extensions/browser/process_map.h

   1 // Copyright 2013 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 EXTENSIONS_BROWSER_PROCESS_MAP_H_
   6 #define EXTENSIONS_BROWSER_PROCESS_MAP_H_
   7
   8 #include <set>
   9 #include <string>
  10
  11 #include "base/basictypes.h"
  12 #include "components/keyed_service/core/keyed_service.h"
  13
  14 namespace content {
  15 class BrowserContext;
  16 }
  17
  18 namespace extensions {
  19
  20 // Contains information about which extensions are assigned to which processes.
  21 //
  22 // The relationship between extensions and processes is complex:
  23 //
  24 // - Extensions can be either "split" mode or "spanning" mode.
  25 // - In spanning mode, extensions share a single process between all incognito
  26 //   and normal windows. This was the original mode for extensions.
  27 // - In split mode, extensions have separate processes in incognito windows.
  28 // - There are also hosted apps, which are a kind of extensions, and those
  29 //   usually have a process model similar to normal web sites: multiple
  30 //   processes per-profile.
  31 // - A single hosted app can have more than one SiteInstance in the same process
  32 //   if we're over the process limit and force them to share a process.
  33 //
  34 // In general, we seem to play with the process model of extensions a lot, so
  35 // it is safest to assume it is many-to-many in most places in the codebase.
  36 //
  37 // Note that because of content scripts, frames, and other edge cases in
  38 // Chrome's process isolation, extension code can still end up running outside
  39 // an assigned process.
  40 //
  41 // But we only allow high-privilege operations to be performed by an extension
  42 // when it is running in an assigned process.
  43 //
  44 // ===========================================================================
  45 // WARNINGS - PLEASE UNDERSTAND THESE BEFORE CALLING OR MODIFYING THIS CLASS
  46 // ===========================================================================
  47 //
  48 // 1. This class contains the processes for hosted apps as well as extensions
  49 //    and packaged apps. Just because a process is present here *does not* mean
  50 //    it is an "extension process" (e.g., for UI purposes). It may contain only
  51 //    hosted apps. See crbug.com/102533.
  52 //
  53 // 2. An extension can show up in multiple processes. That is why there is no
  54 //    GetExtensionProcess() method here. There are two cases: a) The extension
  55 //    is actually a hosted app, in which case this is normal, or b) there is an
  56 //    incognito window open and the extension is "split mode". It is *not safe*
  57 //    to assume that there is one process per extension. If you only care about
  58 //    extensions (not hosted apps), and you are on the UI thread, and you don't
  59 //    care about incognito version of this extension (or vice versa if you're in
  60 //    an incognito profile) then use
  61 //    extensions::ProcessManager::GetSiteInstanceForURL()->[Has|Get]Process().
  62 //
  63 // 3. The process ids contained in this class are *not limited* to the Profile
  64 //    you got this map from. They can also be associated with that profile's
  65 //    incognito/normal twin. If you care about this, use
  66 //    RenderProcessHost::FromID() and check the profile of the resulting object.
  67 //
  68 // TODO(aa): The above warnings suggest this class could use improvement :).
  69 class ProcessMap : public KeyedService {
  70  public:
  71   ProcessMap();
  72   virtual ~ProcessMap();
  73
  74   // Returns the instance for |browser_context|. An instance is shared between
  75   // an incognito and a regular context.
  76   static ProcessMap* Get(content::BrowserContext* browser_context);
  77
  78   size_t size() const { return items_.size(); }
  79
  80   bool Insert(const std::string& extension_id, int process_id,
  81               int site_instance_id);
  82
  83   bool Remove(const std::string& extension_id, int process_id,
  84               int site_instance_id);
  85   int RemoveAllFromProcess(int process_id);
  86
  87   bool Contains(const std::string& extension_id, int process_id) const;
  88   bool Contains(int process_id) const;
  89
  90   std::set<std::string> GetExtensionsInProcess(int process_id) const;
  91
  92  private:
  93   struct Item;
  94
  95   typedef std::set<Item> ItemSet;
  96   ItemSet items_;
  97
  98   DISALLOW_COPY_AND_ASSIGN(ProcessMap);
  99 };
 100
 101 }  // namespace extensions
 102
 103 #endif  // EXTENSIONS_BROWSER_PROCESS_MAP_H_