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pthread: introduce pthread_setname_np() as a mean to give names to threads

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... so that each cloned process at the kernel level can be named
independently. Tools like 'top' can display the CPU/memory statistics
for each process's thread if "Show Threads" mode is on.

With this function in place, we can convert dalvik/Thread.c setThreadName()
function over this function. This feature ought to be provided by the
underlying C library and not coded directly in Dalvik.

Change-Id: Ifa997665dbaa114e0b126f8c667708be9a4137fd
Signed-off-by: André Goddard Rosa <andre.goddard@gmail.com>
This commit is contained in:
André Goddard Rosa
2010-05-19 23:17:16 -03:00
parent 1297428e89
commit 78c1c04ced
3 changed files with 62 additions and 0 deletions
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54
libc/bionic/pthread.c
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@@ -43,6 +43,9 @@
#include <memory.h>
#include <assert.h>
#include <malloc.h>
#include <sys/prctl.h>
#include <sys/stat.h>
#include <fcntl.h>
extern int __pthread_clone(int (*fn)(void*), void *child_stack, int flags, void *arg);
extern void _exit_with_stack_teardown(void * stackBase, int stackSize, int retCode);
@@ -1721,3 +1724,54 @@ int pthread_once( pthread_once_t* once_control, void (*init_routine)(void) )
}
return 0;
}
/* This value is not exported by kernel headers, so hardcode it here */
#define MAX_TASK_COMM_LEN 16
#define TASK_COMM_FMT "/proc/self/task/%u/comm"
int pthread_setname_np(pthread_t thid, const char *thname)
{
size_t thname_len;
int saved_errno, ret;
if (thid == 0 || thname == NULL)
return EINVAL;
thname_len = strlen(thname);
if (thname_len >= MAX_TASK_COMM_LEN)
return ERANGE;
saved_errno = errno;
if (thid == pthread_self())
{
ret = prctl(PR_SET_NAME, (unsigned long)thname, 0, 0, 0) ? errno : 0;
}
else
{
/* Have to change another thread's name */
pthread_internal_t *thread = (pthread_internal_t *)thid;
char comm_name[sizeof(TASK_COMM_FMT) + 8];
ssize_t n;
int fd;
snprintf(comm_name, sizeof(comm_name), TASK_COMM_FMT, (unsigned int)thread->kernel_id);
fd = open(comm_name, O_RDWR);
if (fd == -1)
{
ret = errno;
goto exit;
}
n = TEMP_FAILURE_RETRY(write(fd, thname, thname_len));
close(fd);
if (n < 0)
ret = errno;
else if ((size_t)n != thname_len)
ret = EIO;
else
ret = 0;
}
exit:
errno = saved_errno;
return ret;
}