chrish42 opened a new pull request #7025:
URL: https://github.com/apache/arrow/pull/7025
The following patch ads Gflags support to `plasma-store-server`, leaves out
the backtraces on invalid command-line options, and generally tries to make the
error messages more useful in terms of nudging the user in the right direction.
Now, calling `plasma-store-server` alone prints `plasma-store-server: please
specify socket for incoming connections with -s, and the amount of memory (in
bytes) to use with -m`. Likewise with `-h`, although that's a happy coincidence
(`-h` was already assigned to turn on hugepage support, and the command-line
parsing errors on the missing mandatory options before getting to that).
Calling `plasma-store-server -help` produces:
```
plasma-store-server: Shared-memory server for Arrow data.
Usage:
Flags from ../src/plasma/store.cc:
-d (directory where to create the memory-backed file) type: string
default: "/tmp"
-e (endpoint for external storage service, where objects evicted from
Plasma store can be written to, optional) type: string default: ""
-h (whether to enable hugepage support) type: bool default: false
-m (amount of memory in bytes to use for Plasma store, required)
type: string default: ""
-s (socket name where the Plasma store will listen for requests,
required)
type: string default: ""
Flags from /tmp/gflags-20190105-85639-1w01usg/gflags-2.2.2/src/gflags.cc:
-flagfile (load flags from file) type: string default: ""
-fromenv (set flags from the environment [use 'export
FLAGS_flag1=value'])
type: string default: ""
-tryfromenv (set flags from the environment if present) type: string
default: ""
-undefok (comma-separated list of flag names that it is okay to specify
on
the command line even if the program does not define a flag with that
name. IMPORTANT: flags in this list that have arguments MUST use the
flag=value format) type: string default: ""
Flags from
/tmp/gflags-20190105-85639-1w01usg/gflags-2.2.2/src/gflags_completions.cc:
-tab_completion_columns (Number of columns to use in output for tab
completion) type: int32 default: 80
-tab_completion_word (If non-empty, HandleCommandLineCompletions() will
hijack the process and attempt to do bash-style command line flag
completion on this value.) type: string default: ""
Flags from
/tmp/gflags-20190105-85639-1w01usg/gflags-2.2.2/src/gflags_reporting.cc:
-help (show help on all flags [tip: all flags can have two dashes])
type: bool default: false currently: true
-helpfull (show help on all flags -- same as -help) type: bool
default: false
-helpmatch (show help on modules whose name contains the specified
substr)
type: string default: ""
-helpon (show help on the modules named by this flag value) type: string
default: ""
-helppackage (show help on all modules in the main package) type: bool
default: false
-helpshort (show help on only the main module for this program) type:
bool
default: false
-helpxml (produce an xml version of help) type: bool default: false
-version (show version and build info and exit) type: bool default: false
```
which is rather verbose, but at least does the job.
Outstanding questions:
- Is there a way to ask Gflags to suppress all that other stuff? Or do we
ditch Gflags and go back to `getopt()` but with a handcrafted help option and
message? Or is this good enough?
- I'm assuming we want to be as backward compatible as possible? Otherwise
I'd be tempted to move the non-optional command-line options to arguments, and
maybe leave `-h` for help.
- In the name of being as backward-compatible as possible, I'm exiting with
-1 if the external store directory is not empty, but with 1 for other usage
errors? Was that worth the tiny bit of complexity to preserve that behavior?
- Which version define do I use to report `plasma-store-server`'s version?
- Any comments on the description of "Shared-memory server for Arrow data.",
or is that good?
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