src/third_party/icu/source/common/unifiedcache.cpp - cobalt - Git at Google

 /*
 ******************************************************************************
 * Copyright (C) 2015, International Business Machines Corporation and
 * others. All Rights Reserved.
 ******************************************************************************
 *
 * File UNIFIEDCACHE.CPP
 ******************************************************************************
 */

 #include "starboard/client_porting/poem/assert_poem.h"
 #include "starboard/client_porting/poem/string_poem.h"
 #include "uhash.h"
 #include "unifiedcache.h"
 #include "umutex.h"
 #include "mutex.h"
 #include "uassert.h"
 #include "ucln_cmn.h"

 static icu::UnifiedCache *gCache = NULL;
 static icu::SharedObject *gNoValue = NULL;
 static UMutex gCacheMutex = U_MUTEX_INITIALIZER;
 static UConditionVar gInProgressValueAddedCond = U_CONDITION_INITIALIZER;
 static icu::UInitOnce gCacheInitOnce = U_INITONCE_INITIALIZER;
 static const int32_t MAX_EVICT_ITERATIONS = 10;

 static int32_t DEFAULT_MAX_UNUSED = 1000;
 static int32_t DEFAULT_PERCENTAGE_OF_IN_USE = 100;


 U_CDECL_BEGIN
 static UBool U_CALLCONV unifiedcache_cleanup() {
     gCacheInitOnce.reset();
     if (gCache) {
         delete gCache;
         gCache = NULL;
     }
     if (gNoValue) {
         delete gNoValue;
         gNoValue = NULL;
     }
     return TRUE;
 }
 U_CDECL_END


 U_NAMESPACE_BEGIN

 U_CAPI int32_t U_EXPORT2
 ucache_hashKeys(const UHashTok key) {
     const CacheKeyBase *ckey = (const CacheKeyBase *) key.pointer;
     return ckey->hashCode();
 }

 U_CAPI UBool U_EXPORT2
 ucache_compareKeys(const UHashTok key1, const UHashTok key2) {
     const CacheKeyBase *p1 = (const CacheKeyBase *) key1.pointer;
     const CacheKeyBase *p2 = (const CacheKeyBase *) key2.pointer;
     return *p1 == *p2;
 }

 U_CAPI void U_EXPORT2
 ucache_deleteKey(void *obj) {
     CacheKeyBase *p = (CacheKeyBase *) obj;
     delete p;
 }

 CacheKeyBase::~CacheKeyBase() {
 }

 static void U_CALLCONV cacheInit(UErrorCode &status) {
     U_ASSERT(gCache == NULL);
     ucln_common_registerCleanup(
             UCLN_COMMON_UNIFIED_CACHE, unifiedcache_cleanup);

     // gNoValue must be created first to avoid assertion error in
     // cache constructor.
     gNoValue = new SharedObject();
     gCache = new UnifiedCache(status);
     if (gCache == NULL) {
         status = U_MEMORY_ALLOCATION_ERROR;
     }
     if (U_FAILURE(status)) {
         delete gCache;
         delete gNoValue;
         gCache = NULL;
         gNoValue = NULL;
         return;
     }
     // We add a softref because we want hash elements with gNoValue to be
     // elligible for purging but we don't ever want gNoValue to be deleted.
     gNoValue->addSoftRef();
 }

 UnifiedCache *UnifiedCache::getInstance(UErrorCode &status) {
     umtx_initOnce(gCacheInitOnce, &cacheInit, status);
     if (U_FAILURE(status)) {
         return NULL;
     }
     U_ASSERT(gCache != NULL);
     return gCache;
 }

 UnifiedCache::UnifiedCache(UErrorCode &status) :
         fHashtable(NULL),
         fEvictPos(UHASH_FIRST),
         fItemsInUseCount(0),
         fMaxUnused(DEFAULT_MAX_UNUSED),
         fMaxPercentageOfInUse(DEFAULT_PERCENTAGE_OF_IN_USE),
         fAutoEvictedCount(0) {
     if (U_FAILURE(status)) {
         return;
     }
     U_ASSERT(gNoValue != NULL);
     fHashtable = uhash_open(
             &ucache_hashKeys,
             &ucache_compareKeys,
             NULL,
             &status);
     if (U_FAILURE(status)) {
         return;
     }
     uhash_setKeyDeleter(fHashtable, &ucache_deleteKey);
 }

 void UnifiedCache::setEvictionPolicy(
         int32_t count, int32_t percentageOfInUseItems, UErrorCode &status) {
     if (U_FAILURE(status)) {
         return;
     }
     if (count < 0 || percentageOfInUseItems < 0) {
         status = U_ILLEGAL_ARGUMENT_ERROR;
         return;
     }
     Mutex lock(&gCacheMutex);
     fMaxUnused = count;
     fMaxPercentageOfInUse = percentageOfInUseItems;
 }

 int32_t UnifiedCache::unusedCount() const {
     Mutex lock(&gCacheMutex);
     return uhash_count(fHashtable) - fItemsInUseCount;
 }

 int64_t UnifiedCache::autoEvictedCount() const {
     Mutex lock(&gCacheMutex);
     return fAutoEvictedCount;
 }

 int32_t UnifiedCache::keyCount() const {
     Mutex lock(&gCacheMutex);
     return uhash_count(fHashtable);
 }

 void UnifiedCache::flush() const {
     Mutex lock(&gCacheMutex);

     // Use a loop in case cache items that are flushed held hard references to
     // other cache items making those additional cache items eligible for
     // flushing.
     while (_flush(FALSE));
 }

 #ifdef UNIFIED_CACHE_DEBUG
 #include <stdio.h>

 void UnifiedCache::dump() {
     UErrorCode status = U_ZERO_ERROR;
     const UnifiedCache *cache = getInstance(status);
     if (U_FAILURE(status)) {
         fprintf(stderr, "Unified Cache: Error fetching cache.\n");
         return;
     }
     cache->dumpContents();
 }

 void UnifiedCache::dumpContents() const {
     Mutex lock(&gCacheMutex);
     _dumpContents();
 }

 // Dumps content of cache.
 // On entry, gCacheMutex must be held.
 // On exit, cache contents dumped to stderr.
 void UnifiedCache::_dumpContents() const {
     int32_t pos = UHASH_FIRST;
     const UHashElement *element = uhash_nextElement(fHashtable, &pos);
     char buffer[256];
     int32_t cnt = 0;
     for (; element != NULL; element = uhash_nextElement(fHashtable, &pos)) {
         const SharedObject *sharedObject =
                 (const SharedObject *) element->value.pointer;
         const CacheKeyBase *key =
                 (const CacheKeyBase *) element->key.pointer;
         if (sharedObject->hasHardReferences()) {
             ++cnt;
             fprintf(
                     stderr,
                     "Unified Cache: Key '%s', error %d, value %p, total refcount %d, soft refcount %d\n",
                     key->writeDescription(buffer, 256),
                     key->creationStatus,
                     sharedObject == gNoValue ? NULL :sharedObject,
                     sharedObject->getRefCount(),
                     sharedObject->getSoftRefCount());
         }
     }
     fprintf(stderr, "Unified Cache: %d out of a total of %d still have hard references\n", cnt, uhash_count(fHashtable));
 }
 #endif

 UnifiedCache::~UnifiedCache() {
     // Try our best to clean up first.
     flush();
     {
         // Now all that should be left in the cache are entries that refer to
         // each other and entries with hard references from outside the cache.
         // Nothing we can do about these so proceed to wipe out the cache.
         Mutex lock(&gCacheMutex);
         _flush(TRUE);
     }
     uhash_close(fHashtable);
 }

 // Returns the next element in the cache round robin style.
 // On entry, gCacheMutex must be held.
 const UHashElement *
 UnifiedCache::_nextElement() const {
     const UHashElement *element = uhash_nextElement(fHashtable, &fEvictPos);
     if (element == NULL) {
         fEvictPos = UHASH_FIRST;
         return uhash_nextElement(fHashtable, &fEvictPos);
     }
     return element;
 }

 // Flushes the contents of the cache. If cache values hold references to other
 // cache values then _flush should be called in a loop until it returns FALSE.
 // On entry, gCacheMutex must be held.
 // On exit, those values with are evictable are flushed. If all is true
 // then every value is flushed even if it is not evictable.
 // Returns TRUE if any value in cache was flushed or FALSE otherwise.
 UBool UnifiedCache::_flush(UBool all) const {
     UBool result = FALSE;
     int32_t origSize = uhash_count(fHashtable);
     for (int32_t i = 0; i < origSize; ++i) {
         const UHashElement *element = _nextElement();
         if (all || _isEvictable(element)) {
             const SharedObject *sharedObject =
                     (const SharedObject *) element->value.pointer;
             uhash_removeElement(fHashtable, element);
             sharedObject->removeSoftRef();
             result = TRUE;
         }
     }
     return result;
 }

 // Computes how many items should be evicted.
 // On entry, gCacheMutex must be held.
 // Returns number of items that should be evicted or a value <= 0 if no
 // items need to be evicted.
 int32_t UnifiedCache::_computeCountOfItemsToEvict() const {
     int32_t maxPercentageOfInUseCount =
             fItemsInUseCount * fMaxPercentageOfInUse / 100;
     int32_t maxUnusedCount = fMaxUnused;
     if (maxUnusedCount < maxPercentageOfInUseCount) {
         maxUnusedCount = maxPercentageOfInUseCount;
     }
     return uhash_count(fHashtable) - fItemsInUseCount - maxUnusedCount;
 }

 // Run an eviction slice.
 // On entry, gCacheMutex must be held.
 // _runEvictionSlice runs a slice of the evict pipeline by examining the next
 // 10 entries in the cache round robin style evicting them if they are eligible.
 void UnifiedCache::_runEvictionSlice() const {
     int32_t maxItemsToEvict = _computeCountOfItemsToEvict();
     if (maxItemsToEvict <= 0) {
         return;
     }
     for (int32_t i = 0; i < MAX_EVICT_ITERATIONS; ++i) {
         const UHashElement *element = _nextElement();
         if (_isEvictable(element)) {
             const SharedObject *sharedObject =
                     (const SharedObject *) element->value.pointer;
             uhash_removeElement(fHashtable, element);
             sharedObject->removeSoftRef();
             ++fAutoEvictedCount;
             if (--maxItemsToEvict == 0) {
                 break;
             }
         }
     }
 }


 // Places a new value and creationStatus in the cache for the given key.
 // On entry, gCacheMutex must be held. key must not exist in the cache.
 // On exit, value and creation status placed under key. Soft reference added
 // to value on successful add. On error sets status.
 void UnifiedCache::_putNew(
         const CacheKeyBase &key,
         const SharedObject *value,
         const UErrorCode creationStatus,
         UErrorCode &status) const {
     if (U_FAILURE(status)) {
         return;
     }
     CacheKeyBase *keyToAdopt = key.clone();
     if (keyToAdopt == NULL) {
         status = U_MEMORY_ALLOCATION_ERROR;
         return;
     }
     keyToAdopt->fCreationStatus = creationStatus;
     if (value->noSoftReferences()) {
         _registerMaster(keyToAdopt, value);
     }
     uhash_put(fHashtable, keyToAdopt, (void *) value, &status);
     if (U_SUCCESS(status)) {
         value->addSoftRef();
     }
 }

 // Places value and status at key if there is no value at key or if cache
 // entry for key is in progress. Otherwise, it leaves the current value and
 // status there.
 // On entry. gCacheMutex must not be held. value must be
 // included in the reference count of the object to which it points.
 // On exit, value and status are changed to what was already in the cache if
 // something was there and not in progress. Otherwise, value and status are left
 // unchanged in which case they are placed in the cache on a best-effort basis.
 // Caller must call removeRef() on value.
 void UnifiedCache::_putIfAbsentAndGet(
         const CacheKeyBase &key,
         const SharedObject *&value,
         UErrorCode &status) const {
     Mutex lock(&gCacheMutex);
     const UHashElement *element = uhash_find(fHashtable, &key);
     if (element != NULL && !_inProgress(element)) {
         _fetch(element, value, status);
         return;
     }
     if (element == NULL) {
         UErrorCode putError = U_ZERO_ERROR;
         // best-effort basis only.
         _putNew(key, value, status, putError);
     } else {
         _put(element, value, status);
     }
     // Run an eviction slice. This will run even if we added a master entry
     // which doesn't increase the unused count, but that is still o.k
     _runEvictionSlice();
 }

 // Attempts to fetch value and status for key from cache.
 // On entry, gCacheMutex must not be held value must be NULL and status must
 // be U_ZERO_ERROR.
 // On exit, either returns FALSE (In this
 // case caller should try to create the object) or returns TRUE with value
 // pointing to the fetched value and status set to fetched status. When
 // FALSE is returned status may be set to failure if an in progress hash
 // entry could not be made but value will remain unchanged. When TRUE is
 // returned, caler must call removeRef() on value.
 UBool UnifiedCache::_poll(
         const CacheKeyBase &key,
         const SharedObject *&value,
         UErrorCode &status) const {
     U_ASSERT(value == NULL);
     U_ASSERT(status == U_ZERO_ERROR);
     Mutex lock(&gCacheMutex);
     const UHashElement *element = uhash_find(fHashtable, &key);
     while (element != NULL && _inProgress(element)) {
         umtx_condWait(&gInProgressValueAddedCond, &gCacheMutex);
         element = uhash_find(fHashtable, &key);
     }
     if (element != NULL) {
         _fetch(element, value, status);
         return TRUE;
     }
     _putNew(key, gNoValue, U_ZERO_ERROR, status);
     return FALSE;
 }

 // Gets value out of cache.
 // On entry. gCacheMutex must not be held. value must be NULL. status
 // must be U_ZERO_ERROR.
 // On exit. value and status set to what is in cache at key or on cache
 // miss the key's createObject() is called and value and status are set to
 // the result of that. In this latter case, best effort is made to add the
 // value and status to the cache. If createObject() fails to create a value,
 // gNoValue is stored in cache, and value is set to NULL. Caller must call
 // removeRef on value if non NULL.
 void UnifiedCache::_get(
         const CacheKeyBase &key,
         const SharedObject *&value,
         const void *creationContext,
         UErrorCode &status) const {
     U_ASSERT(value == NULL);
     U_ASSERT(status == U_ZERO_ERROR);
     if (_poll(key, value, status)) {
         if (value == gNoValue) {
             SharedObject::clearPtr(value);
         }
         return;
     }
     if (U_FAILURE(status)) {
         return;
     }
     value = key.createObject(creationContext, status);
     U_ASSERT(value == NULL || value->hasHardReferences());
     U_ASSERT(value != NULL || status != U_ZERO_ERROR);
     if (value == NULL) {
         SharedObject::copyPtr(gNoValue, value);
     }
     _putIfAbsentAndGet(key, value, status);
     if (value == gNoValue) {
         SharedObject::clearPtr(value);
     }
 }

 void UnifiedCache::decrementItemsInUseWithLockingAndEviction() const {
     Mutex mutex(&gCacheMutex);
     decrementItemsInUse();
     _runEvictionSlice();
 }

 void UnifiedCache::incrementItemsInUse() const {
     ++fItemsInUseCount;
 }

 void UnifiedCache::decrementItemsInUse() const {
     --fItemsInUseCount;
 }

 // Register a master cache entry.
 // On entry, gCacheMutex must be held.
 // On exit, items in use count incremented, entry is marked as a master
 // entry, and value registered with cache so that subsequent calls to
 // addRef() and removeRef() on it correctly updates items in use count
 void UnifiedCache::_registerMaster(
         const CacheKeyBase *theKey, const SharedObject *value) const {
     theKey->fIsMaster = TRUE;
     ++fItemsInUseCount;
     value->registerWithCache(this);
 }

 // Store a value and error in given hash entry.
 // On entry, gCacheMutex must be held. Hash entry element must be in progress.
 // value must be non NULL.
 // On Exit, soft reference added to value. value and status stored in hash
 // entry. Soft reference removed from previous stored value. Waiting
 // threads notified.
 void UnifiedCache::_put(
         const UHashElement *element,
         const SharedObject *value,
         const UErrorCode status) const {
     U_ASSERT(_inProgress(element));
     const CacheKeyBase *theKey = (const CacheKeyBase *) element->key.pointer;
     const SharedObject *oldValue = (const SharedObject *) element->value.pointer;
     theKey->fCreationStatus = status;
     if (value->noSoftReferences()) {
         _registerMaster(theKey, value);
     }
     value->addSoftRef();
     UHashElement *ptr = const_cast<UHashElement *>(element);
     ptr->value.pointer = (void *) value;
     oldValue->removeSoftRef();

     // Tell waiting threads that we replace in-progress status with
     // an error.
     umtx_condBroadcast(&gInProgressValueAddedCond);
 }

 void
 UnifiedCache::copyPtr(const SharedObject *src, const SharedObject *&dest) {
     if(src != dest) {
         if(dest != NULL) {
             dest->removeRefWhileHoldingCacheLock();
         }
         dest = src;
         if(src != NULL) {
             src->addRefWhileHoldingCacheLock();
         }
     }
 }

 void
 UnifiedCache::clearPtr(const SharedObject *&ptr) {
     if (ptr != NULL) {
         ptr->removeRefWhileHoldingCacheLock();
         ptr = NULL;
     }
 }


 // Fetch value and error code from a particular hash entry.
 // On entry, gCacheMutex must be held. value must be either NULL or must be
 // included in the ref count of the object to which it points.
 // On exit, value and status set to what is in the hash entry. Caller must
 // eventually call removeRef on value.
 // If hash entry is in progress, value will be set to gNoValue and status will
 // be set to U_ZERO_ERROR.
 void UnifiedCache::_fetch(
         const UHashElement *element,
         const SharedObject *&value,
         UErrorCode &status) {
     const CacheKeyBase *theKey = (const CacheKeyBase *) element->key.pointer;
     status = theKey->fCreationStatus;

     // Since we have the cache lock, calling regular SharedObject methods
     // could cause us to deadlock on ourselves since they may need to lock
     // the cache mutex.
     UnifiedCache::copyPtr((const SharedObject *) element->value.pointer, value);
 }

 // Determine if given hash entry is in progress.
 // On entry, gCacheMutex must be held.
 UBool UnifiedCache::_inProgress(const UHashElement *element) {
     const SharedObject *value = NULL;
     UErrorCode status = U_ZERO_ERROR;
     _fetch(element, value, status);
     UBool result = _inProgress(value, status);

     // Since we have the cache lock, calling regular SharedObject methods
     // could cause us to deadlock on ourselves since they may need to lock
     // the cache mutex.
     UnifiedCache::clearPtr(value);
     return result;
 }

 // Determine if given hash entry is in progress.
 // On entry, gCacheMutex must be held.
 UBool UnifiedCache::_inProgress(
         const SharedObject *theValue, UErrorCode creationStatus) {
     return (theValue == gNoValue && creationStatus == U_ZERO_ERROR);
 }

 // Determine if given hash entry is eligible for eviction.
 // On entry, gCacheMutex must be held.
 UBool UnifiedCache::_isEvictable(const UHashElement *element) {
     const CacheKeyBase *theKey = (const CacheKeyBase *) element->key.pointer;
     const SharedObject *theValue =
             (const SharedObject *) element->value.pointer;

     // Entries that are under construction are never evictable
     if (_inProgress(theValue, theKey->fCreationStatus)) {
         return FALSE;
     }

     // We can evict entries that are either not a master or have just
     // one reference (The one reference being from the cache itself).
     return (!theKey->fIsMaster || (theValue->getSoftRefCount() == 1 && theValue->noHardReferences()));
 }

 U_NAMESPACE_END
	/*
	******************************************************************************
	* Copyright (C) 2015, International Business Machines Corporation and
	* others. All Rights Reserved.
	******************************************************************************
	*
	* File UNIFIEDCACHE.CPP
	******************************************************************************
	*/

	#include "starboard/client_porting/poem/assert_poem.h"
	#include "starboard/client_porting/poem/string_poem.h"
	#include "uhash.h"
	#include "unifiedcache.h"
	#include "umutex.h"
	#include "mutex.h"
	#include "uassert.h"
	#include "ucln_cmn.h"

	static icu::UnifiedCache *gCache = NULL;
	static icu::SharedObject *gNoValue = NULL;
	static UMutex gCacheMutex = U_MUTEX_INITIALIZER;
	static UConditionVar gInProgressValueAddedCond = U_CONDITION_INITIALIZER;
	static icu::UInitOnce gCacheInitOnce = U_INITONCE_INITIALIZER;
	static const int32_t MAX_EVICT_ITERATIONS = 10;

	static int32_t DEFAULT_MAX_UNUSED = 1000;
	static int32_t DEFAULT_PERCENTAGE_OF_IN_USE = 100;


	U_CDECL_BEGIN
	static UBool U_CALLCONV unifiedcache_cleanup() {
	gCacheInitOnce.reset();
	if (gCache) {
	delete gCache;
	gCache = NULL;
	}
	if (gNoValue) {
	delete gNoValue;
	gNoValue = NULL;
	}
	return TRUE;
	}
	U_CDECL_END


	U_NAMESPACE_BEGIN

	U_CAPI int32_t U_EXPORT2
	ucache_hashKeys(const UHashTok key) {
	const CacheKeyBase ckey = (const CacheKeyBase ) key.pointer;
	return ckey->hashCode();
	}

	U_CAPI UBool U_EXPORT2
	ucache_compareKeys(const UHashTok key1, const UHashTok key2) {
	const CacheKeyBase p1 = (const CacheKeyBase ) key1.pointer;
	const CacheKeyBase p2 = (const CacheKeyBase ) key2.pointer;
	return p1 == p2;
	}

	U_CAPI void U_EXPORT2
	ucache_deleteKey(void *obj) {
	CacheKeyBase p = (CacheKeyBase ) obj;
	delete p;
	}

	CacheKeyBase::~CacheKeyBase() {
	}

	static void U_CALLCONV cacheInit(UErrorCode &status) {
	U_ASSERT(gCache == NULL);
	ucln_common_registerCleanup(
	UCLN_COMMON_UNIFIED_CACHE, unifiedcache_cleanup);

	// gNoValue must be created first to avoid assertion error in
	// cache constructor.
	gNoValue = new SharedObject();
	gCache = new UnifiedCache(status);
	if (gCache == NULL) {
	status = U_MEMORY_ALLOCATION_ERROR;
	}
	if (U_FAILURE(status)) {
	delete gCache;
	delete gNoValue;
	gCache = NULL;
	gNoValue = NULL;
	return;
	}
	// We add a softref because we want hash elements with gNoValue to be
	// elligible for purging but we don't ever want gNoValue to be deleted.
	gNoValue->addSoftRef();
	}

	UnifiedCache *UnifiedCache::getInstance(UErrorCode &status) {
	umtx_initOnce(gCacheInitOnce, &cacheInit, status);
	if (U_FAILURE(status)) {
	return NULL;
	}
	U_ASSERT(gCache != NULL);
	return gCache;
	}

	UnifiedCache::UnifiedCache(UErrorCode &status) :
	fHashtable(NULL),
	fEvictPos(UHASH_FIRST),
	fItemsInUseCount(0),
	fMaxUnused(DEFAULT_MAX_UNUSED),
	fMaxPercentageOfInUse(DEFAULT_PERCENTAGE_OF_IN_USE),
	fAutoEvictedCount(0) {
	if (U_FAILURE(status)) {
	return;
	}
	U_ASSERT(gNoValue != NULL);
	fHashtable = uhash_open(
	&ucache_hashKeys,
	&ucache_compareKeys,
	NULL,
	&status);
	if (U_FAILURE(status)) {
	return;
	}
	uhash_setKeyDeleter(fHashtable, &ucache_deleteKey);
	}

	void UnifiedCache::setEvictionPolicy(
	int32_t count, int32_t percentageOfInUseItems, UErrorCode &status) {
	if (U_FAILURE(status)) {
	return;
	}
	if (count < 0 \|\| percentageOfInUseItems < 0) {
	status = U_ILLEGAL_ARGUMENT_ERROR;
	return;
	}
	Mutex lock(&gCacheMutex);
	fMaxUnused = count;
	fMaxPercentageOfInUse = percentageOfInUseItems;
	}

	int32_t UnifiedCache::unusedCount() const {
	Mutex lock(&gCacheMutex);
	return uhash_count(fHashtable) - fItemsInUseCount;
	}

	int64_t UnifiedCache::autoEvictedCount() const {
	Mutex lock(&gCacheMutex);
	return fAutoEvictedCount;
	}

	int32_t UnifiedCache::keyCount() const {
	Mutex lock(&gCacheMutex);
	return uhash_count(fHashtable);
	}

	void UnifiedCache::flush() const {
	Mutex lock(&gCacheMutex);

	// Use a loop in case cache items that are flushed held hard references to
	// other cache items making those additional cache items eligible for
	// flushing.
	while (_flush(FALSE));
	}

	#ifdef UNIFIED_CACHE_DEBUG
	#include <stdio.h>

	void UnifiedCache::dump() {
	UErrorCode status = U_ZERO_ERROR;
	const UnifiedCache *cache = getInstance(status);
	if (U_FAILURE(status)) {
	fprintf(stderr, "Unified Cache: Error fetching cache.\n");
	return;
	}
	cache->dumpContents();
	}

	void UnifiedCache::dumpContents() const {
	Mutex lock(&gCacheMutex);
	_dumpContents();
	}

	// Dumps content of cache.
	// On entry, gCacheMutex must be held.
	// On exit, cache contents dumped to stderr.
	void UnifiedCache::_dumpContents() const {
	int32_t pos = UHASH_FIRST;
	const UHashElement *element = uhash_nextElement(fHashtable, &pos);
	char buffer[256];
	int32_t cnt = 0;
	for (; element != NULL; element = uhash_nextElement(fHashtable, &pos)) {
	const SharedObject *sharedObject =
	(const SharedObject *) element->value.pointer;
	const CacheKeyBase *key =
	(const CacheKeyBase *) element->key.pointer;
	if (sharedObject->hasHardReferences()) {
	++cnt;
	fprintf(
	stderr,
	"Unified Cache: Key '%s', error %d, value %p, total refcount %d, soft refcount %d\n",
	key->writeDescription(buffer, 256),
	key->creationStatus,
	sharedObject == gNoValue ? NULL :sharedObject,
	sharedObject->getRefCount(),
	sharedObject->getSoftRefCount());
	}
	}
	fprintf(stderr, "Unified Cache: %d out of a total of %d still have hard references\n", cnt, uhash_count(fHashtable));
	}
	#endif

	UnifiedCache::~UnifiedCache() {
	// Try our best to clean up first.
	flush();
	{
	// Now all that should be left in the cache are entries that refer to
	// each other and entries with hard references from outside the cache.
	// Nothing we can do about these so proceed to wipe out the cache.
	Mutex lock(&gCacheMutex);
	_flush(TRUE);
	}
	uhash_close(fHashtable);
	}

	// Returns the next element in the cache round robin style.
	// On entry, gCacheMutex must be held.
	const UHashElement *
	UnifiedCache::_nextElement() const {
	const UHashElement *element = uhash_nextElement(fHashtable, &fEvictPos);
	if (element == NULL) {
	fEvictPos = UHASH_FIRST;
	return uhash_nextElement(fHashtable, &fEvictPos);
	}
	return element;
	}

	// Flushes the contents of the cache. If cache values hold references to other
	// cache values then _flush should be called in a loop until it returns FALSE.
	// On entry, gCacheMutex must be held.
	// On exit, those values with are evictable are flushed. If all is true
	// then every value is flushed even if it is not evictable.
	// Returns TRUE if any value in cache was flushed or FALSE otherwise.
	UBool UnifiedCache::_flush(UBool all) const {
	UBool result = FALSE;
	int32_t origSize = uhash_count(fHashtable);
	for (int32_t i = 0; i < origSize; ++i) {
	const UHashElement *element = _nextElement();
	if (all \|\| _isEvictable(element)) {
	const SharedObject *sharedObject =
	(const SharedObject *) element->value.pointer;
	uhash_removeElement(fHashtable, element);
	sharedObject->removeSoftRef();
	result = TRUE;
	}
	}
	return result;
	}

	// Computes how many items should be evicted.
	// On entry, gCacheMutex must be held.
	// Returns number of items that should be evicted or a value <= 0 if no
	// items need to be evicted.
	int32_t UnifiedCache::_computeCountOfItemsToEvict() const {
	int32_t maxPercentageOfInUseCount =
	fItemsInUseCount * fMaxPercentageOfInUse / 100;
	int32_t maxUnusedCount = fMaxUnused;
	if (maxUnusedCount < maxPercentageOfInUseCount) {
	maxUnusedCount = maxPercentageOfInUseCount;
	}
	return uhash_count(fHashtable) - fItemsInUseCount - maxUnusedCount;
	}

	// Run an eviction slice.
	// On entry, gCacheMutex must be held.
	// _runEvictionSlice runs a slice of the evict pipeline by examining the next
	// 10 entries in the cache round robin style evicting them if they are eligible.
	void UnifiedCache::_runEvictionSlice() const {
	int32_t maxItemsToEvict = _computeCountOfItemsToEvict();
	if (maxItemsToEvict <= 0) {
	return;
	}
	for (int32_t i = 0; i < MAX_EVICT_ITERATIONS; ++i) {
	const UHashElement *element = _nextElement();
	if (_isEvictable(element)) {
	const SharedObject *sharedObject =
	(const SharedObject *) element->value.pointer;
	uhash_removeElement(fHashtable, element);
	sharedObject->removeSoftRef();
	++fAutoEvictedCount;
	if (--maxItemsToEvict == 0) {
	break;
	}
	}
	}
	}


	// Places a new value and creationStatus in the cache for the given key.
	// On entry, gCacheMutex must be held. key must not exist in the cache.
	// On exit, value and creation status placed under key. Soft reference added
	// to value on successful add. On error sets status.
	void UnifiedCache::_putNew(
	const CacheKeyBase &key,
	const SharedObject *value,
	const UErrorCode creationStatus,
	UErrorCode &status) const {
	if (U_FAILURE(status)) {
	return;
	}
	CacheKeyBase *keyToAdopt = key.clone();
	if (keyToAdopt == NULL) {
	status = U_MEMORY_ALLOCATION_ERROR;
	return;
	}
	keyToAdopt->fCreationStatus = creationStatus;
	if (value->noSoftReferences()) {
	_registerMaster(keyToAdopt, value);
	}
	uhash_put(fHashtable, keyToAdopt, (void *) value, &status);
	if (U_SUCCESS(status)) {
	value->addSoftRef();
	}
	}

	// Places value and status at key if there is no value at key or if cache
	// entry for key is in progress. Otherwise, it leaves the current value and
	// status there.
	// On entry. gCacheMutex must not be held. value must be
	// included in the reference count of the object to which it points.
	// On exit, value and status are changed to what was already in the cache if
	// something was there and not in progress. Otherwise, value and status are left
	// unchanged in which case they are placed in the cache on a best-effort basis.
	// Caller must call removeRef() on value.
	void UnifiedCache::_putIfAbsentAndGet(
	const CacheKeyBase &key,
	const SharedObject *&value,
	UErrorCode &status) const {
	Mutex lock(&gCacheMutex);
	const UHashElement *element = uhash_find(fHashtable, &key);
	if (element != NULL && !_inProgress(element)) {
	_fetch(element, value, status);
	return;
	}
	if (element == NULL) {
	UErrorCode putError = U_ZERO_ERROR;
	// best-effort basis only.
	_putNew(key, value, status, putError);
	} else {
	_put(element, value, status);
	}
	// Run an eviction slice. This will run even if we added a master entry
	// which doesn't increase the unused count, but that is still o.k
	_runEvictionSlice();
	}

	// Attempts to fetch value and status for key from cache.
	// On entry, gCacheMutex must not be held value must be NULL and status must
	// be U_ZERO_ERROR.
	// On exit, either returns FALSE (In this
	// case caller should try to create the object) or returns TRUE with value
	// pointing to the fetched value and status set to fetched status. When
	// FALSE is returned status may be set to failure if an in progress hash
	// entry could not be made but value will remain unchanged. When TRUE is
	// returned, caler must call removeRef() on value.
	UBool UnifiedCache::_poll(
	const CacheKeyBase &key,
	const SharedObject *&value,
	UErrorCode &status) const {
	U_ASSERT(value == NULL);
	U_ASSERT(status == U_ZERO_ERROR);
	Mutex lock(&gCacheMutex);
	const UHashElement *element = uhash_find(fHashtable, &key);
	while (element != NULL && _inProgress(element)) {
	umtx_condWait(&gInProgressValueAddedCond, &gCacheMutex);
	element = uhash_find(fHashtable, &key);
	}
	if (element != NULL) {
	_fetch(element, value, status);
	return TRUE;
	}
	_putNew(key, gNoValue, U_ZERO_ERROR, status);
	return FALSE;
	}

	// Gets value out of cache.
	// On entry. gCacheMutex must not be held. value must be NULL. status
	// must be U_ZERO_ERROR.
	// On exit. value and status set to what is in cache at key or on cache
	// miss the key's createObject() is called and value and status are set to
	// the result of that. In this latter case, best effort is made to add the
	// value and status to the cache. If createObject() fails to create a value,
	// gNoValue is stored in cache, and value is set to NULL. Caller must call
	// removeRef on value if non NULL.
	void UnifiedCache::_get(
	const CacheKeyBase &key,
	const SharedObject *&value,
	const void *creationContext,
	UErrorCode &status) const {
	U_ASSERT(value == NULL);
	U_ASSERT(status == U_ZERO_ERROR);
	if (_poll(key, value, status)) {
	if (value == gNoValue) {
	SharedObject::clearPtr(value);
	}
	return;
	}
	if (U_FAILURE(status)) {
	return;
	}
	value = key.createObject(creationContext, status);
	U_ASSERT(value == NULL \|\| value->hasHardReferences());
	U_ASSERT(value != NULL \|\| status != U_ZERO_ERROR);
	if (value == NULL) {
	SharedObject::copyPtr(gNoValue, value);
	}
	_putIfAbsentAndGet(key, value, status);
	if (value == gNoValue) {
	SharedObject::clearPtr(value);
	}
	}

	void UnifiedCache::decrementItemsInUseWithLockingAndEviction() const {
	Mutex mutex(&gCacheMutex);
	decrementItemsInUse();
	_runEvictionSlice();
	}

	void UnifiedCache::incrementItemsInUse() const {
	++fItemsInUseCount;
	}

	void UnifiedCache::decrementItemsInUse() const {
	--fItemsInUseCount;
	}

	// Register a master cache entry.
	// On entry, gCacheMutex must be held.
	// On exit, items in use count incremented, entry is marked as a master
	// entry, and value registered with cache so that subsequent calls to
	// addRef() and removeRef() on it correctly updates items in use count
	void UnifiedCache::_registerMaster(
	const CacheKeyBase theKey, const SharedObject value) const {
	theKey->fIsMaster = TRUE;
	++fItemsInUseCount;
	value->registerWithCache(this);
	}

	// Store a value and error in given hash entry.
	// On entry, gCacheMutex must be held. Hash entry element must be in progress.
	// value must be non NULL.
	// On Exit, soft reference added to value. value and status stored in hash
	// entry. Soft reference removed from previous stored value. Waiting
	// threads notified.
	void UnifiedCache::_put(
	const UHashElement *element,
	const SharedObject *value,
	const UErrorCode status) const {
	U_ASSERT(_inProgress(element));
	const CacheKeyBase theKey = (const CacheKeyBase ) element->key.pointer;
	const SharedObject oldValue = (const SharedObject ) element->value.pointer;
	theKey->fCreationStatus = status;
	if (value->noSoftReferences()) {
	_registerMaster(theKey, value);
	}
	value->addSoftRef();
	UHashElement ptr = const_cast<UHashElement >(element);
	ptr->value.pointer = (void *) value;
	oldValue->removeSoftRef();

	// Tell waiting threads that we replace in-progress status with
	// an error.
	umtx_condBroadcast(&gInProgressValueAddedCond);
	}

	void
	UnifiedCache::copyPtr(const SharedObject src, const SharedObject &dest) {
	if(src != dest) {
	if(dest != NULL) {
	dest->removeRefWhileHoldingCacheLock();
	}
	dest = src;
	if(src != NULL) {
	src->addRefWhileHoldingCacheLock();
	}
	}
	}

	void
	UnifiedCache::clearPtr(const SharedObject *&ptr) {
	if (ptr != NULL) {
	ptr->removeRefWhileHoldingCacheLock();
	ptr = NULL;
	}
	}


	// Fetch value and error code from a particular hash entry.
	// On entry, gCacheMutex must be held. value must be either NULL or must be
	// included in the ref count of the object to which it points.
	// On exit, value and status set to what is in the hash entry. Caller must
	// eventually call removeRef on value.
	// If hash entry is in progress, value will be set to gNoValue and status will
	// be set to U_ZERO_ERROR.
	void UnifiedCache::_fetch(
	const UHashElement *element,
	const SharedObject *&value,
	UErrorCode &status) {
	const CacheKeyBase theKey = (const CacheKeyBase ) element->key.pointer;
	status = theKey->fCreationStatus;

	// Since we have the cache lock, calling regular SharedObject methods
	// could cause us to deadlock on ourselves since they may need to lock
	// the cache mutex.
	UnifiedCache::copyPtr((const SharedObject *) element->value.pointer, value);
	}

	// Determine if given hash entry is in progress.
	// On entry, gCacheMutex must be held.
	UBool UnifiedCache::_inProgress(const UHashElement *element) {
	const SharedObject *value = NULL;
	UErrorCode status = U_ZERO_ERROR;
	_fetch(element, value, status);
	UBool result = _inProgress(value, status);

	// Since we have the cache lock, calling regular SharedObject methods
	// could cause us to deadlock on ourselves since they may need to lock
	// the cache mutex.
	UnifiedCache::clearPtr(value);
	return result;
	}

	// Determine if given hash entry is in progress.
	// On entry, gCacheMutex must be held.
	UBool UnifiedCache::_inProgress(
	const SharedObject *theValue, UErrorCode creationStatus) {
	return (theValue == gNoValue && creationStatus == U_ZERO_ERROR);
	}

	// Determine if given hash entry is eligible for eviction.
	// On entry, gCacheMutex must be held.
	UBool UnifiedCache::_isEvictable(const UHashElement *element) {
	const CacheKeyBase theKey = (const CacheKeyBase ) element->key.pointer;
	const SharedObject *theValue =
	(const SharedObject *) element->value.pointer;

	// Entries that are under construction are never evictable
	if (_inProgress(theValue, theKey->fCreationStatus)) {
	return FALSE;
	}

	// We can evict entries that are either not a master or have just
	// one reference (The one reference being from the cache itself).
	return (!theKey->fIsMaster \|\| (theValue->getSoftRefCount() == 1 && theValue->noHardReferences()));
	}

	U_NAMESPACE_END