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Add monotonic logging for bionic

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Primarily a debug feature that can be switched at runtime to permit
developer to have the option of high-resolution Android logs with
either CLOCK_REALTIME (default) or CLOCK_MONOTONIC to correlate with
other system activities like kernel logs or systrace.

Bug: 23668800
Change-Id: Ib29024899540f51a72cad5dde25517a7134d68f7
This commit is contained in:
Mark Salyzyn 2015-11-30 16:23:15 -08:00
parent 2452cf3c33
commit 870f165ceb
1 changed files with 64 additions and 2 deletions
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66
libc/bionic/libc_logging.cpp
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@ -31,6 +31,7 @@
#include <android/set_abort_message.h> #include <android/set_abort_message.h>
#include <assert.h> #include <assert.h>
#include <ctype.h>
#include <errno.h> #include <errno.h>
#include <fcntl.h> #include <fcntl.h>
#include <pthread.h> #include <pthread.h>
@ -46,6 +47,9 @@
#include <time.h> #include <time.h>
#include <unistd.h> #include <unistd.h>
#define _REALLY_INCLUDE_SYS__SYSTEM_PROPERTIES_H_
#include <sys/_system_properties.h>
static pthread_mutex_t g_abort_msg_lock = PTHREAD_MUTEX_INITIALIZER; static pthread_mutex_t g_abort_msg_lock = PTHREAD_MUTEX_INITIALIZER;
__LIBC_HIDDEN__ abort_msg_t** __abort_message_ptr; // Accessible to __libc_init_common. __LIBC_HIDDEN__ abort_msg_t** __abort_message_ptr; // Accessible to __libc_init_common.
@ -481,6 +485,64 @@ static int __libc_open_log_socket() {
return log_fd; return log_fd;
} }
struct cache {
const prop_info* pinfo;
uint32_t serial;
char c;
};
static void refresh_cache(struct cache *cache, const char *key)
{
if (!cache->pinfo) {
cache->pinfo = __system_property_find(key);
if (!cache->pinfo) {
return;
}
}
uint32_t serial = __system_property_serial(cache->pinfo);
if (serial == cache->serial) {
return;
}
cache->serial = serial;
char buf[PROP_VALUE_MAX];
__system_property_read(cache->pinfo, 0, buf);
cache->c = buf[0];
}
// Timestamp state generally remains constant, since a change is
// rare, we can accept a trylock failure gracefully.
static pthread_mutex_t lock_clockid = PTHREAD_MUTEX_INITIALIZER;
static clockid_t android_log_clockid()
{
static struct cache r_time_cache = { NULL, static_cast<uint32_t>(-1), 0 };
static struct cache p_time_cache = { NULL, static_cast<uint32_t>(-1), 0 };
char c;
if (pthread_mutex_trylock(&lock_clockid)) {
// We are willing to accept some race in this context
if (!(c = p_time_cache.c)) {
c = r_time_cache.c;
}
} else {
static uint32_t serial;
uint32_t current_serial = __system_property_area_serial();
if (current_serial != serial) {
refresh_cache(&r_time_cache, "ro.logd.timestamp");
refresh_cache(&p_time_cache, "persist.logd.timestamp");
serial = current_serial;
}
if (!(c = p_time_cache.c)) {
c = r_time_cache.c;
}
pthread_mutex_unlock(&lock_clockid);
}
return (tolower(c) == 'm') ? CLOCK_MONOTONIC : CLOCK_REALTIME;
}
struct log_time { // Wire format struct log_time { // Wire format
uint32_t tv_sec; uint32_t tv_sec;
uint32_t tv_nsec; uint32_t tv_nsec;
@ -501,7 +563,7 @@ static int __libc_write_log(int priority, const char* tag, const char* msg) {
vec[1].iov_base = &tid; vec[1].iov_base = &tid;
vec[1].iov_len = sizeof(tid); vec[1].iov_len = sizeof(tid);
timespec ts; timespec ts;
clock_gettime(CLOCK_REALTIME, &ts); clock_gettime(android_log_clockid(), &ts);
log_time realtime_ts; log_time realtime_ts;
realtime_ts.tv_sec = ts.tv_sec; realtime_ts.tv_sec = ts.tv_sec;
realtime_ts.tv_nsec = ts.tv_nsec; realtime_ts.tv_nsec = ts.tv_nsec;
@ -544,7 +606,7 @@ static int __libc_android_log_event(int32_t tag, char type, const void* payload,
vec[1].iov_base = &tid; vec[1].iov_base = &tid;
vec[1].iov_len = sizeof(tid); vec[1].iov_len = sizeof(tid);
timespec ts; timespec ts;
clock_gettime(CLOCK_REALTIME, &ts); clock_gettime(android_log_clockid(), &ts);
log_time realtime_ts; log_time realtime_ts;
realtime_ts.tv_sec = ts.tv_sec; realtime_ts.tv_sec = ts.tv_sec;
realtime_ts.tv_nsec = ts.tv_nsec; realtime_ts.tv_nsec = ts.tv_nsec;