// Copyright (c) 2011 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.

#ifndef CHROME_BROWSER_EXTENSIONS_PROCESS_MAP_H_
#define CHROME_BROWSER_EXTENSIONS_PROCESS_MAP_H_

#include <set>
#include <string>

#include "base/basictypes.h"

namespace extensions {

// Contains information about which extensions are assigned to which processes.
//
// The relationship between extensions and processes is complex:
//
// - Extensions can be either "split" mode or "spanning" mode.
// - In spanning mode, extensions share a single process between all incognito
//   and normal windows. This was the original mode for extensions.
// - In split mode, extensions have separate processes in incognito windows.
// - There are also hosted apps, which are a kind of extensions, and those
//   usually have a process model similar to normal web sites: multiple
//   processes per-profile.
// - A single hosted app can have more than one SiteInstance in the same process
//   if we're over the process limit and force them to share a process.
//
// In general, we seem to play with the process model of extensions a lot, so
// it is safest to assume it is many-to-many in most places in the codebase.
//
// Note that because of content scripts, frames, and other edge cases in
// Chrome's process isolation, extension code can still end up running outside
// an assigned process.
//
// But we only allow high-privilege operations to be performed by an extension
// when it is running in an assigned process.
//
// ===========================================================================
// WARNINGS - PLEASE UNDERSTAND THESE BEFORE CALLING OR MODIFYING THIS CLASS
// ===========================================================================
//
// 1. This class contains the processes for hosted apps as well as extensions
//    and packaged apps. Just because a process is present here *does not* mean
//    it is an "extension process" (e.g., for UI purposes). It may contain only
//    hosted apps. See crbug.com/102533.
//
// 2. An extension can show up in multiple processes. That is why there is no
//    GetExtensionProcess() method here. There are two cases: a) The extension
//    is actually a hosted app, in which case this is normal, or b) there is an
//    incognito window open and the extension is "split mode". It is *not safe*
//    to assume that there is one process per extension. If you only care about
//    extensions (not hosted apps), and you are on the UI thread, and you don't
//    care about incognito version of this extension (or vice versa if you're in
//    an incognito profile) then use
//    ExtensionProcessManager::GetSiteInstanceForURL()->[Has|Get]Process().
//
// 3. The process ids contained in this class are *not limited* to the Profile
//    you got this map from. They can also be associated with that profile's
//    incognito/normal twin. If you care about this, use
//    RenderProcessHost::FromID() and check the profile of the resulting object.
//
// TODO(aa): The above warnings suggest this class could use improvement :).
class ProcessMap {
 public:
  ProcessMap();
  ~ProcessMap();

  size_t size() const { return items_.size(); }

  bool Insert(const std::string& extension_id, int process_id,
              int site_instance_id);

  bool Remove(const std::string& extension_id, int process_id,
              int site_instance_id);
  int RemoveAllFromProcess(int process_id);

  bool Contains(const std::string& extension_id, int process_id) const;
  bool Contains(int process_id) const;

  std::set<std::string> GetExtensionsInProcess(int process_id) const;

 private:
  struct Item;

  typedef std::set<Item> ItemSet;
  ItemSet items_;

  DISALLOW_COPY_AND_ASSIGN(ProcessMap);
};

}  // extensions

#endif  // CHROME_BROWSER_EXTENSIONS_PROCESS_MAP_H_