File: thread_local_storage.h

package info (click to toggle)
icedove 1:52.3.0-4~deb8u2
  • links: PTS, VCS
  • area: main
  • in suites: jessie
  • size: 1,705,608 kB
  • sloc: cpp: 5,079,451; ansic: 2,051,639; python: 458,782; java: 241,615; xml: 192,378; asm: 178,649; sh: 81,867; makefile: 24,692; perl: 16,874; objc: 4,389; yacc: 1,816; ada: 1,697; lex: 1,257; pascal: 1,251; cs: 879; exp: 499; php: 436; lisp: 258; awk: 152; sed: 51; ruby: 47; csh: 27
file content (96 lines) | stat: -rw-r--r-- 3,012 bytes parent folder | download | duplicates (6)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
// Copyright (c) 2006-2008 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 BASE_THREAD_LOCAL_STORAGE_H_
#define BASE_THREAD_LOCAL_STORAGE_H_

#include "base/basictypes.h"

#if defined(OS_POSIX)
#include <pthread.h>
#endif

// Wrapper for thread local storage.  This class doesn't do much except provide
// an API for portability.
class ThreadLocalStorage {
 public:

  // Prototype for the TLS destructor function, which can be optionally used to
  // cleanup thread local storage on thread exit.  'value' is the data that is
  // stored in thread local storage.
  typedef void (*TLSDestructorFunc)(void* value);

  // A key representing one value stored in TLS.
  class Slot {
   public:
    explicit Slot(TLSDestructorFunc destructor = NULL);

    // This constructor should be used for statics.
    // It returns an uninitialized Slot.
    explicit Slot(base::LinkerInitialized x) {}

    // Set up the TLS slot.  Called by the constructor.
    // 'destructor' is a pointer to a function to perform per-thread cleanup of
    // this object.  If set to NULL, no cleanup is done for this TLS slot.
    // Returns false on error.
    bool Initialize(TLSDestructorFunc destructor);

    // Free a previously allocated TLS 'slot'.
    // If a destructor was set for this slot, removes
    // the destructor so that remaining threads exiting
    // will not free data.
    void Free();

    // Get the thread-local value stored in slot 'slot'.
    // Values are guaranteed to initially be zero.
    void* Get() const;

    // Set the thread-local value stored in slot 'slot' to
    // value 'value'.
    void Set(void* value);

    bool initialized() const { return initialized_; }

   private:
    // The internals of this struct should be considered private.
    bool initialized_;
#if defined(OS_WIN)
    int slot_;
#elif defined(OS_POSIX)
    pthread_key_t key_;
#endif

    DISALLOW_COPY_AND_ASSIGN(Slot);
  };

#if defined(OS_WIN)
  // Function called when on thread exit to call TLS
  // destructor functions.  This function is used internally.
  static void ThreadExit();

 private:
  // Function to lazily initialize our thread local storage.
  static void **Initialize();

 private:
  // The maximum number of 'slots' in our thread local storage stack.
  // For now, this is fixed.  We could either increase statically, or
  // we could make it dynamic in the future.
  static const int kThreadLocalStorageSize = 64;

  static long tls_key_;
  static long tls_max_;
  static TLSDestructorFunc tls_destructors_[kThreadLocalStorageSize];
#endif  // OS_WIN

  DISALLOW_COPY_AND_ASSIGN(ThreadLocalStorage);
};

// Temporary backwards-compatible name.
// TODO(evanm): replace all usage of TLSSlot.
typedef ThreadLocalStorage::Slot TLSSlot;

#endif  // BASE_THREAD_LOCAL_STORAGE_H_