
return true;
if (originInsistsOnFreshness(entry)) return false;
long maxstale = getMaxStale(request);
if (maxstale == -1) return false;

42
httpclient-cache/src/test/java/org/apache/http/impl/client/cache/TestCacheValidityPolicy.java vendored
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@ -250,6 +250,48 @@ public class TestCacheValidityPolicy {
Assert.assertEquals(4, impl.getFreshnessLifetimeSecs(entry));
}
@Test
public void testHeuristicFreshnessLifetime() {
Date now = new Date();
Date oneSecondAgo = new Date(now.getTime() - 1 * 1000L);
Date elevenSecondsAgo = new Date(now.getTime() - 11 * 1000L);
Header[] headers = new Header[] {
new BasicHeader("Date", DateUtils.formatDate(oneSecondAgo)),
new BasicHeader("Last-Modified", DateUtils.formatDate(elevenSecondsAgo))
};
HttpCacheEntry entry = HttpTestUtils.makeCacheEntry(headers);
CacheValidityPolicy impl = new CacheValidityPolicy();
Assert.assertEquals(1, impl.getHeuristicFreshnessLifetimeSecs(entry, 0.1f, 0));
}
@Test
public void testHeuristicFreshnessLifetimeDefaultsProperly() {
long defaultFreshness = 10;
HttpCacheEntry entry = HttpTestUtils.makeCacheEntry();
CacheValidityPolicy impl = new CacheValidityPolicy();
Assert.assertEquals(defaultFreshness, impl.getHeuristicFreshnessLifetimeSecs(entry, 0.1f, defaultFreshness));
}
@Test
public void testHeuristicFreshnessLifetimeIsNonNegative() {
Date now = new Date();
Date oneSecondAgo = new Date(now.getTime() - 1 * 1000L);
Date elevenSecondsAgo = new Date(now.getTime() - 1 * 1000L);
Header[] headers = new Header[] {
new BasicHeader("Date", DateUtils.formatDate(elevenSecondsAgo)),
new BasicHeader("Last-Modified", DateUtils.formatDate(oneSecondAgo))
};
HttpCacheEntry entry = HttpTestUtils.makeCacheEntry(headers);
CacheValidityPolicy impl = new CacheValidityPolicy();
Assert.assertTrue(impl.getHeuristicFreshnessLifetimeSecs(entry, 0.1f, 10) >= 0);
}
@Test
public void testResponseIsFreshIfFreshnessLifetimeExceedsCurrentAge() {
final HttpCacheEntry entry = HttpTestUtils.makeCacheEntry();

37
httpclient-cache/src/test/java/org/apache/http/impl/client/cache/TestCachedResponseSuitabilityChecker.java vendored
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@ -223,4 +223,41 @@ public class TestCachedResponseSuitabilityChecker {
Assert.assertFalse(impl.canCachedResponseBeUsed(host, request, entry, now));
}
@Test
public void testSuitableIfCacheEntryIsHeuristicallyFreshEnough() {
Date oneSecondAgo = new Date(now.getTime() - 1 * 1000L);
Date twentyOneSecondsAgo = new Date(now.getTime() - 21 * 1000L);
Header[] headers = {
new BasicHeader("Date", DateUtils.formatDate(oneSecondAgo)),
new BasicHeader("Last-Modified", DateUtils.formatDate(twentyOneSecondsAgo)),
new BasicHeader("Content-Length", "128")
};
entry = HttpTestUtils.makeCacheEntry(oneSecondAgo, oneSecondAgo, headers);
CacheConfig config = new CacheConfig();
config.setHeuristicCachingEnabled(true);
config.setHeuristicCoefficient(0.1f);
impl = new CachedResponseSuitabilityChecker(config);
Assert.assertTrue(impl.canCachedResponseBeUsed(host, request, entry, now));
}
@Test
public void testSuitableIfCacheEntryIsHeuristicallyFreshEnoughByDefault() {
Header[] headers = {
new BasicHeader("Date", DateUtils.formatDate(tenSecondsAgo)),
new BasicHeader("Content-Length", "128")
};
entry = getEntry(headers);
CacheConfig config = new CacheConfig();
config.setHeuristicCachingEnabled(true);
config.setHeuristicDefaultLifetime(20);
impl = new CachedResponseSuitabilityChecker(config);
Assert.assertTrue(impl.canCachedResponseBeUsed(host, request, entry, now));
}
}