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