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authorVincent Ambo <mail@tazj.in>2020-11-21T13·43+0100
committerVincent Ambo <mail@tazj.in>2020-11-21T14·48+0100
commit082c006c04343a78d87b6c6ab3608c25d6213c3f (patch)
tree16e6f04f8d1d1d2d67e8e917d5e7bb48c1b60375 /third_party/abseil_cpp/absl/base/internal/sysinfo.cc
parentcc27324d0226953943f408ce3c69ad7d648e005e (diff)
merge(3p/absl): subtree merge of Abseil up to e19260f r/1889
... notably, this includes Abseil's own StatusOr type, which
conflicted with our implementation (that was taken from TensorFlow).

Change-Id: Ie7d6764b64055caaeb8dc7b6b9d066291e6b538f
Diffstat (limited to 'third_party/abseil_cpp/absl/base/internal/sysinfo.cc')
-rw-r--r--third_party/abseil_cpp/absl/base/internal/sysinfo.cc14
1 files changed, 14 insertions, 0 deletions
diff --git a/third_party/abseil_cpp/absl/base/internal/sysinfo.cc b/third_party/abseil_cpp/absl/base/internal/sysinfo.cc
index 6c69683faf67..4a3b205034a7 100644
--- a/third_party/abseil_cpp/absl/base/internal/sysinfo.cc
+++ b/third_party/abseil_cpp/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() {
+#ifdef 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