lib/db-ctl-base.h

   1 /*
   2  * Copyright (c) 2015 Nicira, Inc.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License");
   5  * you may not use this file except in compliance with the License.
   6  * You may obtain a copy of the License at:
   7  *
   8  *     http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS,
  12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  13  * See the License for the specific language governing permissions and
  14  * limitations under the License.
  15  */
  16
  17 #ifndef DB_CTL_BASE_H
  18 #define DB_CTL_BASE_H 1
  19
  20 #include "compiler.h"
  21 #include "openvswitch/dynamic-string.h"
  22 #include "openvswitch/shash.h"
  23
  24 struct ctl_context;
  25 struct option;
  26 struct ovsdb_idl;
  27 struct ovsdb_idl_row;
  28 struct ovsdb_idl_txn;
  29 struct ovsdb_symbol_table;
  30 struct table;
  31
  32 /* This library module contains the common parts for ovsdb manipulation
  33  * (structs, commands and functions).  To utilize this module, user must
  34  * define the following:
  35  *
  36  * - the command syntaxes for each command.  (See 'struct ctl_command_syntax'
  37  *   for more info)  and regiters them using ctl_register_commands().
  38  *
  39  * - the *ctl command context by inheriting the 'struct ctl_context' for
  40  *   additional commands implemented by user.  (See 'struct ctl_context' for
  41  *   more info)
  42 */
  43
  44 /* ctl_fatal() also logs the error, so it is preferred in this file. */
  45 #define ovs_fatal please_use_ctl_fatal_instead_of_ovs_fatal
  46
  47 struct ctl_table_class;
  48 struct cmd_show_table;
  49 void ctl_init(const struct ctl_table_class *tables,
  50               const struct cmd_show_table *cmd_show_tables,
  51               void (*ctl_exit_func)(int status));
  52 char *ctl_default_db(void);
  53 OVS_NO_RETURN void ctl_fatal(const char *, ...) OVS_PRINTF_FORMAT(1, 2);
  54
  55 /* *ctl command syntax structure, to be defined by each command implementation.
  56  *
  57  * Execution Path
  58  * ==============
  59  *
  60  * Three stylized functions accompany each of these data structures:
  61  *
  62  *               "pre-run"         "run"        "post-run"
  63  *            ---------------  ------------  -----------------
  64  * *ctl       ->prerequisites     ->run        ->postprocess
  65  *
  66  * Any *ctl command implementation should go through the following execution
  67  * path:
  68  *
  69  *   1. parses user command-line input and finds the corresponding syntax
  70  *      structures.
  71  *
  72  *   2. calls prerequisites() for getting the columns or tables used by each
  73  *      command.
  74  *
  75  *   3. calls run() to execute each command and to generate output.
  76  *
  77  *   4. calls postprocess() after output has been committed.  (Only needed
  78  *      by 'create' command sofar)
  79  *
  80  * Execution Context
  81  * =================
  82  *
  83  * Each of the stylized functions requires the 'struct ctl_context' as input
  84  * to provide context e.g. command-line arguments, table to be modified.  User
  85  * may define more specific context (by inheriting 'struct ctl_context') and
  86  * write stylized functions that use it.  In that case, CONTAINER_OF() can
  87  * be used to cast the generic context to the specific one.
  88  *
  89  * */
  90 struct ctl_command_syntax {
  91     const char *name;           /* e.g. "add-br" */
  92     int min_args;               /* Min number of arguments following name. */
  93     int max_args;               /* Max number of arguments following name. */
  94
  95     /* Names that roughly describe the arguments that the command
  96      * uses.  These should be similar to the names displayed in the
  97      * man page or in the help output. */
  98     const char *arguments;
  99
 100     /* If nonnull, calls ovsdb_idl_add_column() or ovsdb_idl_add_table() for
 101      * each column or table in ctx->idl that it uses. */
 102     void (*prerequisites)(struct ctl_context *ctx);
 103
 104     /* Does the actual work of the command and puts the command's output, if
 105      * any, in ctx->output or ctx->table.
 106      *
 107      * Alternatively, if some prerequisite of the command is not met and the
 108      * caller should wait for something to change and then retry, it may set
 109      * ctx->try_again to true.  (Only the "wait-until" command currently does
 110      * this.) */
 111     void (*run)(struct ctl_context *ctx);
 112
 113     /* If nonnull, called after the transaction has been successfully
 114      * committed.  ctx->output is the output from the "run" function, which
 115      * this function may modify and otherwise postprocess as needed.  (Only the
 116      * "create" command currently does any postprocessing.) */
 117     void (*postprocess)(struct ctl_context *ctx);
 118
 119     /* A comma-separated list of supported options, e.g. "--a,--b", or the
 120      * empty string if the command does not support any options. */
 121     const char *options;
 122
 123     enum { RO, RW } mode;   /* Does this command modify the database? */
 124 };
 125
 126 /* A command extracted from command-line input plus the structs for
 127  * output generation. */
 128 struct ctl_command {
 129     /* Data that remains constant after initialization. */
 130     const struct ctl_command_syntax *syntax;
 131     int argc;
 132     char **argv;
 133     struct shash options;
 134
 135     /* Data modified by commands. */
 136     struct ds output;
 137     struct table *table;
 138 };
 139
 140 bool ctl_might_write_to_db(char **argv);
 141 const char *ctl_get_db_cmd_usage(void);
 142 void ctl_print_commands(void);
 143 void ctl_print_options(const struct option *);
 144 void ctl_add_cmd_options(struct option **, size_t *n_options_p,
 145                          size_t *allocated_options_p, int opt_val);
 146 void ctl_register_commands(const struct ctl_command_syntax *);
 147 struct ctl_command *ctl_parse_commands(int argc, char *argv[],
 148                                        struct shash *local_options,
 149                                        size_t *n_commandsp);
 150
 151 /* Sometimes, it is desirable to print the table with weak reference to
 152  * rows in a 'cmd_show_table' table.  In that case, the 'weak_ref_table'
 153  * should be used and user must define all variables. */
 154 struct weak_ref_table {
 155     const struct ovsdb_idl_table_class *table;
 156     const struct ovsdb_idl_column *name_column;
 157     /* This colum must be a weak reference to the owning
 158      * 'struct cmd_show_table''s table row. */
 159     const struct ovsdb_idl_column *wref_column;
 160 };
 161
 162 /* This struct is for organizing the 'show' command output where:
 163  *
 164  * - 'table' is the table to show.
 165  *
 166  * - if 'name_column' is not null, it is used as the name for each row
 167  *   in 'table'.
 168  *
 169  * - 'columns[]' allows user to specify the print of additional columns
 170  *   in 'table'.
 171  *
 172  * - if 'wref_table' is populated, print 'wref_table.name_column' for
 173  *   each row in table 'wref_table.table' that has a reference to 'table'
 174  *   in 'wref_table.wref_column'.  Every field must be populated.
 175  *
 176  * */
 177 struct cmd_show_table {
 178     const struct ovsdb_idl_table_class *table;
 179     const struct ovsdb_idl_column *name_column;
 180     const struct ovsdb_idl_column *columns[3]; /* Seems like a good number. */
 181     const struct weak_ref_table wref_table;
 182 };
 183
 184 \f
 185 /* The base context struct for conducting the common database
 186  * operations (commands listed in 'db_ctl_commands').  User should
 187  * define the per-schema context by inheriting this struct as base.
 188  *
 189  * Database Caches
 190  * ===============
 191  *
 192  * User may implement caches for contents of the database to facilitate
 193  * specific commands.  In that case, the common commands defined in
 194  * 'db_ctl_commands' that may invalidate the cache must call the
 195  * invalidate_cache().
 196  *
 197  **/
 198 struct ctl_context {
 199     /* Read-only. */
 200     int argc;
 201     char **argv;
 202     struct shash options;
 203
 204     /* Modifiable state. */
 205     struct ds output;
 206     struct table *table;
 207     struct ovsdb_idl *idl;
 208     struct ovsdb_idl_txn *txn;
 209     struct ovsdb_symbol_table *symtab;
 210
 211     /* For implementation with a cache of the contents of the database,
 212      * this function will be called when the database is changed and the
 213      * change makes the cache no longer valid. */
 214     void (*invalidate_cache)(struct ctl_context *);
 215
 216     /* A command may set this member to true if some prerequisite is not met
 217      * and the caller should wait for something to change and then retry. */
 218     bool try_again;
 219 };
 220
 221 void ctl_context_init_command(struct ctl_context *, struct ctl_command *);
 222 void ctl_context_init(struct ctl_context *, struct ctl_command *,
 223                       struct ovsdb_idl *, struct ovsdb_idl_txn *,
 224                       struct ovsdb_symbol_table *,
 225                       void (*invalidate_cache)(struct ctl_context *));
 226 void ctl_context_done_command(struct ctl_context *, struct ctl_command *);
 227 void ctl_context_done(struct ctl_context *, struct ctl_command *);
 228
 229 struct ctl_row_id {
 230     const struct ovsdb_idl_table_class *table;
 231     const struct ovsdb_idl_column *name_column;
 232     const struct ovsdb_idl_column *uuid_column;
 233 };
 234
 235 struct ctl_table_class {
 236     struct ovsdb_idl_table_class *class;
 237     struct ctl_row_id row_ids[2];
 238 };
 239
 240 void ctl_set_column(const char *table_name,
 241                     const struct ovsdb_idl_row *, const char *arg,
 242                     struct ovsdb_symbol_table *);
 243
 244 #endif /* db-ctl-base.h */