700d350d |
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 | * |
b09f3215 |
17 | * |
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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. |
a85b8f41 |
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 | * |
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40 | * Copyright 2006 Mathieu Desnoyers |
41 | * |
42 | */ |
43 | |
b09f3215 |
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> |
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55 | #include <sys/mman.h> |
56 | #include <signal.h> |
77b31f39 |
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() |
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63 | |
1c48e587 |
64 | #include "ltt-usertrace-fast.h" |
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65 | |
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66 | |
e8efa18d |
67 | /* Writer (the traced application) */ |
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68 | |
e8efa18d |
69 | __thread struct ltt_trace_info *thread_trace_info = NULL; |
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70 | |
e8efa18d |
71 | void ltt_usertrace_fast_buffer_switch(void) |
72 | { |
a85b8f41 |
73 | struct ltt_trace_info *tmp = thread_trace_info; |
74 | if(tmp) |
75 | kill(tmp->daemon_id, SIGUSR1); |
e8efa18d |
76 | } |
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77 | |
77b31f39 |
78 | /* The cleanup should never be called from a signal handler */ |
e8efa18d |
79 | static void ltt_usertrace_fast_cleanup(void *arg) |
b09f3215 |
80 | { |
a85b8f41 |
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 | } |
700d350d |
87 | } |
b09f3215 |
88 | |
e8efa18d |
89 | /* Reader (the disk dumper daemon) */ |
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90 | |
a85b8f41 |
91 | static pid_t traced_pid = 0; |
77b31f39 |
92 | static pthread_t traced_thread = 0; |
e8efa18d |
93 | static int parent_exited = 0; |
700d350d |
94 | |
e8efa18d |
95 | /* signal handling */ |
96 | static void handler_sigusr1(int signo) |
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97 | { |
a35eaa9c |
98 | printf("LTT Signal %d received : parent buffer switch.\n", signo); |
e8efa18d |
99 | } |
100 | |
101 | static void handler_sigusr2(int signo) |
102 | { |
a35eaa9c |
103 | printf("LTT Signal %d received : parent exited.\n", signo); |
e8efa18d |
104 | parent_exited = 1; |
105 | } |
106 | |
107 | static void handler_sigalarm(int signo) |
108 | { |
a35eaa9c |
109 | printf("LTT Signal %d received\n", signo); |
e8efa18d |
110 | |
a85b8f41 |
111 | if(getppid() != traced_pid) { |
e8efa18d |
112 | /* Parent died */ |
a85b8f41 |
113 | printf("LTT Parent %lu died, cleaning up\n", traced_pid); |
114 | traced_pid = 0; |
e8efa18d |
115 | } |
116 | alarm(3); |
b09f3215 |
117 | } |
118 | |
e8efa18d |
119 | |
a85b8f41 |
120 | /* This function is called by ltt_rw_init which has signals blocked */ |
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121 | static void ltt_usertrace_fast_daemon(struct ltt_trace_info *shared_trace_info, |
77b31f39 |
122 | sigset_t oldset, pid_t l_traced_pid, pthread_t l_traced_thread) |
700d350d |
123 | { |
124 | struct sigaction act; |
125 | int ret; |
77b31f39 |
126 | int fd_fac; |
127 | int fd_cpu; |
128 | char outfile_name[PATH_MAX]; |
129 | char identifier_name[PATH_MAX]; |
130 | |
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131 | |
a85b8f41 |
132 | traced_pid = l_traced_pid; |
77b31f39 |
133 | traced_thread = l_traced_thread; |
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134 | |
a85b8f41 |
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); |
700d350d |
137 | |
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138 | act.sa_handler = handler_sigusr1; |
700d350d |
139 | act.sa_flags = 0; |
140 | sigemptyset(&(act.sa_mask)); |
141 | sigaddset(&(act.sa_mask), SIGUSR1); |
142 | sigaction(SIGUSR1, &act, NULL); |
e8efa18d |
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 | |
700d350d |
156 | /* Enable signals */ |
157 | ret = pthread_sigmask(SIG_SETMASK, &oldset, NULL); |
158 | if(ret) { |
a35eaa9c |
159 | printf("LTT Error in pthread_sigmask\n"); |
700d350d |
160 | } |
161 | |
e8efa18d |
162 | alarm(3); |
163 | |
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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); |
5efa73ea |
179 | fd_fac = creat(outfile_name, 0644); |
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180 | |
181 | snprintf(outfile_name, PATH_MAX-1, "cpu-%s", identifier_name); |
5efa73ea |
182 | fd_cpu = creat(outfile_name, 0644); |
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183 | |
184 | |
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185 | while(1) { |
186 | pause(); |
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187 | if(traced_pid == 0) break; /* parent died */ |
e8efa18d |
188 | if(parent_exited) break; |
a35eaa9c |
189 | printf("LTT Doing a buffer switch read. pid is : %lu\n", getpid()); |
e8efa18d |
190 | //printf("Test parent. pid is : %lu, ppid is %lu\n", getpid(), getppid()); |
700d350d |
191 | } |
192 | |
e8efa18d |
193 | /* Buffer force switch (flush) */ |
194 | //TODO |
195 | |
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196 | close(fd_fac); |
197 | close(fd_cpu); |
198 | |
e8efa18d |
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); |
700d350d |
203 | } |
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204 | |
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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) |
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213 | { |
700d350d |
214 | pid_t pid; |
215 | struct ltt_trace_info *shared_trace_info; |
216 | int ret; |
217 | sigset_t set, oldset; |
a85b8f41 |
218 | pid_t l_traced_pid = getpid(); |
77b31f39 |
219 | pthread_t l_traced_thread = pthread_self(); |
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220 | |
221 | /* parent : create the shared memory map */ |
a85b8f41 |
222 | shared_trace_info = mmap(0, sizeof(*thread_trace_info), |
700d350d |
223 | PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, 0, 0); |
a85b8f41 |
224 | memset(shared_trace_info, 0, sizeof(*shared_trace_info)); |
225 | shared_trace_info->init = 1; |
700d350d |
226 | |
227 | /* Disable signals */ |
228 | ret = sigfillset(&set); |
229 | if(ret) { |
a35eaa9c |
230 | printf("LTT Error in sigfillset\n"); |
700d350d |
231 | } |
232 | |
233 | |
234 | ret = pthread_sigmask(SIG_BLOCK, &set, &oldset); |
235 | if(ret) { |
a35eaa9c |
236 | printf("LTT Error in pthread_sigmask\n"); |
700d350d |
237 | } |
a85b8f41 |
238 | |
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239 | pid = fork(); |
240 | if(pid > 0) { |
241 | /* Parent */ |
a85b8f41 |
242 | shared_trace_info->daemon_id = pid; |
243 | thread_trace_info = shared_trace_info; |
700d350d |
244 | |
245 | /* Enable signals */ |
246 | ret = pthread_sigmask(SIG_SETMASK, &oldset, NULL); |
247 | if(ret) { |
a35eaa9c |
248 | printf("LTT Error in pthread_sigmask\n"); |
700d350d |
249 | } |
250 | } else if(pid == 0) { |
251 | /* Child */ |
e8efa18d |
252 | role = LTT_ROLE_READER; |
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253 | ltt_usertrace_fast_daemon(shared_trace_info, oldset, l_traced_pid, |
254 | l_traced_thread); |
700d350d |
255 | /* Should never return */ |
256 | exit(-1); |
257 | } else if(pid < 0) { |
258 | /* fork error */ |
a35eaa9c |
259 | perror("LTT Error in forking ltt-usertrace-fast"); |
700d350d |
260 | } |
b09f3215 |
261 | } |
262 | |
e8efa18d |
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 | |
04180f7f |
271 | void __attribute__((constructor)) __ltt_usertrace_fast_init(void) |
b09f3215 |
272 | { |
700d350d |
273 | printf("LTT usertrace-fast init\n"); |
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274 | |
e8efa18d |
275 | ltt_rw_init(); |
700d350d |
276 | } |
277 | |
278 | void __attribute__((destructor)) __ltt_usertrace_fast_fini(void) |
279 | { |
e8efa18d |
280 | if(role == LTT_ROLE_WRITER) { |
281 | printf("LTT usertrace-fast fini\n"); |
282 | ltt_usertrace_fast_cleanup(NULL); |
283 | } |
b09f3215 |
284 | } |
285 | |