feat: use Python Script as UDF in SQL

[discord9]

I hereby agree to the terms of the GreptimeDB CLA

What's changed and what's your intention?

So now you can use sql query like this:

mysql> select system_status(cpu_util, memory_util, disk_util) from system_metrics;
+--------------------------------------------------------------------------------------------+
| system_status(system_metrics.cpu_util,system_metrics.memory_util,system_metrics.disk_util) |
+--------------------------------------------------------------------------------------------+
| green                                                                                      |
| yellow                                                                                     |
| red                                                                                        |
+--------------------------------------------------------------------------------------------+
3 rows in set (0.01 sec)

where system_status is this python script:

@coprocessor(args=["cpu_util", "memory_util", "disk_util"],
             returns = ["status"])
def system_status(cpus, memories, disks)->vector[str]:
    statuses = []
    for cpu, memory, disk in zip(cpus, memories, disks):
        if cpu > 80 or memory > 80 or disk > 80:
            statuses.append("red")
            continue

        status = cpu * 0.4 + memory * 0.4 + disk * 0.2

        if status > 80:
            statuses.append("yellow")
        elif status > 50:
            statuses.append("yellow")
        else:
            statuses.append("green")

    return statuses

• Now every time PyScript get insert&compile it will insert a UDF with same name
  the relevant type is PyUdf

• Need to write explict return type in python script i.e. above -> vector[str], so UDF know its' type

• Can only return one value due to limitation of UDF(Even more vectors are returned, it will be ignore by UDF's eval() function

Checklist

• I have written the necessary rustdoc comments.
• I have added the necessary unit tests and integration tests.

Refer to a related PR or issue link

#675 however still havn't support this feature of creating UDF in SQL(Might need to extend sql parser)
Also fix #232 with Settings to not let Python VM set SIGINT handler(so our tokio can take ctrl_c handler)

[waynexia]

Coooool!

[codecov]

Codecov Report

Merging #839 (2eab28c) into develop (7762873) will increase coverage by 1.03%.
The diff coverage is 77.67%.

@@             Coverage Diff             @@
##           develop     #839      +/-   ##
===========================================
+ Coverage    85.26%   86.29%   +1.03%     
===========================================
  Files          418      422       +4     
  Lines        55285    55885     +600     
===========================================
+ Hits         47140    48228    +1088     
+ Misses        8145     7657     -488     

Flag	Coverage Δ
rust	86.29% <77.67%> (+1.03%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/common/query/src/error.rs	88.04% <ø> (ø)
src/script/src/python/engine.rs	77.02% <70.58%> (-4.00%)	⬇️
src/script/src/manager.rs	94.84% <100.00%> (-0.99%)	⬇️
src/script/src/python/coprocessor.rs	86.32% <100.00%> (+0.27%)	⬆️
src/script/src/python/coprocessor/parse.rs	78.04% <100.00%> (+0.59%)	⬆️
src/script/src/python/test.rs	84.48% <100.00%> (ø)
src/common/query/src/lib.rs	62.50% <0.00%> (-37.50%)	⬇️
src/table/src/table.rs	25.00% <0.00%> (-25.00%)	⬇️
src/servers/src/error.rs	34.54% <0.00%> (-15.46%)	⬇️
src/table/src/requests.rs	55.55% <0.00%> (-6.95%)	⬇️
... and 147 more

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[github-actions]

license-eye has totally checked 645 files.

Valid	Invalid	Ignored	Fixed
539	1	105	0

Click to see the invalid file list

• src/servers/tests/py_script/mod.rs

[killme2008]

LGTM