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1 | // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*- | |
2 | // vim: ts=8 sw=2 smarttab | |
3 | ||
4 | /* | |
5 | * Copyright (C) 2016 Red Hat Inc. | |
6 | */ | |
7 | ||
8 | #pragma once | |
9 | ||
10 | #include <memory> | |
11 | #include <mutex> | |
12 | #include <deque> | |
13 | ||
14 | #include "boost/variant.hpp" | |
15 | ||
16 | #include "ssched_recs.h" | |
17 | ||
18 | #ifdef PROFILE | |
19 | #include "profile.h" | |
20 | #endif | |
21 | ||
22 | namespace crimson { | |
23 | ||
24 | namespace simple_scheduler { | |
25 | ||
26 | template<typename C, typename R, typename Time> | |
27 | class SimpleQueue { | |
28 | ||
29 | public: | |
30 | ||
31 | using RequestRef = std::unique_ptr<R>; | |
32 | ||
33 | // a function to see whether the server can handle another request | |
34 | using CanHandleRequestFunc = std::function<bool(void)>; | |
35 | ||
36 | // a function to submit a request to the server; the second | |
37 | // parameter is a callback when it's completed | |
38 | using HandleRequestFunc = | |
39 | std::function<void(const C&,RequestRef,NullData)>; | |
40 | ||
41 | struct PullReq { | |
42 | enum class Type { returning, none }; | |
43 | ||
44 | struct Retn { | |
45 | C client; | |
46 | RequestRef request; | |
47 | }; | |
48 | ||
49 | Type type; | |
50 | boost::variant<Retn> data; | |
51 | }; | |
52 | ||
53 | protected: | |
54 | ||
55 | enum class Mechanism { push, pull }; | |
56 | ||
57 | struct QRequest { | |
58 | C client; | |
59 | RequestRef request; | |
60 | }; | |
61 | ||
62 | bool finishing = false; | |
63 | Mechanism mechanism; | |
64 | ||
65 | CanHandleRequestFunc can_handle_f; | |
66 | HandleRequestFunc handle_f; | |
67 | ||
68 | mutable std::mutex queue_mtx; | |
69 | using DataGuard = std::lock_guard<decltype(queue_mtx)>; | |
70 | ||
71 | std::deque<QRequest> queue; | |
72 | ||
73 | #ifdef PROFILE | |
74 | public: | |
75 | ProfileTimer<std::chrono::nanoseconds> pull_request_timer; | |
76 | ProfileTimer<std::chrono::nanoseconds> add_request_timer; | |
77 | ProfileTimer<std::chrono::nanoseconds> request_complete_timer; | |
78 | protected: | |
79 | #endif | |
80 | ||
81 | public: | |
82 | ||
83 | // push full constructor | |
84 | SimpleQueue(CanHandleRequestFunc _can_handle_f, | |
85 | HandleRequestFunc _handle_f) : | |
86 | mechanism(Mechanism::push), | |
87 | can_handle_f(_can_handle_f), | |
88 | handle_f(_handle_f) | |
89 | { | |
90 | // empty | |
91 | } | |
92 | ||
93 | SimpleQueue() : | |
94 | mechanism(Mechanism::pull) | |
95 | { | |
96 | // empty | |
97 | } | |
98 | ||
99 | ~SimpleQueue() { | |
100 | finishing = true; | |
101 | } | |
102 | ||
103 | void add_request(const R& request, | |
104 | const C& client_id, | |
105 | const ReqParams& req_params) { | |
106 | add_request(RequestRef(new R(request)), client_id, req_params); | |
107 | } | |
108 | ||
109 | void add_request(RequestRef&& request, | |
110 | const C& client_id, | |
111 | const ReqParams& req_params) { | |
112 | DataGuard g(queue_mtx); | |
113 | ||
114 | #ifdef PROFILE | |
115 | add_request_timer.start(); | |
116 | #endif | |
117 | queue.emplace_back(QRequest{client_id, std::move(request)}); | |
118 | ||
119 | if (Mechanism::push == mechanism) { | |
120 | schedule_request(); | |
121 | } | |
122 | ||
123 | #ifdef PROFILE | |
124 | add_request_timer.stop(); | |
125 | #endif | |
126 | } // add_request | |
127 | ||
128 | void request_completed() { | |
129 | assert(Mechanism::push == mechanism); | |
130 | DataGuard g(queue_mtx); | |
131 | ||
132 | #ifdef PROFILE | |
133 | request_complete_timer.start(); | |
134 | #endif | |
135 | schedule_request(); | |
136 | ||
137 | #ifdef PROFILE | |
138 | request_complete_timer.stop(); | |
139 | #endif | |
140 | } // request_completed | |
141 | ||
142 | PullReq pull_request() { | |
143 | assert(Mechanism::pull == mechanism); | |
144 | PullReq result; | |
145 | DataGuard g(queue_mtx); | |
146 | ||
147 | #ifdef PROFILE | |
148 | pull_request_timer.start(); | |
149 | #endif | |
150 | ||
151 | if (queue.empty()) { | |
152 | result.type = PullReq::Type::none; | |
153 | } else { | |
154 | auto front = queue.front(); | |
155 | result.type = PullReq::Type::returning; | |
156 | result.data = | |
157 | typename PullReq::Retn{front.client, std::move(front.request)}; | |
158 | queue.pop(); | |
159 | } | |
160 | ||
161 | #ifdef PROFILE | |
162 | pull_request_timer.stop(); | |
163 | #endif | |
164 | ||
165 | return result; | |
166 | } | |
167 | ||
168 | protected: | |
169 | ||
170 | // queue_mtx should be held when called; should only be called | |
171 | // when mechanism is push | |
172 | void schedule_request() { | |
173 | if (!queue.empty() && can_handle_f()) { | |
174 | auto& front = queue.front(); | |
175 | static NullData null_data; | |
176 | handle_f(front.client, std::move(front.request), null_data); | |
177 | queue.pop_front(); | |
178 | } | |
179 | } | |
180 | }; | |
181 | }; | |
182 | }; |