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1 /* | |
2 * Copyright (c) 2015 The WebRTC project authors. All Rights Reserved. | |
3 * | |
4 * Use of this source code is governed by a BSD-style license | |
5 * that can be found in the LICENSE file in the root of the source | |
6 * tree. An additional intellectual property rights grant can be found | |
7 * in the file PATENTS. All contributing project authors may | |
8 * be found in the AUTHORS file in the root of the source tree. | |
9 */ | |
10 | |
11 #ifndef WEBRTC_MODULES_AUDIO_PROCESSING_SWAPPED_NONBLOCKING_QUEUE_H_ | |
12 #define WEBRTC_MODULES_AUDIO_PROCESSING_SWAPPED_NONBLOCKING_QUEUE_H_ | |
kwiberg-webrtc
2015/10/12 14:05:48
The include guard name needs updating.
peah-webrtc
2015/10/13 11:56:13
Done.
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13 | |
14 #include <algorithm> | |
15 #include <utility> | |
16 #include <vector> | |
17 | |
18 #include "webrtc/base/checks.h" | |
19 #include "webrtc/base/criticalsection.h" | |
20 | |
21 namespace webrtc { | |
22 | |
23 // This class is to be used as a one-way queue where data is | |
kwiberg-webrtc
2015/10/12 14:05:48
It actually *is* a one-way queue.
peah-webrtc
2015/10/13 11:56:13
Done.
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24 // written from one end and read from the other end. | |
25 // It is safe to access the class concurrently from multiple threads. | |
The Sun (google.com)
2015/10/13 07:53:05
Will git cl format fix the alignment of comment li
peah-webrtc
2015/10/13 11:56:13
You mean whether multiline comments are rearranged
the sun
2015/10/13 12:34:27
yes
peah-webrtc
2015/10/26 08:56:56
Acknowledged.
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26 // The queueable objects must all be swappable. | |
27 // | |
28 // When T is a vector, one way of us using this class is by leveraging that | |
The Sun (google.com)
2015/10/13 07:53:05
What you describe is the general intention of this
peah-webrtc
2015/10/13 11:56:13
I fully agree. I revised the description, and adde
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29 // the vector returned (via a swap) when doing an Insert can be reused if | |
30 // the queue is properly initialized. For instance, if the queue is initialized | |
31 // with N elements sized vectors, and the vectors passed to the Insert and | |
32 // Remove methods also are always N elements long, the vector returned from | |
33 // the Insert method always have a size of N, allowing for a cheap scheme of | |
34 // avoiding vector reallocations. | |
35 template <typename T> | |
36 class SwapQueue { | |
kwiberg-webrtc
2015/10/12 14:05:48
It might be a good idea to reflect the threadsafen
The Sun (google.com)
2015/10/13 07:53:05
+1 -1
I think that is a good idea assuming we are
kwiberg-webrtc
2015/10/13 09:59:53
OK. Then I suggest to err on the side of brevity.
peah-webrtc
2015/10/13 11:56:12
How about omitting threadsafety in the name, but o
kwiberg-webrtc
2015/10/13 12:09:07
Dynamically taking locks or not would make the cod
peah-webrtc
2015/10/26 08:56:56
Acknowledged.
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37 public: | |
38 // Creates a queue of size size. | |
kwiberg-webrtc
2015/10/12 14:05:48
Document that this fills the queue with the specif
peah-webrtc
2015/10/13 11:56:13
Done.
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39 explicit SwapQueue(size_t size) { queue_.resize(size); } | |
kwiberg-webrtc
2015/10/12 14:05:48
explicit SwapQueue(size_t size) : queue_(size) {}
peah-webrtc
2015/10/13 11:56:13
Done.
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40 | |
41 // Creates a queue of size size and initializes each element | |
42 // to have the same size and content of initializer (useful to | |
43 // ensure a certain initial size when T is a vector). | |
44 explicit SwapQueue<T>(size_t size, const T& initializer) | |
45 : SwapQueue<T>(size) { | |
The Sun (google.com)
2015/10/13 07:53:05
: queue_(size, initializer) {
i.e. don't default-
peah-webrtc
2015/10/13 11:56:13
Done.
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46 queue_ = std::vector<T>(size, initializer); | |
47 } | |
kwiberg-webrtc
2015/10/12 14:05:48
"explicit" is only needed for one-argument constru
peah-webrtc
2015/10/13 11:56:13
I removed this constructor.
the sun
2015/10/13 12:34:26
But why? Supplying a prototype object which is cop
kwiberg-webrtc
2015/10/13 14:08:36
Sure, it might be a convenient shortcut.
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48 | |
49 // Ensures that the internal queue elements of type vector | |
50 // are formed as in the supplied empty slots input | |
kwiberg-webrtc
2015/10/12 14:05:48
Maybe just
// Create a queue with "empty" Ts fr
peah-webrtc
2015/10/13 11:56:13
Excellent suggestion.
peah-webrtc
2015/10/13 11:56:13
Done.
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51 // TODO(peah): Change to std::vector<T>&& when we have a C++11 | |
52 // standard library. | |
kwiberg-webrtc
2015/10/12 15:39:10
Actually, I realized on the way home that we only
peah-webrtc
2015/10/13 11:56:12
Nice! But I get a cl upload warning that the below
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53 // | |
54 // If using the above described scheme that ensures that all elements in the | |
55 // queue are of the same size, this is achieved if the following constructor | |
56 // is used with an input of vectors having the same size. | |
kwiberg-webrtc
2015/10/12 14:05:48
You repeat this several times. Maybe just once, in
The Sun (google.com)
2015/10/13 07:53:05
It is confusing that you talk about "input of vect
kwiberg-webrtc
2015/10/13 09:59:53
We don't. std::vector is less convenient than it c
peah-webrtc
2015/10/13 11:56:13
I made an attempt to do that. Could you please hav
peah-webrtc
2015/10/13 11:56:13
I agree about repetition, and I removed that part.
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57 explicit SwapQueue(std::vector<T>* empty_slots) { | |
58 RTC_CHECK_GE(empty_slots->size(), 1u); | |
59 using std::swap; | |
The Sun (google.com)
2015/10/13 07:53:05
Why not just do std::swap on the line below?
kwiberg-webrtc
2015/10/13 09:59:53
Because the author of T might have defined a swap(
peah-webrtc
2015/10/13 11:56:13
I kept it as it is for now. Please let me know if
peah-webrtc
2015/10/13 11:56:13
Acknowledged.
the sun
2015/10/13 12:34:27
Great! Thanks for the explanation.
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60 swap(queue_, *empty_slots); | |
61 } | |
62 | |
63 // Resets the queue to have zero content. | |
64 void Clear() { | |
65 rtc::CritScope cs(&crit_queue_); | |
66 last_write_index_ = 0; | |
67 last_read_index_ = 0; | |
68 num_elements_ = 0; | |
69 } | |
70 | |
71 // Inserts a chunk of data into the queue in a thread safe manner. | |
kwiberg-webrtc
2015/10/12 14:05:48
Document thread safety once, in the class descript
peah-webrtc
2015/10/13 11:56:12
Done.
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72 // The input is swapped with the next available value of type T | |
73 // present in the queue. | |
74 // Returns false if the queue is full, and true if not. | |
kwiberg-webrtc
2015/10/12 14:05:48
Document that the operation is a no-op iff it retu
peah-webrtc
2015/10/13 11:56:13
Done.
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75 // | |
76 // Note that in the case of T being a vector, if using the above described | |
The Sun (google.com)
2015/10/13 07:53:05
Please remove these comments. Too much text will m
peah-webrtc
2015/10/13 11:56:13
Done.
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77 // scheme to ensure that all elements in the queue are of the same size, the | |
78 // resulting content in input after the swap also has the same size. | |
79 bool Insert(T* input) { | |
80 rtc::CritScope cs(&crit_queue_); | |
81 | |
82 // Early return if the queue is full. | |
83 if (num_elements_ == queue_.size()) | |
84 return false; | |
85 | |
86 last_write_index_ = | |
87 (last_write_index_ < (queue_.size() - 1) ? last_write_index_ + 1 : 0); | |
88 | |
89 using std::swap; | |
90 swap(*input, queue_[last_write_index_]); | |
91 | |
92 num_elements_++; | |
93 return true; | |
94 } | |
95 | |
96 // Removes a chunk of data from the queue in a thread safe manner. | |
97 // The queue element is swapped with the previous content of output. | |
98 // Returns false if the queue is empty, and true if not. | |
kwiberg-webrtc
2015/10/12 14:05:48
Same as above: document thread safety once, and sa
peah-webrtc
2015/10/13 11:56:13
Done.
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99 // | |
100 // Note that in the case of T being a vector, if using the above described | |
101 // scheme to ensure that all elements in the queue are of the same size, | |
102 // it is important to ensure that the initial content of output has the | |
103 // same size as the content in the queue. | |
104 bool Remove(T* output) { | |
105 rtc::CritScope cs(&crit_queue_); | |
106 | |
107 // Early return for empty queue. | |
108 if (num_elements_ == 0) | |
109 return false; | |
110 | |
111 last_read_index_ = | |
112 (last_read_index_ < (queue_.size() - 1) ? last_read_index_ + 1 : 0); | |
The Sun (google.com)
2015/10/13 07:53:05
I'd rather you
last_read_index_++;
if (last_read_
peah-webrtc
2015/10/13 11:56:13
Done.
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113 output->swap(queue_[last_read_index_]); | |
kwiberg-webrtc
2015/10/12 14:05:48
Use the same swap idiom as above.
peah-webrtc
2015/10/13 11:56:13
Done.
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114 | |
115 num_elements_--; | |
116 return true; | |
117 } | |
118 | |
119 private: | |
120 std::vector<T> queue_ GUARDED_BY(crit_queue_); | |
121 size_t last_write_index_ GUARDED_BY(crit_queue_) = 0; | |
122 size_t last_read_index_ GUARDED_BY(crit_queue_) = 0; | |
123 size_t num_elements_ GUARDED_BY(crit_queue_) = 0; | |
kwiberg-webrtc
2015/10/12 14:05:48
Document the invariants: queue_.size() never chang
peah-webrtc
2015/10/13 11:56:13
Done.
peah-webrtc
2015/10/13 11:56:13
Good point! I changed to using next, and added the
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124 rtc::CriticalSection crit_queue_; | |
125 | |
126 RTC_DISALLOW_COPY_AND_ASSIGN(SwapQueue); | |
127 }; | |
128 | |
129 } // namespace webrtc | |
130 | |
131 #endif // WEBRTC_MODULES_AUDIO_PROCESSING_SWAPPED_NONBLOCKING_QUEUE_H_ | |
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