commit 5ac4baad2095486e8e742de94bbd1a4bca72e230
author Daniele Di Proietto <ddiproietto@google.com> Fri Nov 29 15:22:45 2024 +0000
committer Daniele Di Proietto <ddiproietto@google.com> Fri Nov 29 15:48:15 2024 +0000
tree 6119f55ce03f08582b632adb20b580ca518a519e
parent a4718cded1b6b2526ffc768c81fc352d14337f7b

shared_lib: Thread safety annotations to TrackEvent::GlobalState

* Add thread safety annotations.
* Fix a bug: GenerateDescriptorFromCategories() did not acquire the
  required lock.
* Change struct to class, as recommended by google C++ style guidelines.
* Refer to `this` instead of `GlobalState::Instance()` in a couple of
  places.

Change-Id: I759319df9e630ef1921d45171772f93ccb037b51

src/shared_lib/track_event.cc

diff --git a/src/shared_lib/track_event.cc b/src/shared_lib/track_event.cc
index 6714032..4a0c70b 100644
--- a/src/shared_lib/track_event.cc
+++ b/src/shared_lib/track_event.cc
@@ -26,6 +26,7 @@
 
 #include "perfetto/base/compiler.h"
 #include "perfetto/base/flat_set.h"
+#include "perfetto/base/thread_annotations.h"
 #include "perfetto/ext/base/file_utils.h"
 #include "perfetto/ext/base/no_destructor.h"
 #include "perfetto/ext/base/string_splitter.h"
@@ -307,14 +308,15 @@
   static internal::DataSourceThreadLocalState** GetTlsState();
 
  private:
-  struct GlobalState {
+  class GlobalState {
+   public:
     static GlobalState& Instance() {
       static GlobalState* instance = new GlobalState();
       return *instance;
     }
 
     void OnStart(const perfetto::protos::gen::TrackEventConfig& config,
-                 uint32_t instance_id) {
+                 uint32_t instance_id) PERFETTO_LOCKS_EXCLUDED(mu_) {
       std::lock_guard<std::mutex> lock(mu_);
       EnableRegisteredCategory(perfetto_te_any_categories, instance_id);
       for (PerfettoTeCategoryImpl* cat : categories_) {
@@ -324,15 +326,16 @@
       }
     }
 
-    void OnStop(uint32_t instance_id) {
-      std::lock_guard<std::mutex> lock(GlobalState::Instance().mu_);
-      for (PerfettoTeCategoryImpl* cat : GlobalState::Instance().categories_) {
+    void OnStop(uint32_t instance_id) PERFETTO_LOCKS_EXCLUDED(mu_) {
+      std::lock_guard<std::mutex> lock(mu_);
+      for (PerfettoTeCategoryImpl* cat : categories_) {
         DisableRegisteredCategory(cat, instance_id);
       }
       DisableRegisteredCategory(perfetto_te_any_categories, instance_id);
     }
 
-    void RegisterCategory(PerfettoTeCategoryImpl* cat) {
+    void RegisterCategory(PerfettoTeCategoryImpl* cat)
+        PERFETTO_LOCKS_EXCLUDED(mu_) {
       {
         std::lock_guard<std::mutex> lock(mu_);
         Trace([cat](TraceContext ctx) {
@@ -343,11 +346,12 @@
           }
         });
         categories_.push_back(cat);
-        cat->cat_iid = ++GlobalState::Instance().interned_categories_;
+        cat->cat_iid = ++interned_categories_;
       }
     }
 
-    void UnregisterCategory(PerfettoTeCategoryImpl* cat) {
+    void UnregisterCategory(PerfettoTeCategoryImpl* cat)
+        PERFETTO_LOCKS_EXCLUDED(mu_) {
       std::lock_guard<std::mutex> lock(mu_);
       categories_.erase(
           std::remove(categories_.begin(), categories_.end(), cat),
@@ -356,7 +360,7 @@
 
     void CategorySetCallback(struct PerfettoTeCategoryImpl* cat,
                              PerfettoTeCategoryImplCallback cb,
-                             void* user_arg) {
+                             void* user_arg) PERFETTO_LOCKS_EXCLUDED(mu_) {
       std::lock_guard<std::mutex> lock(mu_);
       cat->cb = cb;
       cat->cb_user_arg = user_arg;
@@ -376,14 +380,18 @@
       }
     }
 
-    DataSourceDescriptor GenerateDescriptorFromCategories() const {
+    DataSourceDescriptor GenerateDescriptorFromCategories() const
+        PERFETTO_LOCKS_EXCLUDED(mu_) {
       DataSourceDescriptor dsd;
       dsd.set_name("track_event");
 
       protozero::HeapBuffered<perfetto::protos::pbzero::TrackEventDescriptor>
           ted;
-      for (PerfettoTeCategoryImpl* cat : categories_) {
-        SerializeCategory(*cat->desc, ted.get());
+      {
+        std::lock_guard<std::mutex> lock(mu_);
+        for (PerfettoTeCategoryImpl* cat : categories_) {
+          SerializeCategory(*cat->desc, ted.get());
+        }
       }
       dsd.set_track_event_descriptor_raw(ted.SerializeAsString());
       return dsd;
@@ -395,10 +403,9 @@
       perfetto_te_any_categories_enabled = &perfetto_te_any_categories->flag;
     }
 
-    // Guards categories and interned_categories;
-    std::mutex mu_;
-    std::vector<PerfettoTeCategoryImpl*> categories_;
-    uint64_t interned_categories_;
+    mutable std::mutex mu_;
+    std::vector<PerfettoTeCategoryImpl*> categories_ PERFETTO_GUARDED_BY(mu_);
+    uint64_t interned_categories_ PERFETTO_GUARDED_BY(mu_);
   };
 
   uint32_t inst_id_;