mem_entry_impl.h | Explore in Territory

// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_DISK_CACHE_MEMORY_MEM_ENTRY_IMPL_H_
#define NET_DISK_CACHE_MEMORY_MEM_ENTRY_IMPL_H_

#include <stdint.h>

#include <map>
#include <memory>
#include <string>
#include <vector>

#include "base/containers/linked_list.h"
#include "base/gtest_prod_util.h"
#include "base/memory/raw_ptr.h"
#include "base/memory/weak_ptr.h"
#include "base/time/time.h"
#include "base/trace_event/memory_usage_estimator.h"
#include "net/base/interval.h"
#include "net/base/net_export.h"
#include "net/disk_cache/disk_cache.h"
#include "net/log/net_log_with_source.h"

namespace net {
class NetLog;
}

namespace disk_cache {

class MemBackendImpl;

// This class implements the Entry interface for the memory-only cache. An
// object of this class represents a single entry on the cache. We use two types
// of entries, parent and child to support sparse caching.
//
// A parent entry is non-sparse until a sparse method is invoked (i.e.
// ReadSparseData, WriteSparseData, GetAvailableRange) when sparse information
// is initialized. It then manages a list of child entries and delegates the
// sparse API calls to the child entries. It creates and deletes child entries
// and updates the list when needed.
//
// A child entry is used to carry partial cache content, non-sparse methods like
// ReadData and WriteData cannot be applied to them. The lifetime of a child
// entry is managed by the parent entry that created it except that the entry
// can be evicted independently. A child entry does not have a key and it is not
// registered in the backend's entry map.
//
// A sparse child entry has a fixed maximum size and can be partially
// filled. There can only be one continous filled region in a sparse entry, as
// illustrated by the following example:
// | xxx ooooo |
// x = unfilled region
// o = filled region
// It is guaranteed that there is at most one unfilled region and one filled
// region, and the unfilled region (if there is one) is always before the filled
// region. The book keeping for filled region in a sparse entry is done by using
// the variable |child_first_pos_|.

class NET_EXPORT_PRIVATE MemEntryImpl final
    : public Entry,
      public base::LinkNode<MemEntryImpl> { … };

}  // namespace disk_cache

#endif  // NET_DISK_CACHE_MEMORY_MEM_ENTRY_IMPL_H_
chromium/net/disk_cache/memory/mem_entry_impl.h
