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Diffstat (limited to 'trunk/src/maybe_threads.cc')
-rw-r--r-- | trunk/src/maybe_threads.cc | 113 |
1 files changed, 113 insertions, 0 deletions
diff --git a/trunk/src/maybe_threads.cc b/trunk/src/maybe_threads.cc new file mode 100644 index 0000000..6b7d7b9 --- /dev/null +++ b/trunk/src/maybe_threads.cc @@ -0,0 +1,113 @@ +// Copyright (c) 2005, Google Inc. +// All rights reserved. +// +// Redistribution and use in source and binary forms, with or without +// modification, are permitted provided that the following conditions are +// met: +// +// * Redistributions of source code must retain the above copyright +// notice, this list of conditions and the following disclaimer. +// * Redistributions in binary form must reproduce the above +// copyright notice, this list of conditions and the following disclaimer +// in the documentation and/or other materials provided with the +// distribution. +// * Neither the name of Google Inc. nor the names of its +// contributors may be used to endorse or promote products derived from +// this software without specific prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT +// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT +// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +// --- +// Author: Paul Menage <opensource@google.com> +// +// Some wrappers for pthread functions so that we can be LD_PRELOADed +// against non-pthreads apps. +// +// This module will behave very strangely if some pthreads functions +// exist and others don't. + +#include "config.h" +#include <assert.h> +#include <string.h> // for memcmp +// We don't actually need strings. But including this header seems to +// stop the compiler trying to short-circuit our pthreads existence +// tests and claiming that the address of a function is always +// non-zero. I have no idea why ... +#include <string> +#include "maybe_threads.h" +#include "base/basictypes.h" + +// __THROW is defined in glibc systems. It means, counter-intuitively, +// "This function will never throw an exception." It's an optional +// optimization tool, but we may need to use it to match glibc prototypes. +#ifndef __THROW // I guess we're not on a glibc system +# define __THROW // __THROW is just an optimization, so ok to make it "" +#endif + +// These are the methods we're going to conditionally include. +extern "C" { + int pthread_key_create (pthread_key_t*, void (*)(void*)) + __THROW ATTRIBUTE_WEAK; + void *pthread_getspecific(pthread_key_t) + __THROW ATTRIBUTE_WEAK; + int pthread_setspecific(pthread_key_t, const void*) + __THROW ATTRIBUTE_WEAK; + int pthread_once(pthread_once_t *, void (*)(void)) + __THROW ATTRIBUTE_WEAK; +} + +#define MAX_PERTHREAD_VALS 16 +static void *perftools_pthread_specific_vals[MAX_PERTHREAD_VALS]; +static int next_key; + +int perftools_pthread_key_create(pthread_key_t *key, + void (*destr_function) (void *)) { + if (pthread_key_create) { + return pthread_key_create(key, destr_function); + } else { + assert(next_key < MAX_PERTHREAD_VALS); + *key = (pthread_key_t)(next_key++); + return 0; + } +} + +void *perftools_pthread_getspecific(pthread_key_t key) { + if (pthread_getspecific) { + return pthread_getspecific(key); + } else { + return perftools_pthread_specific_vals[(int)key]; + } +} + +int perftools_pthread_setspecific(pthread_key_t key, void *val) { + if (pthread_setspecific) { + return pthread_setspecific(key, val); + } else { + perftools_pthread_specific_vals[(int)key] = val; + return 0; + } +} + +static pthread_once_t pthread_once_init = PTHREAD_ONCE_INIT; +int perftools_pthread_once(pthread_once_t *ctl, + void (*init_routine) (void)) { + if (pthread_once) { + return pthread_once(ctl, init_routine); + } else { + if (memcmp(ctl, &pthread_once_init, sizeof(*ctl)) == 0) { + init_routine(); + ++*(char*)(ctl); // make it so it's no longer equal to init + } + return 0; + } +} |