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1 | /* |
2 | * SPDX-License-Identifier: MIT | |
3 | * | |
4 | * Copyright 2016 Jérémie Galarneau <jeremie.galarneau@efficios.com> | |
5 | * Copyright 2017-2023 Philippe Proulx <pproulx@efficios.com> | |
6 | */ | |
7 | ||
8 | #ifndef BABELTRACE_PLUGINS_UTILS_MUXER_UPSTREAM_MSG_ITER_HPP | |
9 | #define BABELTRACE_PLUGINS_UTILS_MUXER_UPSTREAM_MSG_ITER_HPP | |
10 | ||
11 | #include <memory> | |
12 | ||
13 | #include "common/assert.h" | |
14 | #include "cpp-common/bt2/message-array.hpp" | |
15 | #include "cpp-common/bt2/message-iterator.hpp" | |
16 | #include "cpp-common/bt2c/logging.hpp" | |
17 | #include "cpp-common/bt2s/optional.hpp" | |
18 | ||
19 | namespace bt2mux { | |
20 | ||
21 | /* | |
22 | * An instance of this wraps an upstream libbabeltrace2 message | |
23 | * iterator, keeping an internal array of receives messages, and making | |
24 | * the oldest one available (msg() method). | |
25 | */ | |
26 | class UpstreamMsgIter final | |
27 | { | |
28 | public: | |
29 | /* Unique pointer to upstream message iterator */ | |
30 | using UP = std::unique_ptr<UpstreamMsgIter>; | |
31 | ||
32 | /* Return type of reload() */ | |
33 | enum class ReloadStatus | |
34 | { | |
1c5ea5eb SM |
35 | More, |
36 | NoMore, | |
fca1d0f5 PP |
37 | }; |
38 | ||
39 | /* | |
40 | * Builds an upstream message iterator wrapper using the | |
41 | * libbabeltrace2 message iterator `msgIter`. | |
42 | * | |
43 | * This constructor doesn't immediately gets the next messages from | |
44 | * `*msgIter` (you always need to call reload() before you call | |
45 | * msg()), therefore it won't throw `bt2::Error` or `bt2::TryAgain`. | |
46 | */ | |
47 | explicit UpstreamMsgIter(bt2::MessageIterator::Shared msgIter, std::string portName, | |
48 | const bt2c::Logger& parentLogger); | |
49 | ||
50 | /* Some protection */ | |
51 | UpstreamMsgIter(const UpstreamMsgIter&) = delete; | |
52 | UpstreamMsgIter& operator=(const UpstreamMsgIter&) = delete; | |
53 | ||
54 | /* | |
55 | * Current message. | |
56 | * | |
57 | * Before you call this method: | |
58 | * | |
59 | * 1. If needed, you must call discard(). | |
60 | * | |
61 | * This is not the case immediately after construction and | |
62 | * immediately after seeking. | |
63 | * | |
64 | * 2. You must call reload() successfully (not ended). | |
65 | * | |
66 | * This is always the case. | |
67 | * | |
68 | * This makes it possible to build an `UpstreamMsgIter` instance | |
69 | * without libbabeltrace2 message iterator exceptions. | |
70 | */ | |
71 | bt2::ConstMessage msg() const noexcept | |
72 | { | |
73 | BT_ASSERT_DBG(_mMsgs.msgs && _mMsgs.index < _mMsgs.msgs->length()); | |
74 | return (*_mMsgs.msgs)[_mMsgs.index]; | |
75 | } | |
76 | ||
77 | /* | |
78 | * Timestamp, if any, of the current message. | |
79 | * | |
80 | * It must be valid to call msg() when you call this method. | |
81 | */ | |
82 | const bt2s::optional<std::int64_t> msgTs() const noexcept | |
83 | { | |
84 | return _mMsgTs; | |
85 | } | |
86 | ||
87 | /* | |
88 | * Discards the current message, making this upstream message | |
89 | * iterator ready for a reload (reload()). | |
90 | * | |
91 | * You may only call reload() or seekBeginning() after having called | |
92 | * this. | |
93 | */ | |
94 | void discard() noexcept | |
95 | { | |
96 | BT_ASSERT_DBG(_mMsgs.msgs && _mMsgs.index < _mMsgs.msgs->length()); | |
97 | BT_ASSERT_DBG(_mDiscardRequired); | |
98 | _mDiscardRequired = false; | |
99 | ++_mMsgs.index; | |
100 | ||
101 | if (_mMsgs.index == _mMsgs.msgs->length()) { | |
102 | _mMsgs.msgs.reset(); | |
103 | } | |
104 | } | |
105 | ||
106 | /* | |
107 | * Retrieves the next message, making it available afterwards | |
108 | * through the msg() method. | |
109 | * | |
110 | * You must have called discard() to discard the current message, if | |
111 | * any, before you call this method. | |
112 | * | |
113 | * This method may throw anything bt2::MessageIterator::next() may | |
114 | * throw. | |
115 | * | |
116 | * If this method returns `ReloadStatus::NO_MORE`, then the | |
117 | * underlying libbabeltrace2 message iterator is ended, meaning you | |
118 | * may not call msg(), msgTs(), or reload() again for this message | |
119 | * iterator until you successfully call seekBeginning(). | |
120 | */ | |
121 | ReloadStatus reload(); | |
122 | ||
123 | /* | |
124 | * Forwards to bt2::MessageIterator::canSeekBeginning(). | |
125 | */ | |
126 | bool canSeekBeginning(); | |
127 | ||
128 | /* | |
129 | * Forwards to bt2::MessageIterator::seekBeginning(). | |
130 | * | |
131 | * On success, you may call reload() afterwards. With any exception, | |
132 | * you must call this method again, successfully, before you may | |
133 | * call reload(). | |
134 | */ | |
135 | void seekBeginning(); | |
136 | ||
137 | /* | |
138 | * Forwards to bt2::MessageIterator::canSeekForward(). | |
139 | */ | |
140 | bool canSeekForward() const noexcept; | |
141 | ||
142 | /* | |
143 | * Name of the input port on which the libbabeltrace2 message | |
144 | * iterator was created. | |
145 | */ | |
146 | const std::string& portName() const noexcept | |
147 | { | |
148 | return _mPortName; | |
149 | } | |
150 | ||
151 | private: | |
152 | /* | |
153 | * Tries to get new messages into `_mMsgs.msgs`. | |
154 | */ | |
155 | void _tryGetNewMsgs(); | |
156 | ||
157 | /* Actual upstream message iterator */ | |
158 | bt2::MessageIterator::Shared _mMsgIter; | |
159 | ||
160 | /* | |
161 | * Currently contained messages. | |
162 | * | |
163 | * `index` is the index of the current message (msg()/msgTs()) | |
164 | * within `msgs`. | |
165 | */ | |
166 | struct | |
167 | { | |
168 | bt2s::optional<bt2::ConstMessageArray> msgs; | |
169 | std::size_t index; | |
170 | } _mMsgs; | |
171 | ||
172 | /* Timestamp of the current message, if any */ | |
173 | bt2s::optional<std::int64_t> _mMsgTs; | |
174 | ||
175 | /* | |
176 | * Only relevant in debug mode: true if a call to discard() is | |
177 | * required before calling reload(). | |
178 | */ | |
179 | bool _mDiscardRequired = false; | |
180 | ||
181 | bt2c::Logger _mLogger; | |
182 | std::string _mPortName; | |
183 | }; | |
184 | ||
185 | } /* namespace bt2mux */ | |
186 | ||
187 | #endif /* BABELTRACE_PLUGINS_UTILS_MUXER_UPSTREAM_MSG_ITER_HPP */ |