1 // Copyright (c) 2005, Google Inc. 2 // All rights reserved. 3 // 4 // Redistribution and use in source and binary forms, with or without 5 // modification, are permitted provided that the following conditions are 6 // met: 7 // 8 // * Redistributions of source code must retain the above copyright 9 // notice, this list of conditions and the following disclaimer. 10 // * Redistributions in binary form must reproduce the above 11 // copyright notice, this list of conditions and the following disclaimer 12 // in the documentation and/or other materials provided with the 13 // distribution. 14 // * Neither the name of Google Inc. nor the names of its 15 // contributors may be used to endorse or promote products derived from 16 // this software without specific prior written permission. 17 // 18 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 19 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 20 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 21 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 22 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 23 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 24 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 25 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 26 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 27 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 28 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 30 // --- 31 // Author: Paul Menage <opensource (at) google.com> 32 // 33 // Some wrappers for pthread functions so that we can be LD_PRELOADed 34 // against non-pthreads apps. 35 // 36 // This module will behave very strangely if some pthreads functions 37 // exist and others don't. 38 39 #include "config.h" 40 #include <assert.h> 41 #include <string.h> // for memcmp 42 #include <stdio.h> // for __isthreaded on FreeBSD 43 // We don't actually need strings. But including this header seems to 44 // stop the compiler trying to short-circuit our pthreads existence 45 // tests and claiming that the address of a function is always 46 // non-zero. I have no idea why ... 47 #include <string> 48 #include "maybe_threads.h" 49 #include "base/basictypes.h" 50 51 // __THROW is defined in glibc systems. It means, counter-intuitively, 52 // "This function will never throw an exception." It's an optional 53 // optimization tool, but we may need to use it to match glibc prototypes. 54 #ifndef __THROW // I guess we're not on a glibc system 55 # define __THROW // __THROW is just an optimization, so ok to make it "" 56 #endif 57 58 // These are the methods we're going to conditionally include. 59 extern "C" { 60 int pthread_key_create (pthread_key_t*, void (*)(void*)) 61 __THROW ATTRIBUTE_WEAK; 62 void *pthread_getspecific(pthread_key_t) 63 __THROW ATTRIBUTE_WEAK; 64 int pthread_setspecific(pthread_key_t, const void*) 65 __THROW ATTRIBUTE_WEAK; 66 int pthread_once(pthread_once_t *, void (*)(void)) 67 ATTRIBUTE_WEAK; 68 } 69 70 #define MAX_PERTHREAD_VALS 16 71 static void *perftools_pthread_specific_vals[MAX_PERTHREAD_VALS]; 72 static int next_key; 73 74 int perftools_pthread_key_create(pthread_key_t *key, 75 void (*destr_function) (void *)) { 76 if (pthread_key_create) { 77 return pthread_key_create(key, destr_function); 78 } else { 79 assert(next_key < MAX_PERTHREAD_VALS); 80 *key = (pthread_key_t)(next_key++); 81 return 0; 82 } 83 } 84 85 void *perftools_pthread_getspecific(pthread_key_t key) { 86 if (pthread_getspecific) { 87 return pthread_getspecific(key); 88 } else { 89 return perftools_pthread_specific_vals[(int)key]; 90 } 91 } 92 93 int perftools_pthread_setspecific(pthread_key_t key, void *val) { 94 if (pthread_setspecific) { 95 return pthread_setspecific(key, val); 96 } else { 97 perftools_pthread_specific_vals[(int)key] = val; 98 return 0; 99 } 100 } 101 102 103 static pthread_once_t pthread_once_init = PTHREAD_ONCE_INIT; 104 int perftools_pthread_once(pthread_once_t *ctl, 105 void (*init_routine) (void)) { 106 #ifdef __FreeBSD__ 107 // On __FreeBSD__, calling pthread_once on a system that is not 108 // linked with -pthread is silently a noop. :-( Luckily, we have a 109 // workaround: FreeBSD exposes __isthreaded in <stdio.h>, which is 110 // set to 1 when the first thread is spawned. So on those systems, 111 // we can use our own separate pthreads-once mechanism, which is 112 // used until __isthreaded is 1 (which will never be true if the app 113 // is not linked with -pthread). 114 static bool pthread_once_ran_before_threads = false; 115 if (pthread_once_ran_before_threads) { 116 return 0; 117 } 118 if (!__isthreaded) { 119 init_routine(); 120 pthread_once_ran_before_threads = true; 121 return 0; 122 } 123 #endif 124 if (pthread_once) { 125 return pthread_once(ctl, init_routine); 126 } else { 127 if (memcmp(ctl, &pthread_once_init, sizeof(*ctl)) == 0) { 128 init_routine(); 129 ++*(char*)(ctl); // make it so it's no longer equal to init 130 } 131 return 0; 132 } 133 } 134
