Release the Abseil Logging library

PiperOrigin-RevId: 470080638
Change-Id: I8d9ddfabc7704c383ed5a73abf0411f4c58a4bf7

1 files changed, 148 insertions, 0 deletions

diff --git a/absl/log/globals.cc b/absl/log/globals.cc
new file mode 100644
index 00000000..6dfe81f0
--- /dev/null
+++ b/absl/log/globals.cc
@@ -0,0 +1,148 @@
+// Copyright 2022 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 "absl/log/globals.h"
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <atomic>
+
+#include "absl/base/attributes.h"
+#include "absl/base/config.h"
+#include "absl/base/internal/atomic_hook.h"
+#include "absl/base/log_severity.h"
+#include "absl/hash/hash.h"
+#include "absl/strings/string_view.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace {
+
+// These atomics represent logging library configuration.
+// Integer types are used instead of absl::LogSeverity to ensure that a
+// lock-free std::atomic is used when possible.
+ABSL_CONST_INIT std::atomic<int> min_log_level{
+    static_cast<int>(absl::LogSeverityAtLeast::kInfo)};
+ABSL_CONST_INIT std::atomic<int> stderrthreshold{
+    static_cast<int>(absl::LogSeverityAtLeast::kError)};
+// We evaluate this value as a hash comparison to avoid having to
+// hold a mutex or make a copy (to access the value of a string-typed flag) in
+// very hot codepath.
+ABSL_CONST_INIT std::atomic<size_t> log_backtrace_at_hash{0};
+ABSL_CONST_INIT std::atomic<bool> prepend_log_prefix{true};
+
+ABSL_INTERNAL_ATOMIC_HOOK_ATTRIBUTES
+absl::base_internal::AtomicHook<log_internal::LoggingGlobalsListener>
+    logging_globals_listener;
+
+size_t HashSiteForLogBacktraceAt(absl::string_view file, int line) {
+  return absl::HashOf(file, line);
+}
+
+void TriggerLoggingGlobalsListener() {
+  auto* listener = logging_globals_listener.Load();
+  if (listener != nullptr) listener();
+}
+
+}  // namespace
+
+namespace log_internal {
+
+void RawSetMinLogLevel(absl::LogSeverityAtLeast severity) {
+  min_log_level.store(static_cast<int>(severity), std::memory_order_release);
+}
+
+void RawSetStderrThreshold(absl::LogSeverityAtLeast severity) {
+  stderrthreshold.store(static_cast<int>(severity), std::memory_order_release);
+}
+
+void RawEnableLogPrefix(bool on_off) {
+  prepend_log_prefix.store(on_off, std::memory_order_release);
+}
+
+void SetLoggingGlobalsListener(LoggingGlobalsListener l) {
+  logging_globals_listener.Store(l);
+}
+
+}  // namespace log_internal
+
+absl::LogSeverityAtLeast MinLogLevel() {
+  return static_cast<absl::LogSeverityAtLeast>(
+      min_log_level.load(std::memory_order_acquire));
+}
+
+void SetMinLogLevel(absl::LogSeverityAtLeast severity) {
+  log_internal::RawSetMinLogLevel(severity);
+  TriggerLoggingGlobalsListener();
+}
+
+namespace log_internal {
+
+ScopedMinLogLevel::ScopedMinLogLevel(absl::LogSeverityAtLeast severity)
+    : saved_severity_(absl::MinLogLevel()) {
+  absl::SetMinLogLevel(severity);
+}
+ScopedMinLogLevel::~ScopedMinLogLevel() {
+  absl::SetMinLogLevel(saved_severity_);
+}
+
+}  // namespace log_internal
+
+absl::LogSeverityAtLeast StderrThreshold() {
+  return static_cast<absl::LogSeverityAtLeast>(
+      stderrthreshold.load(std::memory_order_acquire));
+}
+
+void SetStderrThreshold(absl::LogSeverityAtLeast severity) {
+  log_internal::RawSetStderrThreshold(severity);
+  TriggerLoggingGlobalsListener();
+}
+
+ScopedStderrThreshold::ScopedStderrThreshold(absl::LogSeverityAtLeast severity)
+    : saved_severity_(absl::StderrThreshold()) {
+  absl::SetStderrThreshold(severity);
+}
+
+ScopedStderrThreshold::~ScopedStderrThreshold() {
+  absl::SetStderrThreshold(saved_severity_);
+}
+
+namespace log_internal {
+
+bool ShouldLogBacktraceAt(absl::string_view file, int line) {
+  const size_t flag_hash =
+      log_backtrace_at_hash.load(std::memory_order_acquire);
+
+  return flag_hash != 0 && flag_hash == HashSiteForLogBacktraceAt(file, line);
+}
+
+}  // namespace log_internal
+
+void SetLogBacktraceLocation(absl::string_view file, int line) {
+  log_backtrace_at_hash.store(HashSiteForLogBacktraceAt(file, line),
+                              std::memory_order_release);
+}
+
+bool ShouldPrependLogPrefix() {
+  return prepend_log_prefix.load(std::memory_order_acquire);
+}
+
+void EnableLogPrefix(bool on_off) {
+  log_internal::RawEnableLogPrefix(on_off);
+  TriggerLoggingGlobalsListener();
+}
+
+ABSL_NAMESPACE_END
+}  // namespace absl