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// lock.h
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Author: riley@google.com (Michael Riley)
//
// \file
// Google-compatibility locking declarations and inline definitions
//
// Classes and functions here are no-ops (by design); proper locking requires
// actual implementation.
#ifndef FST_LIB_LOCK_H__
#define FST_LIB_LOCK_H__
#include <fst/compat.h> // for DISALLOW_COPY_AND_ASSIGN
namespace fst {
using namespace std;
//
// Single initialization - single-thread implementation
//
typedef int FstOnceType;
static const int FST_ONCE_INIT = 1;
inline int FstOnceInit(FstOnceType *once, void (*init)(void)) {
if (*once)
(*init)();
*once = 0;
return 0;
}
//
// Thread locking - single-thread (non-)implementation
//
class Mutex {
public:
Mutex() {}
private:
DISALLOW_COPY_AND_ASSIGN(Mutex);
};
class MutexLock {
public:
MutexLock(Mutex *) {}
private:
DISALLOW_COPY_AND_ASSIGN(MutexLock);
};
class ReaderMutexLock {
public:
ReaderMutexLock(Mutex *) {}
private:
DISALLOW_COPY_AND_ASSIGN(ReaderMutexLock);
};
// Reference counting - single-thread implementation
class RefCounter {
public:
RefCounter() : count_(1) {}
int count() const { return count_; }
// below lines are modifications of openfst for multi-thrads support,
// from tools/extras/openfst_gcc41up.patch, applied by tools/Makefile,
// applicable to gcc 4.1 or above
// int Incr() const { return ++count_; }
// int Decr() const { return --count_; }
int Incr() const { return __sync_add_and_fetch(&count_, 1); }
int Decr() const { return __sync_sub_and_fetch(&count_, 1); }
// end modifications
private:
mutable int count_;
DISALLOW_COPY_AND_ASSIGN(RefCounter);
};
} // namespace fst
#endif // FST_LIB_LOCK_H__
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