comparison win64-msvc/include/kj/async-win32.h @ 63:0f2d93caa50c

Update Win64 capnp builds to v0.6

+// Copyright (c) 2016 Sandstorm Development Group, Inc. and contributors
+// Licensed under the MIT License:
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+#ifndef KJ_ASYNC_WIN32_H_
+#define KJ_ASYNC_WIN32_H_
+
+#if !_WIN32
+#error "This file is Windows-specific. On Unix, include async-unix.h instead."
+#endif
+
+#include "async.h"
+#include "time.h"
+#include "io.h"
+#include <atomic>
+#include <inttypes.h>
+
+// Include windows.h as lean as possible. (If you need more of the Windows API for your app,
+// #include windows.h yourself before including this header.)
+#define WIN32_LEAN_AND_MEAN 1
+#define NOSERVICE 1
+#define NOMCX 1
+#define NOIME 1
+#include <windows.h>
+#include "windows-sanity.h"
+
+namespace kj {
+
+class Win32EventPort: public EventPort {
+  // Abstract base interface for EventPorts that can listen on Win32 event types. Due to the
+  // absurd complexity of the Win32 API, it's not possible to standardize on a single
+  // implementation of EventPort. In particular, there is no way for a single thread to use I/O
+  // completion ports (the most efficient way of handling I/O) while at the same time waiting for
+  // signalable handles or UI messages.
+  //
+  // Note that UI messages are not supported at all by this interface because the message queue
+  // is implemented by user32.dll and we want libkj to depend only on kernel32.dll. A separate
+  // compat library could provide a Win32EventPort implementation that works with the UI message
+  // queue.
+
+public:
+  // ---------------------------------------------------------------------------
+  // overlapped I/O
+
+  struct IoResult {
+    DWORD errorCode;
+    DWORD bytesTransferred;
+  };
+
+  class IoOperation {
+  public:
+    virtual LPOVERLAPPED getOverlapped() = 0;
+    // Gets the OVERLAPPED structure to pass to the Win32 I/O call. Do NOT modify it; just pass it
+    // on.
+
+    virtual Promise<IoResult> onComplete() = 0;
+    // After making the Win32 call, if the return value indicates that the operation was
+    // successfully queued (i.e. the completion event will definitely occur), call this to wait
+    // for completion.
+    //
+    // You MUST call this if the operation was successfully queued, and you MUST NOT call this
+    // otherwise. If the Win32 call failed (without queuing any operation or event) then you should
+    // simply drop the IoOperation object.
+    //
+    // Dropping the returned Promise cancels the operation via Win32's CancelIoEx(). The destructor
+    // will wait for the cancellation to complete, such that after dropping the proimse it is safe
+    // to free the buffer that the operation was reading from / writing to.
+    //
+    // You may safely drop the `IoOperation` while still waiting for this promise. You may not,
+    // however, drop the `IoObserver`.
+  };
+
+  class IoObserver {
+  public:
+    virtual Own<IoOperation> newOperation(uint64_t offset) = 0;
+    // Begin an I/O operation. For file operations, `offset` is the offset within the file at
+    // which the operation will start. For stream operations, `offset` is ignored.
+  };
+
+  virtual Own<IoObserver> observeIo(HANDLE handle) = 0;
+  // Given a handle which supports overlapped I/O, arrange to receive I/O completion events via
+  // this EventPort.
+  //
+  // Different Win32EventPort implementations may handle this in different ways, such as by using
+  // completion routines (APCs) or by using I/O completion ports. The caller should not assume
+  // any particular technique.
+  //
+  // WARNING: It is only safe to call observeIo() on a particular handle once during its lifetime.
+  //   You cannot observe the same handle from multiple Win32EventPorts, even if not at the same
+  //   time. This is because the Win32 API provides no way to disassociate a handle from an I/O
+  //   completion port once it is associated.
+
+  // ---------------------------------------------------------------------------
+  // signalable handles
+  //
+  // Warning: Due to limitations in the Win32 API, implementations of EventPort may be forced to
+  //   spawn additional threads to wait for signaled objects. This is necessary if the EventPort
+  //   implementation is based on I/O completion ports, or if you need to wait on more than 64
+  //   handles at once.
+
+  class SignalObserver {
+  public:
+    virtual Promise<void> onSignaled() = 0;
+    // Returns a promise that completes the next time the handle enters the signaled state.
+    //
+    // Depending on the type of handle, the handle may automatically be reset to a non-signaled
+    // state before the promise resolves. The underlying implementaiton uses WaitForSingleObject()
+    // or an equivalent wait call, so check the documentation for that to understand the semantics.
+    //
+    // If the handle is a mutex and it is abandoned without being unlocked, the promise breaks with
+    // an exception.
+
+    virtual Promise<bool> onSignaledOrAbandoned() = 0;
+    // Like onSingaled(), but instead of throwing when a mutex is abandoned, resolves to `true`.
+    // Resolves to `false` for non-abandoned signals.
+  };
+
+  virtual Own<SignalObserver> observeSignalState(HANDLE handle) = 0;
+  // Given a handle that supports waiting for it to become "signaled" via WaitForSingleObject(),
+  // return an object that can wait for this state using the EventPort.
+
+  // ---------------------------------------------------------------------------
+  // APCs
+
+  virtual void allowApc() = 0;
+  // If this is ever called, the Win32EventPort will switch modes so that APCs can be scheduled
+  // on the thread, e.g. through the Win32 QueueUserAPC() call. In the future, this may be enabled
+  // by default. However, as of this writing, Wine does not support the necessary
+  // GetQueuedCompletionStatusEx() call, thus allowApc() breaks Wine support. (Tested on Wine
+  // 1.8.7.)
+  //
+  // If the event port implementation can't support APCs for some reason, this throws.
+
+  // ---------------------------------------------------------------------------
+  // time
+
+  virtual Timer& getTimer() = 0;
+};
+
+class Win32WaitObjectThreadPool {
+  // Helper class that implements Win32EventPort::observeSignalState() by spawning additional
+  // threads as needed to perform the actual waiting.
+  //
+  // This class is intended to be used to assist in building Win32EventPort implementations.
+
+public:
+  Win32WaitObjectThreadPool(uint mainThreadCount = 0);
+  // `mainThreadCount` indicates the number of objects the main thread is able to listen on
+  // directly. Typically this would be zero (e.g. if the main thread watches an I/O completion
+  // port) or MAXIMUM_WAIT_OBJECTS (e.g. if the main thread is a UI thread but can use
+  // MsgWaitForMultipleObjectsEx() to wait on some handles at the same time as messages).
+
+  Own<Win32EventPort::SignalObserver> observeSignalState(HANDLE handle);
+  // Implemetns Win32EventPort::observeSignalState().
+
+  uint prepareMainThreadWait(HANDLE* handles[]);
+  // Call immediately before invoking WaitForMultipleObjects() or similar in the main thread.
+  // Fills in `handles` with the handle pointers to wait on, and returns the number of handles
+  // in this array. (The array should be allocated to be at least the size passed to the
+  // constructor).
+  //
+  // There's no need to call this if `mainThreadCount` as passed to the constructor was zero.
+
+  bool finishedMainThreadWait(DWORD returnCode);
+  // Call immediately after invoking WaitForMultipleObjects() or similar in the main thread,
+  // passing the value returend by that call. Returns true if the event indicated by `returnCode`
+  // has been handled (i.e. it was WAIT_OBJECT_n or WAIT_ABANDONED_n where n is in-range for the
+  // last call to prepareMainThreadWait()).
+};
+
+class Win32IocpEventPort final: public Win32EventPort {
+  // An EventPort implementation which uses Windows I/O completion ports to listen for events.
+  //
+  // With this implementation, observeSignalState() requires spawning a separate thread.
+
+public:
+  Win32IocpEventPort();
+  ~Win32IocpEventPort() noexcept(false);
+
+  // implements EventPort ------------------------------------------------------
+  bool wait() override;
+  bool poll() override;
+  void wake() const override;
+
+  // implements Win32IocpEventPort ---------------------------------------------
+  Own<IoObserver> observeIo(HANDLE handle) override;
+  Own<SignalObserver> observeSignalState(HANDLE handle) override;
+  Timer& getTimer() override { return timerImpl; }
+  void allowApc() override { isAllowApc = true; }
+
+private:
+  class IoPromiseAdapter;
+  class IoOperationImpl;
+  class IoObserverImpl;
+
+  AutoCloseHandle iocp;
+  AutoCloseHandle thread;
+  Win32WaitObjectThreadPool waitThreads;
+  TimerImpl timerImpl;
+  mutable std::atomic<bool> sentWake {false};
+  bool isAllowApc = false;
+
+  static TimePoint readClock();
+
+  void waitIocp(DWORD timeoutMs);
+  // Wait on the I/O completion port for up to timeoutMs and pump events. Does not advance the
+  // timer; caller must do that.
+
+  bool receivedWake();
+
+  static AutoCloseHandle newIocpHandle();
+  static AutoCloseHandle openCurrentThread();
+};
+
+} // namespace kj
+
+#endif // KJ_ASYNC_WIN32_H_