OLD | NEW |
1 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 // | 4 // |
5 // A StatsTable is a table of statistics. It can be used across multiple | 5 // A StatsTable is a table of statistics. It can be used across multiple |
6 // processes and threads, maintaining cheap statistics counters without | 6 // processes and threads, maintaining cheap statistics counters without |
7 // locking. | 7 // locking. |
8 // | 8 // |
9 // The goal is to make it very cheap and easy for developers to add | 9 // The goal is to make it very cheap and easy for developers to add |
10 // counters to code, without having to build one-off utilities or mechanisms | 10 // counters to code, without having to build one-off utilities or mechanisms |
11 // to track the counters, and also to allow a single "view" to display | 11 // to track the counters, and also to allow a single "view" to display |
12 // the contents of all counters. | 12 // the contents of all counters. |
13 // | 13 // |
14 // To achieve this, StatsTable creates a shared memory segment to store | 14 // To achieve this, StatsTable creates a shared memory segment to store |
15 // the data for the counters. Upon creation, it has a specific size | 15 // the data for the counters. Upon creation, it has a specific size |
16 // which governs the maximum number of counters and concurrent | 16 // which governs the maximum number of counters and concurrent |
17 // threads/processes which can use it. | 17 // threads/processes which can use it. |
18 // | 18 // |
19 | 19 |
20 #ifndef BASE_STATS_TABLE_H__ | 20 #ifndef BASE_STATS_TABLE_H__ |
21 #define BASE_STATS_TABLE_H__ | 21 #define BASE_STATS_TABLE_H__ |
22 | 22 |
23 #include <string> | 23 #include <string> |
24 #include "base/basictypes.h" | 24 #include "base/basictypes.h" |
25 #include "base/hash_tables.h" | 25 #include "base/hash_tables.h" |
26 #include "base/lock.h" | 26 #include "base/lock.h" |
27 #include "base/shared_memory.h" | |
28 #include "base/thread_local_storage.h" | 27 #include "base/thread_local_storage.h" |
29 | 28 |
30 class StatsTablePrivate; | 29 class StatsTablePrivate; |
31 | 30 |
32 namespace { | 31 namespace { |
33 struct StatsTableTLSData; | 32 struct StatsTableTLSData; |
34 } | 33 } |
35 | 34 |
36 class StatsTable { | 35 class StatsTable { |
37 public: | 36 public: |
(...skipping 120 matching lines...) Expand 10 before | Expand all | Expand 10 after Loading... |
158 // On failure, returns 0. | 157 // On failure, returns 0. |
159 int AddCounter(const std::wstring& name); | 158 int AddCounter(const std::wstring& name); |
160 | 159 |
161 // Get the TLS data for the calling thread. Returns NULL if none is | 160 // Get the TLS data for the calling thread. Returns NULL if none is |
162 // initialized. | 161 // initialized. |
163 StatsTableTLSData* GetTLSData() const; | 162 StatsTableTLSData* GetTLSData() const; |
164 | 163 |
165 typedef base::hash_map<std::wstring, int> CountersMap; | 164 typedef base::hash_map<std::wstring, int> CountersMap; |
166 | 165 |
167 bool opened_; | 166 bool opened_; |
168 SharedMemory shared_memory_; | |
169 StatsTablePrivate* impl_; | 167 StatsTablePrivate* impl_; |
170 // The counters_lock_ protects the counters_ hash table. | 168 // The counters_lock_ protects the counters_ hash table. |
171 Lock counters_lock_; | 169 Lock counters_lock_; |
172 // The counters_ hash map is an in-memory hash of the counters. | 170 // The counters_ hash map is an in-memory hash of the counters. |
173 // It is used for quick lookup of counters, but is cannot be used | 171 // It is used for quick lookup of counters, but is cannot be used |
174 // as a substitute for what is in the shared memory. Even though | 172 // as a substitute for what is in the shared memory. Even though |
175 // we don't have a counter in our hash table, another process may | 173 // we don't have a counter in our hash table, another process may |
176 // have created it. | 174 // have created it. |
177 CountersMap counters_; | 175 CountersMap counters_; |
178 TLSSlot tls_index_; | 176 TLSSlot tls_index_; |
179 | 177 |
180 static StatsTable* global_table_; | 178 static StatsTable* global_table_; |
181 DISALLOW_EVIL_CONSTRUCTORS(StatsTable); | 179 DISALLOW_EVIL_CONSTRUCTORS(StatsTable); |
182 }; | 180 }; |
183 | 181 |
184 #endif // BASE_STATS_TABLE_H__ | 182 #endif // BASE_STATS_TABLE_H__ |
185 | |
OLD | NEW |