Do not leak GFlags.h in widely included headers

Summary: It defines several generically named macros, better avoid including it everywhere.

Reviewed By: aary

Differential Revision: D29870524

fbshipit-source-id: b8703a737a6dc53e00c13daebc445855bfbadd1f

folly/executors/Codel.h

@@ -19,11 +19,6 @@
 #include <atomic>
 #include <chrono>
 
-#include <folly/portability/GFlags.h>
-
-DECLARE_int32(codel_interval);
-DECLARE_int32(codel_target_delay);
-
 namespace folly {
 
 /// CoDel (controlled delay) is an active queue management algorithm from

folly/executors/test/CodelTest.cpp

@@ -19,8 +19,11 @@
 #include <chrono>
 #include <thread>
 
+#include <folly/portability/GFlags.h>
 #include <folly/portability/GTest.h>
 
+DECLARE_int32(codel_target_delay);
+
 using std::chrono::milliseconds;
 using std::this_thread::sleep_for;
 

folly/synchronization/Hazptr-fwd.h

@@ -19,8 +19,6 @@
 #include <atomic>
 #include <memory>
 
-#include <folly/portability/GFlags.h>
-
 ///
 /// Forward declatations and implicit documentation of all hazptr
 /// top-level classes, functions, macros, default values, and globals.
@@ -33,8 +31,6 @@
 #define FOLLY_HAZPTR_THR_LOCAL true
 #endif
 
-DECLARE_bool(folly_hazptr_use_executor);
-
 namespace folly {
 
 ///
@@ -189,6 +185,9 @@ void hazard_pointer_clean_up(
 /** Global default domain defined in Hazptr.cpp */
 extern hazptr_domain<std::atomic> default_domain;
 
+/** Defined in Hazptr.cpp */
+bool hazptr_use_executor();
+
 ///
 /// Classes related to hazard pointer holders.
 /// Defined in HazptrHolder.h

folly/synchronization/Hazptr.cpp

@@ -29,4 +29,8 @@ namespace folly {
 
 FOLLY_STATIC_CTOR_PRIORITY_MAX hazptr_domain<std::atomic> default_domain;
 
+bool hazptr_use_executor() {
+  return FLAGS_folly_hazptr_use_executor;
+}
+
 } // namespace folly

folly/synchronization/HazptrDomain.h

@@ -313,8 +313,7 @@ class hazptr_domain {
         return;
     }
     if (std::is_same<Atom<int>, std::atomic<int>>{} &&
-        this == &default_hazptr_domain<Atom>() &&
-        FLAGS_folly_hazptr_use_executor) {
+        this == &default_hazptr_domain<Atom>() && hazptr_use_executor()) {
       invoke_reclamation_in_executor(rcount);
     } else {
       do_reclamation(rcount);

folly/synchronization/HazptrThreadPoolExecutor.cpp

@@ -38,7 +38,7 @@ folly::Executor* get_hazptr_tpe() {
 namespace folly {
 
 void enable_hazptr_thread_pool_executor() {
-  if (FLAGS_folly_hazptr_use_executor) {
+  if (hazptr_use_executor()) {
     default_hazptr_domain().set_executor(&get_hazptr_tpe);
   }
 }