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authorJeremy Allison <jra@samba.org>2001-02-22 17:39:36 +0000
committerJeremy Allison <jra@samba.org>2001-02-22 17:39:36 +0000
commitffa09ecfc1a77f03174ec0460d566190f2413a4d (patch)
tree053eb310fb0e700338454b3be3ad3f56ff650441 /source3/printing
parent5462cf51ee3056b93dbf48138f5b3268f18a5158 (diff)
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lib/select.c: Fix for Linux 2.0.x kernel that causes select to return true on a pipe
and then a blocking read to fail. Make the pipe read/write non blocking. printing/printing.c: Added a mutex around the code that enumerates all the jobs in a print queue. Allows only one smbd to be doing this at any one time. This fixes a capacity problem discovered at HP with <10,000 jobs in a print queue. Jeremy. (This used to be commit 0d3ae603a2b86d476458ee2a7d4f7d22636c3f66)
Diffstat (limited to 'source3/printing')
-rw-r--r--source3/printing/printing.c132
1 files changed, 115 insertions, 17 deletions
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);
}
/****************************************************************************