diff options
Diffstat (limited to 'chromium/net/disk_cache/v3/eviction_v3.cc')
| -rw-r--r-- | chromium/net/disk_cache/v3/eviction_v3.cc | 502 |
1 files changed, 0 insertions, 502 deletions
diff --git a/chromium/net/disk_cache/v3/eviction_v3.cc b/chromium/net/disk_cache/v3/eviction_v3.cc deleted file mode 100644 index 91275fc7bc2..00000000000 --- a/chromium/net/disk_cache/v3/eviction_v3.cc +++ /dev/null @@ -1,502 +0,0 @@ -// Copyright (c) 2012 The Chromium Authors. All rights reserved. -// Use of this source code is governed by a BSD-style license that can be -// found in the LICENSE file. - -// The eviction policy is a very simple pure LRU, so the elements at the end of -// the list are evicted until kCleanUpMargin free space is available. There is -// only one list in use (Rankings::NO_USE), and elements are sent to the front -// of the list whenever they are accessed. - -// The new (in-development) eviction policy adds re-use as a factor to evict -// an entry. The story so far: - -// Entries are linked on separate lists depending on how often they are used. -// When we see an element for the first time, it goes to the NO_USE list; if -// the object is reused later on, we move it to the LOW_USE list, until it is -// used kHighUse times, at which point it is moved to the HIGH_USE list. -// Whenever an element is evicted, we move it to the DELETED list so that if the -// element is accessed again, we remember the fact that it was already stored -// and maybe in the future we don't evict that element. - -// When we have to evict an element, first we try to use the last element from -// the NO_USE list, then we move to the LOW_USE and only then we evict an entry -// from the HIGH_USE. We attempt to keep entries on the cache for at least -// kTargetTime hours (with frequently accessed items stored for longer periods), -// but if we cannot do that, we fall-back to keep each list roughly the same -// size so that we have a chance to see an element again and move it to another -// list. - -#include "net/disk_cache/eviction.h" - -#include "base/bind.h" -#include "base/compiler_specific.h" -#include "base/logging.h" -#include "base/message_loop/message_loop.h" -#include "base/strings/string_util.h" -#include "base/time/time.h" -#include "net/disk_cache/backend_impl.h" -#include "net/disk_cache/entry_impl.h" -#include "net/disk_cache/experiments.h" -#include "net/disk_cache/histogram_macros.h" -#include "net/disk_cache/trace.h" - -using base::Time; -using base::TimeTicks; - -namespace { - -const int kCleanUpMargin = 1024 * 1024; -const int kHighUse = 10; // Reuse count to be on the HIGH_USE list. -const int kTargetTime = 24 * 7; // Time to be evicted (hours since last use). -const int kMaxDelayedTrims = 60; - -int LowWaterAdjust(int high_water) { - if (high_water < kCleanUpMargin) - return 0; - - return high_water - kCleanUpMargin; -} - -bool FallingBehind(int current_size, int max_size) { - return current_size > max_size - kCleanUpMargin * 20; -} - -} // namespace - -namespace disk_cache { - -// The real initialization happens during Init(), init_ is the only member that -// has to be initialized here. -Eviction::Eviction() - : backend_(NULL), - init_(false), - ptr_factory_(this) { -} - -Eviction::~Eviction() { -} - -void Eviction::Init(BackendImpl* backend) { - // We grab a bunch of info from the backend to make the code a little cleaner - // when we're actually doing work. - backend_ = backend; - rankings_ = &backend->rankings_; - header_ = &backend_->data_->header; - max_size_ = LowWaterAdjust(backend_->max_size_); - index_size_ = backend->mask_ + 1; - new_eviction_ = backend->new_eviction_; - first_trim_ = true; - trimming_ = false; - delay_trim_ = false; - trim_delays_ = 0; - init_ = true; - test_mode_ = false; -} - -void Eviction::Stop() { - // It is possible for the backend initialization to fail, in which case this - // object was never initialized... and there is nothing to do. - if (!init_) - return; - - // We want to stop further evictions, so let's pretend that we are busy from - // this point on. - DCHECK(!trimming_); - trimming_ = true; - ptr_factory_.InvalidateWeakPtrs(); -} - -void Eviction::TrimCache(bool empty) { - if (backend_->disabled_ || trimming_) - return; - - if (!empty && !ShouldTrim()) - return PostDelayedTrim(); - - if (new_eviction_) - return TrimCacheV2(empty); - - Trace("*** Trim Cache ***"); - trimming_ = true; - TimeTicks start = TimeTicks::Now(); - Rankings::ScopedRankingsBlock node(rankings_); - Rankings::ScopedRankingsBlock next( - rankings_, rankings_->GetPrev(node.get(), Rankings::NO_USE)); - int deleted_entries = 0; - int target_size = empty ? 0 : max_size_; - while ((header_->num_bytes > target_size || test_mode_) && next.get()) { - // The iterator could be invalidated within EvictEntry(). - if (!next->HasData()) - break; - node.reset(next.release()); - next.reset(rankings_->GetPrev(node.get(), Rankings::NO_USE)); - if (node->Data()->dirty != backend_->GetCurrentEntryId() || empty) { - // This entry is not being used by anybody. - // Do NOT use node as an iterator after this point. - rankings_->TrackRankingsBlock(node.get(), false); - if (EvictEntry(node.get(), empty, Rankings::NO_USE) && !test_mode_) - deleted_entries++; - - if (!empty && test_mode_) - break; - } - if (!empty && (deleted_entries > 20 || - (TimeTicks::Now() - start).InMilliseconds() > 20)) { - base::MessageLoop::current()->PostTask( - FROM_HERE, - base::Bind(&Eviction::TrimCache, ptr_factory_.GetWeakPtr(), false)); - break; - } - } - - if (empty) { - CACHE_UMA(AGE_MS, "TotalClearTimeV1", 0, start); - } else { - CACHE_UMA(AGE_MS, "TotalTrimTimeV1", 0, start); - } - CACHE_UMA(COUNTS, "TrimItemsV1", 0, deleted_entries); - - trimming_ = false; - Trace("*** Trim Cache end ***"); - return; -} - -void Eviction::OnOpenEntryV2(EntryImpl* entry) { - EntryStore* info = entry->entry()->Data(); - DCHECK_EQ(ENTRY_NORMAL, info->state); - - if (info->reuse_count < kint32max) { - info->reuse_count++; - entry->entry()->set_modified(); - - // We may need to move this to a new list. - if (1 == info->reuse_count) { - rankings_->Remove(entry->rankings(), Rankings::NO_USE, true); - rankings_->Insert(entry->rankings(), false, Rankings::LOW_USE); - entry->entry()->Store(); - } else if (kHighUse == info->reuse_count) { - rankings_->Remove(entry->rankings(), Rankings::LOW_USE, true); - rankings_->Insert(entry->rankings(), false, Rankings::HIGH_USE); - entry->entry()->Store(); - } - } -} - -void Eviction::OnCreateEntryV2(EntryImpl* entry) { - EntryStore* info = entry->entry()->Data(); - switch (info->state) { - case ENTRY_NORMAL: { - DCHECK(!info->reuse_count); - DCHECK(!info->refetch_count); - break; - }; - case ENTRY_EVICTED: { - if (info->refetch_count < kint32max) - info->refetch_count++; - - if (info->refetch_count > kHighUse && info->reuse_count < kHighUse) { - info->reuse_count = kHighUse; - } else { - info->reuse_count++; - } - info->state = ENTRY_NORMAL; - entry->entry()->Store(); - rankings_->Remove(entry->rankings(), Rankings::DELETED, true); - break; - }; - default: - NOTREACHED(); - } - - rankings_->Insert(entry->rankings(), true, GetListForEntryV2(entry)); -} - -void Eviction::SetTestMode() { - test_mode_ = true; -} - -void Eviction::TrimDeletedList(bool empty) { - DCHECK(test_mode_ && new_eviction_); - TrimDeleted(empty); -} - -// ----------------------------------------------------------------------- - -void Eviction::PostDelayedTrim() { - // Prevent posting multiple tasks. - if (delay_trim_) - return; - delay_trim_ = true; - trim_delays_++; - base::MessageLoop::current()->PostDelayedTask( - FROM_HERE, - base::Bind(&Eviction::DelayedTrim, ptr_factory_.GetWeakPtr()), - base::TimeDelta::FromMilliseconds(1000)); -} - -void Eviction::DelayedTrim() { - delay_trim_ = false; - if (trim_delays_ < kMaxDelayedTrims && backend_->IsLoaded()) - return PostDelayedTrim(); - - TrimCache(false); -} - -bool Eviction::ShouldTrim() { - if (!FallingBehind(header_->num_bytes, max_size_) && - trim_delays_ < kMaxDelayedTrims && backend_->IsLoaded()) { - return false; - } - - UMA_HISTOGRAM_COUNTS("DiskCache.TrimDelays", trim_delays_); - trim_delays_ = 0; - return true; -} - -bool Eviction::ShouldTrimDeleted() { - int index_load = header_->num_entries * 100 / index_size_; - - // If the index is not loaded, the deleted list will tend to double the size - // of the other lists 3 lists (40% of the total). Otherwise, all lists will be - // about the same size. - int max_length = (index_load < 25) ? header_->num_entries * 2 / 5 : - header_->num_entries / 4; - return (!test_mode_ && header_->lru.sizes[Rankings::DELETED] > max_length); -} - -bool Eviction::EvictEntry(CacheRankingsBlock* node, bool empty, - Rankings::List list) { - EntryImpl* entry = backend_->GetEnumeratedEntry(node, list); - if (!entry) { - Trace("NewEntry failed on Trim 0x%x", node->address().value()); - return false; - } - - ReportTrimTimes(entry); - if (empty || !new_eviction_) { - entry->DoomImpl(); - } else { - entry->DeleteEntryData(false); - EntryStore* info = entry->entry()->Data(); - DCHECK_EQ(ENTRY_NORMAL, info->state); - - rankings_->Remove(entry->rankings(), GetListForEntryV2(entry), true); - info->state = ENTRY_EVICTED; - entry->entry()->Store(); - rankings_->Insert(entry->rankings(), true, Rankings::DELETED); - } - if (!empty) - backend_->OnEvent(Stats::TRIM_ENTRY); - - entry->Release(); - - return true; -} - -void Eviction::TrimCacheV2(bool empty) { - Trace("*** Trim Cache ***"); - trimming_ = true; - TimeTicks start = TimeTicks::Now(); - - const int kListsToSearch = 3; - Rankings::ScopedRankingsBlock next[kListsToSearch]; - int list = Rankings::LAST_ELEMENT; - - // Get a node from each list. - for (int i = 0; i < kListsToSearch; i++) { - bool done = false; - next[i].set_rankings(rankings_); - if (done) - continue; - next[i].reset(rankings_->GetPrev(NULL, static_cast<Rankings::List>(i))); - if (!empty && NodeIsOldEnough(next[i].get(), i)) { - list = static_cast<Rankings::List>(i); - done = true; - } - } - - // If we are not meeting the time targets lets move on to list length. - if (!empty && Rankings::LAST_ELEMENT == list) - list = SelectListByLength(next); - - if (empty) - list = 0; - - Rankings::ScopedRankingsBlock node(rankings_); - int deleted_entries = 0; - int target_size = empty ? 0 : max_size_; - - for (; list < kListsToSearch; list++) { - while ((header_->num_bytes > target_size || test_mode_) && - next[list].get()) { - // The iterator could be invalidated within EvictEntry(). - if (!next[list]->HasData()) - break; - node.reset(next[list].release()); - next[list].reset(rankings_->GetPrev(node.get(), - static_cast<Rankings::List>(list))); - if (node->Data()->dirty != backend_->GetCurrentEntryId() || empty) { - // This entry is not being used by anybody. - // Do NOT use node as an iterator after this point. - rankings_->TrackRankingsBlock(node.get(), false); - if (EvictEntry(node.get(), empty, static_cast<Rankings::List>(list))) - deleted_entries++; - - if (!empty && test_mode_) - break; - } - if (!empty && (deleted_entries > 20 || - (TimeTicks::Now() - start).InMilliseconds() > 20)) { - base::MessageLoop::current()->PostTask( - FROM_HERE, - base::Bind(&Eviction::TrimCache, ptr_factory_.GetWeakPtr(), false)); - break; - } - } - if (!empty) - list = kListsToSearch; - } - - if (empty) { - TrimDeleted(true); - } else if (ShouldTrimDeleted()) { - base::MessageLoop::current()->PostTask( - FROM_HERE, - base::Bind(&Eviction::TrimDeleted, ptr_factory_.GetWeakPtr(), empty)); - } - - if (empty) { - CACHE_UMA(AGE_MS, "TotalClearTimeV2", 0, start); - } else { - CACHE_UMA(AGE_MS, "TotalTrimTimeV2", 0, start); - } - CACHE_UMA(COUNTS, "TrimItemsV2", 0, deleted_entries); - - Trace("*** Trim Cache end ***"); - trimming_ = false; - return; -} - -// This is a minimal implementation that just discards the oldest nodes. -// TODO(rvargas): Do something better here. -void Eviction::TrimDeleted(bool empty) { - Trace("*** Trim Deleted ***"); - if (backend_->disabled_) - return; - - TimeTicks start = TimeTicks::Now(); - Rankings::ScopedRankingsBlock node(rankings_); - Rankings::ScopedRankingsBlock next( - rankings_, rankings_->GetPrev(node.get(), Rankings::DELETED)); - int deleted_entries = 0; - while (next.get() && - (empty || (deleted_entries < 20 && - (TimeTicks::Now() - start).InMilliseconds() < 20))) { - node.reset(next.release()); - next.reset(rankings_->GetPrev(node.get(), Rankings::DELETED)); - if (RemoveDeletedNode(node.get())) - deleted_entries++; - if (test_mode_) - break; - } - - if (deleted_entries && !empty && ShouldTrimDeleted()) { - base::MessageLoop::current()->PostTask( - FROM_HERE, - base::Bind(&Eviction::TrimDeleted, ptr_factory_.GetWeakPtr(), false)); - } - - CACHE_UMA(AGE_MS, "TotalTrimDeletedTime", 0, start); - CACHE_UMA(COUNTS, "TrimDeletedItems", 0, deleted_entries); - Trace("*** Trim Deleted end ***"); - return; -} - -void Eviction::ReportTrimTimes(EntryImpl* entry) { - if (first_trim_) { - first_trim_ = false; - if (backend_->ShouldReportAgain()) { - CACHE_UMA(AGE, "TrimAge", 0, entry->GetLastUsed()); - ReportListStats(); - } - - if (header_->lru.filled) - return; - - header_->lru.filled = 1; - - if (header_->create_time) { - // This is the first entry that we have to evict, generate some noise. - backend_->FirstEviction(); - } else { - // This is an old file, but we may want more reports from this user so - // lets save some create_time. - Time::Exploded old = {0}; - old.year = 2009; - old.month = 3; - old.day_of_month = 1; - header_->create_time = Time::FromLocalExploded(old).ToInternalValue(); - } - } -} - -bool Eviction::NodeIsOldEnough(CacheRankingsBlock* node, int list) { - if (!node) - return false; - - // If possible, we want to keep entries on each list at least kTargetTime - // hours. Each successive list on the enumeration has 2x the target time of - // the previous list. - Time used = Time::FromInternalValue(node->Data()->last_used); - int multiplier = 1 << list; - return (Time::Now() - used).InHours() > kTargetTime * multiplier; -} - -int Eviction::SelectListByLength(Rankings::ScopedRankingsBlock* next) { - int data_entries = header_->num_entries - - header_->lru.sizes[Rankings::DELETED]; - // Start by having each list to be roughly the same size. - if (header_->lru.sizes[0] > data_entries / 3) - return 0; - - int list = (header_->lru.sizes[1] > data_entries / 3) ? 1 : 2; - - // Make sure that frequently used items are kept for a minimum time; we know - // that this entry is not older than its current target, but it must be at - // least older than the target for list 0 (kTargetTime), as long as we don't - // exhaust list 0. - if (!NodeIsOldEnough(next[list].get(), 0) && - header_->lru.sizes[0] > data_entries / 10) - list = 0; - - return list; -} - -void Eviction::ReportListStats() { - if (!new_eviction_) - return; - - Rankings::ScopedRankingsBlock last1(rankings_, - rankings_->GetPrev(NULL, Rankings::NO_USE)); - Rankings::ScopedRankingsBlock last2(rankings_, - rankings_->GetPrev(NULL, Rankings::LOW_USE)); - Rankings::ScopedRankingsBlock last3(rankings_, - rankings_->GetPrev(NULL, Rankings::HIGH_USE)); - Rankings::ScopedRankingsBlock last4(rankings_, - rankings_->GetPrev(NULL, Rankings::DELETED)); - - if (last1.get()) - CACHE_UMA(AGE, "NoUseAge", 0, - Time::FromInternalValue(last1.get()->Data()->last_used)); - if (last2.get()) - CACHE_UMA(AGE, "LowUseAge", 0, - Time::FromInternalValue(last2.get()->Data()->last_used)); - if (last3.get()) - CACHE_UMA(AGE, "HighUseAge", 0, - Time::FromInternalValue(last3.get()->Data()->last_used)); - if (last4.get()) - CACHE_UMA(AGE, "DeletedAge", 0, - Time::FromInternalValue(last4.get()->Data()->last_used)); -} - -} // namespace disk_cache |