Web MIDI: device open/close for dynamic manager instantiation on Windows

media/midi/dynamically_initialized_midi_manager_win.cc

 // Copyright 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 "media/midi/dynamically_initialized_midi_manager_win.h"
 
 #include <windows.h>
 
 #include <mmreg.h>
 #include <mmsystem.h>
 
 #include <algorithm>
 #include <string>
 
 #include "base/callback.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/strings/string16.h"
 #include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/synchronization/lock.h"
 #include "media/midi/midi_port_info.h"
 #include "media/midi/midi_service.h"
 
 namespace midi {
 
 namespace {
 
+// Assumes that nullptr represents an invalid MIDI handle.
+constexpr HMIDIIN kInvalidInHandle = nullptr;
+constexpr HMIDIOUT kInvalidOutHandle = nullptr;
+
 // Global variables to identify MidiManager instance.
 constexpr int kInvalidInstanceId = -1;
 int g_active_instance_id = kInvalidInstanceId;
 DynamicallyInitializedMidiManagerWin* g_manager_instance = nullptr;
 
 // Obtains base::Lock instance pointer to lock instance_id.
 base::Lock* GetInstanceIdLock() {
   static base::Lock* lock = new base::Lock;
   return lock;
 }
 
 // Issues unique MidiManager instance ID.
 int IssueNextInstanceId() {
   static int id = kInvalidInstanceId;
   return ++id;
 }
 
 // Use single TaskRunner for all tasks running outside the I/O thread.
 constexpr int kTaskRunner = 0;
 
 // Obtains base::Lock instance pointer to ensure tasks run safely on TaskRunner.
+// Since all tasks on TaskRunner run behind a lock of *GetTaskLock(), we can
+// access all members even on the I/O thread if a lock of *GetTaskLock() is
+// obtained.
 base::Lock* GetTaskLock() {
   static base::Lock* lock = new base::Lock;
   return lock;
 }
 
 // Helper function to run a posted task on TaskRunner safely.
 void RunTask(int instance_id, const base::Closure& task) {
   // Obtains task lock to ensure that the instance should not complete
   // Finalize() while running the |task|.
   base::AutoLock task_lock(*GetTaskLock());
   {
     // If Finalize() finished before the lock avobe, do nothing.
     base::AutoLock lock(*GetInstanceIdLock());
     if (instance_id != g_active_instance_id)
       return;
   }
   task.Run();
 }
 
 // TODO(toyoshim): Factor out TaskRunner related functionaliries above, and
 // deprecate MidiScheduler. It should be available via MidiManager::scheduler().
 
+// Helper functions to close MIDI device handles on TaskRunner asynchronously.
+void FinalizeInPort(HMIDIIN handle) {
+  midiInClose(handle);
+}
+
+void FinalizeOutPort(HMIDIOUT handle) {
+  midiOutClose(handle);
+}
+
+// Handles MIDI input port callbacks that runs on a system provided thread.
+void CALLBACK HandleMidiInCallback(HMIDIIN hmi,
+                                   UINT msg,
+                                   DWORD_PTR instance,
+                                   DWORD_PTR param1,
+                                   DWORD_PTR param2) {
+  // TODO(toyoshim): Following patches will implement actual functions.
+}
+
+// Handles MIDI output port callbacks that runs on a system provided thread.
+void CALLBACK HandleMidiOutCallback(HMIDIOUT hmo,
+                                    UINT msg,
+                                    DWORD_PTR instance,
+                                    DWORD_PTR param1,
+                                    DWORD_PTR param2) {
+  // TODO(toyoshim): Following patches will implement actual functions.
+}
+
+// All instances of Port subclasses are always accessed behind a lock of
+// *GetTaskLock(). Port and subclasses implementation do not need to
+// consider thread safety.
 class Port {
  public:
   Port(const std::string& type,
        uint32_t device_id,
        uint16_t manufacturer_id,
        uint16_t product_id,
        uint32_t driver_version,
        const std::string& product_name)
       : index_(0u),
         type_(type),
@@ skipping 73 matching lines @@
 // TODO(toyoshim): Following patches will implement actual functions.
 class DynamicallyInitializedMidiManagerWin::InPort final : public Port {
  public:
   InPort(UINT device_id, const MIDIINCAPS2W& caps)
       : Port("input",
              device_id,
              caps.wMid,
              caps.wPid,
              caps.vDriverVersion,
              base::WideToUTF8(
-                 base::string16(caps.szPname, wcslen(caps.szPname)))) {}
+                 base::string16(caps.szPname, wcslen(caps.szPname)))),
+        in_handle_(kInvalidInHandle) {}
 
   static std::vector<std::unique_ptr<InPort>> EnumerateActivePorts() {
     std::vector<std::unique_ptr<InPort>> ports;
     const UINT num_devices = midiInGetNumDevs();
     for (UINT device_id = 0; device_id < num_devices; ++device_id) {
       MIDIINCAPS2W caps;
       MMRESULT result = midiInGetDevCaps(
           device_id, reinterpret_cast<LPMIDIINCAPSW>(&caps), sizeof(caps));
       if (result != MMSYSERR_NOERROR) {
         LOG(ERROR) << "midiInGetDevCaps fails on device " << device_id;
         continue;
       }
       ports.push_back(base::MakeUnique<InPort>(device_id, caps));
     }
     return ports;
   }
 
+  void Finalize(scoped_refptr<base::SingleThreadTaskRunner> runner) {
+    if (in_handle_ != kInvalidInHandle) {
+      runner->PostTask(FROM_HERE, base::Bind(&FinalizeInPort, in_handle_));

[yhirano, 2017/02/24 04:18:05]

in_handle_ = kInvalidInHandle;

[Takashi Toyoshima, 2017/02/24 06:17:56]

this is not mandatory, but ok just in case.

+    }
+  }
+
   void NotifyPortStateSet(DynamicallyInitializedMidiManagerWin* manager) {
     manager->PostReplyTask(
         base::Bind(&DynamicallyInitializedMidiManagerWin::SetInputPortState,
                    base::Unretained(manager), index_, info_.state));
   }
 
   void NotifyPortAdded(DynamicallyInitializedMidiManagerWin* manager) {
     manager->PostReplyTask(
         base::Bind(&DynamicallyInitializedMidiManagerWin::AddInputPort,
                    base::Unretained(manager), info_));
   }
+
+  // Port overrides:
+  bool Disconnect() override {
+    if (in_handle_ != kInvalidInHandle) {
+      // Following API call may fail because device was already disconnected.
+      // But just in case.
+      midiInClose(in_handle_);
+      in_handle_ = kInvalidInHandle;
+    }
+    return Port::Disconnect();
+  }
+
+  void Open() override {
+    // TODO(toyoshim): Pass instance_id to implement HandleMidiInCallback.

[Takashi Toyoshima, 2017/02/24 06:17:56]

Just in case, |instance_id| is needed only by callback for inputs.

+    MMRESULT result =
+        midiInOpen(&in_handle_, device_id_,
+                   reinterpret_cast<DWORD_PTR>(&HandleMidiInCallback), 0,
+                   CALLBACK_FUNCTION);
+    if (result == MMSYSERR_NOERROR)
+      Port::Open();
+    else

[yhirano, 2017/02/24 04:18:05]

Why isn't this symmetric to OutPort::Open?

[Takashi Toyoshima, 2017/02/24 06:17:56]

Ah, I set kInvalidOutHandle for OutPort::Open just in case.
Actually, passed handles should not be touched when it fails, and they are not
mandatory, but maybe I prefer resetting this explicitly here too.

+      Disconnect();
+  }
+
+ private:
+  HMIDIIN in_handle_;
 };
 
 // TODO(toyoshim): Following patches will implement actual functions.
 class DynamicallyInitializedMidiManagerWin::OutPort final : public Port {
  public:
   OutPort(UINT device_id, const MIDIOUTCAPS2W& caps)
       : Port("output",
              device_id,
              caps.wMid,
              caps.wPid,
              caps.vDriverVersion,
              base::WideToUTF8(
                  base::string16(caps.szPname, wcslen(caps.szPname)))),
-        software_(caps.wTechnology == MOD_SWSYNTH) {}
+        software_(caps.wTechnology == MOD_SWSYNTH),
+        out_handle_(kInvalidOutHandle) {}
 
   static std::vector<std::unique_ptr<OutPort>> EnumerateActivePorts() {
     std::vector<std::unique_ptr<OutPort>> ports;
     const UINT num_devices = midiOutGetNumDevs();
     for (UINT device_id = 0; device_id < num_devices; ++device_id) {
       MIDIOUTCAPS2W caps;
       MMRESULT result = midiOutGetDevCaps(
           device_id, reinterpret_cast<LPMIDIOUTCAPSW>(&caps), sizeof(caps));
       if (result != MMSYSERR_NOERROR) {
         LOG(ERROR) << "midiOutGetDevCaps fails on device " << device_id;
         continue;
       }
       ports.push_back(base::MakeUnique<OutPort>(device_id, caps));
     }
     return ports;
   }
 
+  void Finalize(scoped_refptr<base::SingleThreadTaskRunner> runner) {
+    if (out_handle_ != kInvalidOutHandle)
+      runner->PostTask(FROM_HERE, base::Bind(&FinalizeOutPort, out_handle_));

[yhirano, 2017/02/24 04:18:05]

out_handle_ = kInvalidOutHandle;

[Takashi Toyoshima, 2017/02/24 06:17:56]

Acknowledged.

+  }
+
+  void NotifyPortStateSet(DynamicallyInitializedMidiManagerWin* manager) {
+    manager->PostReplyTask(
+        base::Bind(&DynamicallyInitializedMidiManagerWin::SetOutputPortState,
+                   base::Unretained(manager), index_, info_.state));
+  }
+
+  void NotifyPortAdded(DynamicallyInitializedMidiManagerWin* manager) {
+    manager->PostReplyTask(
+        base::Bind(&DynamicallyInitializedMidiManagerWin::AddOutputPort,
+                   base::Unretained(manager), info_));
+  }
+
   // Port overrides:
   bool Connect() override {
     // Until |software| option is supported, disable Microsoft GS Wavetable
     // Synth that has a known security issue.
     if (software_ && manufacturer_id_ == MM_MICROSOFT &&
         (product_id_ == MM_MSFT_WDMAUDIO_MIDIOUT ||
          product_id_ == MM_MSFT_GENERIC_MIDISYNTH)) {
       return false;
     }
     return Port::Connect();
   }
 
-  // Port Overrides:
-  void NotifyPortStateSet(DynamicallyInitializedMidiManagerWin* manager) {
-    manager->PostReplyTask(
-        base::Bind(&DynamicallyInitializedMidiManagerWin::SetOutputPortState,
-                   base::Unretained(manager), index_, info_.state));
+  bool Disconnect() override {
+    if (out_handle_ != kInvalidOutHandle) {
+      // Following API call may fail because device was already disconnected.
+      // But just in case.
+      midiOutClose(out_handle_);
+      out_handle_ = kInvalidOutHandle;
+    }
+    return Port::Disconnect();
   }
 
-  void NotifyPortAdded(DynamicallyInitializedMidiManagerWin* manager) {
-    manager->PostReplyTask(
-        base::Bind(&DynamicallyInitializedMidiManagerWin::AddOutputPort,
-                   base::Unretained(manager), info_));
+  void Open() override {
+    MMRESULT result =
+        midiOutOpen(&out_handle_, device_id_,
+                    reinterpret_cast<DWORD_PTR>(&HandleMidiOutCallback), 0,
+                    CALLBACK_FUNCTION);
+    if (result == MMSYSERR_NOERROR) {
+      Port::Open();
+    } else {
+      out_handle_ = kInvalidOutHandle;
+      Disconnect();
+    }
   }
 
   const bool software_;
+  HMIDIOUT out_handle_;
 };
 
 DynamicallyInitializedMidiManagerWin::DynamicallyInitializedMidiManagerWin(
     MidiService* service)
     : MidiManager(service), instance_id_(IssueNextInstanceId()) {
   base::AutoLock lock(*GetInstanceIdLock());
   CHECK_EQ(kInvalidInstanceId, g_active_instance_id);
 
   // Obtains the task runner for the current thread that hosts this instnace.
   thread_runner_ = base::ThreadTaskRunnerHandle::Get();
@@ skipping 36 matching lines @@
     base::AutoLock lock(*GetInstanceIdLock());
     CHECK_EQ(instance_id_, g_active_instance_id);
     g_active_instance_id = kInvalidInstanceId;
     CHECK_EQ(this, g_manager_instance);
     g_manager_instance = nullptr;
   }
 
   // Ensures that no task runs on TaskRunner so to destruct the instance safely.
   // Tasks that did not started yet will do nothing after invalidate the
   // instance ID above.
+  // Behind the lock below, we can safely access all members for finalization
+  // even on the I/O thread.
   base::AutoLock lock(*GetTaskLock());
+
+  // Posts tasks that finalize each device port without MidiManager instance
+  // on TaskRunner. If another MidiManager instance is created, its
+  // initialization runs on the same task runner after all tasks posted here
+  // finish.
+  for (const auto& port : input_ports_)
+    port->Finalize(service()->GetTaskRunner(kTaskRunner));
+  for (const auto& port : output_ports_)
+    port->Finalize(service()->GetTaskRunner(kTaskRunner));
 }
 
 void DynamicallyInitializedMidiManagerWin::DispatchSendMidiData(
     MidiManagerClient* client,
     uint32_t port_index,
     const std::vector<uint8_t>& data,
     double timestamp) {
   // TODO(toyoshim): Following patches will implement.
 }
 
@@ skipping 73 matching lines @@
       size_t index = known_ports->size();
       port->set_index(index);
       known_ports->push_back(std::move(port));
       (*known_ports)[index]->Connect();
       (*known_ports)[index]->NotifyPortAdded(this);
     }
   }
 }
 
 }  // namespace midi