[rrd-developers] [PATCH] rrdcached: "PENDING" and "FORGET" for cache management
kevin brintnall
kbrint at rufus.net
Tue Oct 7 23:08:01 CEST 2008
This patch introduces two new commands for cache management:
PENDING: shows any un-written updates for a file
FORGET : remove a file completely from cache
This applies cleanly on top of my previous patch ("better permissions
handling").
---
diff --git a/doc/rrdcached.pod b/doc/rrdcached.pod
index 4bd1bb8..b01165e 100644
--- a/doc/rrdcached.pod
+++ b/doc/rrdcached.pod
@@ -363,6 +363,15 @@ sent B<after> the node has been dequeued.
Causes the daemon to start flushing ALL pending values to disk. This
returns immediately, even though the writes may take a long time.
+=item B<PENDING> I<filename>
+
+Shows any "pending" updates for a file, in order. The updates shown have
+not yet been written to the underlying RRD file.
+
+=item B<FORGET> I<filename>
+
+Removes I<filename> from the cache. Any pending updates B<WILL BE LOST>.
+
=item B<HELP> [I<command>]
Returns a short usage message. If no command is given, or I<command> is
diff --git a/src/rrd_daemon.c b/src/rrd_daemon.c
index 30cf748..9c8847d 100644
--- a/src/rrd_daemon.c
+++ b/src/rrd_daemon.c
@@ -540,6 +540,34 @@ static void remove_from_queue(cache_item_t *ci) /* {{{ */
ci->flags &= ~CI_FLAGS_IN_QUEUE;
} /* }}} static void remove_from_queue */
+/* remove an entry from the tree and free all its resources.
+ * must hold 'cache lock' while calling this.
+ * returns 0 on success, otherwise errno */
+static int forget_file(const char *file)
+{
+ cache_item_t *ci;
+
+ ci = g_tree_lookup(cache_tree, file);
+ if (ci == NULL)
+ return ENOENT;
+
+ g_tree_remove (cache_tree, file);
+ remove_from_queue(ci);
+
+ for (int i=0; i < ci->values_num; i++)
+ free(ci->values[i]);
+
+ free (ci->values);
+ free (ci->file);
+
+ /* in case anyone is waiting */
+ pthread_cond_broadcast(&ci->flushed);
+
+ free (ci);
+
+ return 0;
+} /* }}} static int forget_file */
+
/*
* enqueue_cache_item:
* `cache_lock' must be acquired before calling this function!
@@ -674,26 +702,10 @@ static int flush_old_values (int max_age)
for (k = 0; k < cfd.keys_num; k++)
{
- cache_item_t *ci;
-
- /* This must not fail. */
- ci = (cache_item_t *) g_tree_lookup (cache_tree, cfd.keys[k]);
- assert (ci != NULL);
-
- /* If we end up here with values available, something's seriously
- * messed up. */
- assert (ci->values_num == 0);
-
- /* Remove the node from the tree */
- g_tree_remove (cache_tree, cfd.keys[k]);
- cfd.keys[k] = NULL;
-
- /* Now free and clean up `ci'. */
- free (ci->file);
- ci->file = NULL;
- free (ci);
- ci = NULL;
- } /* for (k = 0; k < cfd.keys_num; k++) */
+ /* should never fail, since we have held the cache_lock
+ * the entire time */
+ assert( forget_file(cfd.keys[k]) == 0 );
+ }
if (cfd.keys != NULL)
{
@@ -977,6 +989,9 @@ static int flush_file (const char *filename) /* {{{ */
pthread_cond_wait(&ci->flushed, &cache_lock);
}
+ /* DO NOT DO ANYTHING WITH ci HERE!! The entry
+ * may have been purged during our cond_wait() */
+
pthread_mutex_unlock(&cache_lock);
return (0);
@@ -993,9 +1008,11 @@ static int handle_request_help (listen_socket_t *sock, /* {{{ */
{
"Command overview\n"
,
+ "HELP [<command>]\n"
"FLUSH <filename>\n"
"FLUSHALL\n"
- "HELP [<command>]\n"
+ "PENDING <filename>\n"
+ "FORGET <filename>\n"
"UPDATE <filename> <values> [<values> ...]\n"
"BATCH\n"
"STATS\n"
@@ -1020,6 +1037,26 @@ static int handle_request_help (listen_socket_t *sock, /* {{{ */
"Triggers writing of all pending updates. Returns immediately.\n"
};
+ char *help_pending[2] =
+ {
+ "Help for PENDING\n"
+ ,
+ "Usage: PENDING <filename>\n"
+ "\n"
+ "Shows any 'pending' updates for a file, in order.\n"
+ "The updates shown have not yet been written to the underlying RRD file.\n"
+ };
+
+ char *help_forget[2] =
+ {
+ "Help for FORGET\n"
+ ,
+ "Usage: FORGET <filename>\n"
+ "\n"
+ "Removes the file completely from the cache.\n"
+ "Any pending updates for the file will be lost.\n"
+ };
+
char *help_update[2] =
{
"Help for UPDATE\n"
@@ -1078,6 +1115,10 @@ static int handle_request_help (listen_socket_t *sock, /* {{{ */
help_text = help_flush;
else if (strcasecmp (command, "flushall") == 0)
help_text = help_flushall;
+ else if (strcasecmp (command, "pending") == 0)
+ help_text = help_pending;
+ else if (strcasecmp (command, "forget") == 0)
+ help_text = help_forget;
else if (strcasecmp (command, "stats") == 0)
help_text = help_stats;
else if (strcasecmp (command, "batch") == 0)
@@ -1198,6 +1239,73 @@ static int handle_request_flushall(listen_socket_t *sock) /* {{{ */
return send_response(sock, RESP_OK, "Started flush.\n");
} /* }}} static int handle_request_flushall */
+static int handle_request_pending(listen_socket_t *sock, /* {{{ */
+ char *buffer, size_t buffer_size)
+{
+ int status;
+ char *file;
+ cache_item_t *ci;
+
+ status = buffer_get_field(&buffer, &buffer_size, &file);
+ if (status != 0)
+ return send_response(sock, RESP_ERR,
+ "Usage: PENDING <filename>\n");
+
+ status = has_privilege(sock, PRIV_HIGH);
+ if (status <= 0)
+ return status;
+
+ pthread_mutex_lock(&cache_lock);
+ ci = g_tree_lookup(cache_tree, file);
+ if (ci == NULL)
+ {
+ pthread_mutex_unlock(&cache_lock);
+ return send_response(sock, RESP_ERR, "%s\n", rrd_strerror(ENOENT));
+ }
+
+ for (int i=0; i < ci->values_num; i++)
+ add_response_info(sock, "%s\n", ci->values[i]);
+
+ pthread_mutex_unlock(&cache_lock);
+ return send_response(sock, RESP_OK, "updates pending\n");
+} /* }}} static int handle_request_pending */
+
+static int handle_request_forget(listen_socket_t *sock, /* {{{ */
+ char *buffer, size_t buffer_size)
+{
+ int status;
+ char *file;
+
+ status = buffer_get_field(&buffer, &buffer_size, &file);
+ if (status != 0)
+ return send_response(sock, RESP_ERR,
+ "Usage: FORGET <filename>\n");
+
+ status = has_privilege(sock, PRIV_HIGH);
+ if (status <= 0)
+ return status;
+
+ if (!check_file_access(file, sock)) return 0;
+
+ pthread_mutex_lock(&cache_lock);
+ status = forget_file(file);
+ pthread_mutex_unlock(&cache_lock);
+
+ if (status == 0)
+ {
+ if (sock != NULL)
+ journal_write("forget", file);
+
+ return send_response(sock, RESP_OK, "Gone!\n");
+ }
+ else
+ return send_response(sock, RESP_ERR, "cannot forget: %s\n",
+ status < 0 ? "Internal error" : rrd_strerror(status));
+
+ /* NOTREACHED */
+ assert(1==0);
+} /* }}} static int handle_request_forget */
+
static int handle_request_update (listen_socket_t *sock, /* {{{ */
char *buffer, size_t buffer_size)
{
@@ -1430,6 +1538,10 @@ static int handle_request (listen_socket_t *sock, /* {{{ */
return (handle_request_flush (sock, buffer_ptr, buffer_size));
else if (strcasecmp (command, "flushall") == 0)
return (handle_request_flushall(sock));
+ else if (strcasecmp (command, "pending") == 0)
+ return (handle_request_pending(sock, buffer_ptr, buffer_size));
+ else if (strcasecmp (command, "forget") == 0)
+ return (handle_request_forget(sock, buffer_ptr, buffer_size));
else if (strcasecmp (command, "stats") == 0)
return (handle_request_stats (sock));
else if (strcasecmp (command, "help") == 0)
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