diff options
Diffstat (limited to 'source3')
| -rw-r--r-- | source3/lib/select.c | 15 | ||||
| -rw-r--r-- | source3/printing/printing.c | 132 |
2 files changed, 130 insertions, 17 deletions
diff --git a/source3/lib/select.c b/source3/lib/select.c index 458642f57e..c654a4a02c 100644 --- a/source3/lib/select.c +++ b/source3/lib/select.c @@ -58,6 +58,21 @@ int sys_select(int maxfd, fd_set *fds,struct timeval *tval) if (initialised != sys_getpid()) { pipe(select_pipe); + + /* + * These next two lines seem to fix a bug with the Linux + * 2.0.x kernel (and probably other UNIXes as well) where + * the one byte read below can block even though the + * select returned that there is data in the pipe and + * the pipe_written variable was incremented. Thanks to + * HP for finding this one. JRA. + */ + + if(set_blocking(select_pipe[0],0)==-1) + smb_panic("select_pipe[0]: O_NONBLOCK failed.\n"); + if(set_blocking(select_pipe[1],0)==-1) + smb_panic("select_pipe[1]: O_NONBLOCK failed.\n"); + initialised = sys_getpid(); } diff --git a/source3/printing/printing.c b/source3/printing/printing.c index 49681d9040..b0b0482cd3 100644 --- a/source3/printing/printing.c +++ b/source3/printing/printing.c @@ -320,8 +320,63 @@ static void print_cache_flush(int snum) } /**************************************************************************** + Check if someone already thinks they are doing the update. +****************************************************************************/ + +static pid_t get_updating_pid(fstring printer_name) +{ + fstring keystr; + TDB_DATA data, key; + pid_t updating_pid; + + slprintf(keystr, sizeof(keystr), "UPDATING/%s", printer_name); + key.dptr = keystr; + key.dsize = strlen(keystr); + + data = tdb_fetch(tdb, key); + if (!data.dptr || data.dsize != sizeof(pid_t)) + return (pid_t)-1; + + memcpy(&updating_pid, data.dptr, sizeof(pid_t)); + free(data.dptr); + + if (process_exists(updating_pid)) + return updating_pid; + + return (pid_t)-1; +} + +/**************************************************************************** + Set the fact that we're doing the update, or have finished doing the update + in th tdb. +****************************************************************************/ + +static void set_updating_pid(fstring printer_name, BOOL delete) +{ + fstring keystr; + TDB_DATA key; + TDB_DATA data; + pid_t updating_pid = getpid(); + + slprintf(keystr, sizeof(keystr), "UPDATING/%s", printer_name); + key.dptr = keystr; + key.dsize = strlen(keystr); + + if (delete) { + tdb_delete(tdb, key); + return; + } + + data.dptr = (void *)&updating_pid; + data.dsize = sizeof(pid_t); + + tdb_store(tdb, key, data, TDB_REPLACE); +} + +/**************************************************************************** update the internal database from the system print queue for a queue ****************************************************************************/ + static void print_queue_update(int snum) { char *path = lp_pathname(snum); @@ -334,21 +389,71 @@ static void print_queue_update(int snum) print_status_struct old_status; struct printjob *pjob; struct traverse_struct tstruct; - fstring keystr, printer_name; + fstring keystr, printer_name, cachestr; TDB_DATA data, key; - + /* Convert printer name (i.e. share name) to unix-codepage for all of the * following tdb key generation */ fstrcpy(printer_name, lp_servicename(snum)); dos_to_unix(printer_name, True); /* - * Update the cache time FIRST ! Stops others doing this - * if the lpq takes a long time. + * Check to see if someone else is doing this update. + * This is essentially a mutex on the update. */ - slprintf(keystr, sizeof(keystr), "CACHE/%s", printer_name); - tdb_store_int(tdb, keystr, (int)time(NULL)); + if (get_updating_pid(printer_name) == -1) { + /* Lock the queue for the database update */ + + slprintf(keystr, sizeof(keystr) - 1, "LOCK/%s", printer_name); + tdb_lock_bystring(tdb, keystr); + + /* + * Ensure that no one else got in here. + * If the updating pid is still -1 then we are + * the winner. + */ + + if (get_updating_pid(printer_name) != -1) { + /* + * Someone else is doing the update, exit. + */ + tdb_unlock_bystring(tdb, keystr); + return; + } + + /* + * We're going to do the update ourselves. + */ + + /* Tell others we're doing the update. */ + set_updating_pid(printer_name, False); + + /* + * Allow others to enter and notice we're doing + * the update. + */ + + tdb_unlock_bystring(tdb, keystr); + + /* + * Update the cache time FIRST ! Stops others even + * attempting to get the lock and doing this + * if the lpq takes a long time. + */ + + slprintf(cachestr, sizeof(cachestr), "CACHE/%s", printer_name); + tdb_store_int(tdb, cachestr, (int)time(NULL)); + + } + else + { + /* + * Someone else is already doing the update, defer to + * them. + */ + return; + } slprintf(tmp_file, sizeof(tmp_file), "%s/smblpq.%d", path, local_pid); @@ -379,11 +484,6 @@ static void print_queue_update(int snum) DEBUG(3, ("%d job%s in queue for %s\n", qcount, (qcount != 1) ? "s" : "", printer_name)); - /* Lock the queue for the database update */ - - slprintf(keystr, sizeof(keystr) - 1, "LOCK/%s", printer_name); - tdb_lock_bystring(tdb, keystr); - /* any job in the internal database that is marked as spooled and doesn't exist in the system queue is considered finished @@ -446,7 +546,7 @@ static void print_queue_update(int snum) /* store the new queue status structure */ slprintf(keystr, sizeof(keystr), "STATUS/%s", printer_name); - key.dptr = keystr; + key.dptr = keystr; key.dsize = strlen(keystr); status.qcount = qcount; @@ -454,11 +554,6 @@ static void print_queue_update(int snum) data.dsize = sizeof(status); tdb_store(tdb, key, data, TDB_REPLACE); - /* Unlock for database update */ - - slprintf(keystr, sizeof(keystr) - 1, "LOCK/%s", printer_name); - tdb_unlock_bystring(tdb, keystr); - /* * Update the cache time again. We want to do this call * as little as possible... @@ -466,6 +561,9 @@ static void print_queue_update(int snum) slprintf(keystr, sizeof(keystr), "CACHE/%s", printer_name); tdb_store_int(tdb, keystr, (int)time(NULL)); + + /* Delete our pid from the db. */ + set_updating_pid(printer_name, True); } /**************************************************************************** |