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// Copyright (c) 2009 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.
#include "net/base/host_cache.h"
#include "base/logging.h"
#include "net/base/net_errors.h"
namespace net {
//-----------------------------------------------------------------------------
HostCache::Entry::Entry(int error,
const AddressList& addrlist,
base::TimeTicks expiration)
: error(error), addrlist(addrlist), expiration(expiration) {
}
HostCache::Entry::~Entry() {
}
//-----------------------------------------------------------------------------
HostCache::HostCache(size_t max_entries, size_t cache_duration_ms)
: max_entries_(max_entries), cache_duration_ms_(cache_duration_ms) {
}
HostCache::~HostCache() {
}
const HostCache::Entry* HostCache::Lookup(const Key& key,
base::TimeTicks now) const {
if (caching_is_disabled())
return NULL;
EntryMap::const_iterator it = entries_.find(key);
if (it == entries_.end())
return NULL; // Not found.
Entry* entry = it->second.get();
if (CanUseEntry(entry, now))
return entry;
return NULL;
}
HostCache::Entry* HostCache::Set(const Key& key,
int error,
const AddressList addrlist,
base::TimeTicks now) {
if (caching_is_disabled())
return NULL;
base::TimeTicks expiration = now +
base::TimeDelta::FromMilliseconds(cache_duration_ms_);
scoped_refptr<Entry>& entry = entries_[key];
if (!entry) {
// Entry didn't exist, creating one now.
Entry* ptr = new Entry(error, addrlist, expiration);
entry = ptr;
// Compact the cache if we grew it beyond limit -- exclude |entry| from
// being pruned though!
if (entries_.size() > max_entries_)
Compact(now, ptr);
return ptr;
} else {
// Update an existing cache entry.
entry->error = error;
entry->addrlist = addrlist;
entry->expiration = expiration;
return entry.get();
}
}
// static
bool HostCache::CanUseEntry(const Entry* entry, const base::TimeTicks now) {
return entry->error == OK && entry->expiration > now;
}
void HostCache::Compact(base::TimeTicks now, const Entry* pinned_entry) {
// Clear out expired entries.
for (EntryMap::iterator it = entries_.begin(); it != entries_.end(); ) {
Entry* entry = (it->second).get();
if (entry != pinned_entry && !CanUseEntry(entry, now)) {
entries_.erase(it++);
} else {
++it;
}
}
if (entries_.size() <= max_entries_)
return;
// If we still have too many entries, start removing unexpired entries
// at random.
// TODO(eroman): this eviction policy could be better (access count FIFO
// or whatever).
for (EntryMap::iterator it = entries_.begin();
it != entries_.end() && entries_.size() > max_entries_; ) {
Entry* entry = (it->second).get();
if (entry != pinned_entry) {
entries_.erase(it++);
} else {
++it;
}
}
if (entries_.size() > max_entries_)
DLOG(WARNING) << "Still above max entries limit";
}
} // namespace net
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