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Avoid initialization of every calloc'd int in fd_map #161

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Merged
arr2036 merged 1 commit into from
Sep 1, 2025
Merged

Avoid initialization of every calloc'd int in fd_map #161

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32 changes: 25 additions & 7 deletions src/linux/platform.c
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Original file line number Diff line number Diff line change
Expand Up @@ -73,6 +73,28 @@ static int nb_max_fd;
static void
linux_kqueue_free(struct kqueue *kq);

/*
* Helper method for dealing with the fd_map to avoid calling calloc()
* on the entire set of fds at once. fd_map uses 0 to indicate that
* an fd is unused instead of -1, so this function adapts the stored
* file descriptors to match.
*/
static void
fd_map_set(int from, int to)
{
fd_map[from] = to + 1;
}

/*
* Helper method for dealing with the fd_map to avoid calling calloc()
* on the entire set of fds at once. See the comment on fd_map_set().
*/
static int
fd_map_get(int fd)
{
return fd_map[fd] - 1;
}

static void
monitoring_thread_cleanup(UNUSED void *arg)
{
Expand Down Expand Up @@ -178,7 +200,7 @@ monitoring_thread_kqueue_cleanup(int signal_fd)
* Signal is received for read side of pipe
* Get FD for write side as it's the kqueue identifier
*/
fd = fd_map[signal_fd];
fd = fd_map_get(signal_fd);
if (fd < 0) {
/* Should not happen */
dbg_printf("fd=%i - not a known FD", fd);
Expand Down Expand Up @@ -235,8 +257,6 @@ monitoring_thread_loop(UNUSED void *arg)
int res = 0;
siginfo_t info;

int i;

sigset_t monitoring_sig_set;

/* Set the thread's name to something descriptive so it shows up in gdb,
Expand All @@ -263,8 +283,6 @@ monitoring_thread_loop(UNUSED void *arg)
error:
return NULL;
}
for (i = 0; i < nb_max_fd; i++)
fd_map[i] = -1;

fd_use_cnt = calloc(nb_max_fd, sizeof(unsigned int));
if (fd_use_cnt == NULL){
Expand Down Expand Up @@ -298,7 +316,7 @@ monitoring_thread_loop(UNUSED void *arg)
*/
pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, NULL);
tracing_mutex_lock(&kq_mtx);
dbg_printf("fd=%i - freeing kqueue due to fd closure (signal) for sfd=%i ", fd_map[info.si_fd], info.si_fd);
dbg_printf("fd=%i - freeing kqueue due to fd closure (signal) for sfd=%i ", fd_map_get(info.si_fd), info.si_fd);

/*
* Release resources used by this kqueue
Expand Down Expand Up @@ -535,7 +553,7 @@ linux_kqueue_init(struct kqueue *kq)
}

/* Update pipe FD map */
fd_map[kq->pipefd[0]] = kq->kq_id;
fd_map_set(kq->pipefd[0], kq->kq_id);

/* Mark this id as in use */
fd_use_cnt[kq->kq_id]++;
Expand Down