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LibC: Add a cache for getpid()

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This works the same as gettid(). No sense in making a syscall to the
kernel every time you ask for the PID since it won't change.
Just like gettid(), the cache is invalidated on fork().
This commit is contained in:
Andreas Kling 2020-07-21 18:45:06 +02:00
parent 15753e9633
commit b820e4626c
1 changed files with 7 additions and 2 deletions
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9
Libraries/LibC/unistd.cpp
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@ -47,6 +47,7 @@
extern "C" { extern "C" {
static __thread int s_cached_tid = 0; static __thread int s_cached_tid = 0;
static __thread int s_cached_pid = 0;
int chown(const char* pathname, uid_t uid, gid_t gid) int chown(const char* pathname, uid_t uid, gid_t gid)
{ {
@ -68,8 +69,10 @@ int fchown(int fd, uid_t uid, gid_t gid)
pid_t fork() pid_t fork()
{ {
int rc = syscall(SC_fork); int rc = syscall(SC_fork);
if (rc == 0) if (rc == 0) {
s_cached_tid = 0; s_cached_tid = 0;
s_cached_pid = 0;
}
__RETURN_WITH_ERRNO(rc, rc, -1); __RETURN_WITH_ERRNO(rc, rc, -1);
} }
@ -199,7 +202,9 @@ gid_t getgid()
pid_t getpid() pid_t getpid()
{ {
return syscall(SC_getpid); if (!s_cached_pid)
s_cached_pid = syscall(SC_getpid);
return s_cached_pid;
} }
pid_t getppid() pid_t getppid()