* sharedobject.cpp
*/
#include "sharedobject.h"
+#include "mutex.h"
#include "uassert.h"
+#include "umutex.h"
+#include "unifiedcache.h"
U_NAMESPACE_BEGIN
UnifiedCacheBase::~UnifiedCacheBase() {}
void
-SharedObject::addRef(UBool fromWithinCache) const {
- umtx_atomic_inc(&totalRefCount);
-
- // Although items in use may not be correct immediately, it
- // will be correct eventually.
- if (umtx_atomic_inc(&hardRefCount) == 1 && cachePtr != NULL) {
- // If this object is cached, and the hardRefCount goes from 0 to 1,
- // then the increment must happen from within the cache while the
- // cache global mutex is locked. In this way, we can be rest assured
- // that data races can't happen if the cache performs some task if
- // the hardRefCount is zero while the global cache mutex is locked.
- (void)fromWithinCache; // Suppress unused variable warning in non-debug builds.
- U_ASSERT(fromWithinCache);
- cachePtr->incrementItemsInUse();
- }
+SharedObject::addRef() const {
+ umtx_atomic_inc(&hardRefCount);
}
+// removeRef Decrement the reference count and delete if it is zero.
+// Note that SharedObjects with a non-null cachePtr are owned by the
+// unified cache, and the cache will be responsible for the actual deletion.
+// The deletion could be as soon as immediately following the
+// update to the reference count, if another thread is running
+// a cache eviction cycle concurrently.
+// NO ACCESS TO *this PERMITTED AFTER REFERENCE COUNT == 0 for cached objects.
+// THE OBJECT MAY ALREADY BE GONE.
void
-SharedObject::removeRef(UBool fromWithinCache) const {
- UBool decrementItemsInUse = (umtx_atomic_dec(&hardRefCount) == 0);
- UBool allReferencesGone = (umtx_atomic_dec(&totalRefCount) == 0);
-
- // Although items in use may not be correct immediately, it
- // will be correct eventually.
- if (decrementItemsInUse && cachePtr != NULL) {
- if (fromWithinCache) {
- cachePtr->decrementItemsInUse();
+SharedObject::removeRef() const {
+ const UnifiedCacheBase *cache = this->cachePtr;
+ int32_t updatedRefCount = umtx_atomic_dec(&hardRefCount);
+ U_ASSERT(updatedRefCount >= 0);
+ if (updatedRefCount == 0) {
+ if (cache) {
+ cache->handleUnreferencedObject();
} else {
- cachePtr->decrementItemsInUseWithLockingAndEviction();
+ delete this;
}
}
- if (allReferencesGone) {
- delete this;
- }
}
-void
-SharedObject::addSoftRef() const {
- umtx_atomic_inc(&totalRefCount);
- ++softRefCount;
-}
-
-void
-SharedObject::removeSoftRef() const {
- --softRefCount;
- if (umtx_atomic_dec(&totalRefCount) == 0) {
- delete this;
- }
-}
int32_t
SharedObject::getRefCount() const {
- return umtx_loadAcquire(totalRefCount);
-}
-
-int32_t
-SharedObject::getHardRefCount() const {
return umtx_loadAcquire(hardRefCount);
}
void
SharedObject::deleteIfZeroRefCount() const {
- if(getRefCount() == 0) {
+ if (this->cachePtr == nullptr && getRefCount() == 0) {
delete this;
}
}
U_NAMESPACE_BEGIN
+class SharedObject;
+
/**
* Base class for unified cache exposing enough methods to SharedObject
* instances to allow their addRef() and removeRef() methods to
UnifiedCacheBase() { }
/**
- * Called by addRefWhileHoldingCacheLock() when the hard reference count
- * of its instance goes from 0 to 1.
+ * Notify the cache implementation that an object was seen transitioning to
+ * zero hard references. The cache may use this to keep track the number of
+ * unreferenced SharedObjects, and to trigger evictions.
*/
- virtual void incrementItemsInUse() const = 0;
+ virtual void handleUnreferencedObject() const = 0;
- /**
- * Called by removeRef() when the hard reference count of its instance
- * drops from 1 to 0.
- */
- virtual void decrementItemsInUseWithLockingAndEviction() const = 0;
-
- /**
- * Called by removeRefWhileHoldingCacheLock() when the hard reference
- * count of its instance drops from 1 to 0.
- */
- virtual void decrementItemsInUse() const = 0;
virtual ~UnifiedCacheBase();
private:
UnifiedCacheBase(const UnifiedCacheBase &);
public:
/** Initializes totalRefCount, softRefCount to 0. */
SharedObject() :
- totalRefCount(0),
softRefCount(0),
hardRefCount(0),
cachePtr(NULL) {}
/** Initializes totalRefCount, softRefCount to 0. */
SharedObject(const SharedObject &other) :
UObject(other),
- totalRefCount(0),
softRefCount(0),
hardRefCount(0),
cachePtr(NULL) {}
virtual ~SharedObject();
/**
- * Increments the number of references to this object. Thread-safe.
- */
- void addRef() const { addRef(FALSE); }
-
- /**
- * Increments the number of references to this object.
- * Must be called only from within the internals of UnifiedCache and
- * only while the cache global mutex is held.
- */
- void addRefWhileHoldingCacheLock() const { addRef(TRUE); }
-
- /**
- * Increments the number of soft references to this object.
- * Must be called only from within the internals of UnifiedCache and
- * only while the cache global mutex is held.
- */
- void addSoftRef() const;
-
- /**
- * Decrements the number of references to this object. Thread-safe.
- */
- void removeRef() const { removeRef(FALSE); }
-
- /**
- * Decrements the number of references to this object.
- * Must be called only from within the internals of UnifiedCache and
- * only while the cache global mutex is held.
+ * Increments the number of hard references to this object. Thread-safe.
+ * Not for use from within the Unified Cache implementation.
*/
- void removeRefWhileHoldingCacheLock() const { removeRef(TRUE); }
+ void addRef() const;
/**
- * Decrements the number of soft references to this object.
- * Must be called only from within the internals of UnifiedCache and
- * only while the cache global mutex is held.
+ * Decrements the number of hard references to this object, and
+ * arrange for possible cache-eviction and/or deletion if ref
+ * count goes to zero. Thread-safe.
+ *
+ * Not for use from within the UnifiedCache implementation.
*/
- void removeSoftRef() const;
+ void removeRef() const;
/**
- * Returns the reference counter including soft references.
+ * Returns the number of hard references for this object.
* Uses a memory barrier.
*/
int32_t getRefCount() const;
- /**
- * Returns the count of soft references only.
- * Must be called only from within the internals of UnifiedCache and
- * only while the cache global mutex is held.
- */
- int32_t getSoftRefCount() const { return softRefCount; }
-
- /**
- * Returns the count of hard references only. Uses a memory barrier.
- * Used for testing the cache. Regular clients won't need this.
- */
- int32_t getHardRefCount() const;
-
/**
* If noHardReferences() == TRUE then this object has no hard references.
* Must be called only from within the internals of UnifiedCache.
*/
- inline UBool noHardReferences() const { return getHardRefCount() == 0; }
+ inline UBool noHardReferences() const { return getRefCount() == 0; }
/**
* If hasHardReferences() == TRUE then this object has hard references.
* Must be called only from within the internals of UnifiedCache.
*/
- inline UBool hasHardReferences() const { return getHardRefCount() != 0; }
+ inline UBool hasHardReferences() const { return getRefCount() != 0; }
/**
- * If noSoftReferences() == TRUE then this object has no soft references.
- * Must be called only from within the internals of UnifiedCache and
- * only while the cache global mutex is held.
- */
- UBool noSoftReferences() const { return (softRefCount == 0); }
-
- /**
- * Deletes this object if it has no references or soft references.
+ * Deletes this object if it has no references.
+ * Available for non-cached SharedObjects only. Ownership of cached objects
+ * is with the UnifiedCache, which is soley responsible for eviction and deletion.
*/
void deleteIfZeroRefCount() const;
- /**
- * @internal For UnifedCache use only to register this object with itself.
- * Must be called before this object is exposed to multiple threads.
- */
- void registerWithCache(const UnifiedCacheBase *ptr) const {
- cachePtr = ptr;
- }
/**
* Returns a writable version of ptr.
}
private:
- mutable u_atomic_int32_t totalRefCount;
-
- // Any thread modifying softRefCount must hold the global cache mutex
+ /**
+ * The number of references from the UnifiedCache, which is
+ * the number of times that the sharedObject is stored as a hash table value.
+ * For use by UnifiedCache implementation code only.
+ * All access is synchronized by UnifiedCache's gCacheMutex
+ */
mutable int32_t softRefCount;
+ friend class UnifiedCache;
+ /**
+ * Reference count, excluding references from within the UnifiedCache implementation.
+ */
mutable u_atomic_int32_t hardRefCount;
+
mutable const UnifiedCacheBase *cachePtr;
- void addRef(UBool withCacheLock) const;
- void removeRef(UBool withCacheLock) const;
};
// License & terms of use: http://www.unicode.org/copyright.html
/*
******************************************************************************
-* Copyright (C) 2015, International Business Machines Corporation and
-* others. All Rights Reserved.
+* Copyright (C) 2015, International Business Machines Corporation and
+* others. All Rights Reserved.
******************************************************************************
-*
-* File UNIFIEDCACHE.CPP
+*
+* File unifiedcache.cpp
******************************************************************************
*/
-#include "uhash.h"
#include "unifiedcache.h"
-#include "umutex.h"
+
+#include <algorithm> // For std::max()
+
#include "mutex.h"
#include "uassert.h"
+#include "uhash.h"
#include "ucln_cmn.h"
+#include "umutex.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 const int32_t MAX_EVICT_ITERATIONS = 10;
static const int32_t DEFAULT_MAX_UNUSED = 1000;
static const int32_t DEFAULT_PERCENTAGE_OF_IN_USE = 100;
delete gCache;
gCache = NULL;
}
- if (gNoValue) {
- delete gNoValue;
- gNoValue = NULL;
- }
return TRUE;
}
U_CDECL_END
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) {
UnifiedCache::UnifiedCache(UErrorCode &status) :
fHashtable(NULL),
fEvictPos(UHASH_FIRST),
- fItemsInUseCount(0),
+ fNumValuesTotal(0),
+ fNumValuesInUse(0),
fMaxUnused(DEFAULT_MAX_UNUSED),
fMaxPercentageOfInUse(DEFAULT_PERCENTAGE_OF_IN_USE),
- fAutoEvictedCount(0) {
+ fAutoEvictedCount(0),
+ fNoValue(nullptr) {
if (U_FAILURE(status)) {
return;
}
- U_ASSERT(gNoValue != NULL);
+ fNoValue = new SharedObject();
+ if (fNoValue == nullptr) {
+ status = U_MEMORY_ALLOCATION_ERROR;
+ return;
+ }
+ fNoValue->softRefCount = 1; // Add fake references to prevent fNoValue from being deleted
+ fNoValue->hardRefCount = 1; // when other references to it are removed.
+ fNoValue->cachePtr = this;
+
fHashtable = uhash_open(
&ucache_hashKeys,
&ucache_compareKeys,
int32_t UnifiedCache::unusedCount() const {
Mutex lock(&gCacheMutex);
- return uhash_count(fHashtable) - fItemsInUseCount;
+ return uhash_count(fHashtable) - fNumValuesInUse;
}
int64_t UnifiedCache::autoEvictedCount() const {
while (_flush(FALSE));
}
+void UnifiedCache::handleUnreferencedObject() const {
+ Mutex lock(&gCacheMutex);
+ --fNumValuesInUse;
+ _runEvictionSlice();
+}
+
#ifdef UNIFIED_CACHE_DEBUG
#include <stdio.h>
++cnt;
fprintf(
stderr,
- "Unified Cache: Key '%s', error %d, value %p, total refcount %d, soft refcount %d\n",
+ "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 == fNoValue ? NULL :sharedObject,
sharedObject->getRefCount(),
sharedObject->getSoftRefCount());
}
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.
+ // 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);
+ fHashtable = nullptr;
+ delete fNoValue;
+ fNoValue = nullptr;
}
-// 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);
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 (element == nullptr) {
+ break;
+ }
if (all || _isEvictable(element)) {
const SharedObject *sharedObject =
(const SharedObject *) element->value.pointer;
+ U_ASSERT(sharedObject->cachePtr = this);
uhash_removeElement(fHashtable, element);
- sharedObject->removeSoftRef();
+ removeSoftRef(sharedObject); // Deletes the sharedObject when softRefCount goes to zero.
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;
+ int32_t totalItems = uhash_count(fHashtable);
+ int32_t evictableItems = totalItems - fNumValuesInUse;
+ U_ASSERT(totalItems >= fNumValuesInUse);
+ U_ASSERT(totalItems >= evictableItems);
+
+ int32_t unusedLimitByPercentage = fNumValuesInUse * fMaxPercentageOfInUse / 100;
+ int32_t unusedLimit = std::max(unusedLimitByPercentage, fMaxUnused);
+ int32_t countOfItemsToEvict = std::max(0, evictableItems - unusedLimit);
+ U_ASSERT(countOfItemsToEvict >= 0 && countOfItemsToEvict <= evictableItems);
+ return countOfItemsToEvict;
}
-// 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) {
}
for (int32_t i = 0; i < MAX_EVICT_ITERATIONS; ++i) {
const UHashElement *element = _nextElement();
+ if (element == nullptr) {
+ break;
+ }
if (_isEvictable(element)) {
const SharedObject *sharedObject =
(const SharedObject *) element->value.pointer;
uhash_removeElement(fHashtable, element);
- sharedObject->removeSoftRef();
+ removeSoftRef(sharedObject); // Deletes sharedObject when SoftRefCount goes to zero.
++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 CacheKeyBase &key,
const SharedObject *value,
const UErrorCode creationStatus,
UErrorCode &status) const {
return;
}
keyToAdopt->fCreationStatus = creationStatus;
- if (value->noSoftReferences()) {
+ if (value->softRefCount == 0) {
_registerMaster(keyToAdopt, value);
}
- uhash_put(fHashtable, keyToAdopt, (void *) value, &status);
+ void *oldValue = uhash_put(fHashtable, keyToAdopt, (void *) value, &status);
+ U_ASSERT(oldValue == nullptr);
+ (void)oldValue;
if (U_SUCCESS(status)) {
- value->addSoftRef();
+ value->softRefCount++;
}
}
-// 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,
_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,
U_ASSERT(status == U_ZERO_ERROR);
Mutex lock(&gCacheMutex);
const UHashElement *element = uhash_find(fHashtable, &key);
- while (element != NULL && _inProgress(element)) {
+
+ // If the hash table contains an inProgress placeholder entry for this key,
+ // this means that another thread is currently constructing the value object.
+ // Loop, waiting for that construction to complete.
+ while (element != NULL && _inProgress(element)) {
umtx_condWait(&gInProgressValueAddedCond, &gCacheMutex);
element = uhash_find(fHashtable, &key);
}
+
+ // If the hash table contains an entry for the key,
+ // fetch out the contents and return them.
if (element != NULL) {
- _fetch(element, value, status);
+ _fetch(element, value, status);
return TRUE;
}
- _putNew(key, gNoValue, U_ZERO_ERROR, status);
+
+ // The hash table contained nothing for this key.
+ // Insert an inProgress place holder value.
+ // Our caller will create the final value and update the hash table.
+ _putNew(key, fNoValue, 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,
U_ASSERT(value == NULL);
U_ASSERT(status == U_ZERO_ERROR);
if (_poll(key, value, status)) {
- if (value == gNoValue) {
+ if (value == fNoValue) {
SharedObject::clearPtr(value);
}
return;
U_ASSERT(value == NULL || value->hasHardReferences());
U_ASSERT(value != NULL || status != U_ZERO_ERROR);
if (value == NULL) {
- SharedObject::copyPtr(gNoValue, value);
+ SharedObject::copyPtr(fNoValue, value);
}
_putIfAbsentAndGet(key, value, status);
- if (value == gNoValue) {
+ if (value == fNoValue) {
SharedObject::clearPtr(value);
}
}
-void UnifiedCache::decrementItemsInUseWithLockingAndEviction() const {
- Mutex mutex(&gCacheMutex);
- decrementItemsInUse();
- _runEvictionSlice();
-}
-
-void UnifiedCache::incrementItemsInUse() const {
- ++fItemsInUseCount;
-}
-
-void UnifiedCache::decrementItemsInUse() const {
- --fItemsInUseCount;
+void UnifiedCache::_registerMaster(
+ const CacheKeyBase *theKey, const SharedObject *value) const {
+ theKey->fIsMaster = true;
+ value->cachePtr = this;
+ ++fNumValuesTotal;
+ ++fNumValuesInUse;
}
-// 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 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()) {
+ if (value->softRefCount == 0) {
_registerMaster(theKey, value);
}
- value->addSoftRef();
+ value->softRefCount++;
UHashElement *ptr = const_cast<UHashElement *>(element);
ptr->value.pointer = (void *) value;
- oldValue->removeSoftRef();
+ U_ASSERT(oldValue == fNoValue);
+ removeSoftRef(oldValue);
// 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) {
+ UErrorCode &status) const {
const CacheKeyBase *theKey = (const CacheKeyBase *) element->key.pointer;
status = theKey->fCreationStatus;
- // Since we have the cache lock, calling regular SharedObject methods
+ // Since we have the cache lock, calling regular SharedObject add/removeRef
// could cause us to deadlock on ourselves since they may need to lock
// the cache mutex.
- UnifiedCache::copyPtr((const SharedObject *) element->value.pointer, value);
+ removeHardRef(value);
+ value = static_cast<const SharedObject *>(element->value.pointer);
+ addHardRef(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;
+
+UBool UnifiedCache::_inProgress(const UHashElement* element) const {
UErrorCode status = U_ZERO_ERROR;
+ const SharedObject * value = NULL;
_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);
+ removeHardRef(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);
+ const SharedObject* theValue, UErrorCode creationStatus) const {
+ return (theValue == fNoValue && 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) {
+UBool UnifiedCache::_isEvictable(const UHashElement *element) const
+{
const CacheKeyBase *theKey = (const CacheKeyBase *) element->key.pointer;
const SharedObject *theValue =
(const SharedObject *) element->value.pointer;
// 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()));
+ return (!theKey->fIsMaster || (theValue->softRefCount == 1 && theValue->noHardReferences()));
+}
+
+void UnifiedCache::removeSoftRef(const SharedObject *value) const {
+ U_ASSERT(value->cachePtr == this);
+ U_ASSERT(value->softRefCount > 0);
+ if (--value->softRefCount == 0) {
+ --fNumValuesTotal;
+ if (value->noHardReferences()) {
+ delete value;
+ } else {
+ // This path only happens from flush(all). Which only happens from the
+ // UnifiedCache destructor. Nulling out value.cacheptr changes the behavior
+ // of value.removeRef(), causing the deletion to be done there.
+ value->cachePtr = nullptr;
+ }
+ }
+}
+
+int32_t UnifiedCache::removeHardRef(const SharedObject *value) const {
+ int refCount = 0;
+ if (value) {
+ refCount = umtx_atomic_dec(&value->hardRefCount);
+ U_ASSERT(refCount >= 0);
+ if (refCount == 0) {
+ --fNumValuesInUse;
+ }
+ }
+ return refCount;
+}
+
+int32_t UnifiedCache::addHardRef(const SharedObject *value) const {
+ int refCount = 0;
+ if (value) {
+ refCount = umtx_atomic_inc(&value->hardRefCount);
+ U_ASSERT(refCount >= 1);
+ if (refCount == 1) {
+ fNumValuesInUse++;
+ }
+ }
+ return refCount;
}
U_NAMESPACE_END
UnifiedCache(UErrorCode &status);
/**
- * Returns the cache instance.
+ * Return a pointer to the global cache instance.
*/
static UnifiedCache *getInstance(UErrorCode &status);
/**
* Configures at what point evcition of unused entries will begin.
- * Eviction is triggered whenever the number of unused entries exeeds
+ * Eviction is triggered whenever the number of evictable keys exeeds
* BOTH count AND (number of in-use items) * (percentageOfInUseItems / 100).
* Once the number of unused entries drops below one of these,
* eviction ceases. Because eviction happens incrementally,
*/
int32_t unusedCount() const;
- virtual void incrementItemsInUse() const;
- virtual void decrementItemsInUseWithLockingAndEviction() const;
- virtual void decrementItemsInUse() const;
+ virtual void handleUnreferencedObject() const;
virtual ~UnifiedCache();
+
private:
UHashtable *fHashtable;
mutable int32_t fEvictPos;
- mutable int32_t fItemsInUseCount;
+ mutable int32_t fNumValuesTotal;
+ mutable int32_t fNumValuesInUse;
int32_t fMaxUnused;
int32_t fMaxPercentageOfInUse;
mutable int64_t fAutoEvictedCount;
+ SharedObject *fNoValue;
+
UnifiedCache(const UnifiedCache &other);
UnifiedCache &operator=(const UnifiedCache &other);
+
+ /**
+ * 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.
+ *
+ * @param all if false flush evictable items only, which are those with no external
+ * references, plus those that can be safely recreated.<br>
+ * if true, flush all elements. Any values (sharedObjects) with remaining
+ * hard (external) references are not deleted, but are detached from
+ * the cache, so that a subsequent removeRefs can delete them.
+ * _flush is not thread safe when all is true.
+ * @return TRUE if any value in cache was flushed or FALSE otherwise.
+ */
UBool _flush(UBool all) const;
+
+ /**
+ * 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,
+ * fNoValue is stored in cache, and value is set to NULL. Caller must call
+ * removeRef on value if non NULL.
+ */
void _get(
const CacheKeyBase &key,
const SharedObject *&value,
const void *creationContext,
UErrorCode &status) const;
- UBool _poll(
- const CacheKeyBase &key,
- const SharedObject *&value,
- UErrorCode &status) const;
- void _putNew(
- const CacheKeyBase &key,
- const SharedObject *value,
- const UErrorCode creationStatus,
- UErrorCode &status) const;
+
+ /**
+ * 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, caller must call removeRef() on value.
+ */
+ UBool _poll(
+ const CacheKeyBase &key,
+ const SharedObject *&value,
+ UErrorCode &status) const;
+
+ /**
+ * 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 _putNew(
+ const CacheKeyBase &key,
+ const SharedObject *value,
+ const UErrorCode creationStatus,
+ UErrorCode &status) const;
+
+ /**
+ * 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 _putIfAbsentAndGet(
const CacheKeyBase &key,
const SharedObject *&value,
UErrorCode &status) const;
- const UHashElement *_nextElement() const;
+
+ /**
+ * Returns the next element in the cache round robin style.
+ * Returns nullptr if the cache is empty.
+ * On entry, gCacheMutex must be held.
+ */
+ const UHashElement *_nextElement() const;
+
+ /**
+ * Return the number of cache items that would need to be evicted
+ * to bring usage into conformance with eviction policy.
+ *
+ * An item corresponds to an entry in the hash table, a hash table element.
+ *
+ * On entry, gCacheMutex must be held.
+ */
int32_t _computeCountOfItemsToEvict() const;
+
+ /**
+ * 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 _runEvictionSlice() const;
- void _registerMaster(
- const CacheKeyBase *theKey, const SharedObject *value) const;
+
+ /**
+ * Register a master cache entry. A master key is the first key to create
+ * a given SharedObject value. Subsequent keys whose create function
+ * produce referneces to an already existing SharedObject are not masters -
+ * they can be evicted and subsequently recreated.
+ *
+ * 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 interact with the cache.
+ */
+ void _registerMaster(const CacheKeyBase *theKey, const SharedObject *value) const;
+
+ /**
+ * Store a value and creation error status 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 _put(
const UHashElement *element,
const SharedObject *value,
const UErrorCode status) const;
+ /**
+ * Remove a soft reference, and delete the SharedObject if no references remain.
+ * To be used from within the UnifiedCache implementation only.
+ * gCacheMutex must be held by caller.
+ * @param value the SharedObject to be acted on.
+ */
+ void removeSoftRef(const SharedObject *value) const;
+
+ /**
+ * Increment the hard reference count of the given SharedObject.
+ * gCacheMutex must be held by the caller.
+ * Update numValuesEvictable on transitions between zero and one reference.
+ *
+ * @param value The SharedObject to be referenced.
+ * @return the hard reference count after the addition.
+ */
+ int32_t addHardRef(const SharedObject *value) const;
+
+ /**
+ * Decrement the hard reference count of the given SharedObject.
+ * gCacheMutex must be held by the caller.
+ * Update numValuesEvictable on transitions between one and zero reference.
+ *
+ * @param value The SharedObject to be referenced.
+ * @return the hard reference count after the removal.
+ */
+ int32_t removeHardRef(const SharedObject *value) const;
+
+
#ifdef UNIFIED_CACHE_DEBUG
void _dumpContents() const;
#endif
- static void copyPtr(const SharedObject *src, const SharedObject *&dest);
- static void clearPtr(const SharedObject *&ptr);
- static void _fetch(
- const UHashElement *element,
- const SharedObject *&value,
- UErrorCode &status);
- static UBool _inProgress(const UHashElement *element);
- static UBool _inProgress(
- const SharedObject *theValue, UErrorCode creationStatus);
- static UBool _isEvictable(const UHashElement *element);
+
+ /**
+ * 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 _fetch(const UHashElement *element, const SharedObject *&value,
+ UErrorCode &status) const;
+
+ /**
+ * Determine if given hash entry is in progress.
+ * On entry, gCacheMutex must be held.
+ */
+ UBool _inProgress(const UHashElement *element) const;
+
+ /**
+ * Determine if given hash entry is in progress.
+ * On entry, gCacheMutex must be held.
+ */
+ UBool _inProgress(const SharedObject *theValue, UErrorCode creationStatus) const;
+
+ /**
+ * Determine if given hash entry is eligible for eviction.
+ * On entry, gCacheMutex must be held.
+ */
+ UBool _isEvictable(const UHashElement *element) const;
};
U_NAMESPACE_END
// "Someone from {2} is receiving a #{0} error - {1}. Their telephone call is costing {3 number,currency}."
static void formatErrorMessage(UErrorCode &realStatus, const UnicodeString& pattern, const Locale& theLocale,
- UErrorCode inStatus0, /* statusString 1 */ const Locale &inCountry2, double currency3, // these numbers are the message arguments.
+ UErrorCode inStatus0, // statusString 1
+ const Locale &inCountry2, double currency3, // these numbers are the message arguments.
UnicodeString &result)
{
if(U_FAILURE(realStatus))
// Keep this data here to avoid static initialization.
FormatThreadTestData kNumberFormatTestData[] =
{
- FormatThreadTestData((double)5.0, UnicodeString("5", "")),
- FormatThreadTestData( 6.0, UnicodeString("6", "")),
- FormatThreadTestData( 20.0, UnicodeString("20", "")),
- FormatThreadTestData( 8.0, UnicodeString("8", "")),
- FormatThreadTestData( 8.3, UnicodeString("8.3", "")),
- FormatThreadTestData( 12345, UnicodeString("12,345", "")),
- FormatThreadTestData( 81890.23, UnicodeString("81,890.23", "")),
+ FormatThreadTestData((double)5.0, UnicodeString(u"5")),
+ FormatThreadTestData( 6.0, UnicodeString(u"6")),
+ FormatThreadTestData( 20.0, UnicodeString(u"20")),
+ FormatThreadTestData( 8.0, UnicodeString(u"8")),
+ FormatThreadTestData( 8.3, UnicodeString(u"8.3")),
+ FormatThreadTestData( 12345, UnicodeString(u"12,345")),
+ FormatThreadTestData( 81890.23, UnicodeString(u"81,890.23")),
};
int32_t kNumberFormatTestDataLength = UPRV_LENGTHOF(kNumberFormatTestData);
} else {
result->addRef();
}
-
+
// Log that we created an object. The first object was already counted,
// don't do it again.
umtx_lock(&gCTMutex);
void UnifiedCacheThread::run() {
// Run the exercise with 2 different locales so that we can exercise
- // eviction more. If each thread exerices just one locale, then
+ // eviction more. If each thread exercises just one locale, then
// eviction can't start until the threads end.
exerciseByLocale(fLoc);
exerciseByLocale(fLoc2);
unusedReference->removeRef();
// unused count not to exeed in use count
- assertEquals("", UPRV_LENGTHOF(usedReferences), cache.unusedCount());
- assertEquals("", 2*UPRV_LENGTHOF(usedReferences), cache.keyCount());
+ assertEquals("T1", UPRV_LENGTHOF(usedReferences), cache.unusedCount());
+ assertEquals("T2", 2*UPRV_LENGTHOF(usedReferences), cache.keyCount());
// Free up those used entries.
for (int32_t i = 0; i < UPRV_LENGTHOF(usedReferences); i++) {
}
// This should free up all cache items
- assertEquals("", 0, cache.keyCount());
+ assertEquals("T3", 0, cache.keyCount());
- assertSuccess("", status);
+ assertSuccess("T4", status);
}
// complete control over it. Real clients should never ever create
// their own cache!
UnifiedCache cache(status);
- assertSuccess("", status);
+ assertSuccess("T0", status);
// Maximum unused count is 3.
cache.setEvictionPolicy(3, 0, status);
const UCTItem *frFr = NULL;
cache.get(LocaleCacheKey<UCTItem>("en_US"), &cache, enUs, status);
cache.get(LocaleCacheKey<UCTItem>("en"), &cache, en, status);
- assertEquals("", 1, cache.unusedCount());
+ assertEquals("T1", 1, cache.unusedCount());
cache.get(LocaleCacheKey<UCTItem>("en_GB"), &cache, enGb, status);
cache.get(LocaleCacheKey<UCTItem>("fr_FR"), &cache, frFr, status);
cache.get(LocaleCacheKey<UCTItem>("fr"), &cache, fr, status);
// Client holds two unique references, "en" and "fr" the other three
// entries are eligible for eviction.
- assertEquals("", 3, cache.unusedCount());
- assertEquals("", 5, cache.keyCount());
+ assertEquals("T2", 3, cache.unusedCount());
+ assertEquals("T3", 5, cache.keyCount());
// Exercise cache more but don't hold the references except for
// the last one. At the end of this, we will hold references to one
// Client holds three unique references, "en", "fr", "de" although we
// could have a total of 8 entries in the cache maxUnusedCount == 3
// so we have only 6 entries.
- assertEquals("", 3, cache.unusedCount());
- assertEquals("", 6, cache.keyCount());
+ assertEquals("T4", 3, cache.unusedCount());
+ assertEquals("T5", 6, cache.keyCount());
// For all the references we have, cache must continue to return
// those same references (#2)
cache.get(LocaleCacheKey<UCTItem>("en"), &cache, throwAway, status);
if (throwAway != en) {
- errln("Expected en to resolve to the same object.");
+ errln("T6: Expected en to resolve to the same object.");
}
cache.get(LocaleCacheKey<UCTItem>("en_US"), &cache, throwAway, status);
if (throwAway != enUs) {
- errln("Expected enUs to resolve to the same object.");
+ errln("T7: Expected enUs to resolve to the same object.");
}
cache.get(LocaleCacheKey<UCTItem>("en_GB"), &cache, throwAway, status);
if (throwAway != enGb) {
- errln("Expected enGb to resolve to the same object.");
+ errln("T8: Expected enGb to resolve to the same object.");
}
cache.get(LocaleCacheKey<UCTItem>("fr_FR"), &cache, throwAway, status);
if (throwAway != frFr) {
- errln("Expected frFr to resolve to the same object.");
+ errln("T9: Expected frFr to resolve to the same object.");
}
cache.get(LocaleCacheKey<UCTItem>("fr_FR"), &cache, throwAway, status);
cache.get(LocaleCacheKey<UCTItem>("fr"), &cache, throwAway, status);
if (throwAway != fr) {
- errln("Expected fr to resolve to the same object.");
+ errln("T10: Expected fr to resolve to the same object.");
}
cache.get(LocaleCacheKey<UCTItem>("de_AU"), &cache, throwAway, status);
if (throwAway != deAu) {
- errln("Expected deAu to resolve to the same object.");
+ errln("T11: Expected deAu to resolve to the same object.");
}
- assertEquals("", 3, cache.unusedCount());
- assertEquals("", 6, cache.keyCount());
+ assertEquals("T12", 3, cache.unusedCount());
+ assertEquals("T13", 6, cache.keyCount());
// Now we hold a references to two more distinct values. Cache size
// should grow to 8.
const UCTItem *ru = NULL;
cache.get(LocaleCacheKey<UCTItem>("es"), &cache, es, status);
cache.get(LocaleCacheKey<UCTItem>("ru"), &cache, ru, status);
- assertEquals("", 3, cache.unusedCount());
- assertEquals("", 8, cache.keyCount());
+ assertEquals("T14", 3, cache.unusedCount());
+ assertEquals("T15", 8, cache.keyCount());
// Now release all the references we hold except for
// es, ru, and en
SharedObject::clearPtr(throwAway);
// Size of cache should magically drop to 3.
- assertEquals("", 3, cache.unusedCount());
- assertEquals("", 3, cache.keyCount());
+ assertEquals("T16", 3, cache.unusedCount());
+ assertEquals("T17", 3, cache.keyCount());
// Be sure nothing happens setting the eviction policy in the middle of
// a run.
cache.setEvictionPolicy(3, 0, status);
- assertSuccess("", status);
+ assertSuccess("T18", status);
}
cache->get(LocaleCacheKey<UCTItem>("en_GB"), enGb, status);
cache->get(LocaleCacheKey<UCTItem>("fr_FR"), frFr, status);
cache->get(LocaleCacheKey<UCTItem>("fr"), fr, status);
- cache->get(LocaleCacheKey<UCTItem>("en_GB"), enGb2, status);
+ cache->get(LocaleCacheKey<UCTItem>("en_GB"), enGb2, status);
SharedObject::clearPtr(enGb2);
if (enGb != enUs) {
errln("Expected en_GB and en_US to resolve to same object.");
if (enGb == fr) {
errln("Expected en_GB and fr to return different objects.");
}
- assertSuccess("", status);
+ assertSuccess("T1", status);
// en_US, en_GB, en share one object; fr_FR and fr don't share.
// 5 keys in all.
- assertEquals("", baseCount + 5, cache->keyCount());
+ assertEquals("T2", baseCount + 5, cache->keyCount());
SharedObject::clearPtr(enGb);
cache->flush();
// Only 2 unique values in the cache. flushing trims cache down
// to this minimum size.
- assertEquals("", baseCount + 2, cache->keyCount());
+ assertEquals("T3", baseCount + 2, cache->keyCount());
SharedObject::clearPtr(enUs);
SharedObject::clearPtr(en);
cache->flush();
// the "en" object, so it gets flushed and the keys that refer to it
// get removed from the cache. Now we have just one unique value, fr, in
// the cache
- assertEquals("", baseCount + 1, cache->keyCount());
+ assertEquals("T4", baseCount + 1, cache->keyCount());
SharedObject::clearPtr(fr);
cache->flush();
- assertEquals("", baseCount + 1, cache->keyCount());
+ assertEquals("T5", baseCount + 1, cache->keyCount());
SharedObject::clearPtr(frFr);
cache->flush();
- assertEquals("", baseCount + 0, cache->keyCount());
- assertSuccess("", status);
+ assertEquals("T6", baseCount + 0, cache->keyCount());
+ assertSuccess("T7", status);
}
void UnifiedCacheTest::TestError() {
projects / icu / commitdiff