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#include "threadimpl.h"
#include "BSD.c"
#include <dlfcn.h>
#define MIN(a,b) ((a) < (b) ? (a) : (b))
#define MAX(a,b) ((a) > (b) ? (a) : (b))
enum {
FD_READ = 1,
FD_WRITE,
FD_RDWR,
FDTBL_MAXSIZE = 128
};
struct fd_entry {
QLock lock;
int fd;
int id;
short rc;
short wc;
short ref;
};
static struct fd_entry fd_entry1 = { .fd -1 };
static struct fd_entry *fd_table = nil;
static spinlock_t fd_table_lock = { 0, 0, nil, 0 };
static spinlock_t mlock = { 0, 0, nil, 0 };
static spinlock_t dl_lock = { 0, 0, nil, 0 };
void
_thread_malloc_lock(void)
{
_spinlock(&mlock);
}
void
_thread_malloc_unlock(void)
{
_spinunlock(&mlock);
}
void
_thread_malloc_init(void)
{
}
/*
* Must set errno on failure because the return value
* of _thread_fd_entry is propagated back to the caller
* of the thread-wrapped libc function.
*/
static struct fd_entry *
_thread_fd_lookup(int fd)
{
struct fd_entry *t;
static int cursize;
int newsize;
if(fd >= FDTBL_MAXSIZE) {
errno = EBADF;
return nil;
}
/*
* There are currently only a few libc functions using
* _thread_fd_*, which are rarely called by P9P programs.
* So the contention for these locks is very small and so
* far have usually been limited to a single fd. So
* rather than malloc the fd_table everytime we just use
* a single fd_entry until a lock request for another fd
* comes in.
*/
if(fd_table == nil)
if(fd_entry1.fd == -1) {
fd_entry1.fd = fd;
return &fd_entry1;
} else if(fd_entry1.fd == fd)
return &fd_entry1;
else {
cursize = MAX(fd_entry1.fd, 16);
fd_table = malloc(cursize*sizeof(fd_table[0]));
if(fd_table == nil) {
errno = ENOMEM;
return nil;
}
memset(fd_table, 0, cursize*sizeof(fd_table[0]));
fd_table[fd_entry1.fd] = fd_entry1;
}
if(fd > cursize) {
newsize = MIN(cursize*2, FDTBL_MAXSIZE);
t = realloc(fd_table, newsize*sizeof(fd_table[0]));
if(t == nil) {
errno = ENOMEM;
return nil;
}
fd_table = t;
cursize = newsize;
memset(fd_table, 0, cursize*sizeof(fd_table[0]));
}
return &fd_table[fd];
}
/*
* Mutiple readers just share the lock by incrementing the read count.
* Writers must obtain an exclusive lock.
*/
int
_thread_fd_lock(int fd, int type, struct timespec *time)
{
struct fd_entry *fde;
int id;
_spinlock(&fd_table_lock);
fde = _thread_fd_lookup(fd);
if(fde == nil)
return -1;
if(type == FD_READ) {
if(fde->rc++ >= 1 && fde->wc == 0) {
_spinunlock(&fd_table_lock);
return 0;
}
} else
fde->wc++;
_spinunlock(&fd_table_lock);
/* handle recursion */
id = proc()->osprocid;
if(id == fde->id) {
fde->ref++;
return 0;
}
qlock(&fde->lock);
fde->id = id;
return 0;
}
void
_thread_fd_unlock(int fd, int type)
{
struct fd_entry *fde;
int id;
fde = _thread_fd_lookup(fd);
if(fde == nil) {
fprint(2, "_thread_fd_unlock: fd %d not in table!\n", fd);
return;
}
if(type == FD_READ && --fde->rc >= 1)
return;
else
fde->wc--;
id = proc()->osprocid;
if(id == fde->id && fde->ref > 0) {
fde->ref--;
return;
}
fde->id = 0;
qunlock(&fde->lock);
}
void
_thread_dl_lock(int t)
{
if(t)
_spinunlock(&dl_lock);
else
_spinlock(&dl_lock);
}
void
_pthreadinit(void)
{
__isthreaded = 1;
dlctl(nil, DL_SETTHREADLCK, _thread_dl_lock);
signal(SIGUSR2, sigusr2handler);
}
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