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 """
  47
  48
  49 class ParamDecl:
  50     param_re = re.compile(r'(?P<decl>'
  51                           r'(?P<type>.*[ *])'
  52                           r'(?P<name>[a-z][a-z0-9_]*)'
  53                           r')')
  54
  55     def __init__(self, param_decl: str) -> None:
  56         m = self.param_re.match(param_decl.strip())
  57         if m is None:
  58             raise ValueError(f'Wrong parameter declaration: "{param_decl}"')
  59         self.decl = m.group('decl')
  60         self.type = m.group('type')
  61         self.name = m.group('name')
  62
  63
  64 class FuncDecl:
  65     def __init__(self, return_type: str, name: str, args: str,
  66                  variant: str) -> None:
  67         self.return_type = return_type.strip()
  68         self.name = name.strip()
  69         self.struct_name = snake_to_camel(self.name)
  70         self.args = [ParamDecl(arg.strip()) for arg in args.split(',')]
  71         self.create_only_co = 'mixed' not in variant
  72         self.graph_rdlock = 'bdrv_rdlock' in variant
  73
  74         subsystem, subname = self.name.split('_', 1)
  75         self.co_name = f'{subsystem}_co_{subname}'
  76
  77         t = self.args[0].type
  78         if t == 'BlockDriverState *':
  79             ctx = 'bdrv_get_aio_context(bs)'
  80         elif t == 'BdrvChild *':
  81             ctx = 'bdrv_get_aio_context(child->bs)'
  82         elif t == 'BlockBackend *':
  83             ctx = 'blk_get_aio_context(blk)'
  84         else:
  85             ctx = 'qemu_get_aio_context()'
  86         self.ctx = ctx
  87
  88     def gen_list(self, format: str) -> str:
  89         return ', '.join(format.format_map(arg.__dict__) for arg in self.args)
  90
  91     def gen_block(self, format: str) -> str:
  92         return '\n'.join(format.format_map(arg.__dict__) for arg in self.args)
  93
  94
  95 # Match wrappers declared with a co_wrapper mark
  96 func_decl_re = re.compile(r'^(?P<return_type>[a-zA-Z][a-zA-Z0-9_]* [\*]?)'
  97                           r'\s*co_wrapper'
  98                           r'(?P<variant>(_[a-z][a-z0-9_]*)?)\s*'
  99                           r'(?P<wrapper_name>[a-z][a-z0-9_]*)'
 100                           r'\((?P<args>[^)]*)\);$', re.MULTILINE)
 101
 102
 103 def func_decl_iter(text: str) -> Iterator:
 104     for m in func_decl_re.finditer(text):
 105         yield FuncDecl(return_type=m.group('return_type'),
 106                        name=m.group('wrapper_name'),
 107                        args=m.group('args'),
 108                        variant=m.group('variant'))
 109
 110
 111 def snake_to_camel(func_name: str) -> str:
 112     """
 113     Convert underscore names like 'some_function_name' to camel-case like
 114     'SomeFunctionName'
 115     """
 116     words = func_name.split('_')
 117     words = [w[0].upper() + w[1:] for w in words]
 118     return ''.join(words)
 119
 120
 121 def create_mixed_wrapper(func: FuncDecl) -> str:
 122     """
 123     Checks if we are already in coroutine
 124     """
 125     name = func.co_name
 126     struct_name = func.struct_name
 127     graph_assume_lock = 'assume_graph_lock();' if func.graph_rdlock else ''
 128
 129     return f"""\
 130 {func.return_type} {func.name}({ func.gen_list('{decl}') })
 131 {{
 132     if (qemu_in_coroutine()) {{
 133         {graph_assume_lock}
 134         return {name}({ func.gen_list('{name}') });
 135     }} else {{
 136         {struct_name} s = {{
 137             .poll_state.ctx = {func.ctx},
 138             .poll_state.in_progress = true,
 139
 140 { func.gen_block('            .{name} = {name},') }
 141         }};
 142
 143         s.poll_state.co = qemu_coroutine_create({name}_entry, &s);
 144
 145         bdrv_poll_co(&s.poll_state);
 146         return s.ret;
 147     }}
 148 }}"""
 149
 150
 151 def create_co_wrapper(func: FuncDecl) -> str:
 152     """
 153     Assumes we are not in coroutine, and creates one
 154     """
 155     name = func.co_name
 156     struct_name = func.struct_name
 157     return f"""\
 158 {func.return_type} {func.name}({ func.gen_list('{decl}') })
 159 {{
 160     {struct_name} s = {{
 161         .poll_state.ctx = {func.ctx},
 162         .poll_state.in_progress = true,
 163
 164 { func.gen_block('        .{name} = {name},') }
 165     }};
 166     assert(!qemu_in_coroutine());
 167
 168     s.poll_state.co = qemu_coroutine_create({name}_entry, &s);
 169
 170     bdrv_poll_co(&s.poll_state);
 171     return s.ret;
 172 }}"""
 173
 174
 175 def gen_wrapper(func: FuncDecl) -> str:
 176     assert not '_co_' in func.name
 177
 178     name = func.co_name
 179     struct_name = func.struct_name
 180
 181     graph_lock=''
 182     graph_unlock=''
 183     if func.graph_rdlock:
 184         graph_lock='    bdrv_graph_co_rdlock();'
 185         graph_unlock='    bdrv_graph_co_rdunlock();'
 186
 187     creation_function = create_mixed_wrapper
 188     if func.create_only_co:
 189         creation_function = create_co_wrapper
 190
 191     return f"""\
 192 /*
 193  * Wrappers for {name}
 194  */
 195
 196 typedef struct {struct_name} {{
 197     BdrvPollCo poll_state;
 198     {func.return_type} ret;
 199 { func.gen_block('    {decl};') }
 200 }} {struct_name};
 201
 202 static void coroutine_fn {name}_entry(void *opaque)
 203 {{
 204     {struct_name} *s = opaque;
 205
 206 {graph_lock}
 207     s->ret = {name}({ func.gen_list('s->{name}') });
 208 {graph_unlock}
 209     s->poll_state.in_progress = false;
 210
 211     aio_wait_kick();
 212 }}
 213
 214 {creation_function(func)}"""
 215
 216
 217 def gen_wrappers(input_code: str) -> str:
 218     res = ''
 219     for func in func_decl_iter(input_code):
 220         res += '\n\n\n'
 221         res += gen_wrapper(func)
 222
 223     return res
 224
 225
 226 if __name__ == '__main__':
 227     if len(sys.argv) < 3:
 228         exit(f'Usage: {sys.argv[0]} OUT_FILE.c IN_FILE.[ch]...')
 229
 230     with open(sys.argv[1], 'w', encoding='utf-8') as f_out:
 231         f_out.write(gen_header())
 232         for fname in sys.argv[2:]:
 233             with open(fname, encoding='utf-8') as f_in:
 234                 f_out.write(gen_wrappers(f_in.read()))
 235                 f_out.write('\n')