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Filewatcher - Fixed bug caused by triggers modifying watcher state

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Some of the filewatcher's state was being fetched before the trigger was
called and then used after that call. When the trigger modified the
filewatcher's state, it would on occasion explode.
This commit is contained in:
Emmanuel BENOîT 2018-03-30 19:16:04 +02:00
parent a266120761
commit b12931c84d
1 changed files with 57 additions and 41 deletions
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98
c-filewatcher.cc
View file

@ -1,6 +1,7 @@
#include "externals.hh"
#include "c-filewatcher.hh"
#define INTRUSIVE_TRACES }}}
/*= T_FilesWatcher ===========================================================*/
@ -28,78 +29,86 @@ void T_FilesWatcher::check( )
// Handle events from inotify
inotify_event ie;
while ( read( fd , &ie , sizeof( ie ) ) == sizeof( ie ) ) {
#ifdef INTRUSIVE_TRACES
#ifdef INTRUSIVE_TRACES // {{{
printf( "inotify wd %d / evt %x\n" , ie.wd , ie.mask ); fflush( stdout );
#endif // INTRUSIVE_TRACES
#endif // INTRUSIVE_TRACES }}}
if ( ( ie.mask & ( IN_CLOSE_WRITE | IN_DELETE_SELF ) ) == 0 ) {
#ifdef INTRUSIVE_TRACES
#ifdef INTRUSIVE_TRACES // {{{
printf( " -> skipping this event\n" );
#endif // INTRUSIVE_TRACES
#endif // INTRUSIVE_TRACES }}}
continue;
}
T_FSPath const* name( inotify_.get( ie.wd ) );
if ( !name ) {
#ifdef INTRUSIVE_TRACES
T_FSPath const* namePtr( inotify_.get( ie.wd ) );
if ( !namePtr ) {
#ifdef INTRUSIVE_TRACES // {{{
printf( " -> no matching file\n" ); fflush( stdout );
#endif // INTRUSIVE_TRACES
#endif // INTRUSIVE_TRACES }}}
continue;
}
#ifdef INTRUSIVE_TRACES
printf( " -> file '%s'\n" , name->toString( ).toOSString( ).data( ) );
#endif // INTRUSIVE_TRACES
const auto name( *namePtr );
#ifdef INTRUSIVE_TRACES // {{{
printf( " -> file '%s'\n" , name.toString( ).toOSString( ).data( ) );
#endif // INTRUSIVE_TRACES }}}
auto* entry( fileWatchers_.get( *name ) );
auto* const entry( fileWatchers_.get( name ) );
assert( entry );
const auto wd{ entry->wd };
entry->trigger( );
if ( ( ie.mask & IN_DELETE_SELF ) != 0 ) {
#ifdef INTRUSIVE_TRACES
printf( " -> deleted, added as missing\n" ); fflush( stdout );
#endif // INTRUSIVE_TRACES
inotify_rm_watch( fd , entry->wd );
missing_.add( *name );
inotify_.remove( entry->wd );
entry->wd = -2;
#ifdef INTRUSIVE_TRACES // {{{
printf( " -> %s deleted, added as missing\n" ,
name.toString( ).toOSString( ).data( ) );
fflush( stdout );
#endif // INTRUSIVE_TRACES }}}
inotify_rm_watch( fd , wd );
missing_.add( name );
inotify_.remove( wd );
// We need to fetch the correct entry back, as the callback
// might have changed the underlying data.
auto* const nEntry{ fileWatchers_.get( name ) };
assert( nEntry );
nEntry->wd = -2;
}
}
// Handle missing/deleted files
for ( auto it = missing_.begin( ) ; it < missing_.end( ) ; ++it ) {
auto const& path( *it );
#ifdef INTRUSIVE_TRACES
#ifdef INTRUSIVE_TRACES // {{{
printf( "Checking missing file '%s'\n" , path.toString( ).toOSString( ).data( ) ); fflush( stdout );
#endif // INTRUSIVE_TRACES
#endif // INTRUSIVE_TRACES }}}
auto* const p( fileWatchers_.get( path ) );
#ifdef INTRUSIVE_TRACES
#ifdef INTRUSIVE_TRACES // {{{
printf( " -> found? %c\n" , p ? 'Y' : 'N' );
#endif // INTRUSIVE_TRACES
#endif // INTRUSIVE_TRACES }}}
assert( p );
#ifdef INTRUSIVE_TRACES
#ifdef INTRUSIVE_TRACES // {{{
printf( " -> wd = %d\n" , p->wd );
#endif // INTRUSIVE_TRACES
#endif // INTRUSIVE_TRACES }}}
assert( p->wd < 0 );
auto& we( *p );
const auto nwd( inotify_add_watch( fd ,
(char*) path.toString( ).toOSString( ).data( ) ,
IN_CLOSE_WRITE | IN_DELETE_SELF ) );
#ifdef INTRUSIVE_TRACES
#ifdef INTRUSIVE_TRACES // {{{
printf( " -> inotify add watch %d\n" , nwd ); fflush( stdout );
#endif // INTRUSIVE_TRACES
#endif // INTRUSIVE_TRACES }}}
if ( nwd < 0 ) {
#ifdef INTRUSIVE_TRACES
#ifdef INTRUSIVE_TRACES // {{{
printf( " -> still missing\n" ); fflush( stdout );
#endif // INTRUSIVE_TRACES
#endif // INTRUSIVE_TRACES }}}
we.wd = -1;
continue;
}
// Trigger if this was really a missing file
if ( we.wd == -1 ) {
#ifdef INTRUSIVE_TRACES
#ifdef INTRUSIVE_TRACES // {{{
printf( " -> triggering\n" ); fflush( stdout );
#endif // INTRUSIVE_TRACES
#endif // INTRUSIVE_TRACES }}}
we.trigger( );
}
@ -127,14 +136,14 @@ void T_FilesWatcher::watchFile(
T_FSPath const& path ,
T_WatchSet_* const watcher )
{
#ifdef INTRUSIVE_TRACES
#ifdef INTRUSIVE_TRACES // {{{
printf( "creating watch on '%s' for watcher %p\n" , path.toString( ).toOSString( ).data( ) , watcher ); fflush( stdout );
#endif // INTRUSIVE_TRACES
#endif // INTRUSIVE_TRACES }}}
auto* const exFilePos( fileWatchers_.get( path ) );
if ( exFilePos ) {
#ifdef INTRUSIVE_TRACES
#ifdef INTRUSIVE_TRACES // {{{
printf( " -> existing\n" ); fflush( stdout );
#endif // INTRUSIVE_TRACES
#endif // INTRUSIVE_TRACES }}}
auto& wl( exFilePos->watchers );
if ( !wl.contains( watcher ) ) {
wl.add( watcher );
@ -144,19 +153,26 @@ void T_FilesWatcher::watchFile(
const auto fstr{ path.toString( ).toOSString( ) };
f.wd = inotify_add_watch( fd , (char*) fstr.data( ) ,
IN_CLOSE_WRITE | IN_DELETE_SELF );
#ifdef INTRUSIVE_TRACES
#ifdef INTRUSIVE_TRACES // {{{
printf( " -> inotify wd %d\n" , f.wd ); fflush( stdout );
#endif // INTRUSIVE_TRACES
#endif // INTRUSIVE_TRACES }}}
if ( f.wd == -1 ) {
missing_.add( path );
#ifdef INTRUSIVE_TRACES
#ifdef INTRUSIVE_TRACES // {{{
printf( " -> missing\n" ); fflush( stdout );
#endif // INTRUSIVE_TRACES
#endif // INTRUSIVE_TRACES }}}
} else {
inotify_.add( f.wd , path );
#ifdef INTRUSIVE_TRACES
#ifdef INTRUSIVE_TRACES // {{{
printf( " -> found\n" ); fflush( stdout );
#endif // INTRUSIVE_TRACES
#endif // INTRUSIVE_TRACES }}}
const int32_t idx{ missing_.indexOf( path ) };
if ( idx >= 0 ) {
missing_.removeSwap( idx );
#ifdef INTRUSIVE_TRACES // {{{
printf( " -> removing from missing files (index %d)\n" , idx ); fflush( stdout );
#endif // INTRUSIVE_TRACES }}}
}
}
f.watchers.add( watcher );
fileWatchers_.add( path , std::move( f ) );