Produce the stack trace in an async safe way.

This commit is contained in:
antirez 2012-04-26 16:04:53 +02:00
parent 3ada43e732
commit 11bd247d2b

View File

@ -7,6 +7,7 @@
#ifdef HAVE_BACKTRACE
#include <execinfo.h>
#include <ucontext.h>
#include <fcntl.h>
#endif /* HAVE_BACKTRACE */
/* ================================= Debugging ============================== */
@ -567,27 +568,30 @@ void logRegisters(ucontext_t *uc) {
#endif
}
/* Logs the stack trace using the backtrace() call. */
sds getStackTrace(ucontext_t *uc) {
/* Logs the stack trace using the backtrace() call. This function is designed
* to be called from signal handlers safely. */
void logStackTrace(ucontext_t *uc) {
void *trace[100];
int i, trace_size = 0;
char **messages = NULL;
sds st = sdsempty();
int trace_size = 0, fd;
/* Open the log file in append mode. */
fd = server.logfile ?
open(server.logfile, O_APPEND|O_CREAT|O_WRONLY, 0644) :
STDOUT_FILENO;
if (fd == -1) return;
/* Generate the stack trace */
trace_size = backtrace(trace, 100);
/* overwrite sigaction with caller's address */
if (getMcontextEip(uc) != NULL) {
if (getMcontextEip(uc) != NULL)
trace[1] = getMcontextEip(uc);
}
messages = backtrace_symbols(trace, trace_size);
for (i=1; i<trace_size; ++i) {
st = sdscat(st,messages[i]);
st = sdscatlen(st,"\n",1);
}
zlibc_free(messages);
return st;
/* Write symbols to log file */
backtrace_symbols_fd(trace, trace_size, fd);
/* Cleanup */
if (server.logfile) close(fd);
}
/* Log information about the "current" client, that is, the client that is
@ -630,7 +634,7 @@ void logCurrentClient(void) {
void sigsegvHandler(int sig, siginfo_t *info, void *secret) {
ucontext_t *uc = (ucontext_t*) secret;
sds infostring, clients, st;
sds infostring, clients;
struct sigaction act;
REDIS_NOTUSED(info);
@ -642,9 +646,8 @@ void sigsegvHandler(int sig, siginfo_t *info, void *secret) {
server.assert_file, server.assert_line);
/* Log the stack trace */
st = getStackTrace(uc);
redisLog(REDIS_WARNING, "--- STACK TRACE\n%s", st);
sdsfree(st);
redisLog(REDIS_WARNING, "--- STACK TRACE");
logStackTrace(uc);
/* Log INFO and CLIENT LIST */
redisLog(REDIS_WARNING, "--- INFO OUTPUT");
@ -692,19 +695,14 @@ void watchdogSignalHandler(int sig, siginfo_t *info, void *secret) {
#endif
REDIS_NOTUSED(info);
REDIS_NOTUSED(sig);
sds st, log;
log = sdsnew("\n--- WATCHDOG TIMER EXPIRED ---\n");
redisLogFromHandler(REDIS_WARNING,"\n--- WATCHDOG TIMER EXPIRED ---");
#ifdef HAVE_BACKTRACE
st = getStackTrace(uc);
logStackTrace(uc);
#else
st = sdsnew("Sorry: no support for backtrace().\n");
redisLogFromHandler(REDIS_WARNING,"Sorry: no support for backtrace().");
#endif
log = sdscatsds(log,st);
log = sdscat(log,"------\n");
redisLogFromHandler(REDIS_WARNING,log);
sdsfree(st);
sdsfree(log);
redisLogFromHandler(REDIS_WARNING,"--------\n");
}
/* Schedule a SIGALRM delivery after the specified period in milliseconds.