Add m-esr52 at 52.6.0

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