[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[]) {
@@ skipping 855 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);
+    m_scheduledOrder.push_back(task);
+    while (m_scheduledOrder.size() - m_scheduledOrderDeleted.size() >
+           kMaxAsyncTaskStacks) {
+      void* task = m_scheduledOrder.front();
+      m_scheduledOrder.pop_front();
+      m_asyncTaskStacks.erase(task);
+      m_recurringTasks.erase(task);
+      m_scheduledOrderDeleted.erase(task);
+    }
   }
 }
 
 void V8Debugger::asyncTaskCanceled(void* task) {
   if (!m_maxAsyncCallStackDepth) return;
   m_asyncTaskStacks.erase(task);
+  m_scheduledOrderDeleted.insert(task);
+  cleanupScheduledOrderIfNeeded();
   m_recurringTasks.erase(task);
 }
 
 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);
+    m_scheduledOrderDeleted.insert(task);
+    cleanupScheduledOrderIfNeeded();
+  }
 }
 
 void V8Debugger::allAsyncTasksCanceled() {
   m_asyncTaskStacks.clear();
+  m_scheduledOrder.clear();
+  m_scheduledOrderDeleted.clear();
   m_recurringTasks.clear();
   m_currentStacks.clear();
   m_currentTasks.clear();
 }
 
+void V8Debugger::cleanupScheduledOrderIfNeeded() {
+  if (m_scheduledOrder.size() < kMaxAsyncTaskStacks * 2) return;
+  std::deque<void*> scheduledOrder;
+  for (void* task : m_scheduledOrder) {
+    if (m_scheduledOrderDeleted.find(task) == m_scheduledOrderDeleted.end()) {
+      scheduledOrder.push_back(task);
+    }
+  }
+  m_scheduledOrder.swap(scheduledOrder);
+  m_scheduledOrderDeleted.clear();
+}
+
 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