App.distro_xxx: Move properties to Distro.xxx

Commit a19679fec reverted the first attempt to make AsyncSSH reuse
one connection during an instance lifetime. That failed because a lot
of distribution-specific properties were filled in a new event loop
thread started by AsyncRunner, and AsyncSSH didn't like that.

This commit is the first part of the solution: Move those properties
from the App class to the Distro class, and load the Distro class
in an async loader. As soon as it's instantiated, it can provide all
its properties without cluttering the code with async keywords.

Signed-off-by: Jan Lindemann <jan@janware.com>

src/python/jw/pkg/App.py

@@ -211,21 +211,15 @@ class App(Base):
                 return True
         return False
 
-    def __init__(self) -> None:
+    def __init__(self, distro: Distro|None=None) -> None:
 
         super().__init__("jw-pkg swiss army knife", modules=["jw.pkg.cmds"])
 
         # -- Members without default values
-        self.__opt_os: str|None = None
         self.__opt_interactive: bool|None = None
         self.__opt_verbose: bool|None = None
         self.__top_name: str|None = None
-        self.__os_release: str|None = None
-        self.__distro_id: str|None = None
-        self.__distro_name: str|None = None
-        self.__distro_codename: str|None = None
-        self.__distro: Distro|None = None
-        self.__os_cascade: list[str]|None = None
+        self.__distro = distro
         self.__res_cache = ResultCache()
         self.__topdir: str|None = None
         self.__pretty_topdir: str|None = None
@@ -236,6 +230,10 @@ class App(Base):
         self.__projs_root = pwd.getpwuid(os.getuid()).pw_dir + "/local/src/jw.dev/proj"
         self.__pretty_projs_root = None
 
+    async def __init_async(self) -> None:
+        if self.__distro is None:
+            self.__distro = await Distro.instantiate(ec=self.exec_context, id=self.args.distro_id)
+
     async def __aexit__(self, exc_type, exc, tb) -> None:
         if self.__exec_context is not None:
             await self.__exec_context.close()
@@ -249,14 +247,12 @@ class App(Base):
             + 'one of "make:<var-name>", "unaltered", "absolute". Absolute topdir by default')
         parser.add_argument('-p', '--prefix', default = None,
             help='Parent directory of project source directories')
-        parser.add_argument('-O', '--os', default = None, help='Target operating system')
         parser.add_argument('--distro-id', default=None, help='Distribution ID (default is taken from /etc/os-release)')
         parser.add_argument('--interactive', choices=['true', 'false', 'auto'], default='true', help="Wait for user input or try to proceed unattended")
         parser.add_argument('--verbose', action='store_true', default=False, help="Be verbose on stderr about what's being done on the distro level")
         parser.add_argument('--uri', default='local', help="Run commands on this host")
 
     async def _run(self, args: argparse.Namespace) -> None:
-        self.__opt_os = args.os
         self.__topdir = args.topdir
         self.__pretty_topdir = self.__format_topdir(self.__topdir, args.topdir_format)
         self.__topdir_fmt = args.topdir_format
@@ -267,6 +263,7 @@ class App(Base):
         if args.prefix is not None:
             self.__projs_root = args.prefix
             self.__pretty_projs_root = args.prefix
+        await self.__init_async()
         return await super()._run(args)
 
     @property
@@ -303,158 +300,15 @@ class App(Base):
     def projs_root(self):
         return self.__projs_root
 
-    @property
-    def os_release(self) -> str:
-        if self.__os_release is None:
-            release_file = '/etc/os-release'
-            try:
-                result = self.call_async(self.exec_context.get(release_file, throw=True))
-                self.__os_release = result.stdout.decode().strip()
-            except Exception as e:
-                log(INFO, f'Failed to read {release_file} ({str(e)}), falling back to uname')
-                result = self.call_async(
-                            self.exec_context.run(
-                                ['uname', '-s'],
-                                throw=False,
-                                cmd_input=InputMode.NonInteractive
-                            )
-                        )
-                if result.status != 0:
-                    log(ERR, f'/etc/os-release and uname both failed, the latter with exit status {result.status}')
-                    raise
-                uname = result.decode().stdout.strip().lower()
-                self.__os_release = f'ID={uname}\nVERSION_CODENAME=unknown'
-
-        return self.__os_release
-
-    def os_release_field(self, key: str, throw: bool=False) -> str:
-        m = re.search(r'^\s*' + key + r'\s*=\s*("?)([^"\n]+)\1\s*$', self.os_release, re.MULTILINE)
-        if m is None:
-            if throw:
-                raise Exception(f'Could not read "{key}=" from /etc/os-release')
-            return None
-        return m.group(2)
-
-    @property
-    def distro_name(self) -> str:
-        if self.__distro_name is None:
-            self.__distro_name = self.os_release_field('NAME', throw=True)
-        return self.__distro_name
-
-    @property
-    def distro_id(self) -> str:
-        if self.__distro_id is None:
-            ret = self.args.distro_id # The distribution ID requested by the command line
-            if ret is None:
-                # The ID of the distribution we run on
-                ret = self.os_release_field('ID', throw=True)
-                match ret:
-                    case 'opensuse-tumbleweed':
-                        ret = 'suse'
-                    case 'kali':
-                        ret = 'kali'
-            self.__distro_id = ret
-        return self.__distro_id
-
-    @property
-    def distro_codename(self) -> str:
-        match self.distro_id:
-            case 'suse':
-                self.__distro_codename = \
-                    self.os_release_field('ID', throw=True).split('-')[1]
-            case 'kali':
-                self.__distro_codename = \
-                    self.os_release_field('VERSION_CODENAME', throw=True).split('-')[1]
-            case _:
-                self.__distro_codename = \
-                        self.os_release_field('VERSION_CODENAME', throw=True)
-        return self.__distro_codename
-
-    @property
-    def distro_cascade(self) -> str:
-        return ' '.join(self.os_cascade())
-
-    @cached_property
-    def distro_pkg_ext(self) -> str:
-        for entry in self.os_cascade():
-            ret = entry.replace('pkg-', '')
-            if ret != entry:
-                return ret
-        raise RuntimeError(f'No package extension in found in {self.distro_cascade}')
-
-    @property
-    def distro_gnu_triplet(self) -> str:
-
-        import sysconfig
-        import shutil
-        import subprocess
-
-        # Best: GNU host triplet Python was built for
-        for key in ("HOST_GNU_TYPE", "BUILD_GNU_TYPE"):  # BUILD_GNU_TYPE can exist too
-            ret = sysconfig.get_config_var(key)
-            if isinstance(ret, str) and ret:
-                return ret
-
-        # Common on Debian/Ubuntu: multiarch component (often looks like a triplet)
-        ret = sysconfig.get_config_var("MULTIARCH")
-        if isinstance(ret, str) and ret:
-            return ret
-
-        # Sometimes exposed (privately) by CPython
-        ret = getattr(sys.implementation, "_multiarch", None)
-        if isinstance(ret, str) and ret:
-            return ret
-
-        # Last resort: ask the system compiler
-        for cc in ("gcc", "cc", "clang"):
-            path = shutil.which(cc)
-            if not path:
-                continue
-            try:
-                ret = subprocess.check_output([path, "-dumpmachine"], text=True, stderr=subprocess.DEVNULL).strip()
-                if ret:
-                    return ret
-            except Exception:
-                pass
-
-        raise RuntimeError('Failed to get GNU triplet from running machine')
-
     @property
     def distro(self) -> Distro:
         if self.__distro is None:
-            ret = Distro.instantiate(self.distro_id, ec=self.exec_context)
-            self.__distro = ret
+            raise Exception('No distro object')
         return self.__distro
 
-    def distro_info(self, fmt: str|Iterable) -> str|Iterable:
-        if not isinstance(fmt, str):
-            ret: list[str] = []
-            for entry in fmt:
-                ret.append(self.distro_info(entry))
-            return ret
-        ret = fmt
-        for macro in re.findall("%{([A-Za-z_-]+)}", fmt):
-            try:
-                name = 'distro_' + macro.replace('-', '_')
-                if name == 'distro_info':
-                    continue
-                val = getattr(self, name)
-                patt = r'%{' + macro + r'}'
-                if ret.find(patt) == -1:
-                    continue
-                ret = ret.replace(patt, val)
-            except Exception as e:
-                log(ERR, f'Failed to expand macro "{macro}" inside "{fmt}": {str(e)}')
-                raise
-        return ret
-
     def find_dir(self, name: str, search_subdirs: list[str]=[], search_absdirs: list[str]=[], pretty: bool=True):
         return self.__find_dir(name, search_subdirs, search_absdirs, pretty)
 
-    @lru_cache(maxsize=None)
-    def get_os(self) -> str:
-        return self.distro_id + '-' + self.distro_codename
-
     # TODO: add support for customizing this in project.conf
     def htdocs_dir(self, project: str) -> str:
         return self.find_dir(project, ["/src/html/htdocs", "/tools/html/htdocs", "/htdocs"],
@@ -464,59 +318,6 @@ class App(Base):
     def tmpl_dir(self, name: str) -> str:
         return self.find_dir(name, ["/tmpl"],  ["/opt/" + name + "/share/tmpl"])
 
-    def os_cascade(self) -> list[str]:
-        def __append(entry: str):
-            if not entry in ret:
-                ret.append(entry)
-        if self.__os_cascade is None:
-            ret = [ 'os' ]
-            match self.distro_id:
-                case 'centos':
-                    __append('linux')
-                    __append('pkg-rpm')
-                    __append('pm-yum')
-                    __append('redhat')
-                    __append('rhel')
-                case 'fedora' | 'rhel':
-                    __append('linux')
-                    __append('pkg-rpm')
-                    __append('pm-yum')
-                    __append('redhat')
-                case 'suse':
-                    __append('linux')
-                    __append('pkg-rpm')
-                    __append('pm-zypper')
-                case 'kali' | 'raspbian':
-                    __append('linux')
-                    __append('pkg-debian')
-                    __append('pm-apt')
-                    __append('debian')
-                case 'ubuntu':
-                    __append('linux')
-                    __append('pkg-debian')
-                    __append('pm-apt')
-                case 'archlinux':
-                    __append('linux')
-                    __append('pkg-pm')
-                    __append('pm-pacman')
-
-            os = self.__opt_os if self.__opt_os is not None else self.get_os()
-            name = re.sub(r'-.*', '', os)
-            series = os
-            rx = re.compile(r'\.[0-9]+$')
-            while True:
-                n = re.sub(rx, '', series)
-                if n == series:
-                    break
-                ret.append(n)
-                series = n
-            __append(name)
-            __append(os)
-            __append(self.distro_id)
-            # e.g. os, linux, suse, suse-tumbleweed
-            self.__os_cascade = ret
-        return self.__os_cascade
-
     def strip_module_from_spec(self, mod):
         return re.sub(r'-dev$|-devel$|-run$', '', re.split('([=><]+)', mod)[0].strip())
 
@@ -660,7 +461,7 @@ class App(Base):
         log(DEBUG, "checking if project " + project + " is excluded from build")
         exclude = self.get_project_refs([ project ], ['build'], 'exclude',
                 scope = Scope.One, add_self=False, names_only=True)
-        cascade = self.os_cascade() + [ 'all' ]
+        cascade = self.distro.os_cascade + [ 'all' ]
         for p1 in exclude:
             for p2 in cascade:
                 if p1 == p2:

src/python/jw/pkg/cmds/distro/CmdInfo.py

@@ -3,20 +3,19 @@
 from argparse import Namespace, ArgumentParser
 
 from ...lib.log import *
+from ...lib.Distro import Distro
 from ..Cmd import Cmd
 from ..CmdProjects import CmdProjects
 
 class CmdInfo(Cmd): # export
 
     def __init__(self, parent: CmdProjects) -> None:
-        super().__init__(parent, 'info', help='Print information about target platform')
+        super().__init__(parent, 'info', help='Retrieve information about target platform')
 
     def add_arguments(self, parser: ArgumentParser) -> None:
         super().add_arguments(parser)
-        macro_names = ', '.join(['%%{' + name.replace('distro_', '').replace('_', '-') + '}'
-                                 for name in dir(self.app) if name.startswith('distro_')])
         parser.add_argument('--format', default='%{cascade}',
-                            help=f'Format string, expanding macros {macro_names}')
+                            help=f'Format string, expanding macros {", ".join(Distro.macros())}')
 
     async def _run(self, args: Namespace) -> None:
-        print(self.app.distro_info(args.format))
+        print(self.app.distro.expand_macros(args.format))

src/python/jw/pkg/cmds/distro/CmdInstall.py

@@ -15,8 +15,8 @@ class CmdInstall(Cmd): # export
         parser.add_argument("names", nargs="*", help="Packages to be installed")
         parser.add_argument('--only-update', default=False, action='store_true', help='Only update the listed packages, don\'t install them')
         parser.add_argument('-F', '--fixed-strings', action='store_true',
-                            help='Don\'t expand platform info macros in <names>')
+                            help='Don\'t expand platform.expand_macros macros in <names>')
 
     async def _run(self, args: Namespace) -> None:
-        names = names if args.fixed_strings else self.app.distro_info(args.names)
+        names = names if args.fixed_strings else self.app.distro.expand_macros(args.names)
         return await self.distro.install(names, only_update=args.only_update)

src/python/jw/pkg/cmds/posix/CmdCopy.py

@@ -23,12 +23,12 @@ class CmdCopy(Cmd): # export
         parser.add_argument('-g', '--group', default=None, help='Destination file group')
         parser.add_argument('-m', '--mode', default=None, help='Destination file mode')
         parser.add_argument('-F', '--fixed-strings', action='store_true',
-                            help='Don\'t expand platform info macros in <src> and <dst>')
+                            help='Don\'t expand platform.expand_macros macros in <src> and <dst>')
 
     async def _run(self, args: Namespace) -> None:
         def __expand(url: str) -> str:
             if args.fixed_strings:
                 return url
-            return self.app.distro_info(url)
+            return self.app.distro.expand_macros(url)
         await copy(__expand(args.src), __expand(args.dst),
                    owner=args.owner, group=args.group, mode=int(args.mode, 0))

src/python/jw/pkg/cmds/projects/BaseCmdPkgRelations.py

@@ -37,7 +37,7 @@ class BaseCmdPkgRelations(Cmd):
         ) -> list[str]:
 
         if subsections is None:
-            subsections = self.app.os_cascade()
+            subsections = self.app.distro.os_cascade
             subsections.append('jw')
 
         expand_semver_revision_range = expand_semver_revision_range

src/python/jw/pkg/cmds/projects/CmdRequiredOsPkg.py

@@ -38,7 +38,7 @@ class CmdRequiredOsPkg(Cmd): # export
             for d in deps:
                 if self.app.is_excluded_from_build(d) is not None:
                     deps.remove(d)
-        subsecs = self.app.os_cascade()
+        subsecs = self.app.distro.os_cascade
         log(DEBUG, "subsecs = ", subsecs)
         requires: set[str] = set()
         for sec in subsecs:

src/python/jw/pkg/lib/Distro.py

@@ -3,32 +3,86 @@
 from __future__ import annotations
 
 from typing import TYPE_CHECKING
+from functools import cached_property
 
 if TYPE_CHECKING:
     import Iterable
 
-import abc, importlib
+import abc, importlib, re
 
 from .ExecContext import ExecContext
-from .base import Result
+from .base import Result, InputMode
 from .Package import Package
 from .log import *
 
 class Distro(abc.ABC):
 
-    def __init__(self, ec: ExecContext):
+    def __init__(self, ec: ExecContext, id: str|None=None, os_release_str: str|None=None):
         assert ec is not None
+        assert id is not None
         self.__exec_context = ec
+        self.__os_release_str: str|None = os_release_str
         self.__id: str|None = None
 
-    def __set_id(self, id: str) -> None:
-        self.__id = id
+    # Names that can be used by code outside this class to retrieve
+    # distribution properties by
+    # getattr(instance, name.replace('-', '_'))
+    macro_names = [
+        'os',
+        'id',
+        'name',
+        'codename',
+        'gnu-triplet',
+        'os-cascade',
+        'os-release',
+        'pkg-ext',
+    ]
 
     # == Load
 
     @classmethod
-    def instantiate(cls, distro_id: str, *args, **kwargs):
-        backend_id = distro_id.lower().replace('-', '_')
+    async def read_os_release_str(cls, ec: ExecContext) -> None:
+        release_file = '/etc/os-release'
+        try:
+            result = await ec.get(release_file, throw=True)
+            ret = result.stdout.decode().strip()
+        except Exception as e:
+            log(INFO, f'Failed to read {release_file} ({str(e)}), falling back to uname')
+            result = await ec.run(
+                            ['uname', '-s'],
+                            throw=False,
+                            cmd_input=InputMode.NonInteractive
+                        )
+            if result.status != 0:
+                log(ERR, f'/etc/os-release and uname both failed, the latter with exit status {result.status}')
+                raise
+            uname = result.decode().stdout.strip().lower()
+            ret = f'ID={uname}\nVERSION_CODENAME=unknown'
+        return ret
+
+    @classmethod
+    def parse_os_release_field(self, key: str, os_release_str: str, throw: bool=False) -> str:
+        m = re.search(r'^\s*' + key + r'\s*=\s*("?)([^"\n]+)\1\s*$', os_release_str, re.MULTILINE)
+        if m is None:
+            if throw:
+                raise Exception(f'Could not read "{key}=" from /etc/os-release')
+            return None
+        return m.group(2)
+
+    @classmethod
+    def parse_os_release_field_id(cls, os_release_str: str, throw: bool=False) -> str:
+        ret = cls.parse_os_release_field('ID', os_release_str, throw=throw)
+        match ret:
+            case 'opensuse-tumbleweed':
+                return 'suse'
+        return ret
+
+    @classmethod
+    async def instantiate(cls, ec: ExecContext, *args, id: str|None=None, os_release_str: str|None=None, **kwargs):
+        if id is None:
+            os_release_str = await cls.read_os_release_str(ec)
+            id = cls.parse_os_release_field_id(os_release_str, throw=True)
+        backend_id = id.lower().replace('-', '_')
         match backend_id:
             case 'ubuntu' | 'raspbian' | 'kali':
                 backend_id = 'debian'
@@ -43,16 +97,172 @@ class Distro(abc.ABC):
             log(ERR, f'Failed to import Distro module {module_path} ({str(e)})')
             raise
         cls = getattr(module, 'Distro')
-        ret = cls(*args, **kwargs)
-        ret.__set_id(backend_id)
+        ret = cls(ec, *args, id=id, os_release_str=os_release_str, **kwargs)
+        return ret
+
+    def os_release_field(self, key: str, throw: bool=False) -> str:
+        return self.parse_os_release_field(key, self.os_release_str, throw)
+
+    async def cache(self) -> None:
+        if self.__os_release_str is None:
+            self.__os_release_str = await self.read_os_release_str(self.__exec_context)
+
+    @cached_property
+    def os_cascade(self) -> list[str]:
+        def __append(entry: str):
+            if not entry in ret:
+                ret.append(entry)
+        ret = [ 'os' ]
+        match self.id:
+            case 'centos':
+                __append('linux')
+                __append('pkg-rpm')
+                __append('pm-yum')
+                __append('redhat')
+                __append('rhel')
+            case 'fedora' | 'rhel':
+                __append('linux')
+                __append('pkg-rpm')
+                __append('pm-yum')
+                __append('redhat')
+            case 'suse':
+                __append('linux')
+                __append('pkg-rpm')
+                __append('pm-zypper')
+            case 'kali' | 'raspbian':
+                __append('linux')
+                __append('pkg-debian')
+                __append('pm-apt')
+                __append('debian')
+            case 'ubuntu':
+                __append('linux')
+                __append('pkg-debian')
+                __append('pm-apt')
+            case 'archlinux':
+                __append('linux')
+                __append('pkg-pm')
+                __append('pm-pacman')
+
+        os = self.os
+        name = re.sub(r'-.*', '', os)
+        series = os
+        rx = re.compile(r'\.[0-9]+$')
+        while True:
+            n = re.sub(rx, '', series)
+            if n == series:
+                break
+            ret.append(n)
+            series = n
+        __append(name)
+        __append(os)
+        __append(self.id)
+        # e.g. os, linux, suse, suse-tumbleweed
+        return ret
+
+    @cached_property
+    def cascade(self) -> str:
+        return ' '.join(self.os_cascade)
+
+    @property
+    def os_release_str(self) -> str:
+        if self.__os_release_str is None:
+            raise Exception(f'Tried to access OS release from an incompletely loaded Distro instance. Call reacache() before')
+        return self.__os_release_str
+
+    @cached_property
+    def name(self) -> str:
+        return self.os_release_field('NAME', throw=True)
+
+    @cached_property
+    def id(self) -> str:
+        return self.parse_os_release_field_id(self.__os_release_str, throw=True)
+
+    @cached_property
+    def codename(self) -> str:
+        match self.id:
+            case 'suse':
+                return self.os_release_field('ID', throw=True).split('-')[1]
+            case 'kali':
+                return self.os_release_field('VERSION_CODENAME', throw=True).split('-')[1]
+            case _:
+                return self.os_release_field('VERSION_CODENAME', throw=True)
+        raise NotImplementedError(f'Can\'t determine code name from distribution ID {self.id}')
+
+    @cached_property
+    def os(self) -> str:
+        return self.id + '-' + self.codename
+
+    @cached_property
+    def pkg_ext(self) -> str:
+        for entry in self.os_cascade():
+            ret = entry.replace('pkg-', '')
+            if ret != entry:
+                return ret
+        raise RuntimeError(f'No package extension in found in {self.os_cascade}')
+
+    @cached_property
+    def gnu_triplet(self) -> str:
+
+        import sysconfig
+        import shutil
+        import subprocess
+
+        # Best: GNU host triplet Python was built for
+        for key in ("HOST_GNU_TYPE", "BUILD_GNU_TYPE"):  # BUILD_GNU_TYPE can exist too
+            ret = sysconfig.get_config_var(key)
+            if isinstance(ret, str) and ret:
+                return ret
+
+        # Common on Debian/Ubuntu: multiarch component (often looks like a triplet)
+        ret = sysconfig.get_config_var("MULTIARCH")
+        if isinstance(ret, str) and ret:
+            return ret
+
+        # Sometimes exposed (privately) by CPython
+        ret = getattr(sys.implementation, "_multiarch", None)
+        if isinstance(ret, str) and ret:
+            return ret
+
+        # Last resort: ask the system compiler
+        for cc in ("gcc", "cc", "clang"):
+            path = shutil.which(cc)
+            if not path:
+                continue
+            try:
+                ret = subprocess.check_output([path, "-dumpmachine"], text=True, stderr=subprocess.DEVNULL).strip()
+                if ret:
+                    return ret
+            except Exception:
+                pass
+
+        raise RuntimeError('Failed to get GNU triplet from running machine')
+
+    @classmethod
+    def macros(cls) -> list[str]:
+        return ['%%{' + name + '}' for name in cls.macro_names]
+
+    def expand_macros(self, fmt: str|Iterable) -> str|Iterable:
+        if not isinstance(fmt, str):
+            ret: list[str] = []
+            for entry in fmt:
+                ret.append(self.expand_macros(entry))
+            return ret
+        ret = fmt
+        for macro in re.findall("%{([A-Za-z_-]+)}", fmt):
+            try:
+                name = macro.replace('-', '_')
+                val = getattr(self, name)
+                patt = r'%{' + macro + r'}'
+                if ret.find(patt) == -1:
+                    continue
+                ret = ret.replace(patt, val)
+            except Exception as e:
+                log(ERR, f'Failed to expand macro "{macro}" inside "{fmt}": {str(e)}')
+                raise
         return ret
 
     # == Convenience methods
 
-    @property
-    def id(self) -> str:
-        return self.__id
-
     @property
     def ctx(self) -> ExecContext:
         return self.__exec_context
@@ -67,7 +277,7 @@ class Distro(abc.ABC):
     def interactive(self) -> bool:
         return self.__exec_context.interactive
 
-    # == Distribution specific methods
+    # == Distribution abstraction methods
 
     # -- ref