adb_winusb_io_completion.h revision f855c4e8469e31114fccca4c28aeb01a806a9a48 
1/*
2 * Copyright (C) 2009 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef ANDROID_USB_API_ADB_WINUSB_IO_COMPLETION_H__
18#define ANDROID_USB_API_ADB_WINUSB_IO_COMPLETION_H__
19/** \file
20  This file consists of declaration of class AdbWinUsbIOCompletion that
21  encapsulates a wrapper around OVERLAPPED Win32 structure returned from
22  asynchronous I/O requests issued via WinUsb API.
23*/
24
25#include "..\api\adb_io_completion.h"
26#include "adb_winusb_endpoint_object.h"
27
28/** \brief Encapsulates encapsulates a wrapper around OVERLAPPED Win32
29  structure returned from asynchronous I/O requests issued via WinUsb API.
30
31  A handle to this object is returned to the caller of each successful
32  asynchronous I/O request. Just like all other handles this handle
33  must be closed after it's no longer needed.
34*/
35class AdbWinUsbIOCompletion : public AdbIOCompletion {
36 public:
37  /** \brief Constructs the object
38
39    @param[in] parent_io_obj Parent WinUsb I/O object that created this
40           instance.
41    @param[in] expected_trans_size Number of bytes expected to be transferred
42          with the I/O.
43    @param[in] event_hndl Event handle that should be signaled when I/O
44           completes. Can be NULL. If it's not NULL this handle will be
45           used to initialize OVERLAPPED structure for this object.
46  */
47  AdbWinUsbIOCompletion(AdbWinUsbEndpointObject* parent_io_obj,
48                        ULONG expected_trans_size,
49                        HANDLE event_hndl);
50
51 protected:
52  /** \brief Destructs the object.
53
54    We hide destructor in order to prevent ourseves from accidentaly allocating
55    instances on the stack. If such attemp occur, compiler will error.
56  */
57  virtual ~AdbWinUsbIOCompletion();
58
59  //
60  // Virtual overrides
61  //
62
63 public:
64  /** \brief Releases the object.
65
66    If refcount drops to zero as the result of this release, the object is
67    destroyed in this method. As a general rule, objects must not be touched
68    after this method returns even if returned value is not zero. We override
69    this method in order to make sure that objects of this class are deleted
70    in contect of the DLL they were created in. The problem is that since
71    objects of this class were created in context of AdbWinUsbApi module, they
72    are allocated from the heap assigned to that module. Now, if these objects
73    are deleted outside of AdbWinUsbApi module, this will lead to the heap
74    corruption in the module that deleted these objects. Since all objects of
75    this class are deleted in the Release method only, by overriding it we make
76    sure that we free memory in the context of the module where it was
77    allocated.
78    @return Value of the reference counter after object is released in this
79            method.
80  */
81  virtual LONG Release();
82
83  //
84  // Abstract overrides
85  //
86
87 public:
88  /** \brief Gets overlapped I/O result
89
90    This method uses WinUsb_GetOverlappedResult to get results of the
91    overlapped I/O operation.
92    @param[out] ovl_data Buffer for the copy of this object's OVERLAPPED
93           structure. Can be NULL.
94    @param[out] bytes_transferred Pointer to a variable that receives the
95           number of bytes that were actually transferred by a read or write
96           operation. See SDK doc on GetOvelappedResult for more information.
97           Unlike regular GetOvelappedResult call this parameter can be NULL.
98    @param[in] wait If this parameter is true, the method does not return
99           until the operation has been completed. If this parameter is false
100           and the operation is still pending, the method returns false and
101           the GetLastError function returns ERROR_IO_INCOMPLETE.
102    @return true if I/O has been completed or false on failure or if request
103           is not yet completed. If false is returned GetLastError() provides
104           extended error information. If GetLastError returns
105           ERROR_IO_INCOMPLETE it means that I/O is not yet completed.
106  */
107  virtual bool GetOvelappedIoResult(LPOVERLAPPED ovl_data,
108                                    ULONG* bytes_transferred,
109                                    bool wait);
110
111 public:
112  /// Gets WinUsb parent object
113  AdbWinUsbEndpointObject* parent_winusb_io_object() const {
114    return reinterpret_cast<AdbWinUsbEndpointObject*>(parent_io_object());
115  }
116};
117
118#endif  // ANDROID_USB_API_ADB_WINUSB_IO_COMPLETION_H__
119