1 /*
2 * Copyright 2018, 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 #include "poller.h"
18
19 #include "log.h"
20
21 #include <errno.h>
22 #include <poll.h>
23 #include <signal.h>
24 #include <stdio.h>
25 #include <string.h>
26
27 #include <unordered_map>
28 #include <vector>
29
30 using std::chrono::duration_cast;
31
calculateTimeout(Pollable::Timestamp deadline,struct timespec * ts)32 static struct timespec* calculateTimeout(Pollable::Timestamp deadline,
33 struct timespec* ts) {
34 Pollable::Timestamp now = Pollable::Clock::now();
35 if (deadline < Pollable::Timestamp::max()) {
36 if (deadline <= now) {
37 LOGE("Poller found past due deadline, setting to zero");
38 ts->tv_sec = 0;
39 ts->tv_nsec = 0;
40 return ts;
41 }
42
43 auto timeout = deadline - now;
44 // Convert and round down to seconds
45 auto seconds = duration_cast<std::chrono::seconds>(timeout);
46 // Then subtract the seconds from the timeout and convert the remainder
47 auto nanos = duration_cast<std::chrono::nanoseconds>(timeout - seconds);
48
49 ts->tv_sec = seconds.count();
50 ts->tv_nsec = nanos.count();
51
52 return ts;
53 }
54 return nullptr;
55 }
56
Poller()57 Poller::Poller() {
58 }
59
addPollable(Pollable * pollable)60 void Poller::addPollable(Pollable* pollable) {
61 mPollables.push_back(pollable);
62 }
63
run()64 int Poller::run() {
65 // Block all signals while we're running. This way we don't have to deal
66 // with things like EINTR. We then uses ppoll to set the original mask while
67 // polling. This way polling can be interrupted but socket writing, reading
68 // and ioctl remain interrupt free. If a signal arrives while we're blocking
69 // it it will be placed in the signal queue and handled once ppoll sets the
70 // original mask. This way no signals are lost.
71 sigset_t blockMask, mask;
72 int status = ::sigfillset(&blockMask);
73 if (status != 0) {
74 LOGE("Unable to fill signal set: %s", strerror(errno));
75 return errno;
76 }
77 status = ::sigprocmask(SIG_SETMASK, &blockMask, &mask);
78 if (status != 0) {
79 LOGE("Unable to set signal mask: %s", strerror(errno));
80 return errno;
81 }
82
83 std::vector<struct pollfd> fds;
84 std::unordered_map<int, Pollable*> pollables;
85 while (true) {
86 fds.clear();
87 pollables.clear();
88 Pollable::Timestamp deadline = Pollable::Timestamp::max();
89 for (auto& pollable : mPollables) {
90 size_t start = fds.size();
91 pollable->getPollData(&fds);
92 Pollable::Timestamp pollableDeadline = pollable->getTimeout();
93 // Create a map from each fd to the pollable
94 for (size_t i = start; i < fds.size(); ++i) {
95 pollables[fds[i].fd] = pollable;
96 }
97 if (pollableDeadline < deadline) {
98 deadline = pollableDeadline;
99 }
100 }
101
102 struct timespec ts = { 0, 0 };
103 struct timespec* tsPtr = calculateTimeout(deadline, &ts);
104 status = ::ppoll(fds.data(), fds.size(), tsPtr, &mask);
105 if (status < 0) {
106 if (errno == EINTR) {
107 // Interrupted, just keep going
108 continue;
109 }
110 // Actual error, time to quit
111 LOGE("Polling failed: %s", strerror(errno));
112 return errno;
113 } else if (status > 0) {
114 // Check for read or close events
115 for (const auto& fd : fds) {
116 if ((fd.revents & (POLLIN | POLLHUP)) == 0) {
117 // Neither POLLIN nor POLLHUP, not interested
118 continue;
119 }
120 auto pollable = pollables.find(fd.fd);
121 if (pollable == pollables.end()) {
122 // No matching fd, weird and unexpected
123 LOGE("Poller could not find fd matching %d", fd.fd);
124 continue;
125 }
126 if (fd.revents & POLLIN) {
127 // This pollable has data available for reading
128 int status = 0;
129 if (!pollable->second->onReadAvailable(fd.fd, &status)) {
130 // The onReadAvailable handler signaled an exit
131 return status;
132 }
133 }
134 if (fd.revents & POLLHUP) {
135 // The fd was closed from the other end
136 int status = 0;
137 if (!pollable->second->onClose(fd.fd, &status)) {
138 // The onClose handler signaled an exit
139 return status;
140 }
141 }
142 }
143 }
144 // Check for timeouts
145 Pollable::Timestamp now = Pollable::Clock::now();
146 for (const auto& pollable : mPollables) {
147 if (pollable->getTimeout() <= now) {
148 int status = 0;
149 if (!pollable->onTimeout(&status)) {
150 // The onTimeout handler signaled an exit
151 return status;
152 }
153 }
154 }
155 }
156
157 return 0;
158 }
159