Yao Chen | b13a102 | 2018-05-07 16:57:13 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 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 | #include "statsd_writer.h" |
| 17 | |
| 18 | #include <cutils/sockets.h> |
| 19 | #include <endian.h> |
| 20 | #include <errno.h> |
| 21 | #include <fcntl.h> |
| 22 | #include <inttypes.h> |
| 23 | #include <poll.h> |
| 24 | #include <private/android_filesystem_config.h> |
| 25 | #include <private/android_logger.h> |
| 26 | #include <stdarg.h> |
| 27 | #include <stdatomic.h> |
| 28 | #include <stdio.h> |
| 29 | #include <stdlib.h> |
| 30 | #include <string.h> |
| 31 | #include <sys/stat.h> |
| 32 | #include <sys/types.h> |
| 33 | #include <sys/un.h> |
| 34 | #include <time.h> |
| 35 | #include <unistd.h> |
| 36 | |
| 37 | /* branchless on many architectures. */ |
| 38 | #define min(x, y) ((y) ^ (((x) ^ (y)) & -((x) < (y)))) |
| 39 | |
| 40 | static pthread_mutex_t log_init_lock = PTHREAD_MUTEX_INITIALIZER; |
| 41 | |
| 42 | void statsd_writer_init_lock() { |
| 43 | /* |
| 44 | * If we trigger a signal handler in the middle of locked activity and the |
| 45 | * signal handler logs a message, we could get into a deadlock state. |
| 46 | */ |
| 47 | pthread_mutex_lock(&log_init_lock); |
| 48 | } |
| 49 | |
| 50 | int statd_writer_trylock() { |
| 51 | return pthread_mutex_trylock(&log_init_lock); |
| 52 | } |
| 53 | |
| 54 | void statsd_writer_init_unlock() { |
| 55 | pthread_mutex_unlock(&log_init_lock); |
| 56 | } |
| 57 | |
| 58 | static int statsdAvailable(); |
| 59 | static int statsdOpen(); |
| 60 | static void statsdClose(); |
| 61 | static int statsdWrite(struct timespec* ts, struct iovec* vec, size_t nr); |
| 62 | |
| 63 | struct android_log_transport_write statsdLoggerWrite = { |
| 64 | .name = "statsd", |
| 65 | .sock = -EBADF, |
| 66 | .available = statsdAvailable, |
| 67 | .open = statsdOpen, |
| 68 | .close = statsdClose, |
| 69 | .write = statsdWrite, |
| 70 | }; |
| 71 | |
| 72 | /* log_init_lock assumed */ |
| 73 | static int statsdOpen() { |
| 74 | int i, ret = 0; |
| 75 | |
| 76 | i = atomic_load(&statsdLoggerWrite.sock); |
| 77 | if (i < 0) { |
| 78 | int sock = TEMP_FAILURE_RETRY(socket(PF_UNIX, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0)); |
| 79 | if (sock < 0) { |
| 80 | ret = -errno; |
| 81 | } else { |
| 82 | struct sockaddr_un un; |
| 83 | memset(&un, 0, sizeof(struct sockaddr_un)); |
| 84 | un.sun_family = AF_UNIX; |
| 85 | strcpy(un.sun_path, "/dev/socket/statsdw"); |
| 86 | |
| 87 | if (TEMP_FAILURE_RETRY( |
| 88 | connect(sock, (struct sockaddr*)&un, sizeof(struct sockaddr_un))) < 0) { |
| 89 | ret = -errno; |
| 90 | switch (ret) { |
| 91 | case -ENOTCONN: |
| 92 | case -ECONNREFUSED: |
| 93 | case -ENOENT: |
| 94 | i = atomic_exchange(&statsdLoggerWrite.sock, ret); |
| 95 | /* FALLTHRU */ |
| 96 | default: |
| 97 | break; |
| 98 | } |
| 99 | close(sock); |
| 100 | } else { |
| 101 | ret = atomic_exchange(&statsdLoggerWrite.sock, sock); |
| 102 | if ((ret >= 0) && (ret != sock)) { |
| 103 | close(ret); |
| 104 | } |
| 105 | ret = 0; |
| 106 | } |
| 107 | } |
| 108 | } |
| 109 | |
| 110 | return ret; |
| 111 | } |
| 112 | |
| 113 | static void __statsdClose(int negative_errno) { |
| 114 | int sock = atomic_exchange(&statsdLoggerWrite.sock, negative_errno); |
| 115 | if (sock >= 0) { |
| 116 | close(sock); |
| 117 | } |
| 118 | } |
| 119 | |
| 120 | static void statsdClose() { |
| 121 | __statsdClose(-EBADF); |
| 122 | } |
| 123 | |
| 124 | static int statsdAvailable() { |
| 125 | if (atomic_load(&statsdLoggerWrite.sock) < 0) { |
| 126 | if (access("/dev/socket/statsdw", W_OK) == 0) { |
| 127 | return 0; |
| 128 | } |
| 129 | return -EBADF; |
| 130 | } |
| 131 | return 1; |
| 132 | } |
| 133 | |
| 134 | static int statsdWrite(struct timespec* ts, struct iovec* vec, size_t nr) { |
| 135 | ssize_t ret; |
| 136 | int sock; |
| 137 | static const unsigned headerLength = 1; |
| 138 | struct iovec newVec[nr + headerLength]; |
| 139 | android_log_header_t header; |
| 140 | size_t i, payloadSize; |
| 141 | static atomic_int dropped; |
| 142 | |
| 143 | sock = atomic_load(&statsdLoggerWrite.sock); |
| 144 | if (sock < 0) switch (sock) { |
| 145 | case -ENOTCONN: |
| 146 | case -ECONNREFUSED: |
| 147 | case -ENOENT: |
| 148 | break; |
| 149 | default: |
| 150 | return -EBADF; |
| 151 | } |
| 152 | /* |
| 153 | * struct { |
| 154 | * // what we provide to socket |
| 155 | * android_log_header_t header; |
| 156 | * // caller provides |
| 157 | * union { |
| 158 | * struct { |
| 159 | * char prio; |
| 160 | * char payload[]; |
| 161 | * } string; |
| 162 | * struct { |
| 163 | * uint32_t tag |
| 164 | * char payload[]; |
| 165 | * } binary; |
| 166 | * }; |
| 167 | * }; |
| 168 | */ |
| 169 | |
| 170 | header.tid = gettid(); |
| 171 | header.realtime.tv_sec = ts->tv_sec; |
| 172 | header.realtime.tv_nsec = ts->tv_nsec; |
| 173 | |
| 174 | newVec[0].iov_base = (unsigned char*)&header; |
| 175 | newVec[0].iov_len = sizeof(header); |
| 176 | |
| 177 | // If we dropped events before, try to tell statsd. |
| 178 | if (sock >= 0) { |
| 179 | int32_t snapshot = atomic_exchange_explicit(&dropped, 0, memory_order_relaxed); |
| 180 | if (snapshot) { |
| 181 | android_log_event_int_t buffer; |
| 182 | header.id = LOG_ID_STATS; |
| 183 | buffer.header.tag = htole32(LIBLOG_LOG_TAG); |
| 184 | buffer.payload.type = EVENT_TYPE_INT; |
| 185 | buffer.payload.data = htole32(snapshot); |
| 186 | |
| 187 | newVec[headerLength].iov_base = &buffer; |
| 188 | newVec[headerLength].iov_len = sizeof(buffer); |
| 189 | |
| 190 | ret = TEMP_FAILURE_RETRY(writev(sock, newVec, 2)); |
| 191 | if (ret != (ssize_t)(sizeof(header) + sizeof(buffer))) { |
| 192 | atomic_fetch_add_explicit(&dropped, snapshot, memory_order_relaxed); |
| 193 | } |
| 194 | } |
| 195 | } |
| 196 | |
| 197 | header.id = LOG_ID_STATS; |
| 198 | |
| 199 | for (payloadSize = 0, i = headerLength; i < nr + headerLength; i++) { |
| 200 | newVec[i].iov_base = vec[i - headerLength].iov_base; |
| 201 | payloadSize += newVec[i].iov_len = vec[i - headerLength].iov_len; |
| 202 | |
| 203 | if (payloadSize > LOGGER_ENTRY_MAX_PAYLOAD) { |
| 204 | newVec[i].iov_len -= payloadSize - LOGGER_ENTRY_MAX_PAYLOAD; |
| 205 | if (newVec[i].iov_len) { |
| 206 | ++i; |
| 207 | } |
| 208 | break; |
| 209 | } |
| 210 | } |
| 211 | |
| 212 | /* |
| 213 | * The write below could be lost, but will never block. |
| 214 | * |
| 215 | * ENOTCONN occurs if statsd has died. |
| 216 | * ENOENT occurs if statsd is not running and socket is missing. |
| 217 | * ECONNREFUSED occurs if we can not reconnect to statsd. |
| 218 | * EAGAIN occurs if statsd is overloaded. |
| 219 | */ |
| 220 | if (sock < 0) { |
| 221 | ret = sock; |
| 222 | } else { |
| 223 | ret = TEMP_FAILURE_RETRY(writev(sock, newVec, i)); |
| 224 | if (ret < 0) { |
| 225 | ret = -errno; |
| 226 | } |
| 227 | } |
| 228 | switch (ret) { |
| 229 | case -ENOTCONN: |
| 230 | case -ECONNREFUSED: |
| 231 | case -ENOENT: |
| 232 | if (statd_writer_trylock()) { |
| 233 | return ret; /* in a signal handler? try again when less stressed |
| 234 | */ |
| 235 | } |
| 236 | __statsdClose(ret); |
| 237 | ret = statsdOpen(); |
| 238 | statsd_writer_init_unlock(); |
| 239 | |
| 240 | if (ret < 0) { |
| 241 | return ret; |
| 242 | } |
| 243 | |
| 244 | ret = TEMP_FAILURE_RETRY(writev(atomic_load(&statsdLoggerWrite.sock), newVec, i)); |
| 245 | if (ret < 0) { |
| 246 | ret = -errno; |
| 247 | } |
| 248 | /* FALLTHRU */ |
| 249 | default: |
| 250 | break; |
| 251 | } |
| 252 | |
| 253 | if (ret > (ssize_t)sizeof(header)) { |
| 254 | ret -= sizeof(header); |
| 255 | } else if (ret == -EAGAIN) { |
| 256 | atomic_fetch_add_explicit(&dropped, 1, memory_order_relaxed); |
| 257 | } |
| 258 | |
| 259 | return ret; |
| 260 | } |