[inspector] avoid cloning of async call chains

src/inspector/v8-debugger.h

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_INSPECTOR_V8DEBUGGER_H_
 #define V8_INSPECTOR_V8DEBUGGER_H_
 
+#include <list>
 #include <vector>
 
 #include "src/base/macros.h"
 #include "src/debug/debug-interface.h"
 #include "src/inspector/java-script-call-frame.h"
 #include "src/inspector/protocol/Debugger.h"
 #include "src/inspector/protocol/Forward.h"
 #include "src/inspector/protocol/Runtime.h"
 #include "src/inspector/v8-debugger-script.h"
 #include "src/inspector/wasm-translation.h"
 
 #include "include/v8-inspector.h"
 
 namespace v8_inspector {
 
+class AsyncStackTrace;
 struct ScriptBreakpoint;
+class V8Debugger;
 class V8DebuggerAgentImpl;
 class V8InspectorImpl;
 class V8StackTraceImpl;
 
 using protocol::Response;
 using ScheduleStepIntoAsyncCallback =
     protocol::Debugger::Backend::ScheduleStepIntoAsyncCallback;
 
 class V8Debugger : public v8::debug::DebugDelegate {
  public:
   V8Debugger(v8::Isolate*, V8InspectorImpl*);
   ~V8Debugger();
 
   bool enabled() const;
+  v8::Isolate* isolate() const { return m_isolate; }
 
   String16 setBreakpoint(const ScriptBreakpoint&, int* actualLineNumber,
                          int* actualColumnNumber);
   void removeBreakpoint(const String16& breakpointId);
   void setBreakpointsActivated(bool);
   bool breakpointsActivated() const { return m_breakpointsActivated; }
 
   v8::debug::ExceptionBreakState getPauseOnExceptionsState();
   void setPauseOnExceptionsState(v8::debug::ExceptionBreakState);
   bool canBreakProgram();
@@ skipping 21 matching lines @@
   // Passing 0 will result in reporting all scripts.
   void getCompiledScripts(int contextGroupId,
                           std::vector<std::unique_ptr<V8DebuggerScript>>&);
   void enable();
   void disable();
 
   bool isPaused() const { return m_runningNestedMessageLoop; }
   v8::Local<v8::Context> pausedContext() { return m_pausedContext; }
 
   int maxAsyncCallChainDepth() { return m_maxAsyncCallStackDepth; }
-  V8StackTraceImpl* currentAsyncCallChain();
-  V8StackTraceImpl* currentAsyncTaskCreationStack();
   void setAsyncCallStackDepth(V8DebuggerAgentImpl*, int);
+
+  std::shared_ptr<AsyncStackTrace> currentAsyncParent();
+  std::shared_ptr<AsyncStackTrace> currentAsyncCreation();
+
   std::unique_ptr<V8StackTraceImpl> createStackTrace(v8::Local<v8::StackTrace>);
   std::unique_ptr<V8StackTraceImpl> captureStackTrace(bool fullStack);
 
   v8::MaybeLocal<v8::Array> internalProperties(v8::Local<v8::Context>,
                                                v8::Local<v8::Value>);
 
   void asyncTaskScheduled(const StringView& taskName, void* task,
                           bool recurring);
   void asyncTaskCanceled(void* task);
   void asyncTaskStarted(void* task);
   void asyncTaskFinished(void* task);
   void allAsyncTasksCanceled();
 
   void muteScriptParsedEvents();
   void unmuteScriptParsedEvents();
 
   V8InspectorImpl* inspector() { return m_inspector; }
 
   WasmTranslation* wasmTranslation() { return &m_wasmTranslation; }
 
-  void setMaxAsyncTaskStacksForTest(int limit) { m_maxAsyncCallStacks = limit; }
+  void setMaxAsyncTaskStacksForTest(int limit);
 
  private:
   void compileDebuggerScript();
   v8::MaybeLocal<v8::Value> callDebuggerMethod(const char* functionName,
                                                int argc,
                                                v8::Local<v8::Value> argv[],
                                                bool catchExceptions);
   v8::Local<v8::Context> debuggerContext() const;
   void clearBreakpoints();
 
@@ skipping 24 matching lines @@
                                   bool recurring);
   void asyncTaskCanceledForStack(void* task);
   void asyncTaskStartedForStack(void* task);
   void asyncTaskFinishedForStack(void* task);
 
   void asyncTaskCandidateForStepping(void* task);
   void asyncTaskStartedForStepping(void* task);
   void asyncTaskFinishedForStepping(void* task);
   void asyncTaskCanceledForStepping(void* task);
 
-  void registerAsyncTaskIfNeeded(void* task);
-
   // v8::debug::DebugEventListener implementation.
   void PromiseEventOccurred(v8::debug::PromiseDebugActionType type, int id,
                             int parentId, bool createdByUser) override;
   void ScriptCompiled(v8::Local<v8::debug::Script> script,
                       bool has_compile_error) override;
   void BreakProgramRequested(v8::Local<v8::Context> paused_context,
                              v8::Local<v8::Object> exec_state,
                              v8::Local<v8::Value> break_points_hit) override;
   void ExceptionThrown(v8::Local<v8::Context> paused_context,
                        v8::Local<v8::Object> exec_state,
@@ skipping 12 matching lines @@
   v8::Global<v8::Object> m_debuggerScript;
   v8::Global<v8::Context> m_debuggerContext;
   v8::Local<v8::Object> m_executionState;
   v8::Local<v8::Context> m_pausedContext;
   bool m_runningNestedMessageLoop;
   int m_ignoreScriptParsedEventsCounter;
   bool m_scheduledOOMBreak = false;
   int m_targetContextGroupId = 0;
 
   using AsyncTaskToStackTrace =
-      protocol::HashMap<void*, std::unique_ptr<V8StackTraceImpl>>;
+      protocol::HashMap<void*, std::weak_ptr<AsyncStackTrace>>;
   AsyncTaskToStackTrace m_asyncTaskStacks;
   AsyncTaskToStackTrace m_asyncTaskCreationStacks;
   int m_maxAsyncCallStacks;
-  std::map<int, void*> m_idToTask;
-  std::unordered_map<void*, int> m_taskToId;
-  int m_lastTaskId;
   protocol::HashSet<void*> m_recurringTasks;
   int m_maxAsyncCallStackDepth;
+
   std::vector<void*> m_currentTasks;
-  std::vector<std::unique_ptr<V8StackTraceImpl>> m_currentStacks;
-  std::vector<std::unique_ptr<V8StackTraceImpl>> m_currentCreationStacks;
+  std::vector<std::shared_ptr<AsyncStackTrace>> m_currentAsyncParent;
+  std::vector<std::shared_ptr<AsyncStackTrace>> m_currentAsyncCreation;
+
+  void collectOldAsyncStacksIfNeeded();
+  void removeOldAsyncTasks(AsyncTaskToStackTrace& map);
+  int m_asyncStacksCount = 0;
+  std::list<std::shared_ptr<AsyncStackTrace>> m_allAsyncStacks;

[dgozman, 2017/04/17 23:03:15]

Let's comment that this owns all the stacks, while most of the other references
are weak, which allows to collect some stacks when there are too many.

[kozy, 2017/04/18 01:04:38]

Done.

+
   protocol::HashMap<V8DebuggerAgentImpl*, int> m_maxAsyncCallStackDepthMap;
   protocol::HashMap<void*, void*> m_parentTask;
   protocol::HashMap<void*, void*> m_firstNextTask;
   void* m_taskWithScheduledBreak = nullptr;
 
   std::unique_ptr<ScheduleStepIntoAsyncCallback> m_stepIntoAsyncCallback;
   bool m_breakRequested = false;
 
   v8::debug::ExceptionBreakState m_pauseOnExceptionsState;
 
   WasmTranslation m_wasmTranslation;
 
   DISALLOW_COPY_AND_ASSIGN(V8Debugger);
 };
 
 }  // namespace v8_inspector
 
 #endif  // V8_INSPECTOR_V8DEBUGGER_H_