Add a Finite State Machine.(fsm.h)

git-svn-id: http://svn.fedorahosted.org/svn/corosync/trunk@3052 fd59a12c-fef9-0310-b244-a6a79926bd2f

exec/fsm.h

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+/*
+ * Copyright (c) 2010 Red Hat
+ *
+ * All rights reserved.
+ *
+ * Author: Angus Salkeld <asalkeld@redhat.com>
+ *
+ * This software licensed under BSD license, the text of which follows:
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright notice,
+ *   this list of conditions and the following disclaimer in the documentation
+ *   and/or other materials provided with the distribution.
+ * - Neither the name of the MontaVista Software, Inc. nor the names of its
+ *   contributors may be used to endorse or promote products derived from this
+ *   software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+ * THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#ifndef FSM_H_DEFINED
+#define FSM_H_DEFINED
+
+#include <sys/time.h>
+#include <corosync/corotypes.h>
+#include "util.h"
+
+struct cs_fsm;
+struct cs_fsm_entry;
+typedef void (*cs_fsm_event_action_fn)(struct cs_fsm* fsm, int32_t event, void * data);
+typedef const char * (*cs_fsm_state_to_str_fn)(struct cs_fsm* fsm, int32_t state);
+typedef const char * (*cs_fsm_event_to_str_fn)(struct cs_fsm* fsm, int32_t event);
+#define CS_FSM_NEXT_STATE_SIZE 32
+struct cs_fsm_entry {
+	int32_t curr_state;
+	int32_t event;
+	cs_fsm_event_action_fn handler_fn;
+	int32_t next_states[CS_FSM_NEXT_STATE_SIZE];
+};
+
+struct cs_fsm {
+	const char *name;
+	int32_t curr_state;
+	int32_t curr_entry;
+	size_t entries;
+	struct cs_fsm_entry *table;
+	cs_fsm_state_to_str_fn state_to_str;
+	cs_fsm_event_to_str_fn event_to_str;
+};
+
+/*
+ * the table entry is defined by the state + event (curr_entry).
+ * so cs_fsm_process() sets the entry and cs_fsm_state_set()
+ * sets the new state.
+ */
+static inline void cs_fsm_process (struct cs_fsm *fsm, int32_t new_event, void * data)
+{
+	int32_t i;
+
+	for (i = 0; i < fsm->entries; i++) {
+		if (fsm->table[i].event == new_event &&
+		    fsm->table[i].curr_state == fsm->curr_state) {
+
+			assert (fsm->table[i].handler_fn != NULL);
+			/* set current entry */
+			fsm->curr_entry = i;
+			fsm->table[i].handler_fn (fsm, new_event, data);
+			return;
+		}
+	}
+	log_printf (LOGSYS_LEVEL_ERROR, "Fsm:%s could not find event \"%s\" in state \"%s\"",
+		fsm->name, fsm->event_to_str(fsm, new_event), fsm->state_to_str(fsm, fsm->curr_state));
+	corosync_exit_error(AIS_DONE_FATAL_ERR);
+}
+
+static inline void cs_fsm_state_set (struct cs_fsm* fsm, int32_t next_state, void* data)
+{
+	int i;
+	struct cs_fsm_entry *entry = &fsm->table[fsm->curr_entry];
+
+	if (fsm->curr_state == next_state) {
+		return;
+	}
+	/*
+	 * confirm that "next_state" is in the current entry's next list
+	 */
+	for (i = 0; i < CS_FSM_NEXT_STATE_SIZE; i++) {
+		if (entry->next_states[i] < 0) {
+			break;
+		}
+		if (entry->next_states[i] == next_state) {
+			log_printf (LOGSYS_LEVEL_INFO, "Fsm:%s event \"%s\", state \"%s\" --> \"%s\"\n",
+				fsm->name,
+				fsm->event_to_str(fsm, entry->event),
+				fsm->state_to_str(fsm, fsm->table[fsm->curr_entry].curr_state),
+				fsm->state_to_str(fsm, next_state));
+			fsm->curr_state = next_state;
+			return;
+		}
+	}
+	log_printf (LOGSYS_LEVEL_CRIT, "Fsm:%s Can't change state from \"%s\" to \"%s\" (event was \"%s\")\n",
+		fsm->name,
+		fsm->state_to_str(fsm, fsm->table[fsm->curr_entry].curr_state),
+		fsm->state_to_str(fsm, next_state),
+		fsm->event_to_str(fsm, entry->event));
+	corosync_exit_error(AIS_DONE_FATAL_ERR);
+}
+
+#endif /* FSM_H_DEFINED */
+
+