scripts/block-coroutine-wrapper.py

   1 #! /usr/bin/env python3
   2 """Generate coroutine wrappers for block subsystem.
   3
   4 The program parses one or several concatenated c files from stdin,
   5 searches for functions with the 'co_wrapper' specifier
   6 and generates corresponding wrappers on stdout.
   7
   8 Usage: block-coroutine-wrapper.py generated-file.c FILE.[ch]...
   9
  10 Copyright (c) 2020 Virtuozzo International GmbH.
  11
  12 This program is free software; you can redistribute it and/or modify
  13 it under the terms of the GNU General Public License as published by
  14 the Free Software Foundation; either version 2 of the License, or
  15 (at your option) any later version.
  16
  17 This program is distributed in the hope that it will be useful,
  18 but WITHOUT ANY WARRANTY; without even the implied warranty of
  19 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  20 GNU General Public License for more details.
  21
  22 You should have received a copy of the GNU General Public License
  23 along with this program.  If not, see <http://www.gnu.org/licenses/>.
  24 """
  25
  26 import sys
  27 import re
  28 from typing import Iterator
  29
  30
  31 def gen_header():
  32     copyright = re.sub('^.*Copyright', 'Copyright', __doc__, flags=re.DOTALL)
  33     copyright = re.sub('^(?=.)', ' * ', copyright.strip(), flags=re.MULTILINE)
  34     copyright = re.sub('^$', ' *', copyright, flags=re.MULTILINE)
  35     return f"""\
  36 /*
  37  * File is generated by scripts/block-coroutine-wrapper.py
  38  *
  39 {copyright}
  40  */
  41
  42 #include "qemu/osdep.h"
  43 #include "block/coroutines.h"
  44 #include "block/block-gen.h"
  45 #include "block/block_int.h"
  46 #include "block/dirty-bitmap.h"
  47 """
  48
  49
  50 class ParamDecl:
  51     param_re = re.compile(r'(?P<decl>'
  52                           r'(?P<type>.*[ *])'
  53                           r'(?P<name>[a-z][a-z0-9_]*)'
  54                           r')')
  55
  56     def __init__(self, param_decl: str) -> None:
  57         m = self.param_re.match(param_decl.strip())
  58         if m is None:
  59             raise ValueError(f'Wrong parameter declaration: "{param_decl}"')
  60         self.decl = m.group('decl')
  61         self.type = m.group('type')
  62         self.name = m.group('name')
  63
  64
  65 class FuncDecl:
  66     def __init__(self, return_type: str, name: str, args: str,
  67                  variant: str) -> None:
  68         self.return_type = return_type.strip()
  69         self.name = name.strip()
  70         self.struct_name = snake_to_camel(self.name)
  71         self.args = [ParamDecl(arg.strip()) for arg in args.split(',')]
  72         self.create_only_co = 'mixed' not in variant
  73         self.graph_rdlock = 'bdrv_rdlock' in variant
  74
  75         subsystem, subname = self.name.split('_', 1)
  76         self.co_name = f'{subsystem}_co_{subname}'
  77
  78         t = self.args[0].type
  79         if t == 'BlockDriverState *':
  80             ctx = 'bdrv_get_aio_context(bs)'
  81         elif t == 'BdrvChild *':
  82             ctx = 'bdrv_get_aio_context(child->bs)'
  83         elif t == 'BlockBackend *':
  84             ctx = 'blk_get_aio_context(blk)'
  85         else:
  86             ctx = 'qemu_get_aio_context()'
  87         self.ctx = ctx
  88
  89     def gen_list(self, format: str) -> str:
  90         return ', '.join(format.format_map(arg.__dict__) for arg in self.args)
  91
  92     def gen_block(self, format: str) -> str:
  93         return '\n'.join(format.format_map(arg.__dict__) for arg in self.args)
  94
  95
  96 # Match wrappers declared with a co_wrapper mark
  97 func_decl_re = re.compile(r'^(?P<return_type>[a-zA-Z][a-zA-Z0-9_]* [\*]?)'
  98                           r'\s*co_wrapper'
  99                           r'(?P<variant>(_[a-z][a-z0-9_]*)?)\s*'
 100                           r'(?P<wrapper_name>[a-z][a-z0-9_]*)'
 101                           r'\((?P<args>[^)]*)\);$', re.MULTILINE)
 102
 103
 104 def func_decl_iter(text: str) -> Iterator:
 105     for m in func_decl_re.finditer(text):
 106         yield FuncDecl(return_type=m.group('return_type'),
 107                        name=m.group('wrapper_name'),
 108                        args=m.group('args'),
 109                        variant=m.group('variant'))
 110
 111
 112 def snake_to_camel(func_name: str) -> str:
 113     """
 114     Convert underscore names like 'some_function_name' to camel-case like
 115     'SomeFunctionName'
 116     """
 117     words = func_name.split('_')
 118     words = [w[0].upper() + w[1:] for w in words]
 119     return ''.join(words)
 120
 121
 122 def create_mixed_wrapper(func: FuncDecl) -> str:
 123     """
 124     Checks if we are already in coroutine
 125     """
 126     name = func.co_name
 127     struct_name = func.struct_name
 128     graph_assume_lock = 'assume_graph_lock();' if func.graph_rdlock else ''
 129
 130     return f"""\
 131 {func.return_type} {func.name}({ func.gen_list('{decl}') })
 132 {{
 133     if (qemu_in_coroutine()) {{
 134         {graph_assume_lock}
 135         return {name}({ func.gen_list('{name}') });
 136     }} else {{
 137         {struct_name} s = {{
 138             .poll_state.ctx = {func.ctx},
 139             .poll_state.in_progress = true,
 140
 141 { func.gen_block('            .{name} = {name},') }
 142         }};
 143
 144         s.poll_state.co = qemu_coroutine_create({name}_entry, &s);
 145
 146         bdrv_poll_co(&s.poll_state);
 147         return s.ret;
 148     }}
 149 }}"""
 150
 151
 152 def create_co_wrapper(func: FuncDecl) -> str:
 153     """
 154     Assumes we are not in coroutine, and creates one
 155     """
 156     name = func.co_name
 157     struct_name = func.struct_name
 158     return f"""\
 159 {func.return_type} {func.name}({ func.gen_list('{decl}') })
 160 {{
 161     {struct_name} s = {{
 162         .poll_state.ctx = {func.ctx},
 163         .poll_state.in_progress = true,
 164
 165 { func.gen_block('        .{name} = {name},') }
 166     }};
 167     assert(!qemu_in_coroutine());
 168
 169     s.poll_state.co = qemu_coroutine_create({name}_entry, &s);
 170
 171     bdrv_poll_co(&s.poll_state);
 172     return s.ret;
 173 }}"""
 174
 175
 176 def gen_wrapper(func: FuncDecl) -> str:
 177     assert not '_co_' in func.name
 178
 179     name = func.co_name
 180     struct_name = func.struct_name
 181
 182     graph_lock=''
 183     graph_unlock=''
 184     if func.graph_rdlock:
 185         graph_lock='    bdrv_graph_co_rdlock();'
 186         graph_unlock='    bdrv_graph_co_rdunlock();'
 187
 188     creation_function = create_mixed_wrapper
 189     if func.create_only_co:
 190         creation_function = create_co_wrapper
 191
 192     return f"""\
 193 /*
 194  * Wrappers for {name}
 195  */
 196
 197 typedef struct {struct_name} {{
 198     BdrvPollCo poll_state;
 199     {func.return_type} ret;
 200 { func.gen_block('    {decl};') }
 201 }} {struct_name};
 202
 203 static void coroutine_fn {name}_entry(void *opaque)
 204 {{
 205     {struct_name} *s = opaque;
 206
 207 {graph_lock}
 208     s->ret = {name}({ func.gen_list('s->{name}') });
 209 {graph_unlock}
 210     s->poll_state.in_progress = false;
 211
 212     aio_wait_kick();
 213 }}
 214
 215 {creation_function(func)}"""
 216
 217
 218 def gen_wrappers(input_code: str) -> str:
 219     res = ''
 220     for func in func_decl_iter(input_code):
 221         res += '\n\n\n'
 222         res += gen_wrapper(func)
 223
 224     return res
 225
 226
 227 if __name__ == '__main__':
 228     if len(sys.argv) < 3:
 229         exit(f'Usage: {sys.argv[0]} OUT_FILE.c IN_FILE.[ch]...')
 230
 231     with open(sys.argv[1], 'w', encoding='utf-8') as f_out:
 232         f_out.write(gen_header())
 233         for fname in sys.argv[2:]:
 234             with open(fname, encoding='utf-8') as f_in:
 235                 f_out.write(gen_wrappers(f_in.read()))
 236                 f_out.write('\n')