ovsdb: Add replication support and refactor files in terms of replication.

An upcoming commit will add support for replicating tables across JSON-RPC
connection.  As a prerequisite ovsdb itself must support basic replication.
This commit adds that support and then reimplements the ovsdb file storage
in terms of that replication.

1 files changed, 341 insertions, 0 deletions

diff --git a/ovsdb/file.c b/ovsdb/file.c
new file mode 100644
index 000000000..377ca280f
--- /dev/null
+++ b/ovsdb/file.c
@@ -0,0 +1,341 @@
+/* Copyright (c) 2009 Nicira Networks
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <config.h>
+
+#include "file.h"
+
+#include <assert.h>
+#include <fcntl.h>
+
+#include "column.h"
+#include "log.h"
+#include "json.h"
+#include "ovsdb.h"
+#include "ovsdb-error.h"
+#include "row.h"
+#include "table.h"
+#include "transaction.h"
+#include "uuid.h"
+#include "util.h"
+
+#define THIS_MODULE VLM_ovsdb_file
+#include "vlog.h"
+
+static struct ovsdb_error *ovsdb_file_txn_from_json(struct ovsdb *,
+                                                    const struct json *,
+                                                    struct ovsdb_txn **);
+static void ovsdb_file_replica_create(struct ovsdb *, struct ovsdb_log *);
+
+struct ovsdb_error *
+ovsdb_file_open(const char *file_name, bool read_only, struct ovsdb **dbp)
+{
+    struct ovsdb_schema *schema;
+    struct ovsdb_error *error;
+    struct ovsdb_log *log;
+    struct json *json;
+    struct ovsdb *db;
+
+    error = ovsdb_log_open(file_name, read_only ? O_RDONLY : O_RDWR, &log);
+    if (error) {
+        return error;
+    }
+
+    error = ovsdb_log_read(log, &json);
+    if (error) {
+        return error;
+    } else if (!json) {
+        return ovsdb_io_error(EOF, "%s: database file contains no schema",
+                              file_name);
+    }
+
+    error = ovsdb_schema_from_json(json, &schema);
+    if (error) {
+        json_destroy(json);
+        return ovsdb_wrap_error(error,
+                                "failed to parse \"%s\" as ovsdb schema",
+                                file_name);
+    }
+    json_destroy(json);
+
+    db = ovsdb_create(schema);
+    while ((error = ovsdb_log_read(log, &json)) == NULL && json) {
+        struct ovsdb_txn *txn;
+
+        error = ovsdb_file_txn_from_json(db, json, &txn);
+        json_destroy(json);
+        if (error) {
+            break;
+        }
+
+        ovsdb_txn_commit(txn, false);
+    }
+    if (error) {
+        char *msg = ovsdb_error_to_string(error);
+        VLOG_WARN("%s", msg);
+        free(msg);
+
+        ovsdb_error_destroy(error);
+    }
+
+    if (!read_only) {
+        ovsdb_file_replica_create(db, log);
+    } else {
+        ovsdb_log_close(log);
+    }
+
+    *dbp = db;
+    return NULL;
+}
+
+static struct ovsdb_error *
+ovsdb_file_txn_row_from_json(struct ovsdb_txn *txn, struct ovsdb_table *table,
+                             const struct uuid *row_uuid, struct json *json)
+{
+    const struct ovsdb_row *row = ovsdb_table_get_row(table, row_uuid);
+    if (json->type == JSON_NULL) {
+        if (!row) {
+            return ovsdb_syntax_error(NULL, NULL, "transaction deletes "
+                                      "row "UUID_FMT" that does not exist",
+                                      UUID_ARGS(row_uuid));
+        }
+        ovsdb_txn_row_delete(txn, row);
+        return NULL;
+    } else if (row) {
+        return ovsdb_row_from_json(ovsdb_txn_row_modify(txn, row),
+                                   json, NULL, NULL);
+    } else {
+        struct ovsdb_error *error;
+        struct ovsdb_row *new;
+
+        new = ovsdb_row_create(table);
+        *ovsdb_row_get_uuid_rw(new) = *row_uuid;
+        error = ovsdb_row_from_json(new, json, NULL, NULL);
+        if (error) {
+            ovsdb_row_destroy(new);
+        }
+
+        ovsdb_txn_row_insert(txn, new);
+
+        return error;
+    }
+}
+
+static struct ovsdb_error *
+ovsdb_file_txn_table_from_json(struct ovsdb_txn *txn,
+                               struct ovsdb_table *table, struct json *json)
+{
+    struct shash_node *node;
+
+    if (json->type != JSON_OBJECT) {
+        return ovsdb_syntax_error(json, NULL, "object expected");
+    }
+
+    SHASH_FOR_EACH (node, json->u.object) {
+        const char *uuid_string = node->name;
+        struct json *txn_row_json = node->data;
+        struct ovsdb_error *error;
+        struct uuid row_uuid;
+
+        if (!uuid_from_string(&row_uuid, uuid_string)) {
+            return ovsdb_syntax_error(json, NULL, "\"%s\" is not a valid UUID",
+                                      uuid_string);
+        }
+
+        error = ovsdb_file_txn_row_from_json(txn, table, &row_uuid,
+                                             txn_row_json);
+        if (error) {
+            return error;
+        }
+    }
+
+    return NULL;
+}
+
+static struct ovsdb_error *
+ovsdb_file_txn_from_json(struct ovsdb *db, const struct json *json,
+                         struct ovsdb_txn **txnp)
+{
+    struct ovsdb_error *error;
+    struct shash_node *node;
+    struct ovsdb_txn *txn;
+
+    *txnp = NULL;
+    if (json->type != JSON_OBJECT) {
+        return ovsdb_syntax_error(json, NULL, "object expected");
+    }
+
+    txn = ovsdb_txn_create(db);
+    SHASH_FOR_EACH (node, json->u.object) {
+        const char *table_name = node->name;
+        struct json *txn_table_json = node->data;
+        struct ovsdb_table *table;
+
+        table = shash_find_data(&db->tables, table_name);
+        if (!table) {
+            error = ovsdb_syntax_error(json, "unknown table",
+                                       "No table named %s.", table_name);
+            goto error;
+        }
+
+        error = ovsdb_file_txn_table_from_json(txn, table, txn_table_json);
+        if (error) {
+            goto error;
+        }
+    }
+    *txnp = txn;
+    return NULL;
+
+error:
+    ovsdb_txn_abort(txn);
+    return error;
+}
+
+/* Replica implementation. */
+
+struct ovsdb_file_replica {
+    struct ovsdb_replica replica;
+    struct ovsdb_log *log;
+};
+
+static const struct ovsdb_replica_class ovsdb_file_replica_class;
+
+static void
+ovsdb_file_replica_create(struct ovsdb *db, struct ovsdb_log *log)
+{
+    struct ovsdb_file_replica *r = xmalloc(sizeof *r);
+    ovsdb_replica_init(&r->replica, &ovsdb_file_replica_class);
+    r->log = log;
+    ovsdb_add_replica(db, &r->replica);
+
+}
+
+static struct ovsdb_file_replica *
+ovsdb_file_replica_cast(struct ovsdb_replica *replica)
+{
+    assert(replica->class == &ovsdb_file_replica_class);
+    return CONTAINER_OF(replica, struct ovsdb_file_replica, replica);
+}
+
+struct ovsdb_file_replica_aux {
+    struct json *json;          /* JSON for the whole transaction. */
+    struct json *table_json;    /* JSON for 'table''s transaction. */
+    struct ovsdb_table *table;  /* Table described in 'table_json'.  */
+};
+
+static bool
+ovsdb_file_replica_change_cb(const struct ovsdb_row *old,
+                             const struct ovsdb_row *new,
+                             void *aux_)
+{
+    struct ovsdb_file_replica_aux *aux = aux_;
+    struct json *row;
+
+    if (!new) {
+        row = json_null_create();
+    } else {
+        struct shash_node *node;
+
+        row = NULL;
+        SHASH_FOR_EACH (node, &new->table->schema->columns) {
+            const struct ovsdb_column *column = node->data;
+            const struct ovsdb_type *type = &column->type;
+            unsigned int idx = column->index;
+
+            if (idx != OVSDB_COL_UUID && column->persistent
+                && (!old || !ovsdb_datum_equals(&old->fields[idx],
+                                                &new->fields[idx], type)))
+            {
+                if (!row) {
+                    row = json_object_create();
+                }
+                json_object_put(row, column->name,
+                                ovsdb_datum_to_json(&new->fields[idx], type));
+            }
+        }
+    }
+
+    if (row) {
+        struct ovsdb_table *table = new ? new->table : old->table;
+        char uuid[UUID_LEN + 1];
+
+        if (table != aux->table) {
+            /* Create JSON object for transaction overall. */
+            if (!aux->json) {
+                aux->json = json_object_create();
+            }
+
+            /* Create JSON object for transaction on this table. */
+            aux->table_json = json_object_create();
+            aux->table = table;
+            json_object_put(aux->json, table->schema->name, aux->table_json);
+        }
+
+        /* Add row to transaction for this table. */
+        snprintf(uuid, sizeof uuid,
+                 UUID_FMT, UUID_ARGS(ovsdb_row_get_uuid(new ? new : old)));
+        json_object_put(aux->table_json, uuid, row);
+    }
+
+    return true;
+}
+
+static struct ovsdb_error *
+ovsdb_file_replica_commit(struct ovsdb_replica *r_,
+                          const struct ovsdb_txn *txn, bool durable)
+{
+    struct ovsdb_file_replica *r = ovsdb_file_replica_cast(r_);
+    struct ovsdb_file_replica_aux aux;
+    struct ovsdb_error *error;
+
+    aux.json = NULL;
+    aux.table_json = NULL;
+    aux.table = NULL;
+    ovsdb_txn_for_each_change(txn, ovsdb_file_replica_change_cb, &aux);
+
+    if (!aux.json) {
+        /* Nothing to commit. */
+        return NULL;
+    }
+
+    error = ovsdb_log_write(r->log, aux.json);
+    json_destroy(aux.json);
+    if (error) {
+        return ovsdb_wrap_error(error, "writing transaction failed");
+    }
+
+    if (durable) {
+        error = ovsdb_log_commit(r->log);
+        if (error) {
+            return ovsdb_wrap_error(error, "committing transaction failed");
+        }
+    }
+
+    return NULL;
+}
+
+static void
+ovsdb_file_replica_destroy(struct ovsdb_replica *r_)
+{
+    struct ovsdb_file_replica *r = ovsdb_file_replica_cast(r_);
+
+    ovsdb_log_close(r->log);
+    free(r);
+}
+
+static const struct ovsdb_replica_class ovsdb_file_replica_class = {
+    ovsdb_file_replica_commit,
+    ovsdb_file_replica_destroy
+};