No compliation-flag-dependent members in CriticalSection

webrtc/base/criticalsection.cc

 /*
  *  Copyright 2015 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #include "webrtc/base/criticalsection.h"
 
 #include "webrtc/base/checks.h"
 #include "webrtc/base/platform_thread.h"
 
 // TODO(tommi): Split this file up to per-platform implementation files.
 
 namespace rtc {
 
 CriticalSection::CriticalSection() {
 #if defined(WEBRTC_WIN)
   InitializeCriticalSection(&crit_);
-#else
+#elif defined(WEBRTC_POSIX)

[eladalon, 2017/06/26 12:35:22]

mutex_ does not really exist otherwise; would be a compilation error if we ever
have a non-WEBRTC_WIN build that's also not WEBRTC_POSIX. I don't know if that's
likely, but might as well have the structure here mimic that of the header.

So we have two options:
1. Change the header to not depend on WEBRTC_POSIX for this.
2. Change everywhere that mute_ is accessed, and make sure that WEBRTC_POSIX.

I prefer the second option. Wdyt?

[nisse-webrtc, 2017/06/26 12:53:09]

If you do it this way, also add an 

#else
#error Platform not supported
#endif

to not fail silently on unexpected platforms.

For the main question, I think the important thing is to get a clear compilation
error for unsupported platforms, but it doesn't matter very much if the the
message says "error unsupported platform" or "mutex_ is not defined".

[eladalon, 2017/06/26 13:38:12]

Added throughout the module.

 #if defined(WEBRTC_MAC) && !USE_NATIVE_MUTEX_ON_MAC
   lock_queue_ = 0;
   owning_thread_ = 0;
   recursion_ = 0;
   semaphore_ = dispatch_semaphore_create(0);
 #else
   pthread_mutexattr_t mutex_attribute;
   pthread_mutexattr_init(&mutex_attribute);
   pthread_mutexattr_settype(&mutex_attribute, PTHREAD_MUTEX_RECURSIVE);
   pthread_mutex_init(&mutex_, &mutex_attribute);
   pthread_mutexattr_destroy(&mutex_attribute);
 #endif
   CS_DEBUG_CODE(thread_ = 0);
   CS_DEBUG_CODE(recursion_count_ = 0);
+  RTC_UNUSED(thread_);           // Depends on CS_DEBUG_CHECKS.

[nisse-webrtc, 2017/06/26 12:53:09]

Drop this comment. Instead, add a comment in the header saying that these member
variables are used for DCHECKs only.

[eladalon, 2017/06/26 13:38:12]

Done.

+  RTC_UNUSED(recursion_count_);  // Depends on CS_DEBUG_CHECKS.
 #endif
 }
 
 CriticalSection::~CriticalSection() {
 #if defined(WEBRTC_WIN)
   DeleteCriticalSection(&crit_);
 #else
 #if defined(WEBRTC_MAC) && !USE_NATIVE_MUTEX_ON_MAC
   dispatch_release(semaphore_);
 #else
@@ skipping 131 matching lines @@
 #endif  // CS_DEBUG_CHECKS
 #endif
 }
 
 CritScope::CritScope(const CriticalSection* cs) : cs_(cs) { cs_->Enter(); }
 CritScope::~CritScope() { cs_->Leave(); }
 
 TryCritScope::TryCritScope(const CriticalSection* cs)
     : cs_(cs), locked_(cs->TryEnter()) {
   CS_DEBUG_CODE(lock_was_called_ = false);
+  RTC_UNUSED(lock_was_called_);  // Depends on CS_DEBUG_CHECKS.
 }
 
 TryCritScope::~TryCritScope() {
   CS_DEBUG_CODE(RTC_DCHECK(lock_was_called_));
   if (locked_)
     cs_->Leave();
 }
 
 bool TryCritScope::locked() const {
   CS_DEBUG_CODE(lock_was_called_ = true);
@@ skipping 28 matching lines @@
 GlobalLockScope::GlobalLockScope(GlobalLockPod* lock)
     : lock_(lock) {
   lock_->Lock();
 }
 
 GlobalLockScope::~GlobalLockScope() {
   lock_->Unlock();
 }
 
 }  // namespace rtc