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, wrapper_type: str, return_type: str, name: str,
  67                  args: str, 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         self.graph_wrlock = 'bdrv_wrlock' in variant
  75
  76         self.wrapper_type = wrapper_type
  77
  78         if wrapper_type == 'co':
  79             if self.graph_wrlock:
  80                 raise ValueError(f"co function can't be wrlock: {self.name}")
  81             subsystem, subname = self.name.split('_', 1)
  82             self.target_name = f'{subsystem}_co_{subname}'
  83         else:
  84             assert wrapper_type == 'no_co'
  85             subsystem, co_infix, subname = self.name.split('_', 2)
  86             if co_infix != 'co':
  87                 raise ValueError(f"Invalid no_co function name: {self.name}")
  88             if not self.create_only_co:
  89                 raise ValueError(f"no_co function can't be mixed: {self.name}")
  90             if self.graph_rdlock and self.graph_wrlock:
  91                 raise ValueError("function can't be both rdlock and wrlock: "
  92                                  f"{self.name}")
  93             self.target_name = f'{subsystem}_{subname}'
  94
  95         self.get_result = 's->ret = '
  96         self.ret = 'return s.ret;'
  97         self.co_ret = 'return '
  98         self.return_field = self.return_type + " ret;"
  99         if self.return_type == 'void':
 100             self.get_result = ''
 101             self.ret = ''
 102             self.co_ret = ''
 103             self.return_field = ''
 104
 105     def gen_ctx(self, prefix: str = '') -> str:
 106         t = self.args[0].type
 107         name = self.args[0].name
 108         if t == 'BlockDriverState *':
 109             return f'bdrv_get_aio_context({prefix}{name})'
 110         elif t == 'BdrvChild *':
 111             return f'bdrv_get_aio_context({prefix}{name}->bs)'
 112         elif t == 'BlockBackend *':
 113             return f'blk_get_aio_context({prefix}{name})'
 114         else:
 115             return 'qemu_get_aio_context()'
 116
 117     def gen_list(self, format: str) -> str:
 118         return ', '.join(format.format_map(arg.__dict__) for arg in self.args)
 119
 120     def gen_block(self, format: str) -> str:
 121         return '\n'.join(format.format_map(arg.__dict__) for arg in self.args)
 122
 123
 124 # Match wrappers declared with a co_wrapper mark
 125 func_decl_re = re.compile(r'^(?P<return_type>[a-zA-Z][a-zA-Z0-9_]* [\*]?)'
 126                           r'(\s*coroutine_fn)?'
 127                           r'\s*(?P<wrapper_type>(no_)?co)_wrapper'
 128                           r'(?P<variant>(_[a-z][a-z0-9_]*)?)\s*'
 129                           r'(?P<wrapper_name>[a-z][a-z0-9_]*)'
 130                           r'\((?P<args>[^)]*)\);$', re.MULTILINE)
 131
 132
 133 def func_decl_iter(text: str) -> Iterator:
 134     for m in func_decl_re.finditer(text):
 135         yield FuncDecl(wrapper_type=m.group('wrapper_type'),
 136                        return_type=m.group('return_type'),
 137                        name=m.group('wrapper_name'),
 138                        args=m.group('args'),
 139                        variant=m.group('variant'))
 140
 141
 142 def snake_to_camel(func_name: str) -> str:
 143     """
 144     Convert underscore names like 'some_function_name' to camel-case like
 145     'SomeFunctionName'
 146     """
 147     words = func_name.split('_')
 148     words = [w[0].upper() + w[1:] for w in words]
 149     return ''.join(words)
 150
 151
 152 def create_mixed_wrapper(func: FuncDecl) -> str:
 153     """
 154     Checks if we are already in coroutine
 155     """
 156     name = func.target_name
 157     struct_name = func.struct_name
 158     graph_assume_lock = 'assume_graph_lock();' if func.graph_rdlock else ''
 159
 160     return f"""\
 161 {func.return_type} {func.name}({ func.gen_list('{decl}') })
 162 {{
 163     if (qemu_in_coroutine()) {{
 164         {graph_assume_lock}
 165         {func.co_ret}{name}({ func.gen_list('{name}') });
 166     }} else {{
 167         {struct_name} s = {{
 168             .poll_state.ctx = qemu_get_current_aio_context(),
 169             .poll_state.in_progress = true,
 170
 171 { func.gen_block('            .{name} = {name},') }
 172         }};
 173
 174         s.poll_state.co = qemu_coroutine_create({name}_entry, &s);
 175
 176         bdrv_poll_co(&s.poll_state);
 177         {func.ret}
 178     }}
 179 }}"""
 180
 181
 182 def create_co_wrapper(func: FuncDecl) -> str:
 183     """
 184     Assumes we are not in coroutine, and creates one
 185     """
 186     name = func.target_name
 187     struct_name = func.struct_name
 188     return f"""\
 189 {func.return_type} {func.name}({ func.gen_list('{decl}') })
 190 {{
 191     {struct_name} s = {{
 192         .poll_state.ctx = qemu_get_current_aio_context(),
 193         .poll_state.in_progress = true,
 194
 195 { func.gen_block('        .{name} = {name},') }
 196     }};
 197     assert(!qemu_in_coroutine());
 198
 199     s.poll_state.co = qemu_coroutine_create({name}_entry, &s);
 200
 201     bdrv_poll_co(&s.poll_state);
 202     {func.ret}
 203 }}"""
 204
 205
 206 def gen_co_wrapper(func: FuncDecl) -> str:
 207     assert not '_co_' in func.name
 208     assert func.wrapper_type == 'co'
 209
 210     name = func.target_name
 211     struct_name = func.struct_name
 212
 213     graph_lock=''
 214     graph_unlock=''
 215     if func.graph_rdlock:
 216         graph_lock='    bdrv_graph_co_rdlock();'
 217         graph_unlock='    bdrv_graph_co_rdunlock();'
 218
 219     creation_function = create_mixed_wrapper
 220     if func.create_only_co:
 221         creation_function = create_co_wrapper
 222
 223     return f"""\
 224 /*
 225  * Wrappers for {name}
 226  */
 227
 228 typedef struct {struct_name} {{
 229     BdrvPollCo poll_state;
 230     {func.return_field}
 231 { func.gen_block('    {decl};') }
 232 }} {struct_name};
 233
 234 static void coroutine_fn {name}_entry(void *opaque)
 235 {{
 236     {struct_name} *s = opaque;
 237
 238 {graph_lock}
 239     {func.get_result}{name}({ func.gen_list('s->{name}') });
 240 {graph_unlock}
 241     s->poll_state.in_progress = false;
 242
 243     aio_wait_kick();
 244 }}
 245
 246 {creation_function(func)}"""
 247
 248
 249 def gen_no_co_wrapper(func: FuncDecl) -> str:
 250     assert '_co_' in func.name
 251     assert func.wrapper_type == 'no_co'
 252
 253     name = func.target_name
 254     struct_name = func.struct_name
 255
 256     graph_lock=''
 257     graph_unlock=''
 258     if func.graph_rdlock:
 259         graph_lock='    bdrv_graph_rdlock_main_loop();'
 260         graph_unlock='    bdrv_graph_rdunlock_main_loop();'
 261     elif func.graph_wrlock:
 262         graph_lock='    bdrv_graph_wrlock();'
 263         graph_unlock='    bdrv_graph_wrunlock();'
 264
 265     return f"""\
 266 /*
 267  * Wrappers for {name}
 268  */
 269
 270 typedef struct {struct_name} {{
 271     Coroutine *co;
 272     {func.return_field}
 273 { func.gen_block('    {decl};') }
 274 }} {struct_name};
 275
 276 static void {name}_bh(void *opaque)
 277 {{
 278     {struct_name} *s = opaque;
 279
 280 {graph_lock}
 281     {func.get_result}{name}({ func.gen_list('s->{name}') });
 282 {graph_unlock}
 283
 284     aio_co_wake(s->co);
 285 }}
 286
 287 {func.return_type} coroutine_fn {func.name}({ func.gen_list('{decl}') })
 288 {{
 289     {struct_name} s = {{
 290         .co = qemu_coroutine_self(),
 291 { func.gen_block('        .{name} = {name},') }
 292     }};
 293     assert(qemu_in_coroutine());
 294
 295     aio_bh_schedule_oneshot(qemu_get_aio_context(), {name}_bh, &s);
 296     qemu_coroutine_yield();
 297
 298     {func.ret}
 299 }}"""
 300
 301
 302 def gen_wrappers(input_code: str) -> str:
 303     res = ''
 304     for func in func_decl_iter(input_code):
 305         res += '\n\n\n'
 306         if func.wrapper_type == 'co':
 307             res += gen_co_wrapper(func)
 308         else:
 309             res += gen_no_co_wrapper(func)
 310
 311     return res
 312
 313
 314 if __name__ == '__main__':
 315     if len(sys.argv) < 3:
 316         exit(f'Usage: {sys.argv[0]} OUT_FILE.c IN_FILE.[ch]...')
 317
 318     with open(sys.argv[1], 'w', encoding='utf-8') as f_out:
 319         f_out.write(gen_header())
 320         for fname in sys.argv[2:]:
 321             with open(fname, encoding='utf-8') as f_in:
 322                 f_out.write(gen_wrappers(f_in.read()))
 323                 f_out.write('\n')