[email protected] | 8e9d06b | 2013-11-19 19:05:18 | [diff] [blame] | 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 CONTENT_BROWSER_RENDERER_DATA_MEMOIZING_STORE_H_ |
| 6 | #define CONTENT_BROWSER_RENDERER_DATA_MEMOIZING_STORE_H_ |
| 7 | |
| 8 | #include <map> |
| 9 | |
| 10 | #include "base/bind.h" |
| 11 | #include "base/synchronization/lock.h" |
[email protected] | 8e9d06b | 2013-11-19 19:05:18 | [diff] [blame] | 12 | #include "content/public/browser/browser_thread.h" |
[email protected] | f68c146 | 2014-04-24 18:17:53 | [diff] [blame] | 13 | #include "content/public/browser/render_process_host.h" |
[email protected] | f235aa89 | 2013-11-22 23:14:27 | [diff] [blame] | 14 | #include "content/public/browser/render_process_host_observer.h" |
[email protected] | 8e9d06b | 2013-11-19 19:05:18 | [diff] [blame] | 15 | |
| 16 | namespace content { |
| 17 | |
| 18 | // RendererDataMemoizingStore is a thread-safe container that retains reference |
| 19 | // counted objects that are associated with one or more render processes. |
| 20 | // Objects are identified by an int and only a single reference to a given |
| 21 | // object is retained. RendererDataMemoizingStore watches for render process |
| 22 | // termination and releases objects that are no longer associated with any |
| 23 | // render process. |
[email protected] | f235aa89 | 2013-11-22 23:14:27 | [diff] [blame] | 24 | // |
| 25 | // TODO(jcampan): Rather than watching for render process termination, we should |
| 26 | // instead be listening to events such as resource cached/ |
| 27 | // removed from cache, and remove the items when we know they |
| 28 | // are not used anymore. |
[email protected] | 8e9d06b | 2013-11-19 19:05:18 | [diff] [blame] | 29 | template <typename T> |
[email protected] | f235aa89 | 2013-11-22 23:14:27 | [diff] [blame] | 30 | class RendererDataMemoizingStore : public RenderProcessHostObserver { |
[email protected] | 8e9d06b | 2013-11-19 19:05:18 | [diff] [blame] | 31 | public: |
| 32 | RendererDataMemoizingStore() : next_item_id_(1) { |
[email protected] | f235aa89 | 2013-11-22 23:14:27 | [diff] [blame] | 33 | } |
| 34 | |
| 35 | ~RendererDataMemoizingStore() { |
| 36 | DCHECK_EQ(0U, id_to_item_.size()) << "Failed to outlive render processes"; |
[email protected] | 8e9d06b | 2013-11-19 19:05:18 | [diff] [blame] | 37 | } |
| 38 | |
| 39 | // Store adds |item| to this collection, associates it with the given render |
| 40 | // process id and returns an opaque identifier for it. If |item| is already |
| 41 | // known, the same identifier will be returned. |
| 42 | int Store(T* item, int process_id) { |
| 43 | DCHECK(item); |
| 44 | base::AutoLock auto_lock(lock_); |
| 45 | |
| 46 | int item_id; |
| 47 | |
| 48 | // Do we already know this item? |
| 49 | typename ReverseItemMap::iterator item_iter = item_to_id_.find(item); |
| 50 | if (item_iter == item_to_id_.end()) { |
| 51 | item_id = next_item_id_++; |
| 52 | // We use 0 as an invalid item_id value. In the unlikely event that |
| 53 | // next_item_id_ wraps around, we reset it to 1. |
| 54 | if (next_item_id_ == 0) |
| 55 | next_item_id_ = 1; |
[email protected] | 8e9d06b | 2013-11-19 19:05:18 | [diff] [blame] | 56 | id_to_item_[item_id] = item; |
| 57 | item_to_id_[item] = item_id; |
| 58 | } else { |
| 59 | item_id = item_iter->second; |
| 60 | } |
| 61 | |
| 62 | // Let's update process_id_to_item_id_. |
| 63 | std::pair<IDMap::iterator, IDMap::iterator> process_ids = |
| 64 | process_id_to_item_id_.equal_range(process_id); |
[email protected] | f235aa89 | 2013-11-22 23:14:27 | [diff] [blame] | 65 | bool already_watching_process = (process_ids.first != process_ids.second); |
[email protected] | 8e9d06b | 2013-11-19 19:05:18 | [diff] [blame] | 66 | if (std::find_if(process_ids.first, process_ids.second, |
| 67 | MatchSecond<int>(item_id)) == process_ids.second) { |
| 68 | process_id_to_item_id_.insert(std::make_pair(process_id, item_id)); |
| 69 | } |
| 70 | |
| 71 | // And item_id_to_process_id_. |
| 72 | std::pair<IDMap::iterator, IDMap::iterator> item_ids = |
| 73 | item_id_to_process_id_.equal_range(item_id); |
| 74 | if (std::find_if(item_ids.first, item_ids.second, |
| 75 | MatchSecond<int>(process_id)) == item_ids.second) { |
| 76 | item_id_to_process_id_.insert(std::make_pair(item_id, process_id)); |
| 77 | } |
| 78 | |
[email protected] | f235aa89 | 2013-11-22 23:14:27 | [diff] [blame] | 79 | // If we're not doing so already, keep an eye for the process host deletion. |
| 80 | if (!already_watching_process) { |
| 81 | if (BrowserThread::CurrentlyOn(BrowserThread::UI)) { |
| 82 | StartObservingProcess(process_id); |
| 83 | } else { |
| 84 | BrowserThread::PostTask( |
| 85 | BrowserThread::UI, |
| 86 | FROM_HERE, |
| 87 | base::Bind(&RendererDataMemoizingStore::StartObservingProcess, |
| 88 | base::Unretained(this), |
| 89 | process_id)); |
| 90 | } |
| 91 | } |
| 92 | |
[email protected] | 9ef0b6a | 2014-02-27 00:10:02 | [diff] [blame] | 93 | DCHECK(item_id); |
[email protected] | 8e9d06b | 2013-11-19 19:05:18 | [diff] [blame] | 94 | return item_id; |
| 95 | } |
| 96 | |
| 97 | // Retrieve fetches a previously Stored() item, identified by |item_id|. |
| 98 | // If |item_id| is recognized, |item| will be updated and Retrieve() will |
| 99 | // return true, it will otherwise return false. |
| 100 | bool Retrieve(int item_id, scoped_refptr<T>* item) { |
| 101 | base::AutoLock auto_lock(lock_); |
| 102 | |
| 103 | typename ItemMap::iterator iter = id_to_item_.find(item_id); |
| 104 | if (iter == id_to_item_.end()) |
| 105 | return false; |
| 106 | if (item) |
| 107 | *item = iter->second; |
| 108 | return true; |
| 109 | } |
| 110 | |
| 111 | private: |
| 112 | typedef std::multimap<int, int> IDMap; |
| 113 | typedef std::map<int, scoped_refptr<T> > ItemMap; |
| 114 | typedef std::map<T*, int, typename T::LessThan> ReverseItemMap; |
| 115 | |
| 116 | template <typename M> |
| 117 | struct MatchSecond { |
| 118 | explicit MatchSecond(const M& t) : value(t) {} |
| 119 | |
| 120 | template <typename Pair> |
| 121 | bool operator()(const Pair& p) const { |
| 122 | return (value == p.second); |
| 123 | } |
| 124 | |
| 125 | M value; |
| 126 | }; |
| 127 | |
[email protected] | f235aa89 | 2013-11-22 23:14:27 | [diff] [blame] | 128 | void StartObservingProcess(int process_id) { |
| 129 | DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI)); |
| 130 | RenderProcessHost* host = RenderProcessHost::FromID(process_id); |
| 131 | if (!host) { |
| 132 | // We lost the race to observe the host before it was destroyed. Since |
| 133 | // this function was called because we're managing objects tied to that |
| 134 | // (now destroyed) RenderProcessHost, let's clean up. |
| 135 | RemoveRenderProcessItems(process_id); |
| 136 | return; |
| 137 | } |
[email protected] | 8e9d06b | 2013-11-19 19:05:18 | [diff] [blame] | 138 | |
[email protected] | f235aa89 | 2013-11-22 23:14:27 | [diff] [blame] | 139 | host->AddObserver(this); |
[email protected] | 8e9d06b | 2013-11-19 19:05:18 | [diff] [blame] | 140 | } |
| 141 | |
[email protected] | 7635eed6 | 2013-11-20 08:38:02 | [diff] [blame] | 142 | // Remove the item specified by |item_id| from id_to_item_ and item_to_id_. |
[email protected] | f235aa89 | 2013-11-22 23:14:27 | [diff] [blame] | 143 | // NOTE: the caller (RemoveRenderProcessItems) must hold lock_. |
[email protected] | 8e9d06b | 2013-11-19 19:05:18 | [diff] [blame] | 144 | void RemoveInternal(int item_id) { |
| 145 | typename ItemMap::iterator item_iter = id_to_item_.find(item_id); |
| 146 | DCHECK(item_iter != id_to_item_.end()); |
| 147 | |
| 148 | typename ReverseItemMap::iterator id_iter = |
| 149 | item_to_id_.find(item_iter->second.get()); |
| 150 | DCHECK(id_iter != item_to_id_.end()); |
| 151 | item_to_id_.erase(id_iter); |
| 152 | |
[email protected] | 8e9d06b | 2013-11-19 19:05:18 | [diff] [blame] | 153 | id_to_item_.erase(item_iter); |
| 154 | } |
| 155 | |
dmichael | c1a4941 | 2014-12-18 17:35:42 | [diff] [blame] | 156 | void RenderProcessHostDestroyed(RenderProcessHost* host) override { |
[email protected] | f235aa89 | 2013-11-22 23:14:27 | [diff] [blame] | 157 | DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI)); |
| 158 | RemoveRenderProcessItems(host->GetID()); |
| 159 | } |
| 160 | |
[email protected] | 8e9d06b | 2013-11-19 19:05:18 | [diff] [blame] | 161 | // Removes all the items associated with the specified process from the store. |
[email protected] | f235aa89 | 2013-11-22 23:14:27 | [diff] [blame] | 162 | void RemoveRenderProcessItems(int process_id) { |
[email protected] | 8e9d06b | 2013-11-19 19:05:18 | [diff] [blame] | 163 | base::AutoLock auto_lock(lock_); |
| 164 | |
| 165 | // We iterate through all the item ids for that process. |
| 166 | std::pair<IDMap::iterator, IDMap::iterator> process_ids = |
| 167 | process_id_to_item_id_.equal_range(process_id); |
| 168 | for (IDMap::iterator ids_iter = process_ids.first; |
| 169 | ids_iter != process_ids.second; ++ids_iter) { |
| 170 | int item_id = ids_iter->second; |
| 171 | // Find all the processes referring to this item id in |
| 172 | // item_id_to_process_id_, then locate the process being removed within |
| 173 | // that range. |
| 174 | std::pair<IDMap::iterator, IDMap::iterator> item_ids = |
| 175 | item_id_to_process_id_.equal_range(item_id); |
| 176 | IDMap::iterator proc_iter = std::find_if( |
| 177 | item_ids.first, item_ids.second, MatchSecond<int>(process_id)); |
| 178 | DCHECK(proc_iter != item_ids.second); |
| 179 | |
| 180 | // Before removing, determine if no other processes refer to the current |
| 181 | // item id. If |proc_iter| (the current process) is the lower bound of |
| 182 | // processes containing the current item id and if |next_proc_iter| is the |
| 183 | // upper bound (the first process that does not), then only one process, |
| 184 | // the one being removed, refers to the item id. |
| 185 | IDMap::iterator next_proc_iter = proc_iter; |
| 186 | ++next_proc_iter; |
| 187 | bool last_process_for_item_id = |
| 188 | (proc_iter == item_ids.first && next_proc_iter == item_ids.second); |
| 189 | item_id_to_process_id_.erase(proc_iter); |
| 190 | |
| 191 | if (last_process_for_item_id) { |
| 192 | // The current item id is not referenced by any other processes, so |
| 193 | // remove it from id_to_item_ and item_to_id_. |
| 194 | RemoveInternal(item_id); |
| 195 | } |
| 196 | } |
| 197 | if (process_ids.first != process_ids.second) |
| 198 | process_id_to_item_id_.erase(process_ids.first, process_ids.second); |
| 199 | } |
| 200 | |
[email protected] | 8e9d06b | 2013-11-19 19:05:18 | [diff] [blame] | 201 | IDMap process_id_to_item_id_; |
| 202 | IDMap item_id_to_process_id_; |
| 203 | ItemMap id_to_item_; |
| 204 | ReverseItemMap item_to_id_; |
| 205 | |
| 206 | int next_item_id_; |
| 207 | |
| 208 | // This lock protects: process_id_to_item_id_, item_id_to_process_id_, |
| 209 | // id_to_item_, and item_to_id_. |
| 210 | base::Lock lock_; |
| 211 | }; |
| 212 | |
| 213 | } // namespace content |
| 214 | |
| 215 | #endif // CONTENT_BROWSER_RENDERER_DATA_MEMOIZING_STORE_H_ |