Export of internal Abseil changes

--
873b52b0a691e759413c5db27dafc541a5da5263 by Andy Getzendanner <durandal@google.com>:

Introduce an internal-only thread-local caching wrapper around GetTID.

PiperOrigin-RevId: 323055682

--
091a4537f1ef6e158acbf4261cfae1af7a3bdb7f by Abseil Team <absl-team@google.com>:

Internal change

PiperOrigin-RevId: 322864497

--
c80ccfff2a825819f31826a30f48cca3297699f8 by Evan Brown <ezb@google.com>:

Roll forward b-tree changes simplifying deletion and getting rid of recursion in clear_and_delete().

We also change clear_and_delete() to avoid some unnecessary comparisons by restructuring the loops.

PiperOrigin-RevId: 322658938

--
81464c0fb9c8c6268dca2e530aba99e75e1e59ae by Gennadiy Rozental <rogeeff@google.com>:

Eliminate definition of RunningOnValgrind inside the library.

Fixes #674
Fixes #657

PiperOrigin-RevId: 322508440
GitOrigin-RevId: 873b52b0a691e759413c5db27dafc541a5da5263
Change-Id: I20b40c9e8fc62edcf981caab467cca33cf6fd2ba

6 files changed, 52 insertions, 109 deletions

diff --git a/absl/base/BUILD.bazel b/absl/base/BUILD.bazel
index 23f2763a..ad29bb0d 100644
--- a/absl/base/BUILD.bazel
+++ b/absl/base/BUILD.bazel
@@ -116,7 +116,6 @@ cc_library(
 cc_library(
     name = "dynamic_annotations",
     srcs = [
-        "dynamic_annotations.cc",
         "internal/dynamic_annotations.h",
     ],
     hdrs = [
@@ -126,6 +125,7 @@ cc_library(
     linkopts = ABSL_DEFAULT_LINKOPTS,
     deps = [
         ":config",
+        ":core_headers",
     ],
 )
 
diff --git a/absl/base/CMakeLists.txt b/absl/base/CMakeLists.txt
index 62486f9d..f5cfc792 100644
--- a/absl/base/CMakeLists.txt
+++ b/absl/base/CMakeLists.txt
@@ -105,7 +105,6 @@ absl_cc_library(
   HDRS
     "dynamic_annotations.h"
   SRCS
-    "dynamic_annotations.cc"
     "internal/dynamic_annotations.h"
   COPTS
     ${ABSL_DEFAULT_COPTS}
diff --git a/absl/base/dynamic_annotations.cc b/absl/base/dynamic_annotations.cc
deleted file mode 100644
index f26e673e..00000000
--- a/absl/base/dynamic_annotations.cc
+++ /dev/null
@@ -1,72 +0,0 @@
-// Copyright 2017 The Abseil Authors.
-//
-// 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
-//
-//      https://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.
-
-#include <stdlib.h>
-#include <string.h>
-
-#include "absl/base/dynamic_annotations.h"
-
-// Compiler-based ThreadSanitizer defines
-// DYNAMIC_ANNOTATIONS_EXTERNAL_IMPL = 1
-// and provides its own definitions of the functions.
-
-#ifndef DYNAMIC_ANNOTATIONS_EXTERNAL_IMPL
-# define DYNAMIC_ANNOTATIONS_EXTERNAL_IMPL 0
-#endif
-
-#if DYNAMIC_ANNOTATIONS_EXTERNAL_IMPL == 0 && !defined(__native_client__)
-
-extern "C" {
-
-static int GetRunningOnValgrind(void) {
-#ifdef RUNNING_ON_VALGRIND
-  if (RUNNING_ON_VALGRIND) return 1;
-#endif
-  char *running_on_valgrind_str = getenv("RUNNING_ON_VALGRIND");
-  if (running_on_valgrind_str) {
-    return strcmp(running_on_valgrind_str, "0") != 0;
-  }
-  return 0;
-}
-
-// See the comments in dynamic_annotations.h
-int RunningOnValgrind(void) {
-  static volatile int running_on_valgrind = -1;
-  int local_running_on_valgrind = running_on_valgrind;
-  // C doesn't have thread-safe initialization of statics, and we
-  // don't want to depend on pthread_once here, so hack it.
-  ANNOTATE_BENIGN_RACE(&running_on_valgrind, "safe hack");
-  if (local_running_on_valgrind == -1)
-    running_on_valgrind = local_running_on_valgrind = GetRunningOnValgrind();
-  return local_running_on_valgrind;
-}
-
-// See the comments in dynamic_annotations.h
-double ValgrindSlowdown(void) {
-  // Same initialization hack as in RunningOnValgrind().
-  static volatile double slowdown = 0.0;
-  double local_slowdown = slowdown;
-  ANNOTATE_BENIGN_RACE(&slowdown, "safe hack");
-  if (RunningOnValgrind() == 0) {
-    return 1.0;
-  }
-  if (local_slowdown == 0.0) {
-    char *env = getenv("VALGRIND_SLOWDOWN");
-    slowdown = local_slowdown = env ? atof(env) : 50.0;
-  }
-  return local_slowdown;
-}
-
-}  // extern "C"
-#endif  // DYNAMIC_ANNOTATIONS_EXTERNAL_IMPL == 0
diff --git a/absl/base/dynamic_annotations.h b/absl/base/dynamic_annotations.h
index 5ea697b7..c470c747 100644
--- a/absl/base/dynamic_annotations.h
+++ b/absl/base/dynamic_annotations.h
@@ -47,7 +47,11 @@
 
 #include <stddef.h>
 
+#include "absl/base/attributes.h"
 #include "absl/base/config.h"
+#ifdef __cplusplus
+#include "absl/base/macros.h"
+#endif
 
 // TODO(rogeeff): Remove after the backward compatibility period.
 #include "absl/base/internal/dynamic_annotations.h"  // IWYU pragma: export
@@ -90,7 +94,8 @@
 // Read/write annotations are enabled in Annotalysis mode; disabled otherwise.
 #define ABSL_INTERNAL_READS_WRITES_ANNOTATIONS_ENABLED \
   ABSL_INTERNAL_ANNOTALYSIS_ENABLED
-#endif
+
+#endif  // ABSL_HAVE_THREAD_SANITIZER
 
 #ifdef __cplusplus
 #define ABSL_INTERNAL_BEGIN_EXTERN_C extern "C" {
@@ -152,7 +157,7 @@
   ABSL_INTERNAL_GLOBAL_SCOPED(AnnotateRWLockCreate)(__FILE__, __LINE__, lock)
 
 // Report that a linker initialized lock has been created at address `lock`.
-#ifdef THREAD_SANITIZER
+#ifdef ABSL_HAVE_THREAD_SANITIZER
 #define ABSL_ANNOTATE_RWLOCK_CREATE_STATIC(lock)          \
   ABSL_INTERNAL_GLOBAL_SCOPED(AnnotateRWLockCreateStatic) \
   (__FILE__, __LINE__, lock)
@@ -417,41 +422,30 @@ ABSL_NAMESPACE_END
 
 #endif
 
+#ifdef __cplusplus
+#ifdef ABSL_HAVE_THREAD_SANITIZER
 ABSL_INTERNAL_BEGIN_EXTERN_C
-
-// -------------------------------------------------------------------------
-// Return non-zero value if running under valgrind.
-//
-//  If "valgrind.h" is included into dynamic_annotations.cc,
-//  the regular valgrind mechanism will be used.
-//  See http://valgrind.org/docs/manual/manual-core-adv.html about
-//  RUNNING_ON_VALGRIND and other valgrind "client requests".
-//  The file "valgrind.h" may be obtained by doing
-//     svn co svn://svn.valgrind.org/valgrind/trunk/include
-//
-//  If for some reason you can't use "valgrind.h" or want to fake valgrind,
-//  there are two ways to make this function return non-zero:
-//    - Use environment variable: export RUNNING_ON_VALGRIND=1
-//    - Make your tool intercept the function RunningOnValgrind() and
-//      change its return value.
-//
-int RunningOnValgrind(void);
-
-// ValgrindSlowdown returns:
-//    * 1.0, if (RunningOnValgrind() == 0)
-//    * 50.0, if (RunningOnValgrind() != 0 && getenv("VALGRIND_SLOWDOWN") ==
-//    NULL)
-//    * atof(getenv("VALGRIND_SLOWDOWN")) otherwise
-//   This function can be used to scale timeout values:
-//   EXAMPLE:
-//   for (;;) {
-//     DoExpensiveBackgroundTask();
-//     SleepForSeconds(5 * ValgrindSlowdown());
-//   }
-//
-double ValgrindSlowdown(void);
-
+int RunningOnValgrind();
+double ValgrindSlowdown();
 ABSL_INTERNAL_END_EXTERN_C
+#else
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace base_internal {
+ABSL_DEPRECATED(
+    "Don't use this interface. It is misleading and is being deleted.")
+ABSL_ATTRIBUTE_ALWAYS_INLINE inline int RunningOnValgrind() { return 0; }
+ABSL_DEPRECATED(
+    "Don't use this interface. It is misleading and is being deleted.")
+ABSL_ATTRIBUTE_ALWAYS_INLINE inline double ValgrindSlowdown() { return 1.0; }
+}  // namespace base_internal
+ABSL_NAMESPACE_END
+}  // namespace absl
+
+using absl::base_internal::RunningOnValgrind;
+using absl::base_internal::ValgrindSlowdown;
+#endif
+#endif
 
 // -------------------------------------------------------------------------
 // Address sanitizer annotations
diff --git a/absl/base/internal/sysinfo.cc b/absl/base/internal/sysinfo.cc
index 6c69683f..349d9268 100644
--- a/absl/base/internal/sysinfo.cc
+++ b/absl/base/internal/sysinfo.cc
@@ -39,6 +39,7 @@
 #endif
 
 #include <string.h>
+
 #include <cassert>
 #include <cstdint>
 #include <cstdio>
@@ -50,6 +51,7 @@
 #include <vector>
 
 #include "absl/base/call_once.h"
+#include "absl/base/config.h"
 #include "absl/base/internal/raw_logging.h"
 #include "absl/base/internal/spinlock.h"
 #include "absl/base/internal/unscaledcycleclock.h"
@@ -420,6 +422,18 @@ pid_t GetTID() {
 
 #endif
 
+// GetCachedTID() caches the thread ID in thread-local storage (which is a
+// userspace construct) to avoid unnecessary system calls. Without this caching,
+// it can take roughly 98ns, while it takes roughly 1ns with this caching.
+pid_t GetCachedTID() {
+#if ABSL_HAVE_THREAD_LOCAL
+  static thread_local pid_t thread_id = GetTID();
+  return thread_id;
+#else
+  return GetTID();
+#endif  // ABSL_HAVE_THREAD_LOCAL
+}
+
 }  // namespace base_internal
 ABSL_NAMESPACE_END
 }  // namespace absl
diff --git a/absl/base/internal/sysinfo.h b/absl/base/internal/sysinfo.h
index 7246d5dd..119cf1f0 100644
--- a/absl/base/internal/sysinfo.h
+++ b/absl/base/internal/sysinfo.h
@@ -30,6 +30,7 @@
 
 #include <cstdint>
 
+#include "absl/base/config.h"
 #include "absl/base/port.h"
 
 namespace absl {
@@ -59,6 +60,13 @@ using pid_t = uint32_t;
 #endif
 pid_t GetTID();
 
+// Like GetTID(), but caches the result in thread-local storage in order
+// to avoid unnecessary system calls. Note that there are some cases where
+// one must call through to GetTID directly, which is why this exists as a
+// separate function. For example, GetCachedTID() is not safe to call in
+// an asynchronous signal-handling context nor right after a call to fork().
+pid_t GetCachedTID();
+
 }  // namespace base_internal
 ABSL_NAMESPACE_END
 }  // namespace absl