Query NaCl processes' GDB debug port on the correct thread.

chrome/browser/task_manager/sampling/task_group.cc

 // Copyright 2015 The Chromium 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 "chrome/browser/task_manager/sampling/task_group.h"
 
 #include <algorithm>
 #include <limits>
 
 #include "base/bind.h"
@@ skipping 13 matching lines @@
 
 // A mask for the refresh types that are done in the background thread.
 const int kBackgroundRefreshTypesMask =
     REFRESH_TYPE_CPU | REFRESH_TYPE_MEMORY | REFRESH_TYPE_IDLE_WAKEUPS |
 #if defined(OS_WIN)
     REFRESH_TYPE_START_TIME | REFRESH_TYPE_CPU_TIME |
 #endif  // defined(OS_WIN)
 #if defined(OS_LINUX)
     REFRESH_TYPE_FD_COUNT |
 #endif  // defined(OS_LINUX)
-    REFRESH_TYPE_PRIORITY;
+    REFRESH_TYPE_NACL | REFRESH_TYPE_PRIORITY;

[afakhry, 2017/02/10 20:08:52]

You still need to wrap REFRESH_TYPE_NACL inside:

#if !defined(DISABLE_NACL)

#endif

One of your tests should have caught this bug.

[Wez, 2017/02/13 01:22:19]

Done.

 
 #if defined(OS_WIN)
 // Gets the GDI and USER Handles on Windows at one shot.
 void GetWindowsHandles(base::ProcessHandle handle,
                        int64_t* out_gdi_current,
                        int64_t* out_gdi_peak,
                        int64_t* out_user_current,
                        int64_t* out_user_peak) {
   *out_gdi_current = 0;
   *out_gdi_peak = 0;
@@ skipping 37 matching lines @@
       gpu_memory_(-1),
       memory_state_(base::MemoryState::UNKNOWN),
       per_process_network_usage_(-1),
 #if defined(OS_WIN)
       gdi_current_handles_(-1),
       gdi_peak_handles_(-1),
       user_current_handles_(-1),
       user_peak_handles_(-1),
 #endif  // defined(OS_WIN)
 #if !defined(DISABLE_NACL)
-      nacl_debug_stub_port_(-1),
+      nacl_debug_stub_port_(nacl::kGdbDebugStubPortUnknown),
 #endif  // !defined(DISABLE_NACL)
       idle_wakeups_per_second_(-1),
 #if defined(OS_LINUX)
       open_fd_count_(-1),
 #endif  // defined(OS_LINUX)
       gpu_memory_has_duplicates_(false),
       is_backgrounded_(false),
       weak_ptr_factory_(this) {
   scoped_refptr<TaskGroupSampler> sampler(
       new TaskGroupSampler(base::Process::Open(proc_id),
@@ skipping 66 matching lines @@
   }
 
   // 3- Refresh Windows handles (if enabled).
 #if defined(OS_WIN)
   if (TaskManagerObserver::IsResourceRefreshEnabled(REFRESH_TYPE_HANDLES,
                                                     refresh_flags)) {
     RefreshWindowsHandles();
   }
 #endif  // defined(OS_WIN)
 
-  // 4- Refresh the NACL debug stub port (if enabled).
+// 4- Refresh the NACL debug stub port (if enabled). This calls out to
+//    NaClBrowser on the browser's IO thread, completing asynchronously.
 #if !defined(DISABLE_NACL)
   if (TaskManagerObserver::IsResourceRefreshEnabled(REFRESH_TYPE_NACL,
-                                                    refresh_flags) &&
-      !tasks_.empty()) {
-    RefreshNaClDebugStubPort(tasks_[0]->GetChildProcessUniqueID());
+                                                    refresh_flags)) {
+    if (!tasks_.empty()) {
+      RefreshNaClDebugStubPort(tasks_[0]->GetChildProcessUniqueID());
+    } else {
+      expected_on_bg_done_flags_ &= ~REFRESH_TYPE_NACL;

[afakhry, 2017/02/10 20:08:52]

Thanks for adding this!

Nit: Can you please remove the braces?

[Wez, 2017/02/13 01:22:19]

I thought there was a general preference for including braces, especially for
nested if()'s, after the OpenSSL goto issue, but OK. :)

Under what circumstances can a TaskGroup have zero tasks, out of interest?

[afakhry, 2017/02/15 02:58:19]

That shouldn't happen (See my comment on the unittest in the new patch). We can
probably replace this if with a DCHECK. I think I added that as a sanity check
before doing tasks_[0]. I *think* I wrote TaskGroup before I wrote
TaskManagerImpl.

[Wez, 2017/02/16 22:44:19]

Looking at TaskManagerImpl, it's clear that TaskGroup is removed as soon as it
is empty(), so I'm adding DCHECK(!empty()) to the top of the Refresh() call, as
a sanity-check.

+    }
   }
 #endif  // !defined(DISABLE_NACL)
 
   int64_t shared_refresh_flags =
       refresh_flags & shared_sampler_->GetSupportedFlags();
 
   // 5- Refresh resources via SharedSampler if the current platform
   // implementation supports that. The actual work is done on the worker thread.
   // At the moment this is supported only on OS_WIN.
   if (shared_refresh_flags != 0) {
@@ skipping 53 matching lines @@
 void TaskGroup::RefreshWindowsHandles() {
 #if defined(OS_WIN)
   GetWindowsHandles(process_handle_,
                     &gdi_current_handles_,
                     &gdi_peak_handles_,
                     &user_current_handles_,
                     &user_peak_handles_);
 #endif  // defined(OS_WIN)
 }
 
+#if !defined(DISABLE_NACL)
+static int GetNaClDebugStubPortOnIoThread(int process_id) {

[afakhry, 2017/02/10 20:08:52]

No DCHECK for IO?

Ideally the DCHECK should be placed inside
NaClBrowser::GetProcessGdbDebugStubPort() so that no other clients of that code
may repeat the same bug.

What about moving this function to the anonymous namespace above?

[Wez, 2017/02/13 01:22:19]

Yes, that's the change that prompted this patch, in fact. :) (see
https://codereview.chromium.org/2630443003/).
Done.

[afakhry, 2017/02/15 02:58:19]

Acknowledged.

+  return nacl::NaClBrowser::GetInstance()->GetProcessGdbDebugStubPort(
+      process_id);
+}
+
 void TaskGroup::RefreshNaClDebugStubPort(int child_process_unique_id) {
-#if !defined(DISABLE_NACL)
-  nacl::NaClBrowser* nacl_browser = nacl::NaClBrowser::GetInstance();
-  nacl_debug_stub_port_ =
-      nacl_browser->GetProcessGdbDebugStubPort(child_process_unique_id);
+  content::BrowserThread::PostTaskAndReplyWithResult(
+      content::BrowserThread::IO, FROM_HERE,
+      base::Bind(&GetNaClDebugStubPortOnIoThread, child_process_unique_id),
+      base::Bind(&TaskGroup::OnRefreshNaClDebugStubPortDone,
+                 weak_ptr_factory_.GetWeakPtr()));
+}
+
+void TaskGroup::OnRefreshNaClDebugStubPortDone(int nacl_debug_stub_port) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
+
+  nacl_debug_stub_port_ = nacl_debug_stub_port;
+  OnBackgroundRefreshTypeFinished(REFRESH_TYPE_NACL);
+}
 #endif  // !defined(DISABLE_NACL)
-}
 
 void TaskGroup::OnCpuRefreshDone(double cpu_usage) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
 
   cpu_usage_ = cpu_usage;
   OnBackgroundRefreshTypeFinished(REFRESH_TYPE_CPU);
 }
 
 void TaskGroup::OnStartTimeRefreshDone(base::Time start_time) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
@@ skipping 56 matching lines @@
 
 void TaskGroup::OnBackgroundRefreshTypeFinished(int64_t finished_refresh_type) {
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
 
   current_on_bg_done_flags_ |= finished_refresh_type;
   if (AreBackgroundCalculationsDone())
     on_background_calculations_done_.Run();
 }
 
 }  // namespace task_manager