Mojo Log service and a thread-safe client library.

mojo/services/log/cpp/tests/log_client_unittest.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 <set>
+#include <thread>
+#include <vector>
+
+#include "mojo/public/cpp/application/application_test_base.h"
+#include "mojo/public/cpp/bindings/strong_binding.h"
+#include "mojo/public/cpp/system/macros.h"
+#include "mojo/public/cpp/utility/run_loop.h"
+#include "mojo/services/log/cpp/log_client.h"
+#include "mojo/services/log/interfaces/entry.mojom.h"
+#include "mojo/services/log/interfaces/log.mojom.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using LogClientTest = mojo::test::ApplicationTestBase;
+using mojo::Environment;
+using mojo::internal::ValidationError;
+
+namespace mojo {
+namespace {
+
+// A Log implementation that remembers the set of all incoming messages.
+class TestLogServiceImpl : public log::Log {
+ public:
+  explicit TestLogServiceImpl(InterfaceRequest<log::Log> log_req)
+      : binding_(this, std::move(log_req)) {
+    EXPECT_TRUE(binding_.is_bound());
+    binding_.set_connection_error_handler([this]() {
+      FAIL() << "Log service lost connection to the log client.";
+    });
+    validation_observer_.set_last_error(ValidationError::NONE);
+  }
+  void AddEntry(mojo::log::EntryPtr entry) override {
+    entry_msgs_.insert(entry->message.To<std::string>());
+  }
+  const std::set<std::string>& entries() { return entry_msgs_; }
+  mojo::internal::ValidationError previous_validation_error() {
+    return validation_observer_.last_error();
+  }
+
+ private:
+  mojo::StrongBinding<log::Log> binding_;
+  std::set<std::string> entry_msgs_;
+  mojo::internal::ValidationErrorObserverForTesting validation_observer_;
+};
+
+MojoLogLevel g_fallback_logger_level = MOJO_LOG_LEVEL_INFO;

[viettrungluu, 2015/12/18 00:32:56]

You should set |g_fallback_logger_level| and |g_fallback_logger_invoked| at the
beginning of the test below, in case this test is repeated. (In that case, you
don't really *need* to initialize it here, I guess.)

Actually, come to think of it, I guess you don't even need these to be global,
since you're using lambdas, right?

[vardhan, 2015/12/18 03:56:29]

Good point!  Done.
I need these to be global because I can't use these two variables as captures
(otherwise, the lambdas don't have function signatures compatible with
MojoLogger)

+bool g_fallback_logger_invoked = false;

[viettrungluu, 2015/12/18 00:32:56]

nit: add a blank line below

[vardhan, 2015/12/18 03:56:29]

Done.

+// This tests that multiple threads can use the MojoLogger that
+// mojo::log::LogClient produces, by spawning off |kNumLogEntries| threads, each
+// issuing one unique log message.
+TEST_F(LogClientTest, ConcurrentAddEntry) {
+  log::LogPtr log_ptr;
+  std::unique_ptr<mojo::TestLogServiceImpl> log_impl(
+      new mojo::TestLogServiceImpl(mojo::GetProxy(&log_ptr)));
+
+  // This is our test fallback logger + state.  We simply records whether it's
+  // been called.
+  MojoLogger fallback_logger = {
+      // LogMessage
+      [](MojoLogLevel log_level, const char* source_file, uint32_t source_line,
+         const char* message) { g_fallback_logger_invoked = true; },
+      // SetMinimumLogLevel
+      []() -> MojoLogLevel { return g_fallback_logger_level; },
+      // GetMinimumLogLevel
+      [](MojoLogLevel lvl) { g_fallback_logger_level = lvl; }};
+  log::InitializeLogger(std::move(log_ptr), &fallback_logger);
+  Environment::SetDefaultLogger(log::GetLogger());
+
+  // Spawn off numerous threads, each of them issuing a unique log message.
+  std::vector<std::thread> threads;
+  std::set<std::string> expected_entries;
+
+  // The number of log entries to issue.
+  const int kNumLogEntries = 1000;
+  for (int i = 0; i < kNumLogEntries; i++) {
+    std::stringstream msg;
+    msg << "Test message: " << i;
+    EXPECT_TRUE(expected_entries.insert(msg.str()).second);
+
+    std::thread t([](std::string msg) { MOJO_LOG(INFO) << msg; }, msg.str());
+
+    threads.push_back(std::move(t));
+  }
+  for (auto& t : threads) {
+    t.join();
+  }
+
+  // The log message calls should now be processed by TestLogServiceImpl.
+  mojo::RunLoop::current()->RunUntilIdle();
+
+  EXPECT_EQ(expected_entries, log_impl->entries());
+  EXPECT_EQ(ValidationError::NONE, log_impl->previous_validation_error());
+
+  // We kill our binding, closing the connection to the log client and
+  // causing the log client to revert to using its fallback logger.
+  log_impl.reset();
+
+  EXPECT_FALSE(mojo::g_fallback_logger_invoked);
+  MOJO_LOG(INFO) << "Ignore this log message.";
+  EXPECT_TRUE(mojo::g_fallback_logger_invoked);
+
+  // Check that this logger propogates get/set min level calls to the fallback
+  // logger.
+  auto* logger = log::GetLogger();
+  EXPECT_EQ(MOJO_LOG_LEVEL_INFO, logger->GetMinimumLogLevel());
+  logger->SetMinimumLogLevel(MOJO_LOG_LEVEL_FATAL);
+  EXPECT_EQ(MOJO_LOG_LEVEL_FATAL, logger->GetMinimumLogLevel());
+  EXPECT_EQ(MOJO_LOG_LEVEL_FATAL, fallback_logger.GetMinimumLogLevel());
+
+  log::DestroyLogger();
+}
+
+}  // namespace
+}  // namespace mojo