1 /*-
2 * Copyright (c) 2011, 2012, 2013, 2014 Spectra Logic Corporation
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions, and the following disclaimer,
10 * without modification.
11 * 2. Redistributions in binary form must reproduce at minimum a disclaimer
12 * substantially similar to the "NO WARRANTY" disclaimer below
13 * ("Disclaimer") and any redistribution must be conditioned upon
14 * including a substantially similar Disclaimer requirement for further
15 * binary redistribution.
16 *
17 * NO WARRANTY
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
19 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
20 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
21 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
22 * HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
26 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
27 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
28 * POSSIBILITY OF SUCH DAMAGES.
29 *
30 * Authors: Justin T. Gibbs (Spectra Logic Corporation)
31 */
32
33 /**
34 * \file devdctl_consumer.h
35 */
36 #ifndef _DEVDCTL_CONSUMER_H_
37 #define _DEVDCTL_CONSUMER_H_
38
39 /*============================ Namespace Control =============================*/
40 namespace DevdCtl
41 {
42
43 /*=========================== Forward Declarations ===========================*/
44 class Event;
45
46 /*============================ Class Declarations ============================*/
47 /*----------------------------- DevdCtl::Consumer ----------------------------*/
48
49 /**
50 */
51 class Consumer
52 {
53 public:
54 Consumer(Event::BuildMethod *defBuilder = NULL,
55 EventFactory::Record *regEntries = NULL,
56 size_t numEntries = 0);
57 virtual ~Consumer();
58
59 bool Connected() const;
60
61 /**
62 * Return file descriptor useful for client's wishing to poll(2)
63 * for new events.
64 */
65 int GetPollFd();
66
67 /**
68 * Queue an event for deferred processing or replay.
69 */
70 bool SaveEvent(const Event &event);
71
72 /**
73 * Reprocess any events saved via the SaveEvent() facility.
74 *
75 * \param discardUnconsumed If true, events that are not consumed
76 * during replay are discarded.
77 */
78 void ReplayUnconsumedEvents(bool discardUnconsumed);
79
80 /** Return an event, if one is available. */
81 Event *NextEvent();
82
83 /**
84 * Extract events and invoke each event's Process method.
85 */
86 void ProcessEvents();
87
88 /** Discard all data pending in m_devdSockFD. */
89 void FlushEvents();
90
91 /**
92 * Test for data pending in m_devdSockFD
93 *
94 * \return True if data is pending. Otherwise false.
95 */
96 bool EventsPending();
97
98 /**
99 * Open a connection to devd's unix domain socket.
100 *
101 * \return True if the connection attempt is successful. Otherwise
102 * false.
103 */
104 bool ConnectToDevd();
105
106 /**
107 * Close a connection (if any) to devd's unix domain socket.
108 */
109 void DisconnectFromDevd();
110
111 EventFactory GetFactory();
112
113 protected:
114 /**
115 * \brief Reads the most recent record
116 *
117 * On error, "" is returned, and errno will be set by the OS
118 *
119 * \returns A string containing the record
120 */
121 std::string ReadEvent();
122
123 enum {
124 /*
125 * The maximum event size supported by libdevdctl.
126 */
127 MAX_EVENT_SIZE = 8192,
128 };
129
130 static const char s_devdSockPath[];
131
132 /**
133 * File descriptor representing the unix domain socket
134 * connection with devd.
135 */
136 int m_devdSockFD;
137
138 EventFactory m_eventFactory;
139
140 /** Queued events for replay. */
141 EventList m_unconsumedEvents;
142
143 /**
144 * Flag controlling whether events can be queued. This boolean
145 * is set during event replay to ensure that previosuly deferred
146 * events are not requeued and thus retained forever.
147 */
148 bool m_replayingEvents;
149 };
150
151 //- Consumer Const Public Inline Methods ---------------------------------------
152 inline bool
Connected()153 Consumer::Connected() const
154 {
155 return (m_devdSockFD != -1);
156 }
157
158 //- Consumer Public Inline Methods ---------------------------------------------
159 inline int
GetPollFd()160 Consumer::GetPollFd()
161 {
162 return (m_devdSockFD);
163 }
164
165 inline EventFactory
GetFactory()166 Consumer::GetFactory()
167 {
168 return (m_eventFactory);
169 }
170
171 } // namespace DevdCtl
172 #endif /* _DEVDCTL_CONSUMER_H_ */
173