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author | Felix Lange <fjl@twurst.com> | 2016-09-26 02:49:02 +0800 |
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committer | Péter Szilágyi <peterke@gmail.com> | 2016-09-28 16:27:28 +0800 |
commit | cd791bd855b55b95afc8a5c8f56b8bf67863d099 (patch) | |
tree | 3955fe3abf4079eee5412119043ade1b7001bb61 /trie/arc.go | |
parent | 863d166c7b0250cf2e99c8aad69578cdd144d386 (diff) | |
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core, trie: replace state caches with trie journal
Diffstat (limited to 'trie/arc.go')
-rw-r--r-- | trie/arc.go | 206 |
1 files changed, 0 insertions, 206 deletions
diff --git a/trie/arc.go b/trie/arc.go deleted file mode 100644 index fc7a3259f..000000000 --- a/trie/arc.go +++ /dev/null @@ -1,206 +0,0 @@ -// Copyright (c) 2015 Hans Alexander Gugel <alexander.gugel@gmail.com> -// -// Permission is hereby granted, free of charge, to any person obtaining a copy -// of this software and associated documentation files (the "Software"), to deal -// in the Software without restriction, including without limitation the rights -// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell -// copies of the Software, and to permit persons to whom the Software is -// furnished to do so, subject to the following conditions: -// -// The above copyright notice and this permission notice shall be included in all -// copies or substantial portions of the Software. -// -// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR -// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, -// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE -// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER -// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, -// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE -// SOFTWARE. - -// This file contains a modified version of package arc from -// https://github.com/alexanderGugel/arc -// -// It implements the ARC (Adaptive Replacement Cache) algorithm as detailed in -// https://www.usenix.org/legacy/event/fast03/tech/full_papers/megiddo/megiddo.pdf - -package trie - -import ( - "container/list" - "sync" -) - -type arc struct { - p int - c int - t1 *list.List - b1 *list.List - t2 *list.List - b2 *list.List - cache map[string]*entry - mutex sync.Mutex -} - -type entry struct { - key hashNode - value node - ll *list.List - el *list.Element -} - -// newARC returns a new Adaptive Replacement Cache with the -// given capacity. -func newARC(c int) *arc { - return &arc{ - c: c, - t1: list.New(), - b1: list.New(), - t2: list.New(), - b2: list.New(), - cache: make(map[string]*entry, c), - } -} - -// Clear clears the cache -func (a *arc) Clear() { - a.mutex.Lock() - defer a.mutex.Unlock() - a.p = 0 - a.t1 = list.New() - a.b1 = list.New() - a.t2 = list.New() - a.b2 = list.New() - a.cache = make(map[string]*entry, a.c) -} - -// Put inserts a new key-value pair into the cache. -// This optimizes future access to this entry (side effect). -func (a *arc) Put(key hashNode, value node) bool { - a.mutex.Lock() - defer a.mutex.Unlock() - ent, ok := a.cache[string(key)] - if ok != true { - ent = &entry{key: key, value: value} - a.req(ent) - a.cache[string(key)] = ent - } else { - ent.value = value - a.req(ent) - } - return ok -} - -// Get retrieves a previously via Set inserted entry. -// This optimizes future access to this entry (side effect). -func (a *arc) Get(key hashNode) (value node, ok bool) { - a.mutex.Lock() - defer a.mutex.Unlock() - ent, ok := a.cache[string(key)] - if ok { - a.req(ent) - return ent.value, ent.value != nil - } - return nil, false -} - -func (a *arc) req(ent *entry) { - if ent.ll == a.t1 || ent.ll == a.t2 { - // Case I - ent.setMRU(a.t2) - } else if ent.ll == a.b1 { - // Case II - // Cache Miss in t1 and t2 - - // Adaptation - var d int - if a.b1.Len() >= a.b2.Len() { - d = 1 - } else { - d = a.b2.Len() / a.b1.Len() - } - a.p = a.p + d - if a.p > a.c { - a.p = a.c - } - - a.replace(ent) - ent.setMRU(a.t2) - } else if ent.ll == a.b2 { - // Case III - // Cache Miss in t1 and t2 - - // Adaptation - var d int - if a.b2.Len() >= a.b1.Len() { - d = 1 - } else { - d = a.b1.Len() / a.b2.Len() - } - a.p = a.p - d - if a.p < 0 { - a.p = 0 - } - - a.replace(ent) - ent.setMRU(a.t2) - } else if ent.ll == nil { - // Case IV - - if a.t1.Len()+a.b1.Len() == a.c { - // Case A - if a.t1.Len() < a.c { - a.delLRU(a.b1) - a.replace(ent) - } else { - a.delLRU(a.t1) - } - } else if a.t1.Len()+a.b1.Len() < a.c { - // Case B - if a.t1.Len()+a.t2.Len()+a.b1.Len()+a.b2.Len() >= a.c { - if a.t1.Len()+a.t2.Len()+a.b1.Len()+a.b2.Len() == 2*a.c { - a.delLRU(a.b2) - } - a.replace(ent) - } - } - - ent.setMRU(a.t1) - } -} - -func (a *arc) delLRU(list *list.List) { - lru := list.Back() - list.Remove(lru) - delete(a.cache, string(lru.Value.(*entry).key)) -} - -func (a *arc) replace(ent *entry) { - if a.t1.Len() > 0 && ((a.t1.Len() > a.p) || (ent.ll == a.b2 && a.t1.Len() == a.p)) { - lru := a.t1.Back().Value.(*entry) - lru.value = nil - lru.setMRU(a.b1) - } else { - lru := a.t2.Back().Value.(*entry) - lru.value = nil - lru.setMRU(a.b2) - } -} - -func (e *entry) setLRU(list *list.List) { - e.detach() - e.ll = list - e.el = e.ll.PushBack(e) -} - -func (e *entry) setMRU(list *list.List) { - e.detach() - e.ll = list - e.el = e.ll.PushFront(e) -} - -func (e *entry) detach() { - if e.ll != nil { - e.ll.Remove(e.el) - } -} |