summaryrefslogtreecommitdiffstats
path: root/intl/icu/source/common/unifiedcache.cpp
diff options
context:
space:
mode:
authorMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
committerMatt A. Tobin <mattatobin@localhost.localdomain>2018-02-02 04:16:08 -0500
commit5f8de423f190bbb79a62f804151bc24824fa32d8 (patch)
tree10027f336435511475e392454359edea8e25895d /intl/icu/source/common/unifiedcache.cpp
parent49ee0794b5d912db1f95dce6eb52d781dc210db5 (diff)
downloadUXP-5f8de423f190bbb79a62f804151bc24824fa32d8.tar
UXP-5f8de423f190bbb79a62f804151bc24824fa32d8.tar.gz
UXP-5f8de423f190bbb79a62f804151bc24824fa32d8.tar.lz
UXP-5f8de423f190bbb79a62f804151bc24824fa32d8.tar.xz
UXP-5f8de423f190bbb79a62f804151bc24824fa32d8.zip
Add m-esr52 at 52.6.0
Diffstat (limited to 'intl/icu/source/common/unifiedcache.cpp')
-rw-r--r--intl/icu/source/common/unifiedcache.cpp555
1 files changed, 555 insertions, 0 deletions
diff --git a/intl/icu/source/common/unifiedcache.cpp b/intl/icu/source/common/unifiedcache.cpp
new file mode 100644
index 000000000..6e7156f87
--- /dev/null
+++ b/intl/icu/source/common/unifiedcache.cpp
@@ -0,0 +1,555 @@
+// Copyright (C) 2016 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html
+/*
+******************************************************************************
+* Copyright (C) 2015, International Business Machines Corporation and
+* others. All Rights Reserved.
+******************************************************************************
+*
+* File UNIFIEDCACHE.CPP
+******************************************************************************
+*/
+
+#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