diff options
Diffstat (limited to 'mysys/mf_iocache.c')
| -rw-r--r-- | mysys/mf_iocache.c | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/mysys/mf_iocache.c b/mysys/mf_iocache.c index bfdda25cafa..72385daef42 100644 --- a/mysys/mf_iocache.c +++ b/mysys/mf_iocache.c @@ -397,8 +397,9 @@ void end_slave_io_cache(IO_CACHE *cache) void seek_io_cache(IO_CACHE *cache, my_off_t needed_offset) { my_off_t cached_data_start= cache->pos_in_file; - my_off_t cached_data_end= cache->pos_in_file + (cache->read_pos - + my_off_t cached_data_end= cache->pos_in_file + (cache->read_end - cache->buffer); + if (needed_offset >= cached_data_start && needed_offset < cached_data_end) { @@ -416,11 +417,17 @@ void seek_io_cache(IO_CACHE *cache, my_off_t needed_offset) The offset we're seeking to is not in the buffer. - Set the buffer to be exhausted. - Make the next read to a mysql_file_seek() call to the required - offset (but still use aligned reads). + offset. + TODO(cvicentiu, spetrunia) properly implement aligned seeks for + efficiency. */ - cache->read_pos= cache->read_end; cache->seek_not_done= 1; - cache->pos_in_file= (needed_offset / IO_SIZE) * IO_SIZE; + cache->pos_in_file= needed_offset; + /* When reading it must appear as if we've started from the offset + that we've seeked here. We must let _my_b_cache_read assume that + by implying "no reading starting from pos_in_file" has happened. */ + cache->read_pos= cache->buffer; + cache->read_end= cache->buffer; } } |