[inspector] introduce limit for amount of stored async stacks

src/inspector/v8-debugger.cc

 // 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.
 
 #include "src/inspector/v8-debugger.h"
 
 #include "src/inspector/debugger-script.h"
 #include "src/inspector/inspected-context.h"
 #include "src/inspector/protocol/Protocol.h"
 #include "src/inspector/script-breakpoint.h"
 #include "src/inspector/string-util.h"
 #include "src/inspector/v8-debugger-agent-impl.h"
 #include "src/inspector/v8-inspector-impl.h"
 #include "src/inspector/v8-internal-value-type.h"
 #include "src/inspector/v8-stack-trace-impl.h"
 #include "src/inspector/v8-value-copier.h"
 
 #include "include/v8-util.h"
 
 namespace v8_inspector {
 
 namespace {
 static const char v8AsyncTaskEventEnqueue[] = "enqueue";
 static const char v8AsyncTaskEventEnqueueRecurring[] = "enqueueRecurring";
 static const char v8AsyncTaskEventWillHandle[] = "willHandle";
 static const char v8AsyncTaskEventDidHandle[] = "didHandle";
 static const char v8AsyncTaskEventCancel[] = "cancel";
 
+// Based on DevTools frontend measurement, with asyncCallStackDepth = 4,
+// average async call stack tail requires ~1 Kb. Let's reserve ~ 128 Mb
+// for async stacks.
+static const int kMaxAsyncTaskStacks = 128 * 1024;
+
 inline v8::Local<v8::Boolean> v8Boolean(bool value, v8::Isolate* isolate) {
   return value ? v8::True(isolate) : v8::False(isolate);
 }
 
 }  // namespace
 
 static bool inLiveEditScope = false;
 
 v8::MaybeLocal<v8::Value> V8Debugger::callDebuggerMethod(
     const char* functionName, int argc, v8::Local<v8::Value> argv[]) {
   v8::MicrotasksScope microtasks(m_isolate,
                                  v8::MicrotasksScope::kDoNotRunMicrotasks);
   DCHECK(m_isolate->InContext());
   v8::Local<v8::Context> context = m_isolate->GetCurrentContext();
   v8::Local<v8::Object> debuggerScript = m_debuggerScript.Get(m_isolate);
   v8::Local<v8::Function> function = v8::Local<v8::Function>::Cast(
       debuggerScript
           ->Get(context, toV8StringInternalized(m_isolate, functionName))
           .ToLocalChecked());
   return function->Call(context, debuggerScript, argc, argv);
 }
 
 V8Debugger::V8Debugger(v8::Isolate* isolate, V8InspectorImpl* inspector)
     : m_isolate(isolate),
       m_inspector(inspector),
       m_enableCount(0),
       m_breakpointsActivated(true),
       m_runningNestedMessageLoop(false),
       m_ignoreScriptParsedEventsCounter(0),
+      m_lastId(0),
       m_maxAsyncCallStackDepth(0),
       m_pauseOnExceptionsState(v8::debug::NoBreakOnException),
       m_wasmTranslation(isolate) {}
 
 V8Debugger::~V8Debugger() {}
 
 void V8Debugger::enable() {
   if (m_enableCount++) return;
   DCHECK(!enabled());
   v8::HandleScope scope(m_isolate);
@@ skipping 826 matching lines @@
   int contextGroupId =
       m_isolate->InContext()
           ? m_inspector->contextGroupId(m_isolate->GetCurrentContext())
           : 0;
   std::unique_ptr<V8StackTraceImpl> chain = V8StackTraceImpl::capture(
       this, contextGroupId, V8StackTraceImpl::maxCallStackSizeToCapture,
       taskName);
   if (chain) {
     m_asyncTaskStacks[task] = std::move(chain);
     if (recurring) m_recurringTasks.insert(task);
+    int id = ++m_lastId;
+    m_rawIdToId[task] = id;
+    m_idToRawId[id] = task;
+    while (m_idToRawId.size() > kMaxAsyncTaskStacks) {

[dgozman, 2016/12/16 23:59:49]

while -> if ?

[kozy, 2016/12/17 01:12:41]

Done.

+      void* taskToRemove = m_idToRawId.begin()->second;
+      asyncTaskCanceled(taskToRemove);
+    }
   }
 }
 
 void V8Debugger::asyncTaskCanceled(void* task) {

[dgozman, 2016/12/16 23:59:49]

Note that task can be messing from any of our maps now.

[kozy, 2016/12/17 01:12:41]

Done.

   if (!m_maxAsyncCallStackDepth) return;
   m_asyncTaskStacks.erase(task);
   m_recurringTasks.erase(task);
+  auto it = m_rawIdToId.find(task);
+  m_idToRawId.erase(it->second);
+  m_rawIdToId.erase(it);
 }
 
 void V8Debugger::asyncTaskStarted(void* task) {
   if (!m_maxAsyncCallStackDepth) return;
   m_currentTasks.push_back(task);
   AsyncTaskToStackTrace::iterator stackIt = m_asyncTaskStacks.find(task);
   // Needs to support following order of events:
   // - asyncTaskScheduled
   //   <-- attached here -->
   // - asyncTaskStarted
   // - asyncTaskCanceled <-- canceled before finished
   //   <-- async stack requested here -->
   // - asyncTaskFinished
   std::unique_ptr<V8StackTraceImpl> stack;
   if (stackIt != m_asyncTaskStacks.end() && stackIt->second)
     stack = stackIt->second->cloneImpl();
   m_currentStacks.push_back(std::move(stack));
 }
 
 void V8Debugger::asyncTaskFinished(void* task) {
   if (!m_maxAsyncCallStackDepth) return;
   // We could start instrumenting half way and the stack is empty.
   if (!m_currentStacks.size()) return;
 
   DCHECK(m_currentTasks.back() == task);
   m_currentTasks.pop_back();
 
   m_currentStacks.pop_back();
-  if (m_recurringTasks.find(task) == m_recurringTasks.end())
+  if (m_recurringTasks.find(task) == m_recurringTasks.end()) {
     m_asyncTaskStacks.erase(task);
+    auto it = m_rawIdToId.find(task);
+    m_idToRawId.erase(it->second);
+    m_rawIdToId.erase(it);
+  }
 }
 
 void V8Debugger::allAsyncTasksCanceled() {
   m_asyncTaskStacks.clear();
   m_recurringTasks.clear();
   m_currentStacks.clear();
   m_currentTasks.clear();
+  m_idToRawId.clear();
+  m_rawIdToId.clear();
+  m_lastId = 0;
 }
 
 void V8Debugger::muteScriptParsedEvents() {
   ++m_ignoreScriptParsedEventsCounter;
 }
 
 void V8Debugger::unmuteScriptParsedEvents() {
   --m_ignoreScriptParsedEventsCounter;
   DCHECK_GE(m_ignoreScriptParsedEventsCounter, 0);
 }
 
 std::unique_ptr<V8StackTraceImpl> V8Debugger::captureStackTrace(
     bool fullStack) {
   if (!m_isolate->InContext()) return nullptr;
 
   v8::HandleScope handles(m_isolate);
   int contextGroupId =
       m_inspector->contextGroupId(m_isolate->GetCurrentContext());
   if (!contextGroupId) return nullptr;
 
   size_t stackSize =
       fullStack ? V8StackTraceImpl::maxCallStackSizeToCapture : 1;
   if (m_inspector->enabledRuntimeAgentForGroup(contextGroupId))
     stackSize = V8StackTraceImpl::maxCallStackSizeToCapture;
 
   return V8StackTraceImpl::capture(this, contextGroupId, stackSize);
 }
 
 }  // namespace v8_inspector