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