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