Web MIDI: introduce pending client count limit to start sessions

media/midi/midi_manager_unittest.cc

Index: media/midi/midi_manager_unittest.cc
diff --git a/media/midi/midi_manager_unittest.cc b/media/midi/midi_manager_unittest.cc
index 178b0f66d0382863d3d005127902114d994f2882..5fc9a7f4d4f3327e74737c05a9f7d04b0409b8b9 100644
--- a/media/midi/midi_manager_unittest.cc
+++ b/media/midi/midi_manager_unittest.cc
@@ -4,6 +4,8 @@
 
 #include "media/midi/midi_manager.h"
 
+#include <vector>
+
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -53,13 +55,18 @@ class FakeMidiManager : public MidiManager {
 
 class FakeMidiManagerClient : public MidiManagerClient {
  public:
-  FakeMidiManagerClient(int client_id) : client_id_(client_id) {}
+  FakeMidiManagerClient(int client_id)
+      : client_id_(client_id),
+        result_(MIDI_NOT_SUPPORTED),
+        start_session_is_completed_(false) {}
   virtual ~FakeMidiManagerClient() {}
 
   // MidiManagerClient implementation.
   virtual void CompleteStartSession(int client_id, MidiResult result) OVERRIDE {
-    DCHECK_EQ(client_id_, client_id);
+    EXPECT_FALSE(start_session_is_completed_);

[Takashi Toyoshima, 2014/05/04 09:13:36]

do not allow multiple completion callbacks

+    EXPECT_EQ(client_id_, client_id);
     result_ = result;
+    start_session_is_completed_ = true;
   }
 
   virtual void ReceiveMidiData(uint32 port_index, const uint8* data,
@@ -77,6 +84,7 @@ class FakeMidiManagerClient : public MidiManagerClient {
  private:
   int client_id_;
   MidiResult result_;
+  bool start_session_is_completed_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeMidiManagerClient);
 };
@@ -110,15 +118,17 @@ class MidiManagerTest : public ::testing::Test {
     }
   }
 
-  void StartTheSecondSession(FakeMidiManagerClient* client) {
-    EXPECT_TRUE(manager_->start_initialization_is_called_);
+  void StartTheNthSession(FakeMidiManagerClient* client, size_t nth) {
+    EXPECT_EQ(nth != 1, manager_->start_initialization_is_called_);
     EXPECT_EQ(0U, manager_->GetClientCount());
-    EXPECT_EQ(1U, manager_->GetPendingClientCount());
+    EXPECT_EQ(nth - 1, manager_->GetPendingClientCount());
 
-    // StartInitialization() should not be called for the second session.
+    // StartInitialization() should not be called for the second and later
+    // sessions.
     manager_->start_initialization_is_called_ = false;
     manager_->StartSession(client, client->GetClientId());
-    EXPECT_FALSE(manager_->start_initialization_is_called_);
+    EXPECT_EQ(nth == 1, manager_->start_initialization_is_called_);
+    manager_->start_initialization_is_called_ = true;
   }
 
   void EndSession(FakeMidiManagerClient* client, size_t before, size_t after) {
@@ -131,9 +141,10 @@ class MidiManagerTest : public ::testing::Test {
     manager_->CallCompleteInitialization(result);
   }
 
- private:
+ protected:
   scoped_ptr<FakeMidiManager> manager_;
 
+ private:
   DISALLOW_COPY_AND_ASSIGN(MidiManagerTest);
 };
 
@@ -174,7 +185,7 @@ TEST_F(MidiManagerTest, StartMultipleSessions) {
   client2.reset(new FakeMidiManagerClient(1));
 
   StartTheFirstSession(client1.get(), false);
-  StartTheSecondSession(client2.get());
+  StartTheNthSession(client2.get(), 2);
   CompleteInitialization(MIDI_OK);
   EXPECT_EQ(MIDI_OK, client1->GetResult());
   EXPECT_EQ(MIDI_OK, client2->GetResult());
@@ -182,6 +193,40 @@ TEST_F(MidiManagerTest, StartMultipleSessions) {
   EndSession(client2.get(), 1U, 0U);
 }
 
+TEST_F(MidiManagerTest, TooManyPendingSessions) {
+  // Push as many client requests for starting session as possible.
+  std::vector<FakeMidiManagerClient*> clients;
+  clients.resize(MidiManager::kMaxPendingClientCount);
+  for (size_t i = 0; i < MidiManager::kMaxPendingClientCount; ++i) {
+    scoped_ptr<FakeMidiManagerClient> client(new FakeMidiManagerClient(i));
+    StartTheNthSession(client.get(), i + 1);
+    clients[i] = client.release();
+  }
+
+  // Push the last client that should be rejected for too many pending requests.
+  scoped_ptr<FakeMidiManagerClient> client(
+      new FakeMidiManagerClient(MidiManager::kMaxPendingClientCount));
+  manager_->start_initialization_is_called_ = false;
+  manager_->StartSession(client.get(), client->GetClientId());
+  EXPECT_FALSE(manager_->start_initialization_is_called_);
+  EXPECT_EQ(MIDI_INITIALIZATION_ERROR, client->GetResult());
+
+  // Other clients still should not receive a result.
+  for (size_t i = 0; i < clients.size(); ++i)
+    EXPECT_EQ(MIDI_NOT_SUPPORTED, clients[i]->GetResult());
+
+  // The result MIDI_OK should be distributed to other clients.
+  CompleteInitialization(MIDI_OK);
+  for (size_t i = 0; i < clients.size(); ++i)
+    EXPECT_EQ(MIDI_OK, clients[i]->GetResult());
+
+  // Close all successful sessions in FIFO order.
+  size_t sessions = clients.size();
+  for (size_t i = 0; i < clients.size(); ++i, --sessions) {
+    EndSession(clients[i], sessions, sessions - 1);
+  }
+}
+
 }  // namespace
 
 }  // namespace media