Thread-safe lazy initialization pattern

Author: jbachorik

ddprof-lib/src/main/cpp/libraries.cpp

@@ -5,8 +5,6 @@
 #include "vmEntry.h"
 #include "vmStructs.h"
 
-Libraries* Libraries::_instance = new Libraries();
-
 void Libraries::mangle(const char *name, char *buf, size_t size) {
   char *buf_end = buf + size;
   strcpy(buf, "_ZN");

ddprof-lib/src/main/cpp/libraries.h

@@ -5,8 +5,6 @@
 
 class Libraries {
  private:
-  static Libraries * _instance;
-
   CodeCacheArray _native_libs;
   CodeCache _runtime_stubs;
 
@@ -21,7 +19,14 @@ class Libraries {
   CodeCache *findLibraryByName(const char *lib_name);
   CodeCache *findLibraryByAddress(const void *address);
 
-  static Libraries *instance() { return _instance; }
+  static Libraries *instance() {
+    static Libraries instance;
+    return &instance;
+  }
+
+  // Delete copy constructor and assignment operator to prevent copies
+  Libraries(const Libraries&) = delete;
+  Libraries& operator=(const Libraries&) = delete;
 };
 
 #endif // _LIBRARIES_H

ddprof-lib/src/main/cpp/livenessTracker.cpp

@@ -33,7 +33,6 @@
 #include <jni.h>
 #include <string.h>
 
-LivenessTracker *const LivenessTracker::_instance = new LivenessTracker();
 constexpr int LivenessTracker::MAX_TRACKING_TABLE_SIZE;
 constexpr int LivenessTracker::MIN_SAMPLING_INTERVAL;
 

ddprof-lib/src/main/cpp/livenessTracker.h

@@ -82,10 +82,14 @@ class LivenessTracker {
 
   jlong getMaxMemory(JNIEnv *env);
 
-  static LivenessTracker *const _instance;
-
 public:
-  static LivenessTracker *instance() { return _instance; }
+  static LivenessTracker *instance() {
+    static LivenessTracker instance;
+    return &instance;
+  }
+  // Delete copy constructor and assignment operator to prevent copies
+  LivenessTracker(const LivenessTracker&) = delete;
+  LivenessTracker& operator=(const LivenessTracker&) = delete;
 
   LivenessTracker()
       : _initialized(false), _enabled(false), _stored_error(Error::OK),