chrome/browser/extensions/process_map.h

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef CHROME_BROWSER_EXTENSIONS_PROCESS_MAP_H_
   6 #define CHROME_BROWSER_EXTENSIONS_PROCESS_MAP_H_
   7
   8 #include <set>
   9 #include <string>
  10
  11 #include "base/basictypes.h"
  12
  13 namespace extensions {
  14
  15 // Contains information about which extensions are assigned to which processes.
  16 //
  17 // The relationship between extensions and processes is complex:
  18 //
  19 // - Extensions can be either "split" mode or "spanning" mode.
  20 // - In spanning mode, extensions share a single process between all incognito
  21 //   and normal windows. This was the original mode for extensions.
  22 // - In split mode, extensions have separate processes in incognito windows.
  23 // - There are also hosted apps, which are a kind of extensions, and those
  24 //   usually have a process model similar to normal web sites: multiple
  25 //   processes per-profile.
  26 // - A single hosted app can have more than one SiteInstance in the same process
  27 //   if we're over the process limit and force them to share a process.
  28 //
  29 // In general, we seem to play with the process model of extensions a lot, so
  30 // it is safest to assume it is many-to-many in most places in the codebase.
  31 //
  32 // Note that because of content scripts, frames, and other edge cases in
  33 // Chrome's process isolation, extension code can still end up running outside
  34 // an assigned process.
  35 //
  36 // But we only allow high-privilege operations to be performed by an extension
  37 // when it is running in an assigned process.
  38 //
  39 // ===========================================================================
  40 // WARNINGS - PLEASE UNDERSTAND THESE BEFORE CALLING OR MODIFYING THIS CLASS
  41 // ===========================================================================
  42 //
  43 // 1. This class contains the processes for hosted apps as well as extensions
  44 //    and packaged apps. Just because a process is present here *does not* mean
  45 //    it is an "extension process" (e.g., for UI purposes). It may contain only
  46 //    hosted apps. See crbug.com/102533.
  47 //
  48 // 2. An extension can show up in multiple processes. That is why there is no
  49 //    GetExtensionProcess() method here. There are two cases: a) The extension
  50 //    is actually a hosted app, in which case this is normal, or b) there is an
  51 //    incognito window open and the extension is "split mode". It is *not safe*
  52 //    to assume that there is one process per extension. If you only care about
  53 //    extensions (not hosted apps), and you are on the UI thread, and you don't
  54 //    care about incognito version of this extension (or vice versa if you're in
  55 //    an incognito profile) then use
  56 //    ExtensionProcessManager::GetSiteInstanceForURL()->[Has|Get]Process().
  57 //
  58 // 3. The process ids contained in this class are *not limited* to the Profile
  59 //    you got this map from. They can also be associated with that profile's
  60 //    incognito/normal twin. If you care about this, use
  61 //    RenderProcessHost::FromID() and check the profile of the resulting object.
  62 //
  63 // TODO(aa): The above warnings suggest this class could use improvement :).
  64 class ProcessMap {
  65  public:
  66   ProcessMap();
  67   ~ProcessMap();
  68
  69   size_t size() const { return items_.size(); }
  70
  71   bool Insert(const std::string& extension_id, int process_id,
  72               int site_instance_id);
  73
  74   bool Remove(const std::string& extension_id, int process_id,
  75               int site_instance_id);
  76   int RemoveAllFromProcess(int process_id);
  77
  78   bool Contains(const std::string& extension_id, int process_id) const;
  79   bool Contains(int process_id) const;
  80
  81   std::set<std::string> GetExtensionsInProcess(int process_id) const;
  82
  83  private:
  84   struct Item;
  85
  86   typedef std::set<Item> ItemSet;
  87   ItemSet items_;
  88
  89   DISALLOW_COPY_AND_ASSIGN(ProcessMap);
  90 };
  91
  92 }  // extensions
  93
  94 #endif  // CHROME_BROWSER_EXTENSIONS_PROCESS_MAP_H_