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Issue 121643003: Reorganize net/disk_cache into backend specific directories. (Closed) Base URL: svn://svn.chromium.org/chrome/trunk/src
Patch Set: fix ios breakage Created 6 years, 9 months ago
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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be 2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file. 3 // found in the LICENSE file.
4 4
5 // The eviction policy is a very simple pure LRU, so the elements at the end of 5 // The eviction policy is a very simple pure LRU, so the elements at the end of
6 // the list are evicted until kCleanUpMargin free space is available. There is 6 // the list are evicted until kCleanUpMargin free space is available. There is
7 // only one list in use (Rankings::NO_USE), and elements are sent to the front 7 // only one list in use (Rankings::NO_USE), and elements are sent to the front
8 // of the list whenever they are accessed. 8 // of the list whenever they are accessed.
9 9
10 // The new (in-development) eviction policy adds re-use as a factor to evict 10 // The new (in-development) eviction policy adds re-use as a factor to evict
11 // an entry. The story so far: 11 // an entry. The story so far:
12 12
13 // Entries are linked on separate lists depending on how often they are used. 13 // Entries are linked on separate lists depending on how often they are used.
14 // When we see an element for the first time, it goes to the NO_USE list; if 14 // When we see an element for the first time, it goes to the NO_USE list; if
15 // the object is reused later on, we move it to the LOW_USE list, until it is 15 // the object is reused later on, we move it to the LOW_USE list, until it is
16 // used kHighUse times, at which point it is moved to the HIGH_USE list. 16 // used kHighUse times, at which point it is moved to the HIGH_USE list.
17 // Whenever an element is evicted, we move it to the DELETED list so that if the 17 // Whenever an element is evicted, we move it to the DELETED list so that if the
18 // element is accessed again, we remember the fact that it was already stored 18 // element is accessed again, we remember the fact that it was already stored
19 // and maybe in the future we don't evict that element. 19 // and maybe in the future we don't evict that element.
20 20
21 // When we have to evict an element, first we try to use the last element from 21 // When we have to evict an element, first we try to use the last element from
22 // the NO_USE list, then we move to the LOW_USE and only then we evict an entry 22 // the NO_USE list, then we move to the LOW_USE and only then we evict an entry
23 // from the HIGH_USE. We attempt to keep entries on the cache for at least 23 // from the HIGH_USE. We attempt to keep entries on the cache for at least
24 // kTargetTime hours (with frequently accessed items stored for longer periods), 24 // kTargetTime hours (with frequently accessed items stored for longer periods),
25 // but if we cannot do that, we fall-back to keep each list roughly the same 25 // but if we cannot do that, we fall-back to keep each list roughly the same
26 // size so that we have a chance to see an element again and move it to another 26 // size so that we have a chance to see an element again and move it to another
27 // list. 27 // list.
28 28
29 #include "net/disk_cache/eviction.h" 29 #include "net/disk_cache/blockfile/eviction.h"
30 30
31 #include "base/bind.h" 31 #include "base/bind.h"
32 #include "base/compiler_specific.h" 32 #include "base/compiler_specific.h"
33 #include "base/logging.h" 33 #include "base/logging.h"
34 #include "base/message_loop/message_loop.h" 34 #include "base/message_loop/message_loop.h"
35 #include "base/strings/string_util.h" 35 #include "base/strings/string_util.h"
36 #include "base/time/time.h" 36 #include "base/time/time.h"
37 #include "net/disk_cache/backend_impl.h" 37 #include "net/disk_cache/blockfile/backend_impl.h"
38 #include "net/disk_cache/disk_format.h" 38 #include "net/disk_cache/blockfile/disk_format.h"
39 #include "net/disk_cache/entry_impl.h" 39 #include "net/disk_cache/blockfile/entry_impl.h"
40 #include "net/disk_cache/experiments.h" 40 #include "net/disk_cache/blockfile/experiments.h"
41 #include "net/disk_cache/histogram_macros.h" 41 #include "net/disk_cache/blockfile/histogram_macros.h"
42 #include "net/disk_cache/trace.h" 42 #include "net/disk_cache/blockfile/trace.h"
43 43
44 // Provide a BackendImpl object to macros from histogram_macros.h. 44 // Provide a BackendImpl object to macros from histogram_macros.h.
45 #define CACHE_UMA_BACKEND_IMPL_OBJ backend_ 45 #define CACHE_UMA_BACKEND_IMPL_OBJ backend_
46 46
47 using base::Time; 47 using base::Time;
48 using base::TimeTicks; 48 using base::TimeTicks;
49 49
50 namespace { 50 namespace {
51 51
52 const int kCleanUpMargin = 1024 * 1024; 52 const int kCleanUpMargin = 1024 * 1024;
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591 Time::FromInternalValue(last2.get()->Data()->last_used)); 591 Time::FromInternalValue(last2.get()->Data()->last_used));
592 if (last3.get()) 592 if (last3.get())
593 CACHE_UMA(AGE, "HighUseAge", 0, 593 CACHE_UMA(AGE, "HighUseAge", 0,
594 Time::FromInternalValue(last3.get()->Data()->last_used)); 594 Time::FromInternalValue(last3.get()->Data()->last_used));
595 if (last4.get()) 595 if (last4.get())
596 CACHE_UMA(AGE, "DeletedAge", 0, 596 CACHE_UMA(AGE, "DeletedAge", 0,
597 Time::FromInternalValue(last4.get()->Data()->last_used)); 597 Time::FromInternalValue(last4.get()->Data()->last_used));
598 } 598 }
599 599
600 } // namespace disk_cache 600 } // namespace disk_cache
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