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