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// Copyright (C) 2012 Internet Systems Consortium, Inc. ("ISC")
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
// AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
// OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
// PERFORMANCE OF THIS SOFTWARE.
#include "sync.h"
#include <exceptions/exceptions.h>
#include <cstring>
#include <memory>
#include <cerrno>
#include <cassert>
#include <pthread.h>
using std::auto_ptr;
namespace isc {
namespace util {
namespace thread {
class Mutex::Impl {
public:
Impl() :
locked_count(0)
{}
pthread_mutex_t mutex;
// Only in debug mode
size_t locked_count;
};
namespace {
struct Deinitializer {
Deinitializer(pthread_mutexattr_t& attributes):
attributes_(attributes)
{}
~Deinitializer() {
const int result = pthread_mutexattr_destroy(&attributes_);
// This should never happen. According to the man page,
// if there's error, it's our fault.
assert(result == 0);
}
pthread_mutexattr_t& attributes_;
};
}
Mutex::Mutex() :
impl_(NULL)
{
pthread_mutexattr_t attributes;
int result = pthread_mutexattr_init(&attributes);
switch (result) {
case 0: // All 0K
break;
case ENOMEM:
throw std::bad_alloc();
default:
isc_throw(isc::InvalidOperation, std::strerror(result));
}
Deinitializer deinitializer(attributes);
// TODO: Distinguish if debug mode is enabled in compilation.
// If so, it should be PTHREAD_MUTEX_NORMAL or NULL
result = pthread_mutexattr_settype(&attributes, PTHREAD_MUTEX_ERRORCHECK);
if (result != 0) {
isc_throw(isc::InvalidOperation, std::strerror(result));
}
auto_ptr<Impl> impl(new Impl);
result = pthread_mutex_init(&impl->mutex, &attributes);
switch (result) {
case 0: // All 0K
impl_ = impl.release();
break;
case ENOMEM:
case EAGAIN:
throw std::bad_alloc();
default:
isc_throw(isc::InvalidOperation, std::strerror(result));
}
}
Mutex::~Mutex() {
if (impl_ != NULL) {
const int result = pthread_mutex_destroy(&impl_->mutex);
const bool locked = impl_->locked_count != 0;
delete impl_;
// We don't want to throw from the destructor. Also, if this ever
// fails, something is really screwed up a lot.
assert(result == 0);
// We should not try to destroy a locked mutex, bad threaded monsters
// could get loose if we ever do and it is also forbidden by pthreads.
// This should not be possible to happen, since the
// pthread_mutex_destroy should check for it already. But it seems
// there are systems that don't check it.
assert(!locked);
}
}
void
Mutex::postLockAction() {
// This assertion would fail only in non-debugging mode, in which case
// this method wouldn't be called either, so we simply assert the
// condition.
assert(impl_->locked_count == 0);
++impl_->locked_count;
}
void
Mutex::lock() {
assert(impl_ != NULL);
const int result = pthread_mutex_lock(&impl_->mutex);
if (result != 0) {
isc_throw(isc::InvalidOperation, std::strerror(result));
}
postLockAction(); // Only in debug mode
}
void
Mutex::preUnlockAction(bool throw_ok) {
if (impl_->locked_count == 0) {
if (throw_ok) {
isc_throw(isc::InvalidOperation,
"Unlock attempt for unlocked mutex");
} else {
assert(false);
}
}
--impl_->locked_count;
}
void
Mutex::unlock() {
assert(impl_ != NULL);
preUnlockAction(false); // Only in debug mode. Ensure no throw.
const int result = pthread_mutex_unlock(&impl_->mutex);
assert(result == 0); // This should never be possible
}
// TODO: Disable in non-debug build
bool
Mutex::locked() const {
return (impl_->locked_count != 0);
}
class CondVar::Impl {
public:
Impl() {
const int result = pthread_cond_init(&cond_, NULL);
if (result != 0) {
isc_throw(isc::Unexpected, "pthread_cond_init failed: "
<< std::strerror(result));
}
}
~Impl() {
const int result = pthread_cond_destroy(&cond_);
// This can happen if we try to destroy cond_ while some other thread
// is waiting on it. assert() may be too strong for such a case,
// but we cannot safely destroy cond_ anyway. In order to avoid
// throwing from a destructor we simply let the process die.
assert(result == 0);
}
// For convenience allow the main class to access this directly.
pthread_cond_t cond_;
};
CondVar::CondVar() : impl_(new Impl)
{}
CondVar::~CondVar() {
delete impl_;
}
void
CondVar::wait(Mutex& mutex) {
mutex.preUnlockAction(true); // Only in debug mode
const int result = pthread_cond_wait(&impl_->cond_, &mutex.impl_->mutex);
mutex.postLockAction(); // Only in debug mode
// pthread_cond_wait should normally succeed unless mutex is completely
// broken.
if (result != 0) {
isc_throw(isc::BadValue, "pthread_cond_wait failed unexpectedly: " <<
std::strerror(result));
}
}
void
CondVar::signal() {
const int result = pthread_cond_signal(&impl_->cond_);
// pthread_cond_signal() can only fail when if cond_ is invalid. It
//should be impossible as long as this is a valid CondVar object.
assert(result == 0);
}
}
}
}
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