d/freebsd-nq
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Remove (int) file descriptor locking. It should be up to the

Browse Source 
application to provide locking for I/O operations.  This doesn't
break any of my tests, but the old behavior can be restored by
compiling with _FDLOCKS_ENABLED.  This will eventually be removed
when it is obvious it does not cause any problems.

Remove most of flockfile implementation, with the exception of
flockfile_debug.

Make error messages more informational (submitted by Mike Heffner
<spock@techfour.net>, who's now known as mikeh@FreeBSD.org).
This commit is contained in:
Daniel Eischen 2001-02-11 22:07:32 +00:00
parent 29ac6bd228
commit f434cd45ed
11 changed files with 59 additions and 512 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
lib/libc_r/uthread/pthread_private.h
View File

@ -1208,8 +1208,6 @@ void _cond_wait_backout(pthread_t);
void _fd_lock_backout(pthread_t);
int _find_dead_thread(pthread_t);
int _find_thread(pthread_t);
void _flockfile_backout(pthread_t);
void _funlock_owned(pthread_t);
struct pthread *_get_curthread(void);
void _set_curthread(struct pthread *);
void _join_backout(pthread_t);
@ -1241,6 +1239,7 @@ int _pthread_mutexattr_init(pthread_mutexattr_t *);
int _pthread_mutexattr_destroy(pthread_mutexattr_t *);
int _pthread_mutexattr_settype(pthread_mutexattr_t *, int);
int _pthread_once(pthread_once_t *, void (*) (void));
pthread_t _pthread_self(void);
int _pthread_setspecific(pthread_key_t, const void *);
void _waitq_insert(pthread_t pthread);
void _waitq_remove(pthread_t pthread);

13
lib/libc_r/uthread/uthread_exit.c
View File

@ -87,13 +87,9 @@ _thread_exit(char *fname, int lineno, char *string)
char s[256];
/* Prepare an error message string: */
strcpy(s, "Fatal error '");
strcat(s, string);
strcat(s, "' at line ? ");
strcat(s, "in file ");
strcat(s, fname);
strcat(s, " (errno = ?");
strcat(s, ")\n");
snprintf(s, sizeof(s),
"Fatal error '%s' at line %d in file %s (errno = %d)\n",
string, lineno, fname, errno);
/* Write the string to the standard error file descriptor: */
__sys_write(2, s, strlen(s));
@ -127,9 +123,6 @@ _thread_exit_cleanup(void)
/* Unlock all owned fd locks: */
_thread_fd_unlock_owned(curthread);
/* Unlock all owned file locks: */
_funlock_owned(curthread);
/* Unlock all private mutexes: */
_mutex_unlock_private(curthread);

40
lib/libc_r/uthread/uthread_fd.c
View File

@ -58,8 +58,10 @@ do { \
static spinlock_t fd_table_lock = _SPINLOCK_INITIALIZER;
/* Prototypes: */
#ifdef _FDLOCKS_ENABLED
static inline pthread_t fd_next_reader(int fd);
static inline pthread_t fd_next_writer(int fd);
#endif
/*
@ -180,6 +182,7 @@ _thread_fd_table_init(int fd)
return (ret);
}
#ifdef _FDLOCKS_ENABLED
void
_thread_fd_unlock(int fd, int lock_type)
{
@ -991,3 +994,40 @@ fd_next_writer(int fd)
return (pthread);
}
#else
void
_thread_fd_unlock(int fd, int lock_type)
{
}
int
_thread_fd_lock(int fd, int lock_type, struct timespec * timeout)
{
return (0);
}
void
_thread_fd_unlock_debug(int fd, int lock_type, char *fname, int lineno)
{
}
int
_thread_fd_lock_debug(int fd, int lock_type, struct timespec * timeout,
char *fname, int lineno)
{
return (0);
}
void
_thread_fd_unlock_owned(pthread_t pthread)
{
}
void
_fd_lock_backout(pthread_t pthread)
{
}
#endif

468
lib/libc_r/uthread/uthread_file.c
View File

@ -1,5 +1,6 @@
/*
* Copyright (c) 1995 John Birrell <jb@cimlogic.com.au>.
* Copyright (c) 2001 Daniel Eischen <deischen@FreeBSD.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@ -37,472 +38,17 @@
*
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/queue.h>
#include <pthread.h>
#include "pthread_private.h"
/*
* Weak symbols for externally visible functions in this file:
*/
#pragma weak flockfile=_flockfile
#pragma weak ftrylockfile=_ftrylockfile
#pragma weak funlockfile=_funlockfile
/*
* The FILE lock structure. The FILE *fp is locked if the owner is
* not NULL. If not locked, the file lock structure can be
* reassigned to a different file by setting fp.
*/
struct file_lock {
LIST_ENTRY(file_lock) entry; /* Entry if file list. */
TAILQ_HEAD(lock_head, pthread)
l_head; /* Head of queue for threads */
/* waiting on this lock. */
FILE *fp; /* The target file. */
pthread_t owner; /* Thread that owns lock. */
int count; /* Lock count for owner. */
};
/*
* The number of file lock lists into which the file pointer is
* hashed. Ideally, the FILE structure size would have been increased,
* but this causes incompatibility, so separate data structures are
* required.
*/
#define NUM_HEADS 128
/*
* This macro casts a file pointer to a long integer and right
* shifts this by the number of bytes in a pointer. The shifted
* value is then remaindered using the maximum number of hash
* entries to produce and index into the array of static lock
* structures. If there is a collision, a linear search of the
* dynamic list of locks linked to each static lock is perfomed.
*/
#define file_idx(_p) ((((u_long) _p) >> sizeof(void *)) % NUM_HEADS)
/*
* Global array of file locks. The first lock for each hash bucket is
* allocated statically in the hope that there won't be too many
* collisions that require a malloc and an element added to the list.
*/
struct static_file_lock {
LIST_HEAD(file_list_head, file_lock) head;
struct file_lock fl;
} flh[NUM_HEADS];
/* Set to non-zero when initialisation is complete: */
static int init_done = 0;
/* Lock for accesses to the hash table: */
static spinlock_t hash_lock = _SPINLOCK_INITIALIZER;
/*
* Find a lock structure for a FILE, return NULL if the file is
* not locked:
*/
static
struct file_lock *
find_lock(int idx, FILE *fp)
{
struct file_lock *p;
/* Check if the file is locked using the static structure: */
if (flh[idx].fl.fp == fp && flh[idx].fl.owner != NULL)
/* Return a pointer to the static lock: */
p = &flh[idx].fl;
else {
/* Point to the first dynamic lock: */
p = LIST_FIRST(&flh[idx].head);
/*
* Loop through the dynamic locks looking for the
* target file:
*/
while (p != NULL && (p->fp != fp || p->owner == NULL))
/* Not this file, try the next: */
p = LIST_NEXT(p, entry);
}
return(p);
}
/*
* Lock a file, assuming that there is no lock structure currently
* assigned to it.
*/
static
struct file_lock *
do_lock(int idx, FILE *fp)
{
struct pthread *curthread = _get_curthread();
struct file_lock *p;
/* Check if the static structure is not being used: */
if (flh[idx].fl.owner == NULL) {
/* Return a pointer to the static lock: */
p = &flh[idx].fl;
}
else {
/* Point to the first dynamic lock: */
p = LIST_FIRST(&flh[idx].head);
/*
* Loop through the dynamic locks looking for a
* lock structure that is not being used:
*/
while (p != NULL && p->owner != NULL)
/* This one is used, try the next: */
p = LIST_NEXT(p, entry);
}
/*
* If an existing lock structure has not been found,
* allocate memory for a new one:
*/
if (p == NULL && (p = (struct file_lock *)
malloc(sizeof(struct file_lock))) != NULL) {
/* Add the new element to the list: */
LIST_INSERT_HEAD(&flh[idx].head, p, entry);
}
/* Check if there is a lock structure to acquire: */
if (p != NULL) {
/* Acquire the lock for the running thread: */
p->fp = fp;
p->owner = curthread;
p->count = 1;
TAILQ_INIT(&p->l_head);
}
return(p);
}
extern void _flockfile(FILE *);
void
_flockfile_debug(FILE * fp, char *fname, int lineno)
_flockfile_debug(FILE *fp, char *fname, int lineno)
{
struct pthread *curthread = _get_curthread();
int idx = file_idx(fp);
struct file_lock *p;
pthread_t curthread = _pthread_self();
/* Check if this is a real file: */
if (fp->_file >= 0) {
/* Lock the hash table: */
_SPINLOCK(&hash_lock);
/* Check if the static array has not been initialised: */
if (!init_done) {
/* Initialise the global array: */
memset(flh,0,sizeof(flh));
/* Flag the initialisation as complete: */
init_done = 1;
}
/* Get a pointer to any existing lock for the file: */
if ((p = find_lock(idx, fp)) == NULL) {
/*
* The file is not locked, so this thread can
* grab the lock:
*/
p = do_lock(idx, fp);
/* Unlock the hash table: */
_SPINUNLOCK(&hash_lock);
/*
* The file is already locked, so check if the
* running thread is the owner:
*/
} else if (p->owner == curthread) {
/*
* The running thread is already the
* owner, so increment the count of
* the number of times it has locked
* the file:
*/
p->count++;
/* Unlock the hash table: */
_SPINUNLOCK(&hash_lock);
} else {
/* Clear the interrupted flag: */
curthread->interrupted = 0;
/*
* Prevent being context switched out while
* adding this thread to the file lock queue.
*/
_thread_kern_sig_defer();
/*
* The file is locked for another thread.
* Append this thread to the queue of
* threads waiting on the lock.
*/
TAILQ_INSERT_TAIL(&p->l_head,curthread,qe);
curthread->flags |= PTHREAD_FLAGS_IN_FILEQ;
/* Unlock the hash table: */
_SPINUNLOCK(&hash_lock);
curthread->data.fp = fp;
/* Wait on the FILE lock: */
_thread_kern_sched_state(PS_FILE_WAIT, fname, lineno);
if ((curthread->flags & PTHREAD_FLAGS_IN_FILEQ) != 0) {
TAILQ_REMOVE(&p->l_head,curthread,qe);
curthread->flags &= ~PTHREAD_FLAGS_IN_FILEQ;
}
_thread_kern_sig_undefer();
if (curthread->interrupted != 0 &&
curthread->continuation != NULL)
curthread->continuation((void *)curthread);
}
}
curthread->lineno = lineno;
curthread->fname = fname;
_flockfile(fp);
}
void
_flockfile(FILE * fp)
{
_flockfile_debug(fp, __FILE__, __LINE__);
}
int
_ftrylockfile(FILE * fp)
{
struct pthread *curthread = _get_curthread();
int ret = -1;
int idx = file_idx(fp);
struct file_lock *p;
/* Check if this is a real file: */
if (fp->_file >= 0) {
/* Lock the hash table: */
_SPINLOCK(&hash_lock);
/* Get a pointer to any existing lock for the file: */
if ((p = find_lock(idx, fp)) == NULL) {
/*
* The file is not locked, so this thread can
* grab the lock:
*/
p = do_lock(idx, fp);
/*
* The file is already locked, so check if the
* running thread is the owner:
*/
} else if (p->owner == curthread) {
/*
* The running thread is already the
* owner, so increment the count of
* the number of times it has locked
* the file:
*/
p->count++;
} else {
/*
* The file is locked for another thread,
* so this try fails.
*/
p = NULL;
}
/* Check if the lock was obtained: */
if (p != NULL)
/* Return success: */
ret = 0;
/* Unlock the hash table: */
_SPINUNLOCK(&hash_lock);
}
return (ret);
}
void
_funlockfile(FILE * fp)
{
struct pthread *curthread = _get_curthread();
int idx = file_idx(fp);
struct file_lock *p;
/* Check if this is a real file: */
if (fp->_file >= 0) {
/*
* Defer signals to protect the scheduling queues from
* access by the signal handler:
*/
_thread_kern_sig_defer();
/* Lock the hash table: */
_SPINLOCK(&hash_lock);
/*
* Get a pointer to the lock for the file and check that
* the running thread is the one with the lock:
*/
if ((p = find_lock(idx, fp)) != NULL &&
p->owner == curthread) {
/*
* Check if this thread has locked the FILE
* more than once:
*/
if (p->count > 1)
/*
* Decrement the count of the number of
* times the running thread has locked this
* file:
*/
p->count--;
else {
/*
* The running thread will release the
* lock now:
*/
p->count = 0;
/* Get the new owner of the lock: */
while ((p->owner = TAILQ_FIRST(&p->l_head)) != NULL) {
/* Pop the thread off the queue: */
TAILQ_REMOVE(&p->l_head,p->owner,qe);
p->owner->flags &= ~PTHREAD_FLAGS_IN_FILEQ;
if (p->owner->interrupted == 0) {
/*
* This is the first lock for
* the new owner:
*/
p->count = 1;
/* Allow the new owner to run: */
PTHREAD_NEW_STATE(p->owner,PS_RUNNING);
/* End the loop when we find a
* thread that hasn't been
* cancelled or interrupted;
*/
break;
}
}
}
}
/* Unlock the hash table: */
_SPINUNLOCK(&hash_lock);
/*
* Undefer and handle pending signals, yielding if
* necessary:
*/
_thread_kern_sig_undefer();
}
}
void
_funlock_owned(pthread_t pthread)
{
int idx;
struct file_lock *p, *next_p;
/*
* Defer signals to protect the scheduling queues from
* access by the signal handler:
*/
_thread_kern_sig_defer();
/* Lock the hash table: */
_SPINLOCK(&hash_lock);
for (idx = 0; idx < NUM_HEADS; idx++) {
/* Check the static file lock first: */
p = &flh[idx].fl;
next_p = LIST_FIRST(&flh[idx].head);
while (p != NULL) {
if (p->owner == pthread) {
/*
* The running thread will release the
* lock now:
*/
p->count = 0;
/* Get the new owner of the lock: */
while ((p->owner = TAILQ_FIRST(&p->l_head)) != NULL) {
/* Pop the thread off the queue: */
TAILQ_REMOVE(&p->l_head,p->owner,qe);
p->owner->flags &= ~PTHREAD_FLAGS_IN_FILEQ;
if (p->owner->interrupted == 0) {
/*
* This is the first lock for
* the new owner:
*/
p->count = 1;
/* Allow the new owner to run: */
PTHREAD_NEW_STATE(p->owner,PS_RUNNING);
/* End the loop when we find a
* thread that hasn't been
* cancelled or interrupted;
*/
break;
}
}
}
p = next_p;
if (next_p != NULL)
next_p = LIST_NEXT(next_p, entry);
}
}
/* Unlock the hash table: */
_SPINUNLOCK(&hash_lock);
/*
* Undefer and handle pending signals, yielding if
* necessary:
*/
_thread_kern_sig_undefer();
}
void
_flockfile_backout(pthread_t pthread)
{
int idx = file_idx(pthread->data.fp);
struct file_lock *p;
/*
* Defer signals to protect the scheduling queues from
* access by the signal handler:
*/
_thread_kern_sig_defer();
/*
* Get a pointer to the lock for the file and check that
* the running thread is the one with the lock:
*/
if (((pthread->flags & PTHREAD_FLAGS_IN_FILEQ) != 0) &&
((p = find_lock(idx, pthread->data.fp)) != NULL)) {
/* Lock the hash table: */
_SPINLOCK(&hash_lock);
/* Remove the thread from the queue: */
TAILQ_REMOVE(&p->l_head, pthread, qe);
pthread->flags &= ~PTHREAD_FLAGS_IN_FILEQ;
/* Unlock the hash table: */
_SPINUNLOCK(&hash_lock);
}
/*
* Undefer and handle pending signals, yielding if necessary:
*/
_thread_kern_sig_undefer();
}

5
lib/libc_r/uthread/uthread_sig.c
View File

@ -941,11 +941,6 @@ _thread_sig_wrapper(void)
psf->saved_state.psd_state = PS_RUNNING;
break;
case PS_FILE_WAIT:
_flockfile_backout(thread);
psf->saved_state.psd_state = PS_RUNNING;
break;
case PS_COND_WAIT:
_cond_wait_backout(thread);
psf->saved_state.psd_state = PS_RUNNING;

13
lib/libkse/thread/thr_exit.c
View File

@ -87,13 +87,9 @@ _thread_exit(char *fname, int lineno, char *string)
char s[256];
/* Prepare an error message string: */
strcpy(s, "Fatal error '");
strcat(s, string);
strcat(s, "' at line ? ");
strcat(s, "in file ");
strcat(s, fname);
strcat(s, " (errno = ?");
strcat(s, ")\n");
snprintf(s, sizeof(s),
"Fatal error '%s' at line %d in file %s (errno = %d)\n",
string, lineno, fname, errno);
/* Write the string to the standard error file descriptor: */
__sys_write(2, s, strlen(s));
@ -127,9 +123,6 @@ _thread_exit_cleanup(void)
/* Unlock all owned fd locks: */
_thread_fd_unlock_owned(curthread);
/* Unlock all owned file locks: */
_funlock_owned(curthread);
/* Unlock all private mutexes: */
_mutex_unlock_private(curthread);

3
lib/libkse/thread/thr_private.h
View File

@ -1208,8 +1208,6 @@ void _cond_wait_backout(pthread_t);
void _fd_lock_backout(pthread_t);
int _find_dead_thread(pthread_t);
int _find_thread(pthread_t);
void _flockfile_backout(pthread_t);
void _funlock_owned(pthread_t);
struct pthread *_get_curthread(void);
void _set_curthread(struct pthread *);
void _join_backout(pthread_t);
@ -1241,6 +1239,7 @@ int _pthread_mutexattr_init(pthread_mutexattr_t *);
int _pthread_mutexattr_destroy(pthread_mutexattr_t *);
int _pthread_mutexattr_settype(pthread_mutexattr_t *, int);
int _pthread_once(pthread_once_t *, void (*) (void));
pthread_t _pthread_self(void);
int _pthread_setspecific(pthread_key_t, const void *);
void _waitq_insert(pthread_t pthread);
void _waitq_remove(pthread_t pthread);

5
lib/libkse/thread/thr_sig.c
View File

@ -941,11 +941,6 @@ _thread_sig_wrapper(void)
psf->saved_state.psd_state = PS_RUNNING;
break;
case PS_FILE_WAIT:
_flockfile_backout(thread);
psf->saved_state.psd_state = PS_RUNNING;
break;
case PS_COND_WAIT:
_cond_wait_backout(thread);
psf->saved_state.psd_state = PS_RUNNING;

13
lib/libpthread/thread/thr_exit.c
View File

@ -87,13 +87,9 @@ _thread_exit(char *fname, int lineno, char *string)
char s[256];
/* Prepare an error message string: */
strcpy(s, "Fatal error '");
strcat(s, string);
strcat(s, "' at line ? ");
strcat(s, "in file ");
strcat(s, fname);
strcat(s, " (errno = ?");
strcat(s, ")\n");
snprintf(s, sizeof(s),
"Fatal error '%s' at line %d in file %s (errno = %d)\n",
string, lineno, fname, errno);
/* Write the string to the standard error file descriptor: */
__sys_write(2, s, strlen(s));
@ -127,9 +123,6 @@ _thread_exit_cleanup(void)
/* Unlock all owned fd locks: */
_thread_fd_unlock_owned(curthread);
/* Unlock all owned file locks: */
_funlock_owned(curthread);
/* Unlock all private mutexes: */
_mutex_unlock_private(curthread);

3
lib/libpthread/thread/thr_private.h
View File

@ -1208,8 +1208,6 @@ void _cond_wait_backout(pthread_t);
void _fd_lock_backout(pthread_t);
int _find_dead_thread(pthread_t);
int _find_thread(pthread_t);
void _flockfile_backout(pthread_t);
void _funlock_owned(pthread_t);
struct pthread *_get_curthread(void);
void _set_curthread(struct pthread *);
void _join_backout(pthread_t);
@ -1241,6 +1239,7 @@ int _pthread_mutexattr_init(pthread_mutexattr_t *);
int _pthread_mutexattr_destroy(pthread_mutexattr_t *);
int _pthread_mutexattr_settype(pthread_mutexattr_t *, int);
int _pthread_once(pthread_once_t *, void (*) (void));
pthread_t _pthread_self(void);
int _pthread_setspecific(pthread_key_t, const void *);
void _waitq_insert(pthread_t pthread);
void _waitq_remove(pthread_t pthread);

5
lib/libpthread/thread/thr_sig.c
View File

@ -941,11 +941,6 @@ _thread_sig_wrapper(void)
psf->saved_state.psd_state = PS_RUNNING;
break;
case PS_FILE_WAIT:
_flockfile_backout(thread);
psf->saved_state.psd_state = PS_RUNNING;
break;
case PS_COND_WAIT:
_cond_wait_backout(thread);
psf->saved_state.psd_state = PS_RUNNING;