Record async "task backtraces"
Places a small array in PendingTask that records the past 4 PostTasks
that result in this task being run. In essence, it creates a backtrace
of the asynchronous call stack resulting in this task being run.
This array is copied onto the stack during execution so that it is
available in crash dumps.
BUG=690197
Review-Url: https://codereview.chromium.org/1044413002
Cr-Commit-Position: refs/heads/master@{#449471}
diff --git a/base/pending_task_unittest.cc b/base/pending_task_unittest.cc
new file mode 100644
index 0000000..8d52daa9
--- /dev/null
+++ b/base/pending_task_unittest.cc
@@ -0,0 +1,169 @@
+// Copyright (c) 2017 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 "base/pending_task.h"
+
+#include <vector>
+
+#include "base/bind.h"
+#include "base/message_loop/message_loop.h"
+#include "base/run_loop.h"
+#include "base/strings/stringprintf.h"
+#include "base/threading/thread.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+class PendingTaskTest : public ::testing::Test {
+ public:
+ PendingTaskTest() = default;
+
+ ~PendingTaskTest() override = default;
+
+ protected:
+ using ExpectedTrace = std::vector<const void*>;
+
+ static void VerifyTraceAndPost(
+ const scoped_refptr<TaskRunner>& task_runner,
+ const tracked_objects::Location& posted_from,
+ const tracked_objects::Location& next_from_here,
+ const std::vector<const void*>& expected_trace,
+ Closure task) {
+ SCOPED_TRACE(StringPrintf("Callback Depth: %zu", expected_trace.size()));
+
+ // Beyond depth + 1, the trace is nonsensical because there haven't been
+ // enough nested tasks called.
+ const PendingTask* current_pending_task =
+ MessageLoop::current()->current_pending_task_;
+ size_t window = std::min(current_pending_task->task_backtrace.size(),
+ expected_trace.size());
+
+ EXPECT_EQ(posted_from,
+ MessageLoop::current()->current_pending_task_->posted_from);
+ for (size_t i = 0; i < window; i++) {
+ SCOPED_TRACE(StringPrintf("Trace frame: %zu", i));
+ EXPECT_EQ(expected_trace[i], current_pending_task->task_backtrace[i]);
+ }
+ task_runner->PostTask(next_from_here, std::move(task));
+ }
+
+ static void RunTwo(Closure c1, Closure c2) {
+ c1.Run();
+ c2.Run();
+ }
+};
+
+// Ensure the task backtrace populates correctly.
+TEST_F(PendingTaskTest, SingleThreadedSimple) {
+ MessageLoop loop;
+ const tracked_objects::Location& location0 = FROM_HERE;
+ const tracked_objects::Location& location1 = FROM_HERE;
+ const tracked_objects::Location& location2 = FROM_HERE;
+ const tracked_objects::Location& location3 = FROM_HERE;
+ const tracked_objects::Location& location4 = FROM_HERE;
+ const tracked_objects::Location& location5 = FROM_HERE;
+
+ Closure task5 = Bind(
+ &PendingTaskTest::VerifyTraceAndPost, loop.task_runner(), location4,
+ location5,
+ ExpectedTrace({location3.program_counter(), location2.program_counter(),
+ location1.program_counter(), location0.program_counter()}),
+ Bind(&DoNothing));
+ Closure task4 = Bind(
+ &PendingTaskTest::VerifyTraceAndPost, loop.task_runner(), location3,
+ location4,
+ ExpectedTrace({location2.program_counter(), location1.program_counter(),
+ location0.program_counter(), nullptr}),
+ task5);
+ Closure task3 = Bind(
+ &PendingTaskTest::VerifyTraceAndPost, loop.task_runner(), location2,
+ location3, ExpectedTrace({location1.program_counter(),
+ location0.program_counter(), nullptr, nullptr}),
+ task4);
+ Closure task2 =
+ Bind(&PendingTaskTest::VerifyTraceAndPost, loop.task_runner(), location1,
+ location2, ExpectedTrace({location0.program_counter()}), task3);
+ Closure task1 = Bind(&PendingTaskTest::VerifyTraceAndPost, loop.task_runner(),
+ location0, location1, ExpectedTrace({}), task2);
+
+ loop.task_runner()->PostTask(location0, task1);
+
+ RunLoop().RunUntilIdle();
+}
+
+// Post a task onto another thread. Ensure on the other thread, it has the
+// right stack trace.
+TEST_F(PendingTaskTest, MultipleThreads) {
+ MessageLoop loop; // Implicitly "thread a."
+ Thread thread_b("pt_test_b");
+ Thread thread_c("pt_test_c");
+ thread_b.StartAndWaitForTesting();
+ thread_c.StartAndWaitForTesting();
+
+ const tracked_objects::Location& location_a0 = FROM_HERE;
+ const tracked_objects::Location& location_a1 = FROM_HERE;
+ const tracked_objects::Location& location_a2 = FROM_HERE;
+ const tracked_objects::Location& location_a3 = FROM_HERE;
+
+ const tracked_objects::Location& location_b0 = FROM_HERE;
+ const tracked_objects::Location& location_b1 = FROM_HERE;
+
+ const tracked_objects::Location& location_c0 = FROM_HERE;
+
+ // On thread c, post a task back to thread a that verifies its trace
+ // and terminates after one more self-post.
+ Closure task_a2 =
+ Bind(&PendingTaskTest::VerifyTraceAndPost, loop.task_runner(),
+ location_a2, location_a3,
+ ExpectedTrace(
+ {location_c0.program_counter(), location_b0.program_counter(),
+ location_a1.program_counter(), location_a0.program_counter()}),
+ Bind(&DoNothing));
+ Closure task_c0 = Bind(&PendingTaskTest::VerifyTraceAndPost,
+ loop.task_runner(), location_c0, location_a2,
+ ExpectedTrace({location_b0.program_counter(),
+ location_a1.program_counter(),
+ location_a0.program_counter()}),
+ task_a2);
+
+ // On thread b run two tasks that conceptually come from the same location
+ // (managed via RunTwo().) One will post back to thread b and another will
+ // post to thread c to test spawning multiple tasks on different message
+ // loops. The task posted to thread c will not get location b1 whereas the
+ // one posted back to thread b will.
+ Closure task_b0_fork =
+ Bind(&PendingTaskTest::VerifyTraceAndPost,
+ thread_c.message_loop()->task_runner(), location_b0, location_c0,
+ ExpectedTrace({location_a1.program_counter(),
+ location_a0.program_counter(), nullptr}),
+ task_c0);
+ Closure task_b0_local =
+ Bind(&PendingTaskTest::VerifyTraceAndPost,
+ thread_b.message_loop()->task_runner(), location_b0, location_b1,
+ ExpectedTrace({location_a1.program_counter(),
+ location_a0.program_counter(), nullptr}),
+ Bind(&DoNothing));
+
+ // Push one frame onto the stack in thread a then pass to thread b.
+ Closure task_a1 =
+ Bind(&PendingTaskTest::VerifyTraceAndPost,
+ thread_b.message_loop()->task_runner(), location_a1, location_b0,
+ ExpectedTrace({location_a0.program_counter(), nullptr}),
+ Bind(&PendingTaskTest::RunTwo, task_b0_local, task_b0_fork));
+ Closure task_a0 =
+ Bind(&PendingTaskTest::VerifyTraceAndPost, loop.task_runner(),
+ location_a0, location_a1, ExpectedTrace({nullptr}), task_a1);
+
+ loop.task_runner()->PostTask(location_a0, task_a0);
+
+ RunLoop().RunUntilIdle();
+
+ thread_b.FlushForTesting();
+ thread_b.Stop();
+
+ thread_c.FlushForTesting();
+ thread_c.Stop();
+}
+
+} // namespace base
