66 lines
2.2 KiB
Markdown
66 lines
2.2 KiB
Markdown
# Module commands
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Introduced in MaxScale 2.1, the module commands are special, module-specific
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commands. They allow the modules to expand beyond the capabilities of the module
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API. Currently, only MaxAdmin implements an interface to the module commands.
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All registered module commands can be shown with `maxadmin list commands` and
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they can be executed with `maxadmin call command <module> <name> ARGS...` where
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_<module>_ is the name of the module and _<name>_ is the name of the command.
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_ARGS_ is a command specific list of arguments.
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## Developer reference
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The module command API is defined in the _modulecmd.h_ header. It consists of
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various functions to register and call module commands. Read the function
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documentation in the header for more details.
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The following example registers the module command _my_command_ for module
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_my_module_.
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```
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#include <maxscale/modulecmd.hh>
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bool my_simple_cmd(const MODULECMD_ARG *argv)
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{
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printf("%d arguments given\n", argv->argc);
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}
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int main(int argc, char **argv)
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{
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modulecmd_arg_type_t my_args[] =
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{
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{MODULECMD_ARG_BOOLEAN, "This is a boolean parameter"},
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{MODULECMD_ARG_STRING | MODULECMD_ARG_OPTIONAL, "This is an optional string parameter"}
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};
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// Register the command
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modulecmd_register_command("my_module", "my_command", my_simple_cmd, 2, my_args);
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// Find the registered command
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const MODULECMD *cmd = modulecmd_find_command("my_module", "my_command");
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// Parse the arguments for the command
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const void *arglist[] = {"true", "optional string"};
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MODULECMD_ARG *arg = modulecmd_arg_parse(cmd, arglist, 2);
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// Call the module command
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modulecmd_call_command(cmd, arg);
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// Free the parsed arguments
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modulecmd_arg_free(arg);
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return 0;
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}
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```
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The array _my_args_ of type _modulecmd_arg_type_t_ is used to tell what kinds of
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arguments the command expects. The first argument is a boolean and the second
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argument is an optional string.
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Arguments are passed to the parsing function as an array of void pointers. They
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are interpreted as the types the command expects.
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When the module command is executed, the _argv_ parameter for the
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_my_simple_cmd_ contains the parsed arguments received from the caller of the
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command.
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