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      1 // Protocol Buffers - Google's data interchange format
      2 // Copyright 2008 Google Inc.  All rights reserved.
      3 // http://code.google.com/p/protobuf/
      4 //
      5 // Redistribution and use in source and binary forms, with or without
      6 // modification, are permitted provided that the following conditions are
      7 // met:
      8 //
      9 //     * Redistributions of source code must retain the above copyright
     10 // notice, this list of conditions and the following disclaimer.
     11 //     * Redistributions in binary form must reproduce the above
     12 // copyright notice, this list of conditions and the following disclaimer
     13 // in the documentation and/or other materials provided with the
     14 // distribution.
     15 //     * Neither the name of Google Inc. nor the names of its
     16 // contributors may be used to endorse or promote products derived from
     17 // this software without specific prior written permission.
     18 //
     19 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     20 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     21 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     22 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     23 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     24 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     25 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     26 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     27 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     28 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     29 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     30 
     31 // Author: kenton (at) google.com (Kenton Varda)
     32 //
     33 // emulates google3/base/once.h
     34 //
     35 // This header is intended to be included only by internal .cc files and
     36 // generated .pb.cc files.  Users should not use this directly.
     37 
     38 #ifdef _WIN32
     39 #include <windows.h>
     40 #endif
     41 
     42 #include <google/protobuf/stubs/once.h>
     43 
     44 namespace google {
     45 namespace protobuf {
     46 
     47 #ifdef _WIN32
     48 
     49 struct ProtobufOnceInternal {
     50   ProtobufOnceInternal() {
     51     InitializeCriticalSection(&critical_section);
     52   }
     53   ~ProtobufOnceInternal() {
     54     DeleteCriticalSection(&critical_section);
     55   }
     56   CRITICAL_SECTION critical_section;
     57 };
     58 
     59 ProtobufOnceType::~ProtobufOnceType()
     60 {
     61   delete internal_;
     62   internal_ = NULL;
     63 }
     64 
     65 ProtobufOnceType::ProtobufOnceType() {
     66   // internal_ may be non-NULL if Init() was already called.
     67   if (internal_ == NULL) internal_ = new ProtobufOnceInternal;
     68 }
     69 
     70 void ProtobufOnceType::Init(void (*init_func)()) {
     71   // internal_ may be NULL if we're still in dynamic initialization and the
     72   // constructor has not been called yet.  As mentioned in once.h, we assume
     73   // that the program is still single-threaded at this time, and therefore it
     74   // should be safe to initialize internal_ like so.
     75   if (internal_ == NULL) internal_ = new ProtobufOnceInternal;
     76 
     77   EnterCriticalSection(&internal_->critical_section);
     78   if (!initialized_) {
     79     init_func();
     80     initialized_ = true;
     81   }
     82   LeaveCriticalSection(&internal_->critical_section);
     83 }
     84 
     85 #endif
     86 
     87 }  // namespace protobuf
     88 }  // namespace google
     89