Reland "Move webrtc/{base => rtc_base}" (https://codereview.webrtc.org/2877023002)

Reland the base->rtc_base without adding stub headers (will be
done in follow-up CL). This preserves git blame history of all files.

BUG=webrtc:7634
NOTRY=True
TBR=kwiberg@webrtc.org

Change-Id: Iea3bb6f3f67b8374c96337b63e8f5aa3e6181012
Reviewed-on: https://chromium-review.googlesource.com/554611
Reviewed-by: Henrik Kjellander <kjellander@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#18821}

webrtc/rtc_base/criticalsection.h

@@ -0,0 +1,156 @@
+/*
+ *  Copyright 2004 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.
+ */
+
+#ifndef WEBRTC_RTC_BASE_CRITICALSECTION_H_
+#define WEBRTC_RTC_BASE_CRITICALSECTION_H_
+
+#include "webrtc/base/atomicops.h"
+#include "webrtc/base/checks.h"
+#include "webrtc/base/constructormagic.h"
+#include "webrtc/base/platform_thread_types.h"
+#include "webrtc/base/thread_annotations.h"
+#include "webrtc/typedefs.h"
+
+#if defined(WEBRTC_WIN)
+// Include winsock2.h before including <windows.h> to maintain consistency with
+// win32.h.  We can't include win32.h directly here since it pulls in
+// headers such as basictypes.h which causes problems in Chromium where webrtc
+// exists as two separate projects, webrtc and libjingle.
+#include <winsock2.h>
+#include <windows.h>
+#include <sal.h>  // must come after windows headers.
+#endif  // defined(WEBRTC_WIN)
+
+#if defined(WEBRTC_POSIX)
+#include <pthread.h>
+#endif
+
+// See notes in the 'Performance' unit test for the effects of this flag.
+#define USE_NATIVE_MUTEX_ON_MAC 0
+
+#if defined(WEBRTC_MAC) && !USE_NATIVE_MUTEX_ON_MAC
+#include <dispatch/dispatch.h>
+#endif
+
+#define CS_DEBUG_CHECKS RTC_DCHECK_IS_ON
+
+#if CS_DEBUG_CHECKS
+#define CS_DEBUG_CODE(x) x
+#else  // !CS_DEBUG_CHECKS
+#define CS_DEBUG_CODE(x)
+#endif  // !CS_DEBUG_CHECKS
+
+namespace rtc {
+
+// Locking methods (Enter, TryEnter, Leave)are const to permit protecting
+// members inside a const context without requiring mutable CriticalSections
+// everywhere.
+class LOCKABLE CriticalSection {
+ public:
+  CriticalSection();
+  ~CriticalSection();
+
+  void Enter() const EXCLUSIVE_LOCK_FUNCTION();
+  bool TryEnter() const EXCLUSIVE_TRYLOCK_FUNCTION(true);
+  void Leave() const UNLOCK_FUNCTION();
+
+ private:
+  // Use only for RTC_DCHECKing.
+  bool CurrentThreadIsOwner() const;
+
+#if defined(WEBRTC_WIN)
+  mutable CRITICAL_SECTION crit_;
+#elif defined(WEBRTC_POSIX)
+# if defined(WEBRTC_MAC) && !USE_NATIVE_MUTEX_ON_MAC
+  // Number of times the lock has been locked + number of threads waiting.
+  // TODO(tommi): We could use this number and subtract the recursion count
+  // to find places where we have multiple threads contending on the same lock.
+  mutable volatile int lock_queue_;
+  // |recursion_| represents the recursion count + 1 for the thread that owns
+  // the lock. Only modified by the thread that owns the lock.
+  mutable int recursion_;
+  // Used to signal a single waiting thread when the lock becomes available.
+  mutable dispatch_semaphore_t semaphore_;
+  // The thread that currently holds the lock. Required to handle recursion.
+  mutable PlatformThreadRef owning_thread_;
+# else
+  mutable pthread_mutex_t mutex_;
+# endif
+  mutable PlatformThreadRef thread_;  // Only used by RTC_DCHECKs.
+  mutable int recursion_count_;       // Only used by RTC_DCHECKs.
+#else  // !defined(WEBRTC_WIN) && !defined(WEBRTC_POSIX)
+# error Unsupported platform.
+#endif
+};
+
+// CritScope, for serializing execution through a scope.
+class SCOPED_LOCKABLE CritScope {
+ public:
+  explicit CritScope(const CriticalSection* cs) EXCLUSIVE_LOCK_FUNCTION(cs);
+  ~CritScope() UNLOCK_FUNCTION();
+ private:
+  const CriticalSection* const cs_;
+  RTC_DISALLOW_COPY_AND_ASSIGN(CritScope);
+};
+
+// Tries to lock a critical section on construction via
+// CriticalSection::TryEnter, and unlocks on destruction if the
+// lock was taken. Never blocks.
+//
+// IMPORTANT: Unlike CritScope, the lock may not be owned by this thread in
+// subsequent code. Users *must* check locked() to determine if the
+// lock was taken. If you're not calling locked(), you're doing it wrong!
+class TryCritScope {
+ public:
+  explicit TryCritScope(const CriticalSection* cs);
+  ~TryCritScope();
+#if defined(WEBRTC_WIN)
+  _Check_return_ bool locked() const;
+#elif defined(WEBRTC_POSIX)
+  bool locked() const __attribute__ ((__warn_unused_result__));
+#else  // !defined(WEBRTC_WIN) && !defined(WEBRTC_POSIX)
+# error Unsupported platform.
+#endif
+ private:
+  const CriticalSection* const cs_;
+  const bool locked_;
+  mutable bool lock_was_called_;  // Only used by RTC_DCHECKs.
+  RTC_DISALLOW_COPY_AND_ASSIGN(TryCritScope);
+};
+
+// A POD lock used to protect global variables. Do NOT use for other purposes.
+// No custom constructor or private data member should be added.
+class LOCKABLE GlobalLockPod {
+ public:
+  void Lock() EXCLUSIVE_LOCK_FUNCTION();
+
+  void Unlock() UNLOCK_FUNCTION();
+
+  volatile int lock_acquired;
+};
+
+class GlobalLock : public GlobalLockPod {
+ public:
+  GlobalLock();
+};
+
+// GlobalLockScope, for serializing execution through a scope.
+class SCOPED_LOCKABLE GlobalLockScope {
+ public:
+  explicit GlobalLockScope(GlobalLockPod* lock) EXCLUSIVE_LOCK_FUNCTION(lock);
+  ~GlobalLockScope() UNLOCK_FUNCTION();
+ private:
+  GlobalLockPod* const lock_;
+  RTC_DISALLOW_COPY_AND_ASSIGN(GlobalLockScope);
+};
+
+} // namespace rtc
+
+#endif // WEBRTC_RTC_BASE_CRITICALSECTION_H_