From 81e0d616edeb73cbd06d6c40bc4f90593ac0c5d1 Mon Sep 17 00:00:00 2001
From: Tongliang Liao <xkszltl@gmail.com>
Date: Thu, 13 May 2021 08:24:08 +0800
Subject: [PATCH] Expose `IsGoogleLoggingInitialized()` in public API. Usually
 library does not have control of the process lifespan. Without this function,
 it is impossible to init/shutdown reliably. It has been one of the major pain
 points for years when using glog in libraries.

AFAIK 3 workarounds have been used previously:
1. Init without checking. This causes compatiblity issues with other libs using glog.
2. Also provide a init function in library's API. This makes API complicated and stateful, especially for libs that does not mean to stay for the entire life of process.
3. Steal the utility function in internal namespace. Does not work with msvc (due to missing dllexport) or `gcc -fvisibility=hidden`.

None of them are perfect, except for the last hack that usually works well on Linux.
0.5.0 changes default visibility to hidden and it does not work anymore.

Resolve https://github.com/google/glog/issues/125
---
 src/glog/logging.h.in                 | 3 +++
 src/logging_custom_prefix_unittest.cc | 6 ++++++
 src/logging_unittest.cc               | 6 ++++++
 src/utilities.cc                      | 8 ++++----
 src/utilities.h                       | 2 --
 5 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/src/glog/logging.h.in b/src/glog/logging.h.in
index 421f1e026..a9b0d461d 100644
--- a/src/glog/logging.h.in
+++ b/src/glog/logging.h.in
@@ -594,6 +594,9 @@ GOOGLE_GLOG_DLL_DECL void InitGoogleLogging(const char* argv0,
                                             void* prefix_callback_data = NULL);
 #endif
 
+// Check if google's logging library has been initialized.
+GOOGLE_GLOG_DLL_DECL bool IsGoogleLoggingInitialized();
+
 // Shutdown google's logging library.
 GOOGLE_GLOG_DLL_DECL void ShutdownGoogleLogging();
 
diff --git a/src/logging_custom_prefix_unittest.cc b/src/logging_custom_prefix_unittest.cc
index c9fb5b819..55da56c5d 100644
--- a/src/logging_custom_prefix_unittest.cc
+++ b/src/logging_custom_prefix_unittest.cc
@@ -221,11 +221,15 @@ int main(int argc, char **argv) {
   LogWithLevels(0, 0, 0, 0);  // simulate "before global c-tors"
   const string early_stderr = GetCapturedTestStderr();
 
+  EXPECT_FALSE(IsGoogleLoggingInitialized());
+
   // Setting a custom prefix generator (it will use the default format so that
   // the golden outputs can be reused):
   string prefix_attacher_data = "good data";
   InitGoogleLogging(argv[0], &PrefixAttacher, static_cast<void*>(&prefix_attacher_data));
 
+  EXPECT_TRUE(IsGoogleLoggingInitialized());
+
   RunSpecifiedBenchmarks();
 
   FLAGS_logtostderr = true;
@@ -992,8 +996,10 @@ static void TestCustomLoggerDeletionOnShutdown() {
   base::SetLogger(GLOG_INFO,
                   new RecordDeletionLogger(&custom_logger_deleted,
                                            base::GetLogger(GLOG_INFO)));
+  EXPECT_TRUE(IsGoogleLoggingInitialized());
   ShutdownGoogleLogging();
   EXPECT_TRUE(custom_logger_deleted);
+  EXPECT_FALSE(IsGoogleLoggingInitialized());
 }
 
 _START_GOOGLE_NAMESPACE_
diff --git a/src/logging_unittest.cc b/src/logging_unittest.cc
index edc7d35d7..37cc247cc 100644
--- a/src/logging_unittest.cc
+++ b/src/logging_unittest.cc
@@ -197,8 +197,12 @@ int main(int argc, char **argv) {
   LogWithLevels(0, 0, 0, 0);  // simulate "before global c-tors"
   const string early_stderr = GetCapturedTestStderr();
 
+  EXPECT_FALSE(IsGoogleLoggingInitialized());
+
   InitGoogleLogging(argv[0]);
 
+  EXPECT_TRUE(IsGoogleLoggingInitialized());
+
   RunSpecifiedBenchmarks();
 
   FLAGS_logtostderr = true;
@@ -965,8 +969,10 @@ static void TestCustomLoggerDeletionOnShutdown() {
   base::SetLogger(GLOG_INFO,
                   new RecordDeletionLogger(&custom_logger_deleted,
                                            base::GetLogger(GLOG_INFO)));
+  EXPECT_TRUE(IsGoogleLoggingInitialized());
   ShutdownGoogleLogging();
   EXPECT_TRUE(custom_logger_deleted);
+  EXPECT_FALSE(IsGoogleLoggingInitialized());
 }
 
 _START_GOOGLE_NAMESPACE_
diff --git a/src/utilities.cc b/src/utilities.cc
index 6b9a69e63..63d90305d 100644
--- a/src/utilities.cc
+++ b/src/utilities.cc
@@ -62,6 +62,10 @@ _START_GOOGLE_NAMESPACE_
 
 static const char* g_program_invocation_short_name = NULL;
 
+bool IsGoogleLoggingInitialized() {
+  return g_program_invocation_short_name != NULL;
+}
+
 _END_GOOGLE_NAMESPACE_
 
 // The following APIs are all internal.
@@ -176,10 +180,6 @@ const char* ProgramInvocationShortName() {
   }
 }
 
-bool IsGoogleLoggingInitialized() {
-  return g_program_invocation_short_name != NULL;
-}
-
 #ifdef OS_WINDOWS
 struct timeval {
   long tv_sec, tv_usec;
diff --git a/src/utilities.h b/src/utilities.h
index e4115ad45..052d8705f 100644
--- a/src/utilities.h
+++ b/src/utilities.h
@@ -163,8 +163,6 @@ namespace glog_internal_namespace_ {
 
 const char* ProgramInvocationShortName();
 
-bool IsGoogleLoggingInitialized();
-
 int64 CycleClock_Now();
 
 int64 UsecToCycles(int64 usec);