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