s3: Implement global locks in a g_lock tdb

This is the basis to implement global locks in ctdb without depending on a
shared file system. The initial goal is to make ctdb persistent transactions
deterministic without too many timeouts.

1 files changed, 213 insertions, 0 deletions

diff --git a/source3/utils/net_g_lock.c b/source3/utils/net_g_lock.c
new file mode 100644
index 0000000000..f30ed331be
--- /dev/null
+++ b/source3/utils/net_g_lock.c
@@ -0,0 +1,213 @@
+/*
+ * Samba Unix/Linux SMB client library
+ * Interface to the g_lock facility
+ * Copyright (C) Volker Lendecke 2009
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "includes.h"
+#include "net.h"
+#include "g_lock.h"
+
+static bool net_g_lock_init(TALLOC_CTX *mem_ctx,
+			    struct tevent_context **pev,
+			    struct messaging_context **pmsg,
+			    struct g_lock_ctx **pg_ctx)
+{
+	struct tevent_context *ev = NULL;
+	struct messaging_context *msg = NULL;
+	struct g_lock_ctx *g_ctx = NULL;
+
+	ev = tevent_context_init(talloc_tos());
+	if (ev == NULL) {
+		d_fprintf(stderr, "ERROR: could not init event context\n");
+		goto fail;
+	}
+	msg = messaging_init(talloc_tos(), server_id_self(), ev);
+	if (msg == NULL) {
+		d_fprintf(stderr, "ERROR: could not init messaging context\n");
+		goto fail;
+	}
+	g_ctx = g_lock_ctx_init(talloc_tos(), msg);
+	if (g_ctx == NULL) {
+		d_fprintf(stderr, "ERROR: could not init g_lock context\n");
+		goto fail;
+	}
+
+	*pev = ev;
+	*pmsg = msg;
+	*pg_ctx = g_ctx;
+	return true;
+fail:
+	TALLOC_FREE(g_ctx);
+	TALLOC_FREE(msg);
+	TALLOC_FREE(ev);
+	return false;
+}
+
+
+static int net_g_lock_do(struct net_context *c, int argc, const char **argv)
+{
+	struct tevent_context *ev = NULL;
+	struct messaging_context *msg = NULL;
+	struct g_lock_ctx *g_ctx = NULL;
+	const char *name, *cmd;
+	int timeout, res;
+	bool locked = false;
+	NTSTATUS status;
+	int ret = -1;
+
+	if (argc != 3) {
+		d_printf("Usage: net g_lock do <lockname> <timeout> "
+			 "<command>\n");
+		return -1;
+	}
+	name = argv[0];
+	timeout = atoi(argv[1]);
+	cmd = argv[2];
+
+	if (!net_g_lock_init(talloc_tos(), &ev, &msg, &g_ctx)) {
+		goto done;
+	}
+
+	status = g_lock_lock(g_ctx, name, G_LOCK_WRITE,
+			     timeval_set(timeout / 1000, timeout % 1000));
+	if (!NT_STATUS_IS_OK(status)) {
+		d_fprintf(stderr, "ERROR: Could not get lock: %s\n",
+			  nt_errstr(status));
+		goto done;
+	}
+	locked = true;
+
+	res = system(cmd);
+
+	if (res == -1) {
+		d_fprintf(stderr, "ERROR: system() returned %s\n",
+			  strerror(errno));
+		goto done;
+	}
+	d_fprintf(stderr, "command returned %d\n", res);
+
+	ret = 0;
+
+done:
+	if (locked) {
+		g_lock_unlock(g_ctx, name);
+	}
+	TALLOC_FREE(g_ctx);
+	TALLOC_FREE(msg);
+	TALLOC_FREE(ev);
+	return ret;
+}
+
+static int net_g_lock_dump_fn(struct server_id pid, enum g_lock_type lock_type,
+			      void *private_data)
+{
+	char *pidstr;
+
+	pidstr = procid_str(talloc_tos(), &pid);
+	d_printf("%s: %s (%s)\n", pidstr,
+		 (lock_type & 1) ? "WRITE" : "READ",
+		 (lock_type & G_LOCK_PENDING) ? "pending" : "holder");
+	TALLOC_FREE(pidstr);
+	return 0;
+}
+
+static int net_g_lock_dump(struct net_context *c, int argc, const char **argv)
+{
+	struct tevent_context *ev = NULL;
+	struct messaging_context *msg = NULL;
+	struct g_lock_ctx *g_ctx = NULL;
+	NTSTATUS status;
+	int ret = -1;
+
+	if (argc != 1) {
+		d_printf("Usage: net g_lock dump <lockname>\n");
+		return -1;
+	}
+
+	if (!net_g_lock_init(talloc_tos(), &ev, &msg, &g_ctx)) {
+		goto done;
+	}
+
+	status = g_lock_dump(g_ctx, argv[0], net_g_lock_dump_fn, NULL);
+
+	ret = 0;
+done:
+	TALLOC_FREE(g_ctx);
+	TALLOC_FREE(msg);
+	TALLOC_FREE(ev);
+	return ret;
+}
+
+static int net_g_lock_locks_fn(const char *name, void *private_data)
+{
+	d_printf("%s\n", name);
+	return 0;
+}
+
+static int net_g_lock_locks(struct net_context *c, int argc, const char **argv)
+{
+	struct tevent_context *ev = NULL;
+	struct messaging_context *msg = NULL;
+	struct g_lock_ctx *g_ctx = NULL;
+	int ret = -1;
+
+	if (argc != 0) {
+		d_printf("Usage: net g_lock locks\n");
+		return -1;
+	}
+
+	if (!net_g_lock_init(talloc_tos(), &ev, &msg, &g_ctx)) {
+		goto done;
+	}
+
+	ret = g_lock_locks(g_ctx, net_g_lock_locks_fn, NULL);
+done:
+	TALLOC_FREE(g_ctx);
+	TALLOC_FREE(msg);
+	TALLOC_FREE(ev);
+	return ret;
+}
+
+int net_g_lock(struct net_context *c, int argc, const char **argv)
+{
+	struct functable func[] = {
+		{
+			"do",
+			net_g_lock_do,
+			NET_TRANSPORT_LOCAL,
+			N_("Execute a shell command under a lock"),
+			N_("net g_lock do <lock name> <timeout> <command>\n")
+		},
+		{
+			"locks",
+			net_g_lock_locks,
+			NET_TRANSPORT_LOCAL,
+			N_("List all locknames"),
+			N_("net g_lock locks\n")
+		},
+		{
+			"dump",
+			net_g_lock_dump,
+			NET_TRANSPORT_LOCAL,
+			N_("Dump a g_lock locking table"),
+			N_("net g_lock dump <lock name>\n")
+		},
+		{NULL, NULL, 0, NULL, NULL}
+	};
+
+	return net_run_function(c, argc, argv, "net g_lock", func);
+}