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https://github.com/samba-team/samba.git
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1be6d849ab
This simplifies the g_lock implementation. The new implementation tries to acquire a lock. If that fails due to a lock conflict, wait for the g_lock record to change. Upon change, just try again. The old logic had to cope with pending records and an ugly hack into ctdb itself. As a bonus, we now get a really clean async g_lock_lock_send/recv that can asynchronously wait for a global lock. This would have been almost impossible to do without the dbwrap_record_watch infrastructure.
209 lines
4.7 KiB
C
209 lines
4.7 KiB
C
/*
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* Samba Unix/Linux SMB client library
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* Interface to the g_lock facility
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* Copyright (C) Volker Lendecke 2009
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "includes.h"
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#include "net.h"
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#include "g_lock.h"
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#include "messages.h"
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static bool net_g_lock_init(TALLOC_CTX *mem_ctx,
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struct tevent_context **pev,
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struct messaging_context **pmsg,
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struct g_lock_ctx **pg_ctx)
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{
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struct tevent_context *ev = NULL;
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struct messaging_context *msg = NULL;
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struct g_lock_ctx *g_ctx = NULL;
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ev = tevent_context_init(mem_ctx);
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if (ev == NULL) {
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d_fprintf(stderr, "ERROR: could not init event context\n");
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goto fail;
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}
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msg = messaging_init(mem_ctx, ev);
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if (msg == NULL) {
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d_fprintf(stderr, "ERROR: could not init messaging context\n");
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goto fail;
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}
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g_ctx = g_lock_ctx_init(mem_ctx, msg);
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if (g_ctx == NULL) {
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d_fprintf(stderr, "ERROR: could not init g_lock context\n");
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goto fail;
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}
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*pev = ev;
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*pmsg = msg;
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*pg_ctx = g_ctx;
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return true;
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fail:
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TALLOC_FREE(g_ctx);
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TALLOC_FREE(msg);
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TALLOC_FREE(ev);
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return false;
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}
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struct net_g_lock_do_state {
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const char *cmd;
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int result;
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};
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static void net_g_lock_do_fn(void *private_data)
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{
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struct net_g_lock_do_state *state =
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(struct net_g_lock_do_state *)private_data;
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state->result = system(state->cmd);
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}
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static int net_g_lock_do(struct net_context *c, int argc, const char **argv)
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{
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struct net_g_lock_do_state state;
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const char *name, *cmd;
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int timeout;
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NTSTATUS status;
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if (argc != 3) {
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d_printf("Usage: net g_lock do <lockname> <timeout> "
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"<command>\n");
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return -1;
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}
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name = argv[0];
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timeout = atoi(argv[1]);
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cmd = argv[2];
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state.cmd = cmd;
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state.result = -1;
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status = g_lock_do(name, G_LOCK_WRITE,
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timeval_set(timeout / 1000, timeout % 1000),
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net_g_lock_do_fn, &state);
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if (!NT_STATUS_IS_OK(status)) {
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d_fprintf(stderr, "ERROR: g_lock_do failed: %s\n",
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nt_errstr(status));
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goto done;
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}
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if (state.result == -1) {
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d_fprintf(stderr, "ERROR: system() returned %s\n",
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strerror(errno));
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goto done;
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}
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d_fprintf(stderr, "command returned %d\n", state.result);
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done:
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return state.result;
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}
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static int net_g_lock_dump_fn(struct server_id pid, enum g_lock_type lock_type,
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void *private_data)
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{
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char *pidstr;
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pidstr = server_id_str(talloc_tos(), &pid);
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d_printf("%s: %s\n", pidstr,
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(lock_type & 1) ? "WRITE" : "READ");
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TALLOC_FREE(pidstr);
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return 0;
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}
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static int net_g_lock_dump(struct net_context *c, int argc, const char **argv)
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{
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struct tevent_context *ev = NULL;
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struct messaging_context *msg = NULL;
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struct g_lock_ctx *g_ctx = NULL;
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NTSTATUS status;
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int ret = -1;
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if (argc != 1) {
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d_printf("Usage: net g_lock dump <lockname>\n");
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return -1;
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}
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if (!net_g_lock_init(talloc_tos(), &ev, &msg, &g_ctx)) {
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goto done;
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}
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status = g_lock_dump(g_ctx, argv[0], net_g_lock_dump_fn, NULL);
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ret = 0;
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done:
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TALLOC_FREE(g_ctx);
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TALLOC_FREE(msg);
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TALLOC_FREE(ev);
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return ret;
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}
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static int net_g_lock_locks_fn(const char *name, void *private_data)
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{
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d_printf("%s\n", name);
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return 0;
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}
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static int net_g_lock_locks(struct net_context *c, int argc, const char **argv)
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{
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struct tevent_context *ev = NULL;
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struct messaging_context *msg = NULL;
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struct g_lock_ctx *g_ctx = NULL;
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int ret = -1;
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if (argc != 0) {
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d_printf("Usage: net g_lock locks\n");
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return -1;
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}
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if (!net_g_lock_init(talloc_tos(), &ev, &msg, &g_ctx)) {
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goto done;
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}
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ret = g_lock_locks(g_ctx, net_g_lock_locks_fn, NULL);
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done:
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TALLOC_FREE(g_ctx);
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TALLOC_FREE(msg);
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TALLOC_FREE(ev);
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return ret < 0 ? -1 : ret;
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}
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int net_g_lock(struct net_context *c, int argc, const char **argv)
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{
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struct functable func[] = {
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{
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"do",
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net_g_lock_do,
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NET_TRANSPORT_LOCAL,
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N_("Execute a shell command under a lock"),
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N_("net g_lock do <lock name> <timeout> <command>\n")
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},
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{
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"locks",
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net_g_lock_locks,
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NET_TRANSPORT_LOCAL,
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N_("List all locknames"),
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N_("net g_lock locks\n")
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},
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{
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"dump",
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net_g_lock_dump,
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NET_TRANSPORT_LOCAL,
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N_("Dump a g_lock locking table"),
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N_("net g_lock dump <lock name>\n")
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},
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{NULL, NULL, 0, NULL, NULL}
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};
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return net_run_function(c, argc, argv, "net g_lock", func);
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}
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