1 files changed, 295 insertions, 0 deletions
diff --git a/absl/log/internal/log_sink_set.cc b/absl/log/internal/log_sink_set.cc
new file mode 100644
index 00000000..4fe301c6
--- /dev/null
+++ b/absl/log/internal/log_sink_set.cc
@@ -0,0 +1,295 @@
+//
+// 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/internal/log_sink_set.h"
+
+#ifndef ABSL_HAVE_THREAD_LOCAL
+#include <pthread.h>
+#endif
+
+#ifdef __ANDROID__
+#include <android/log.h>
+#endif
+
+#ifdef _WIN32
+#include <windows.h>
+#endif
+
+#include <algorithm>
+#include <vector>
+
+#include "absl/base/attributes.h"
+#include "absl/base/call_once.h"
+#include "absl/base/config.h"
+#include "absl/base/internal/raw_logging.h"
+#include "absl/base/log_severity.h"
+#include "absl/base/thread_annotations.h"
+#include "absl/cleanup/cleanup.h"
+#include "absl/log/globals.h"
+#include "absl/log/internal/config.h"
+#include "absl/log/internal/globals.h"
+#include "absl/log/log_entry.h"
+#include "absl/log/log_sink.h"
+#include "absl/strings/string_view.h"
+#include "absl/synchronization/mutex.h"
+#include "absl/types/span.h"
+
+namespace absl {
+ABSL_NAMESPACE_BEGIN
+namespace log_internal {
+namespace {
+
+// Returns a mutable reference to a thread-local variable that should be true if
+// a globally-registered `LogSink`'s `Send()` is currently being invoked on this
+// thread.
+bool& ThreadIsLoggingStatus() {
+#ifdef ABSL_HAVE_THREAD_LOCAL
+  ABSL_CONST_INIT thread_local bool thread_is_logging = false;
+  return thread_is_logging;
+#else
+  ABSL_CONST_INIT static pthread_key_t thread_is_logging_key;
+  static const bool unused = [] {
+    if (pthread_key_create(&thread_is_logging_key, [](void* data) {
+          delete reinterpret_cast<bool*>(data);
+        })) {
+      perror("pthread_key_create failed!");
+      abort();
+    }
+    return true;
+  }();
+  bool* thread_is_logging_ptr =
+      reinterpret_cast<bool*>(pthread_getspecific(thread_is_logging_key));
+
+  if (ABSL_PREDICT_FALSE(!thread_is_logging_ptr)) {
+    thread_is_logging_ptr = new bool{false};
+    if (pthread_setspecific(thread_is_logging_key, thread_is_logging_ptr)) {
+      perror("pthread_setspecific failed");
+      abort();
+    }
+  }
+  return *thread_is_logging_ptr;
+#endif
+}
+
+class StderrLogSink final : public LogSink {
+ public:
+  ~StderrLogSink() override = default;
+
+  void Send(const absl::LogEntry& entry) override {
+    if (entry.log_severity() < absl::StderrThreshold() &&
+        absl::log_internal::IsInitialized()) {
+      return;
+    }
+
+    ABSL_CONST_INIT static absl::once_flag warn_if_not_initialized;
+    absl::call_once(warn_if_not_initialized, []() {
+      if (absl::log_internal::IsInitialized()) return;
+      const char w[] =
+          "WARNING: All log messages before absl::InitializeLog() is called"
+          " are written to STDERR\n";
+      absl::log_internal::WriteToStderr(w, absl::LogSeverity::kWarning);
+    });
+
+    if (!entry.stacktrace().empty()) {
+      absl::log_internal::WriteToStderr(entry.stacktrace(),
+                                        entry.log_severity());
+    } else {
+      // TODO(b/226937039): do this outside else condition once we avoid
+      // ReprintFatalMessage
+      absl::log_internal::WriteToStderr(
+          entry.text_message_with_prefix_and_newline(), entry.log_severity());
+    }
+  }
+};
+
+#if defined(__ANDROID__)
+class AndroidLogSink final : public LogSink {
+ public:
+  ~AndroidLogSink() override = default;
+
+  void Send(const absl::LogEntry& entry) override {
+    const int level = AndroidLogLevel(entry);
+    // TODO(b/37587197): make the tag ("native") configurable.
+    __android_log_write(level, "native",
+                        entry.text_message_with_prefix_and_newline_c_str());
+    if (entry.log_severity() == absl::LogSeverity::kFatal)
+      __android_log_write(ANDROID_LOG_FATAL, "native", "terminating.\n");
+  }
+
+ private:
+  static int AndroidLogLevel(const absl::LogEntry& entry) {
+    switch (entry.log_severity()) {
+      case absl::LogSeverity::kFatal:
+        return ANDROID_LOG_FATAL;
+      case absl::LogSeverity::kError:
+        return ANDROID_LOG_ERROR;
+      case absl::LogSeverity::kWarning:
+        return ANDROID_LOG_WARN;
+      default:
+        if (entry.verbosity() >= 2) return ANDROID_LOG_VERBOSE;
+        if (entry.verbosity() == 1) return ANDROID_LOG_DEBUG;
+        return ANDROID_LOG_INFO;
+    }
+  }
+};
+#endif  // !defined(__ANDROID__)
+
+#if defined(_WIN32)
+class WindowsDebuggerLogSink final : public LogSink {
+ public:
+  ~WindowsDebuggerLogSink() override = default;
+
+  void Send(const absl::LogEntry& entry) override {
+    if (entry.log_severity() < absl::StderrThreshold() &&
+        absl::log_internal::IsInitialized()) {
+      return;
+    }
+    ::OutputDebugStringA(entry.text_message_with_prefix_and_newline_c_str());
+  }
+};
+#endif  // !defined(_WIN32)
+
+class GlobalLogSinkSet final {
+ public:
+  GlobalLogSinkSet() {
+#if defined(__myriad2__) || defined(__Fuchsia__)
+    // myriad2 and Fuchsia do not log to stderr by default.
+#else
+    static StderrLogSink* stderr_log_sink = new StderrLogSink;
+    AddLogSink(stderr_log_sink);
+#endif
+#ifdef __ANDROID__
+    static AndroidLogSink* android_log_sink = new AndroidLogSink;
+    AddLogSink(android_log_sink);
+#endif
+#if defined(_WIN32)
+    static WindowsDebuggerLogSink* debugger_log_sink =
+        new WindowsDebuggerLogSink;
+    AddLogSink(debugger_log_sink);
+#endif  // !defined(_WIN32)
+  }
+
+  void LogToSinks(const absl::LogEntry& entry,
+                  absl::Span<absl::LogSink*> extra_sinks, bool extra_sinks_only)
+      ABSL_LOCKS_EXCLUDED(guard_) {
+    SendToSinks(entry, extra_sinks);
+
+    if (!extra_sinks_only) {
+      if (ThreadIsLoggingToLogSink()) {
+        absl::log_internal::WriteToStderr(
+            entry.text_message_with_prefix_and_newline(), entry.log_severity());
+      } else {
+        absl::ReaderMutexLock global_sinks_lock(&guard_);
+        ThreadIsLoggingStatus() = true;
+        // Ensure the "thread is logging" status is reverted upon leaving the
+        // scope even in case of exceptions.
+        auto status_cleanup =
+            absl::MakeCleanup([] { ThreadIsLoggingStatus() = false; });
+        SendToSinks(entry, absl::MakeSpan(sinks_));
+      }
+    }
+  }
+
+  void AddLogSink(absl::LogSink* sink) ABSL_LOCKS_EXCLUDED(guard_) {
+    {
+      absl::WriterMutexLock global_sinks_lock(&guard_);
+      auto pos = std::find(sinks_.begin(), sinks_.end(), sink);
+      if (pos == sinks_.end()) {
+        sinks_.push_back(sink);
+        return;
+      }
+    }
+    ABSL_INTERNAL_LOG(FATAL, "Duplicate log sinks are not supported");
+  }
+
+  void RemoveLogSink(absl::LogSink* sink) ABSL_LOCKS_EXCLUDED(guard_) {
+    {
+      absl::WriterMutexLock global_sinks_lock(&guard_);
+      auto pos = std::find(sinks_.begin(), sinks_.end(), sink);
+      if (pos != sinks_.end()) {
+        sinks_.erase(pos);
+        return;
+      }
+    }
+    ABSL_INTERNAL_LOG(FATAL, "Mismatched log sink being removed");
+  }
+
+  void FlushLogSinks() ABSL_LOCKS_EXCLUDED(guard_) {
+    if (ThreadIsLoggingToLogSink()) {
+      // The thread_local condition demonstrates that we're already holding the
+      // lock in order to iterate over `sinks_` for dispatch.  The thread-safety
+      // annotations don't know this, so we use `ABSL_NO_THREAD_SAFETY_ANALYSIS`
+      guard_.AssertReaderHeld();
+      FlushLogSinksLocked();
+    } else {
+      absl::ReaderMutexLock global_sinks_lock(&guard_);
+      // In case if LogSink::Flush overload decides to log
+      ThreadIsLoggingStatus() = true;
+      // Ensure the "thread is logging" status is reverted upon leaving the
+      // scope even in case of exceptions.
+      auto status_cleanup =
+          absl::MakeCleanup([] { ThreadIsLoggingStatus() = false; });
+      FlushLogSinksLocked();
+    }
+  }
+
+ private:
+  void FlushLogSinksLocked() ABSL_SHARED_LOCKS_REQUIRED(guard_) {
+    for (absl::LogSink* sink : sinks_) {
+      sink->Flush();
+    }
+  }
+
+  // Helper routine for LogToSinks.
+  static void SendToSinks(const absl::LogEntry& entry,
+                          absl::Span<absl::LogSink*> sinks) {
+    for (absl::LogSink* sink : sinks) {
+      sink->Send(entry);
+    }
+  }
+
+  using LogSinksSet = std::vector<absl::LogSink*>;
+  absl::Mutex guard_;
+  LogSinksSet sinks_ ABSL_GUARDED_BY(guard_);
+};
+
+// Returns reference to the global LogSinks set.
+GlobalLogSinkSet& GlobalSinks() {
+  static GlobalLogSinkSet* global_sinks = new GlobalLogSinkSet;
+  return *global_sinks;
+}
+
+}  // namespace
+
+bool ThreadIsLoggingToLogSink() { return ThreadIsLoggingStatus(); }
+
+void LogToSinks(const absl::LogEntry& entry,
+                absl::Span<absl::LogSink*> extra_sinks, bool extra_sinks_only) {
+  log_internal::GlobalSinks().LogToSinks(entry, extra_sinks, extra_sinks_only);
+}
+
+void AddLogSink(absl::LogSink* sink) {
+  log_internal::GlobalSinks().AddLogSink(sink);
+}
+
+void RemoveLogSink(absl::LogSink* sink) {
+  log_internal::GlobalSinks().RemoveLogSink(sink);
+}
+
+void FlushLogSinks() { log_internal::GlobalSinks().FlushLogSinks(); }
+
+}  // namespace log_internal
+ABSL_NAMESPACE_END
+}  // namespace absl