| 1 | /* LTTng user-space "fast" library |
| 2 | * |
| 3 | * This daemon is spawned by each traced thread (to share the mmap). |
| 4 | * |
| 5 | * Its job is to dump periodically this buffer to disk (when it receives a |
| 6 | * SIGUSR1 from its parent). |
| 7 | * |
| 8 | * It uses the control information in the shared memory area (producer/consumer |
| 9 | * count). |
| 10 | * |
| 11 | * When the parent thread dies (yes, those thing may happen) ;) , this daemon |
| 12 | * will flush the last buffer and write it to disk. |
| 13 | * |
| 14 | * Supplement note for streaming : the daemon is responsible for flushing |
| 15 | * periodically the buffer if it is streaming data. |
| 16 | * |
| 17 | * |
| 18 | * Notes : |
| 19 | * shm memory is typically limited to 4096 units (system wide limit SHMMNI in |
| 20 | * /proc/sys/kernel/shmmni). As it requires computation time upon creation, we |
| 21 | * do not use it : we will use a shared mmap() instead which is passed through |
| 22 | * the fork(). |
| 23 | * MAP_SHARED mmap segment. Updated when msync or munmap are called. |
| 24 | * MAP_ANONYMOUS. |
| 25 | * Memory mapped by mmap() is preserved across fork(2), with the same |
| 26 | * attributes. |
| 27 | * |
| 28 | * Eventually, there will be two mode : |
| 29 | * * Slow thread spawn : a fork() is done for each new thread. If the process |
| 30 | * dies, the data is not lost. |
| 31 | * * Fast thread spawn : a pthread_create() is done by the application for each |
| 32 | * new thread. |
| 33 | * |
| 34 | * We use a timer to check periodically if the parent died. I think it is less |
| 35 | * intrusive than a ptrace() on the parent, which would get every signal. The |
| 36 | * side effect of this is that we won't be notified if the parent does an |
| 37 | * exec(). In this case, we will just sit there until the parent exits. |
| 38 | * |
| 39 | * |
| 40 | * Copyright 2006 Mathieu Desnoyers |
| 41 | * |
| 42 | */ |
| 43 | |
| 44 | #include <sys/types.h> |
| 45 | #include <sys/wait.h> |
| 46 | #include <unistd.h> |
| 47 | #include <stdlib.h> |
| 48 | #include <stdio.h> |
| 49 | #include <signal.h> |
| 50 | #include <syscall.h> |
| 51 | #include <features.h> |
| 52 | #include <pthread.h> |
| 53 | #include <malloc.h> |
| 54 | #include <string.h> |
| 55 | #include <sys/mman.h> |
| 56 | #include <signal.h> |
| 57 | #include <sys/stat.h> |
| 58 | #include <fcntl.h> |
| 59 | #include <stdlib.h> |
| 60 | #include <sys/param.h> |
| 61 | |
| 62 | #include <asm/timex.h> //for get_cycles() |
| 63 | |
| 64 | #include "ltt-usertrace-fast.h" |
| 65 | |
| 66 | |
| 67 | /* Writer (the traced application) */ |
| 68 | |
| 69 | __thread struct ltt_trace_info *thread_trace_info = NULL; |
| 70 | |
| 71 | void ltt_usertrace_fast_buffer_switch(void) |
| 72 | { |
| 73 | struct ltt_trace_info *tmp = thread_trace_info; |
| 74 | if(tmp) |
| 75 | kill(tmp->daemon_id, SIGUSR1); |
| 76 | } |
| 77 | |
| 78 | /* The cleanup should never be called from a signal handler */ |
| 79 | static void ltt_usertrace_fast_cleanup(void *arg) |
| 80 | { |
| 81 | struct ltt_trace_info *tmp = thread_trace_info; |
| 82 | if(tmp) { |
| 83 | thread_trace_info = NULL; |
| 84 | kill(tmp->daemon_id, SIGUSR2); |
| 85 | munmap(tmp, sizeof(*tmp)); |
| 86 | } |
| 87 | } |
| 88 | |
| 89 | /* Reader (the disk dumper daemon) */ |
| 90 | |
| 91 | static pid_t traced_pid = 0; |
| 92 | static pthread_t traced_thread = 0; |
| 93 | static int parent_exited = 0; |
| 94 | |
| 95 | /* signal handling */ |
| 96 | static void handler_sigusr1(int signo) |
| 97 | { |
| 98 | printf("LTT Signal %d received : parent buffer switch.\n", signo); |
| 99 | } |
| 100 | |
| 101 | static void handler_sigusr2(int signo) |
| 102 | { |
| 103 | printf("LTT Signal %d received : parent exited.\n", signo); |
| 104 | parent_exited = 1; |
| 105 | } |
| 106 | |
| 107 | static void handler_sigalarm(int signo) |
| 108 | { |
| 109 | printf("LTT Signal %d received\n", signo); |
| 110 | |
| 111 | if(getppid() != traced_pid) { |
| 112 | /* Parent died */ |
| 113 | printf("LTT Parent %lu died, cleaning up\n", traced_pid); |
| 114 | traced_pid = 0; |
| 115 | } |
| 116 | alarm(3); |
| 117 | } |
| 118 | |
| 119 | |
| 120 | /* This function is called by ltt_rw_init which has signals blocked */ |
| 121 | static void ltt_usertrace_fast_daemon(struct ltt_trace_info *shared_trace_info, |
| 122 | sigset_t oldset, pid_t l_traced_pid, pthread_t l_traced_thread) |
| 123 | { |
| 124 | struct sigaction act; |
| 125 | int ret; |
| 126 | int fd_fac; |
| 127 | int fd_cpu; |
| 128 | char outfile_name[PATH_MAX]; |
| 129 | char identifier_name[PATH_MAX]; |
| 130 | |
| 131 | |
| 132 | traced_pid = l_traced_pid; |
| 133 | traced_thread = l_traced_thread; |
| 134 | |
| 135 | printf("LTT ltt_usertrace_fast_daemon : init is %d, pid is %lu, traced_pid is %lu\n", |
| 136 | shared_trace_info->init, getpid(), traced_pid); |
| 137 | |
| 138 | act.sa_handler = handler_sigusr1; |
| 139 | act.sa_flags = 0; |
| 140 | sigemptyset(&(act.sa_mask)); |
| 141 | sigaddset(&(act.sa_mask), SIGUSR1); |
| 142 | sigaction(SIGUSR1, &act, NULL); |
| 143 | |
| 144 | act.sa_handler = handler_sigusr2; |
| 145 | act.sa_flags = 0; |
| 146 | sigemptyset(&(act.sa_mask)); |
| 147 | sigaddset(&(act.sa_mask), SIGUSR2); |
| 148 | sigaction(SIGUSR2, &act, NULL); |
| 149 | |
| 150 | act.sa_handler = handler_sigalarm; |
| 151 | act.sa_flags = 0; |
| 152 | sigemptyset(&(act.sa_mask)); |
| 153 | sigaddset(&(act.sa_mask), SIGALRM); |
| 154 | sigaction(SIGALRM, &act, NULL); |
| 155 | |
| 156 | /* Enable signals */ |
| 157 | ret = pthread_sigmask(SIG_SETMASK, &oldset, NULL); |
| 158 | if(ret) { |
| 159 | printf("LTT Error in pthread_sigmask\n"); |
| 160 | } |
| 161 | |
| 162 | alarm(3); |
| 163 | |
| 164 | /* Open output files */ |
| 165 | umask(00000); |
| 166 | ret = mkdir(LTT_USERTRACE_ROOT, 0777); |
| 167 | if(ret < 0 && errno != EEXIST) { |
| 168 | perror("LTT Error in creating output (mkdir)"); |
| 169 | exit(-1); |
| 170 | } |
| 171 | ret = chdir(LTT_USERTRACE_ROOT); |
| 172 | if(ret < 0) { |
| 173 | perror("LTT Error in creating output (chdir)"); |
| 174 | exit(-1); |
| 175 | } |
| 176 | snprintf(identifier_name, PATH_MAX-1, "%lu.%lu.%llu", |
| 177 | traced_pid, traced_thread, get_cycles()); |
| 178 | snprintf(outfile_name, PATH_MAX-1, "facilities-%s", identifier_name); |
| 179 | fd_fac = creat(outfile_name, 0644); |
| 180 | |
| 181 | snprintf(outfile_name, PATH_MAX-1, "cpu-%s", identifier_name); |
| 182 | fd_cpu = creat(outfile_name, 0644); |
| 183 | |
| 184 | |
| 185 | while(1) { |
| 186 | pause(); |
| 187 | if(traced_pid == 0) break; /* parent died */ |
| 188 | if(parent_exited) break; |
| 189 | printf("LTT Doing a buffer switch read. pid is : %lu\n", getpid()); |
| 190 | //printf("Test parent. pid is : %lu, ppid is %lu\n", getpid(), getppid()); |
| 191 | } |
| 192 | |
| 193 | /* Buffer force switch (flush) */ |
| 194 | //TODO |
| 195 | |
| 196 | close(fd_fac); |
| 197 | close(fd_cpu); |
| 198 | |
| 199 | /* The parent thread is dead and we have finished with the buffer */ |
| 200 | munmap(shared_trace_info, sizeof(*shared_trace_info)); |
| 201 | |
| 202 | exit(0); |
| 203 | } |
| 204 | |
| 205 | |
| 206 | /* Reader-writer initialization */ |
| 207 | |
| 208 | static enum ltt_process_role { LTT_ROLE_WRITER, LTT_ROLE_READER } |
| 209 | role = LTT_ROLE_WRITER; |
| 210 | |
| 211 | |
| 212 | void ltt_rw_init(void) |
| 213 | { |
| 214 | pid_t pid; |
| 215 | struct ltt_trace_info *shared_trace_info; |
| 216 | int ret; |
| 217 | sigset_t set, oldset; |
| 218 | pid_t l_traced_pid = getpid(); |
| 219 | pthread_t l_traced_thread = pthread_self(); |
| 220 | |
| 221 | /* parent : create the shared memory map */ |
| 222 | shared_trace_info = mmap(0, sizeof(*thread_trace_info), |
| 223 | PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, 0, 0); |
| 224 | memset(shared_trace_info, 0, sizeof(*shared_trace_info)); |
| 225 | shared_trace_info->init = 1; |
| 226 | |
| 227 | /* Disable signals */ |
| 228 | ret = sigfillset(&set); |
| 229 | if(ret) { |
| 230 | printf("LTT Error in sigfillset\n"); |
| 231 | } |
| 232 | |
| 233 | |
| 234 | ret = pthread_sigmask(SIG_BLOCK, &set, &oldset); |
| 235 | if(ret) { |
| 236 | printf("LTT Error in pthread_sigmask\n"); |
| 237 | } |
| 238 | |
| 239 | pid = fork(); |
| 240 | if(pid > 0) { |
| 241 | /* Parent */ |
| 242 | shared_trace_info->daemon_id = pid; |
| 243 | thread_trace_info = shared_trace_info; |
| 244 | |
| 245 | /* Enable signals */ |
| 246 | ret = pthread_sigmask(SIG_SETMASK, &oldset, NULL); |
| 247 | if(ret) { |
| 248 | printf("LTT Error in pthread_sigmask\n"); |
| 249 | } |
| 250 | } else if(pid == 0) { |
| 251 | /* Child */ |
| 252 | role = LTT_ROLE_READER; |
| 253 | ltt_usertrace_fast_daemon(shared_trace_info, oldset, l_traced_pid, |
| 254 | l_traced_thread); |
| 255 | /* Should never return */ |
| 256 | exit(-1); |
| 257 | } else if(pid < 0) { |
| 258 | /* fork error */ |
| 259 | perror("LTT Error in forking ltt-usertrace-fast"); |
| 260 | } |
| 261 | } |
| 262 | |
| 263 | static __thread struct _pthread_cleanup_buffer cleanup_buffer; |
| 264 | |
| 265 | void ltt_thread_init(void) |
| 266 | { |
| 267 | _pthread_cleanup_push(&cleanup_buffer, ltt_usertrace_fast_cleanup, NULL); |
| 268 | ltt_rw_init(); |
| 269 | } |
| 270 | |
| 271 | void __attribute__((constructor)) __ltt_usertrace_fast_init(void) |
| 272 | { |
| 273 | printf("LTT usertrace-fast init\n"); |
| 274 | |
| 275 | ltt_rw_init(); |
| 276 | } |
| 277 | |
| 278 | void __attribute__((destructor)) __ltt_usertrace_fast_fini(void) |
| 279 | { |
| 280 | if(role == LTT_ROLE_WRITER) { |
| 281 | printf("LTT usertrace-fast fini\n"); |
| 282 | ltt_usertrace_fast_cleanup(NULL); |
| 283 | } |
| 284 | } |
| 285 | |