X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=lib%2Fovsdb-idl.c;h=3eca2feb320b58a76497cfbe4bec7cf8e99a98fd;hb=71baec0655e41bb93f125d162bc62cc9da0be73b;hp=56b432868c71077f5b9401d3c006e0263f874100;hpb=9b446bfaa25c3cf44ace4821bd06c675d432df56;p=sliver-openvswitch.git diff --git a/lib/ovsdb-idl.c b/lib/ovsdb-idl.c index 56b432868..3eca2feb3 100644 --- a/lib/ovsdb-idl.c +++ b/lib/ovsdb-idl.c @@ -1,4 +1,4 @@ -/* Copyright (c) 2009, 2010, 2011 Nicira Networks. +/* Copyright (c) 2009, 2010, 2011, 2012 Nicira, Inc. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. @@ -91,11 +91,12 @@ struct ovsdb_idl_txn { char *error; bool dry_run; struct ds comment; + unsigned int commit_seqno; /* Increments. */ - char *inc_table; - char *inc_column; - struct json *inc_where; + const char *inc_table; + const char *inc_column; + struct uuid inc_row; unsigned int inc_index; int64_t inc_new_value; @@ -269,32 +270,12 @@ ovsdb_idl_clear(struct ovsdb_idl *idl) } } -/* Processes a batch of messages from the database server on 'idl'. Returns - * true if the database as seen through 'idl' changed, false if it did not - * change. The initial fetch of the entire contents of the remote database is - * considered to be one kind of change. If 'idl' has been configured to - * acquire a database lock (with ovsdb_idl_set_lock()), then successfully - * acquiring the lock is also considered to be a change. - * - * When this function returns false, the client may continue to use any data - * structures it obtained from 'idl' in the past. But when it returns true, - * the client must not access any of these data structures again, because they - * could have freed or reused for other purposes. - * - * This function can return occasional false positives, that is, report that - * the database changed even though it didn't. This happens if the connection - * to the database drops and reconnects, which causes the database contents to - * be reloaded even if they didn't change. (It could also happen if the - * database server sends out a "change" that reflects what we already thought - * was in the database, but the database server is not supposed to do that.) - * - * As an alternative to checking the return value, the client may check for - * changes in the value returned by ovsdb_idl_get_seqno(). - */ -bool +/* Processes a batch of messages from the database server on 'idl'. This may + * cause the IDL's contents to change. The client may check for that with + * ovsdb_idl_get_seqno(). */ +void ovsdb_idl_run(struct ovsdb_idl *idl) { - unsigned int initial_change_seqno = idl->change_seqno; int i; assert(!idl->txn); @@ -365,8 +346,6 @@ ovsdb_idl_run(struct ovsdb_idl *idl) } jsonrpc_msg_destroy(msg); } - - return initial_change_seqno != idl->change_seqno; } /* Arranges for poll_block() to wake up when ovsdb_idl_run() has something to @@ -378,8 +357,23 @@ ovsdb_idl_wait(struct ovsdb_idl *idl) jsonrpc_session_recv_wait(idl->session); } -/* Returns a number that represents the state of 'idl'. When 'idl' is updated - * (by ovsdb_idl_run()), the return value changes. */ +/* Returns a "sequence number" that represents the state of 'idl'. When + * ovsdb_idl_run() changes the database, the sequence number changes. The + * initial fetch of the entire contents of the remote database is considered to + * be one kind of change. Successfully acquiring a lock, if one has been + * configured with ovsdb_idl_set_lock(), is also considered to be a change. + * + * As long as the sequence number does not change, the client may continue to + * use any data structures it obtains from 'idl'. But when it changes, the + * client must not access any of these data structures again, because they + * could have freed or reused for other purposes. + * + * The sequence number can occasionally change even if the database does not. + * This happens if the connection to the database drops and reconnects, which + * causes the database contents to be reloaded even if they didn't change. (It + * could also happen if the database server sends out a "change" that reflects + * what the IDL already thought was in the database. The database server is + * not supposed to do that, but bugs could in theory cause it to do so.) */ unsigned int ovsdb_idl_get_seqno(const struct ovsdb_idl *idl) { @@ -912,6 +906,7 @@ static struct ovsdb_idl_row * ovsdb_idl_row_create__(const struct ovsdb_idl_table_class *class) { struct ovsdb_idl_row *row = xzalloc(class->allocation_size); + class->row_init(row); list_init(&row->src_arcs); list_init(&row->dst_arcs); hmap_node_nullify(&row->txn_node); @@ -1013,6 +1008,7 @@ ovsdb_idl_table_from_class(const struct ovsdb_idl *idl, return &idl->tables[table_class - idl->class->tables]; } +/* Called by ovsdb-idlc generated code. */ struct ovsdb_idl_row * ovsdb_idl_get_row_arc(struct ovsdb_idl_row *src, struct ovsdb_idl_table_class *dst_table_class, @@ -1057,6 +1053,8 @@ ovsdb_idl_get_row_arc(struct ovsdb_idl_row *src, } } +/* Searches 'tc''s table in 'idl' for a row with UUID 'uuid'. Returns a + * pointer to the row if there is one, otherwise a null pointer. */ const struct ovsdb_idl_row * ovsdb_idl_get_row_for_uuid(const struct ovsdb_idl *idl, const struct ovsdb_idl_table_class *tc, @@ -1079,6 +1077,12 @@ next_real_row(struct ovsdb_idl_table *table, struct hmap_node *node) return NULL; } +/* Returns a row in 'table_class''s table in 'idl', or a null pointer if that + * table is empty. + * + * Database tables are internally maintained as hash tables, so adding or + * removing rows while traversing the same table can cause some rows to be + * visited twice or not at apply. */ const struct ovsdb_idl_row * ovsdb_idl_first_row(const struct ovsdb_idl *idl, const struct ovsdb_idl_table_class *table_class) @@ -1088,6 +1092,8 @@ ovsdb_idl_first_row(const struct ovsdb_idl *idl, return next_real_row(table, hmap_first(&table->rows)); } +/* Returns a row following 'row' within its table, or a null pointer if 'row' + * is the last row in its table. */ const struct ovsdb_idl_row * ovsdb_idl_next_row(const struct ovsdb_idl_row *row) { @@ -1111,8 +1117,13 @@ const struct ovsdb_datum * ovsdb_idl_read(const struct ovsdb_idl_row *row, const struct ovsdb_idl_column *column) { - const struct ovsdb_idl_table_class *class = row->table->class; - size_t column_idx = column - class->columns; + const struct ovsdb_idl_table_class *class; + size_t column_idx; + + assert(!ovsdb_idl_row_is_synthetic(row)); + + class = row->table->class; + column_idx = column - class->columns; assert(row->new != NULL); assert(column_idx < class->n_columns); @@ -1159,6 +1170,11 @@ ovsdb_idl_row_is_synthetic(const struct ovsdb_idl_row *row) static void ovsdb_idl_txn_complete(struct ovsdb_idl_txn *txn, enum ovsdb_idl_txn_status); +/* Returns a string representation of 'status'. The caller must not modify or + * free the returned string. + * + * The return value is probably useful only for debug log messages and unit + * tests. */ const char * ovsdb_idl_txn_status_to_string(enum ovsdb_idl_txn_status status) { @@ -1183,6 +1199,9 @@ ovsdb_idl_txn_status_to_string(enum ovsdb_idl_txn_status status) return ""; } +/* Starts a new transaction on 'idl'. A given ovsdb_idl may only have a single + * active transaction at a time. See the large comment in ovsdb-idl.h for + * general information on transactions. */ struct ovsdb_idl_txn * ovsdb_idl_txn_create(struct ovsdb_idl *idl) { @@ -1197,10 +1216,10 @@ ovsdb_idl_txn_create(struct ovsdb_idl *idl) txn->error = NULL; txn->dry_run = false; ds_init(&txn->comment); + txn->commit_seqno = txn->idl->change_seqno; txn->inc_table = NULL; txn->inc_column = NULL; - txn->inc_where = NULL; hmap_init(&txn->inserted_rows); @@ -1225,22 +1244,50 @@ ovsdb_idl_txn_add_comment(struct ovsdb_idl_txn *txn, const char *s, ...) va_end(args); } +/* Marks 'txn' as a transaction that will not actually modify the database. In + * almost every way, the transaction is treated like other transactions. It + * must be committed or aborted like other transactions, it will be sent to the + * database server like other transactions, and so on. The only difference is + * that the operations sent to the database server will include, as the last + * step, an "abort" operation, so that any changes made by the transaction will + * not actually take effect. */ void ovsdb_idl_txn_set_dry_run(struct ovsdb_idl_txn *txn) { txn->dry_run = true; } +/* Causes 'txn', when committed, to increment the value of 'column' within + * 'row' by 1. 'column' must have an integer type. After 'txn' commits + * successfully, the client may retrieve the final (incremented) value of + * 'column' with ovsdb_idl_txn_get_increment_new_value(). + * + * The client could accomplish something similar with ovsdb_idl_read(), + * ovsdb_idl_txn_verify() and ovsdb_idl_txn_write(), or with ovsdb-idlc + * generated wrappers for these functions. However, ovsdb_idl_txn_increment() + * will never (by itself) fail because of a verify error. + * + * The intended use is for incrementing the "next_cfg" column in the + * Open_vSwitch table. */ void -ovsdb_idl_txn_increment(struct ovsdb_idl_txn *txn, const char *table, - const char *column, const struct json *where) +ovsdb_idl_txn_increment(struct ovsdb_idl_txn *txn, + const struct ovsdb_idl_row *row, + const struct ovsdb_idl_column *column) { assert(!txn->inc_table); - txn->inc_table = xstrdup(table); - txn->inc_column = xstrdup(column); - txn->inc_where = where ? json_clone(where) : json_array_create_empty(); + assert(column->type.key.type == OVSDB_TYPE_INTEGER); + assert(column->type.value.type == OVSDB_TYPE_VOID); + + txn->inc_table = row->table->class->name; + txn->inc_column = column->name; + txn->inc_row = row->uuid; } +/* Destroys 'txn' and frees all associated memory. If ovsdb_idl_txn_commit() + * has been called for 'txn' but the commit is still incomplete (that is, the + * last call returned TXN_INCOMPLETE) then the transaction may or may not still + * end up committing at the database server, but the client will not be able to + * get any further status information back. */ void ovsdb_idl_txn_destroy(struct ovsdb_idl_txn *txn) { @@ -1253,9 +1300,6 @@ ovsdb_idl_txn_destroy(struct ovsdb_idl_txn *txn) ovsdb_idl_txn_abort(txn); ds_destroy(&txn->comment); free(txn->error); - free(txn->inc_table); - free(txn->inc_column); - json_destroy(txn->inc_where); HMAP_FOR_EACH_SAFE (insert, next, hmap_node, &txn->inserted_rows) { free(insert); } @@ -1263,6 +1307,7 @@ ovsdb_idl_txn_destroy(struct ovsdb_idl_txn *txn) free(txn); } +/* Causes poll_block() to wake up if 'txn' has completed committing. */ void ovsdb_idl_txn_wait(const struct ovsdb_idl_txn *txn) { @@ -1393,6 +1438,55 @@ ovsdb_idl_txn_disassemble(struct ovsdb_idl_txn *txn) hmap_init(&txn->txn_rows); } +/* Attempts to commit 'txn'. Returns the status of the commit operation, one + * of the following TXN_* constants: + * + * TXN_INCOMPLETE: + * + * The transaction is in progress, but not yet complete. The caller + * should call again later, after calling ovsdb_idl_run() to let the IDL + * do OVSDB protocol processing. + * + * TXN_UNCHANGED: + * + * The transaction is complete. (It didn't actually change the database, + * so the IDL didn't send any request to the database server.) + * + * TXN_ABORTED: + * + * The caller previously called ovsdb_idl_txn_abort(). + * + * TXN_SUCCESS: + * + * The transaction was successful. The update made by the transaction + * (and possibly other changes made by other database clients) should + * already be visible in the IDL. + * + * TXN_TRY_AGAIN: + * + * The transaction failed for some transient reason, e.g. because a + * "verify" operation reported an inconsistency or due to a network + * problem. The caller should wait for a change to the database, then + * compose a new transaction, and commit the new transaction. + * + * Use the return value of ovsdb_idl_get_seqno() to wait for a change in + * the database. It is important to use its return value *before* the + * initial call to ovsdb_idl_txn_commit() as the baseline for this + * purpose, because the change that one should wait for can happen after + * the initial call but before the call that returns TXN_TRY_AGAIN, and + * using some other baseline value in that situation could cause an + * indefinite wait if the database rarely changes. + * + * TXN_NOT_LOCKED: + * + * The transaction failed because the IDL has been configured to require + * a database lock (with ovsdb_idl_set_lock()) but didn't get it yet or + * has already lost it. + * + * Committing a transaction rolls back all of the changes that it made to the + * IDL's copy of the database. If the transaction commits successfully, then + * the database server will send an update and, thus, the IDL will be updated + * with the committed changes. */ enum ovsdb_idl_txn_status ovsdb_idl_txn_commit(struct ovsdb_idl_txn *txn) { @@ -1543,7 +1637,8 @@ ovsdb_idl_txn_commit(struct ovsdb_idl_txn *txn) json_object_put_string(op, "op", "mutate"); json_object_put_string(op, "table", txn->inc_table); json_object_put(op, "where", - substitute_uuids(json_clone(txn->inc_where), txn)); + substitute_uuids(where_uuid_equals(&txn->inc_row), + txn)); json_object_put(op, "mutations", json_array_create_1( json_array_create_3( @@ -1556,7 +1651,8 @@ ovsdb_idl_txn_commit(struct ovsdb_idl_txn *txn) json_object_put_string(op, "op", "select"); json_object_put_string(op, "table", txn->inc_table); json_object_put(op, "where", - substitute_uuids(json_clone(txn->inc_where), txn)); + substitute_uuids(where_uuid_equals(&txn->inc_row), + txn)); json_object_put(op, "columns", json_array_create_1(json_string_create( txn->inc_column))); @@ -1596,7 +1692,10 @@ ovsdb_idl_txn_commit(struct ovsdb_idl_txn *txn) /* Attempts to commit 'txn', blocking until the commit either succeeds or * fails. Returns the final commit status, which may be any TXN_* value other - * than TXN_INCOMPLETE. */ + * than TXN_INCOMPLETE. + * + * This function calls ovsdb_idl_run() on 'txn''s IDL, so it may cause the + * return value of ovsdb_idl_get_seqno() to change. */ enum ovsdb_idl_txn_status ovsdb_idl_txn_commit_block(struct ovsdb_idl_txn *txn) { @@ -1612,6 +1711,9 @@ ovsdb_idl_txn_commit_block(struct ovsdb_idl_txn *txn) return status; } +/* Returns the final (incremented) value of the column in 'txn' that was set to + * be incremented by ovsdb_idl_txn_increment(). 'txn' must have committed + * successfully. */ int64_t ovsdb_idl_txn_get_increment_new_value(const struct ovsdb_idl_txn *txn) { @@ -1619,6 +1721,12 @@ ovsdb_idl_txn_get_increment_new_value(const struct ovsdb_idl_txn *txn) return txn->inc_new_value; } +/* Aborts 'txn' without sending it to the database server. This is effective + * only if ovsdb_idl_txn_commit() has not yet been called for 'txn'. + * Otherwise, it has no effect. + * + * Aborting a transaction doesn't free its memory. Use + * ovsdb_idl_txn_destroy() to do that. */ void ovsdb_idl_txn_abort(struct ovsdb_idl_txn *txn) { @@ -1628,6 +1736,14 @@ ovsdb_idl_txn_abort(struct ovsdb_idl_txn *txn) } } +/* Returns a string that reports the error status for 'txn'. The caller must + * not modify or free the returned string. A call to ovsdb_idl_txn_destroy() + * for 'txn' may free the returned string. + * + * The return value is ordinarily one of the strings that + * ovsdb_idl_txn_status_to_string() would return, but if the transaction failed + * due to an error reported by the database server, the return value is that + * error. */ const char * ovsdb_idl_txn_get_error(const struct ovsdb_idl_txn *txn) { @@ -1709,6 +1825,7 @@ ovsdb_idl_txn_write(const struct ovsdb_idl_row *row_, size_t column_idx; if (ovsdb_idl_row_is_synthetic(row)) { + ovsdb_datum_destroy(datum, &column->type); return; } @@ -1762,7 +1879,9 @@ ovsdb_idl_txn_write(const struct ovsdb_idl_row *row_, * prerequisite to completing the transaction. That is, if 'column' in 'row_' * changed (or if 'row_' was deleted) between the time that the IDL originally * read its contents and the time that the transaction commits, then the - * transaction aborts and ovsdb_idl_txn_commit() returns TXN_TRY_AGAIN. + * transaction aborts and ovsdb_idl_txn_commit() returns TXN_AGAIN_WAIT or + * TXN_AGAIN_NOW (depending on whether the database change has already been + * received). * * The intention is that, to ensure that no transaction commits based on dirty * reads, an application should call ovsdb_idl_txn_verify() on each data item @@ -2099,6 +2218,8 @@ ovsdb_idl_txn_process_reply(struct ovsdb_idl *idl, return true; } +/* Returns the transaction currently active for 'row''s IDL. A transaction + * must currently be active. */ struct ovsdb_idl_txn * ovsdb_idl_txn_get(const struct ovsdb_idl_row *row) { @@ -2107,6 +2228,7 @@ ovsdb_idl_txn_get(const struct ovsdb_idl_row *row) return txn; } +/* Returns the IDL on which 'txn' acts. */ struct ovsdb_idl * ovsdb_idl_txn_get_idl (struct ovsdb_idl_txn *txn) {