/src/botan/src/lib/utils/thread_utils/thread_pool.cpp
Line | Count | Source (jump to first uncovered line) |
1 | | /* |
2 | | * (C) 2019 Jack Lloyd |
3 | | * |
4 | | * Botan is released under the Simplified BSD License (see license.txt) |
5 | | */ |
6 | | |
7 | | #include <botan/internal/thread_pool.h> |
8 | | #include <botan/internal/os_utils.h> |
9 | | #include <botan/exceptn.h> |
10 | | #include <thread> |
11 | | |
12 | | namespace Botan { |
13 | | |
14 | | //static |
15 | | Thread_Pool& Thread_Pool::global_instance() |
16 | 0 | { |
17 | 0 | static Thread_Pool g_thread_pool(OS::read_env_variable_sz("BOTAN_THREAD_POOL_SIZE")); |
18 | 0 | return g_thread_pool; |
19 | 0 | } |
20 | | |
21 | | Thread_Pool::Thread_Pool(size_t pool_size) |
22 | 0 | { |
23 | 0 | if(pool_size == 0) |
24 | 0 | { |
25 | 0 | pool_size = OS::get_cpu_available(); |
26 | 0 |
|
27 | 0 | /* |
28 | 0 | * For large machines don't create too many threads, unless |
29 | 0 | * explicitly asked to by the caller. |
30 | 0 | */ |
31 | 0 | if(pool_size > 16) |
32 | 0 | pool_size = 16; |
33 | 0 | } |
34 | 0 |
|
35 | 0 | if(pool_size <= 1) |
36 | 0 | pool_size = 2; |
37 | 0 |
|
38 | 0 | m_shutdown = false; |
39 | 0 |
|
40 | 0 | for(size_t i = 0; i != pool_size; ++i) |
41 | 0 | { |
42 | 0 | m_workers.push_back(std::thread(&Thread_Pool::worker_thread, this)); |
43 | 0 | } |
44 | 0 | } |
45 | | |
46 | | void Thread_Pool::shutdown() |
47 | 0 | { |
48 | 0 | { |
49 | 0 | std::unique_lock<std::mutex> lock(m_mutex); |
50 | 0 |
|
51 | 0 | if(m_shutdown == true) |
52 | 0 | return; |
53 | 0 | |
54 | 0 | m_shutdown = true; |
55 | 0 |
|
56 | 0 | m_more_tasks.notify_all(); |
57 | 0 | } |
58 | 0 |
|
59 | 0 | for(auto&& thread : m_workers) |
60 | 0 | { |
61 | 0 | thread.join(); |
62 | 0 | } |
63 | 0 | m_workers.clear(); |
64 | 0 | } |
65 | | |
66 | | void Thread_Pool::queue_thunk(std::function<void ()> fn) |
67 | 0 | { |
68 | 0 | std::unique_lock<std::mutex> lock(m_mutex); |
69 | 0 |
|
70 | 0 | if(m_shutdown) |
71 | 0 | throw Invalid_State("Cannot add work after thread pool has shut down"); |
72 | 0 | |
73 | 0 | m_tasks.push_back(fn); |
74 | 0 | m_more_tasks.notify_one(); |
75 | 0 | } |
76 | | |
77 | | void Thread_Pool::worker_thread() |
78 | 0 | { |
79 | 0 | for(;;) |
80 | 0 | { |
81 | 0 | std::function<void()> task; |
82 | 0 |
|
83 | 0 | { |
84 | 0 | std::unique_lock<std::mutex> lock(m_mutex); |
85 | 0 | m_more_tasks.wait(lock, [this]{ return m_shutdown || !m_tasks.empty(); }); |
86 | 0 |
|
87 | 0 | if(m_tasks.empty()) |
88 | 0 | { |
89 | 0 | if(m_shutdown) |
90 | 0 | return; |
91 | 0 | else |
92 | 0 | continue; |
93 | 0 | } |
94 | 0 | |
95 | 0 | task = m_tasks.front(); |
96 | 0 | m_tasks.pop_front(); |
97 | 0 | } |
98 | 0 |
|
99 | 0 | task(); |
100 | 0 | } |
101 | 0 | } |
102 | | |
103 | | } |