1 // Copyright (c) 2009-2010 Satoshi Nakamoto
2 // Copyright (c) 2009-2020 The Bitcoin Core developers
3 // Distributed under the MIT software license, see the accompanying
4 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
5 
6 #include <shutdown.h>
7 
8 #include <logging.h>
9 #include <node/ui_interface.h>
10 #include <util/tokenpipe.h>
11 #include <warnings.h>
12 
13 #include <config/bitcoin-config.h>
14 
15 #include <assert.h>
16 #include <atomic>
17 #ifdef WIN32
18 #include <condition_variable>
19 #endif
20 
AbortNode(const std::string & strMessage,bilingual_str user_message)21 bool AbortNode(const std::string& strMessage, bilingual_str user_message)
22 {
23     SetMiscWarning(Untranslated(strMessage));
24     LogPrintf("*** %s\n", strMessage);
25     if (user_message.empty()) {
26         user_message = _("A fatal internal error occurred, see debug.log for details");
27     }
28     AbortError(user_message);
29     StartShutdown();
30     return false;
31 }
32 
33 static std::atomic<bool> fRequestShutdown(false);
34 #ifdef WIN32
35 /** On windows it is possible to simply use a condition variable. */
36 std::mutex g_shutdown_mutex;
37 std::condition_variable g_shutdown_cv;
38 #else
39 /** On UNIX-like operating systems use the self-pipe trick.
40  */
41 static TokenPipeEnd g_shutdown_r;
42 static TokenPipeEnd g_shutdown_w;
43 #endif
44 
InitShutdownState()45 bool InitShutdownState()
46 {
47 #ifndef WIN32
48     std::optional<TokenPipe> pipe = TokenPipe::Make();
49     if (!pipe) return false;
50     g_shutdown_r = pipe->TakeReadEnd();
51     g_shutdown_w = pipe->TakeWriteEnd();
52 #endif
53     return true;
54 }
55 
StartShutdown()56 void StartShutdown()
57 {
58 #ifdef WIN32
59     std::unique_lock<std::mutex> lk(g_shutdown_mutex);
60     fRequestShutdown = true;
61     g_shutdown_cv.notify_one();
62 #else
63     // This must be reentrant and safe for calling in a signal handler, so using a condition variable is not safe.
64     // Make sure that the token is only written once even if multiple threads call this concurrently or in
65     // case of a reentrant signal.
66     if (!fRequestShutdown.exchange(true)) {
67         // Write an arbitrary byte to the write end of the shutdown pipe.
68         int res = g_shutdown_w.TokenWrite('x');
69         if (res != 0) {
70             LogPrintf("Sending shutdown token failed\n");
71             assert(0);
72         }
73     }
74 #endif
75 }
76 
AbortShutdown()77 void AbortShutdown()
78 {
79     if (fRequestShutdown) {
80         // Cancel existing shutdown by waiting for it, this will reset condition flags and remove
81         // the shutdown token from the pipe.
82         WaitForShutdown();
83     }
84     fRequestShutdown = false;
85 }
86 
ShutdownRequested()87 bool ShutdownRequested()
88 {
89     return fRequestShutdown;
90 }
91 
WaitForShutdown()92 void WaitForShutdown()
93 {
94 #ifdef WIN32
95     std::unique_lock<std::mutex> lk(g_shutdown_mutex);
96     g_shutdown_cv.wait(lk, [] { return fRequestShutdown.load(); });
97 #else
98     int res = g_shutdown_r.TokenRead();
99     if (res != 'x') {
100         LogPrintf("Reading shutdown token failed\n");
101         assert(0);
102     }
103 #endif
104 }
105