X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=lib%2Fovsdb-idl.c;h=be4b255a3a4367e84ee5ed7b281475c255e3edfb;hb=4cceacb94cfc1d75a961d3d746d2ae369c397ae5;hp=439a40a1e66cadecb197c0c7a336309a6b837b4f;hpb=4fdfe5ccf84c473ad98300cb9050889b033768df;p=openvswitch diff --git a/lib/ovsdb-idl.c b/lib/ovsdb-idl.c index 439a40a1..be4b255a 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. @@ -70,6 +70,7 @@ struct ovsdb_idl { struct json *monitor_request_id; unsigned int last_monitor_request_seqno; unsigned int change_seqno; + bool verify_write_only; /* Database locking. */ char *lock_name; /* Name of lock we need, NULL if none. */ @@ -94,9 +95,9 @@ struct ovsdb_idl_txn { 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; @@ -230,6 +231,7 @@ ovsdb_idl_destroy(struct ovsdb_idl *idl) json_destroy(idl->monitor_request_id); free(idl->lock_name); json_destroy(idl->lock_request_id); + hmap_destroy(&idl->outstanding_txns); free(idl); } } @@ -270,32 +272,12 @@ 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); @@ -366,8 +348,6 @@ 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 @@ -379,8 +359,23 @@ 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) { @@ -408,6 +403,16 @@ ovsdb_idl_force_reconnect(struct ovsdb_idl *idl) { jsonrpc_session_force_reconnect(idl->session); } + +/* Some IDL users should only write to write-only columns. Furthermore, + * writing to a column which is not write-only can cause serious performance + * degradations for these users. This function causes 'idl' to reject writes + * to columns which are not marked write only using ovsdb_idl_omit_alert(). */ +void +ovsdb_idl_verify_write_only(struct ovsdb_idl *idl) +{ + idl->verify_write_only = true; +} static unsigned char * ovsdb_idl_get_mode(struct ovsdb_idl *idl, @@ -913,6 +918,7 @@ 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); @@ -1014,6 +1020,7 @@ 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, @@ -1058,6 +1065,8 @@ 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, @@ -1080,6 +1089,12 @@ 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) @@ -1089,6 +1104,8 @@ 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) { @@ -1112,8 +1129,13 @@ 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); @@ -1160,6 +1182,11 @@ 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) { @@ -1174,10 +1201,8 @@ ovsdb_idl_txn_status_to_string(enum ovsdb_idl_txn_status status) return "aborted"; case TXN_SUCCESS: return "success"; - case TXN_AGAIN_WAIT: - return "wait then try again"; - case TXN_AGAIN_NOW: - return "try again now"; + case TXN_TRY_AGAIN: + return "try again"; case TXN_NOT_LOCKED: return "not locked"; case TXN_ERROR: @@ -1186,6 +1211,9 @@ 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) { @@ -1204,7 +1232,6 @@ ovsdb_idl_txn_create(struct ovsdb_idl *idl) txn->inc_table = NULL; txn->inc_column = NULL; - txn->inc_where = NULL; hmap_init(&txn->inserted_rows); @@ -1229,22 +1256,50 @@ 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) { @@ -1257,9 +1312,6 @@ 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); } @@ -1267,6 +1319,7 @@ 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) { @@ -1397,6 +1450,55 @@ 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) { @@ -1547,7 +1649,8 @@ 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( @@ -1560,7 +1663,8 @@ 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))); @@ -1591,7 +1695,7 @@ ovsdb_idl_txn_commit(struct ovsdb_idl_txn *txn) json_hash(txn->request_id, 0)); txn->status = TXN_INCOMPLETE; } else { - txn->status = TXN_AGAIN_WAIT; + txn->status = TXN_TRY_AGAIN; } ovsdb_idl_txn_disassemble(txn); @@ -1600,7 +1704,10 @@ 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) { @@ -1616,6 +1723,9 @@ 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) { @@ -1623,6 +1733,12 @@ 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) { @@ -1632,6 +1748,14 @@ 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) { @@ -1708,22 +1832,32 @@ ovsdb_idl_txn_write(const struct ovsdb_idl_row *row_, const struct ovsdb_idl_column *column, struct ovsdb_datum *datum) { - struct ovsdb_idl_row *row = (struct ovsdb_idl_row *) row_; + struct ovsdb_idl_row *row = CONST_CAST(struct ovsdb_idl_row *, row_); const struct ovsdb_idl_table_class *class; size_t column_idx; + bool write_only; if (ovsdb_idl_row_is_synthetic(row)) { + ovsdb_datum_destroy(datum, &column->type); return; } class = row->table->class; column_idx = column - class->columns; + write_only = row->table->modes[column_idx] == OVSDB_IDL_MONITOR; assert(row->new != NULL); assert(column_idx < class->n_columns); assert(row->old == NULL || row->table->modes[column_idx] & OVSDB_IDL_MONITOR); + if (row->table->idl->verify_write_only && !write_only) { + VLOG_ERR("Bug: Attempt to write to a read/write column (%s:%s) when" + " explicitly configured not to.", class->name, column->name); + ovsdb_datum_destroy(datum, &column->type); + return; + } + /* If this is a write-only column and the datum being written is the same * as the one already there, just skip the update entirely. This is worth * optimizing because we have a lot of columns that get periodically @@ -1735,9 +1869,8 @@ ovsdb_idl_txn_write(const struct ovsdb_idl_row *row_, * transaction only does writes of existing values, without making any real * changes, we will drop the whole transaction later in * ovsdb_idl_txn_commit().) */ - if (row->table->modes[column_idx] == OVSDB_IDL_MONITOR - && ovsdb_datum_equals(ovsdb_idl_read(row, column), - datum, &column->type)) { + if (write_only && ovsdb_datum_equals(ovsdb_idl_read(row, column), + datum, &column->type)) { ovsdb_datum_destroy(datum, &column->type); return; } @@ -1794,7 +1927,7 @@ void ovsdb_idl_txn_verify(const struct ovsdb_idl_row *row_, const struct ovsdb_idl_column *column) { - struct ovsdb_idl_row *row = (struct ovsdb_idl_row *) row_; + struct ovsdb_idl_row *row = CONST_CAST(struct ovsdb_idl_row *, row_); const struct ovsdb_idl_table_class *class; size_t column_idx; @@ -1833,7 +1966,7 @@ ovsdb_idl_txn_verify(const struct ovsdb_idl_row *row_, void ovsdb_idl_txn_delete(const struct ovsdb_idl_row *row_) { - struct ovsdb_idl_row *row = (struct ovsdb_idl_row *) row_; + struct ovsdb_idl_row *row = CONST_CAST(struct ovsdb_idl_row *, row_); if (ovsdb_idl_row_is_synthetic(row)) { return; @@ -1896,7 +2029,7 @@ ovsdb_idl_txn_abort_all(struct ovsdb_idl *idl) struct ovsdb_idl_txn *txn; HMAP_FOR_EACH (txn, hmap_node, &idl->outstanding_txns) { - ovsdb_idl_txn_complete(txn, TXN_AGAIN_WAIT); + ovsdb_idl_txn_complete(txn, TXN_TRY_AGAIN); } } @@ -2097,9 +2230,7 @@ ovsdb_idl_txn_process_reply(struct ovsdb_idl *idl, status = (hard_errors ? TXN_ERROR : lock_errors ? TXN_NOT_LOCKED - : soft_errors ? (txn->commit_seqno == idl->change_seqno - ? TXN_AGAIN_WAIT - : TXN_AGAIN_NOW) + : soft_errors ? TXN_TRY_AGAIN : TXN_SUCCESS); } @@ -2107,6 +2238,8 @@ 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) { @@ -2115,6 +2248,7 @@ 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) {