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authorroot <root>2011-07-18 02:59:58 +0000
committerroot <root>2011-07-18 02:59:58 +0000
commit96045cbe9a089897107decefa9ff97d0d3b2810e (patch)
tree986553ac3cf61d4548b0e744a8dc3d4ba6da1f2b
parent7b5974c9e146f327c9a27f1d97d7fb6a8b95d15d (diff)
*** empty log message ***rel-4_0
-rw-r--r--eio.c43
-rw-r--r--eio.pod36
2 files changed, 35 insertions, 44 deletions
diff --git a/eio.c b/eio.c
index b367868..063e50a 100644
--- a/eio.c
+++ b/eio.c
@@ -235,13 +235,13 @@ static void eio_destroy (eio_req *req);
#define EIO_BUFSIZE 65536
#define dBUF \
- char *eio_buf; \
- ETP_WORKER_LOCK (self); \
- self->dbuf = eio_buf = malloc (EIO_BUFSIZE); \
- ETP_WORKER_UNLOCK (self); \
+ char *eio_buf = malloc (EIO_BUFSIZE); \
errno = ENOMEM; \
if (!eio_buf) \
- return -1;
+ return -1
+
+#define FUBd \
+ free (eio_buf)
#define EIO_TICKS ((1000000 + 1023) >> 10)
@@ -257,16 +257,6 @@ static int eio_finish (eio_req *req);
static void eio_execute (struct etp_worker *self, eio_req *req);
#define ETP_EXECUTE(wrk,req) eio_execute (wrk,req)
-#define ETP_WORKER_CLEAR(req) \
- if (wrk->dbuf) \
- { \
- free (wrk->dbuf); \
- wrk->dbuf = 0; \
- }
-
-#define ETP_WORKER_COMMON \
- void *dbuf;
-
/*****************************************************************************/
#define ETP_NUM_PRI (ETP_PRI_MAX - ETP_PRI_MIN + 1)
@@ -317,7 +307,9 @@ typedef struct etp_worker
/* locked by reslock, reqlock or wrklock */
ETP_REQ *req; /* currently processed request */
+#ifdef ETP_WORKER_COMMON
ETP_WORKER_COMMON
+#endif
} etp_worker;
static etp_worker wrk_first; /* NOT etp */
@@ -330,7 +322,6 @@ static etp_worker wrk_first; /* NOT etp */
static void ecb_cold
etp_worker_clear (etp_worker *wrk)
{
- ETP_WORKER_CLEAR (wrk);
}
static void ecb_cold
@@ -999,6 +990,8 @@ eio__readahead (int fd, off_t offset, size_t count, etp_worker *self)
todo -= len;
}
+ FUBd;
+
errno = 0;
return count;
}
@@ -1007,7 +1000,7 @@ eio__readahead (int fd, off_t offset, size_t count, etp_worker *self)
/* sendfile always needs emulation */
static eio_ssize_t
-eio__sendfile (int ofd, int ifd, off_t offset, size_t count, etp_worker *self)
+eio__sendfile (int ofd, int ifd, off_t offset, size_t count)
{
eio_ssize_t written = 0;
eio_ssize_t res;
@@ -1153,6 +1146,8 @@ eio__sendfile (int ofd, int ifd, off_t offset, size_t count, etp_worker *self)
res += cnt;
count -= cnt;
}
+
+ FUBd;
}
return res;
@@ -2027,7 +2022,7 @@ eio_execute (etp_worker *self, eio_req *req)
: write (req->int1, req->ptr2, req->size); break;
case EIO_READAHEAD: req->result = readahead (req->int1, req->offs, req->size); break;
- case EIO_SENDFILE: req->result = eio__sendfile (req->int1, req->int2, req->offs, req->size, self); break;
+ case EIO_SENDFILE: req->result = eio__sendfile (req->int1, req->int2, req->offs, req->size); break;
case EIO_STAT: ALLOC (sizeof (EIO_STRUCT_STAT));
req->result = stat (req->ptr1, (EIO_STRUCT_STAT *)req->ptr2); break;
@@ -2427,16 +2422,6 @@ eio_grp_add (eio_req *grp, eio_req *req)
eio_ssize_t
eio_sendfile_sync (int ofd, int ifd, off_t offset, size_t count)
{
- etp_worker wrk;
- eio_ssize_t ret;
-
- wrk.dbuf = 0;
-
- ret = eio__sendfile (ofd, ifd, offset, count, &wrk);
-
- if (wrk.dbuf)
- free (wrk.dbuf);
-
- return ret;
+ return eio__sendfile (ofd, ifd, offset, count);
}
diff --git a/eio.pod b/eio.pod
index a2ccf24..5c81d4b 100644
--- a/eio.pod
+++ b/eio.pod
@@ -47,21 +47,24 @@ time differences throughout libeio.
=head2 FORK SUPPORT
-Calling C<fork ()> is fully supported by this module - but you must not
-rely on this. It is currently implemented in these steps:
-
- 1. wait till all requests in "execute" state have been handled
- (basically requests that are already handed over to the kernel).
- 2. fork
- 3. in the parent, continue business as usual, done
- 4. in the child, destroy all ready and pending requests and free the
- memory used by the worker threads. This gives you a fully empty
- libeio queue.
-
-Note, however, since libeio does use threads, the above guarantee doesn't
-cover your libc, for example, malloc and other libc functions are not
-fork-safe, so there is very little you can do after a fork, and in fact,
-the above might crash, and thus change.
+Usage of pthreads in a program changes the semantics of fork
+considerably. Specifically, only async-safe functions can be called after
+fork. Libeio uses pthreads, so this applies, and makes using fork hard for
+anything but relatively fork + exec uses.
+
+This library only works in the process that initialised it: Forking is
+fully supported, but using libeio in any other process than the one that
+called C<eio_init> is not.
+
+You might get around by not I<using> libeio before (or after) forking in
+the parent, and using it in the child afterwards. You could also try to
+call the L<eio_init> function again in the child, which will brutally
+reinitialise all data structures, which isn't POSIX conformant, but
+typically works.
+
+Otherwise, the only recommendation you should follow is: treat fork code
+the same way you treat signal handlers, and only ever call C<eio_init> in
+the process that uses it, and only once ever.
=head1 INITIALISATION/INTEGRATION
@@ -81,6 +84,9 @@ failure it returns C<-1> and sets C<errno> appropriately.
It accepts two function pointers specifying callbacks as argument, both of
which can be C<0>, in which case the callback isn't called.
+There is currently no way to change these callbacks later, or to
+"uninitialise" the library again.
+
=item want_poll callback
The C<want_poll> callback is invoked whenever libeio wants attention (i.e.