diff options
Diffstat (limited to 'mysys/mf_iocache.c')
| -rw-r--r-- | mysys/mf_iocache.c | 102 |
1 files changed, 90 insertions, 12 deletions
diff --git a/mysys/mf_iocache.c b/mysys/mf_iocache.c index 0007784c2b2..709a3250f39 100644 --- a/mysys/mf_iocache.c +++ b/mysys/mf_iocache.c @@ -440,11 +440,24 @@ int _my_b_read(register IO_CACHE *info, byte *Buffer, uint Count) /* pos_in_file always point on where info->buffer was read */ pos_in_file=info->pos_in_file+(uint) (info->read_end - info->buffer); + + /* + Whenever a function which operates on IO_CACHE flushes/writes + some part of the IO_CACHE to disk it will set the property + "seek_not_done" to indicate this to other functions operating + on the IO_CACHE. + */ if (info->seek_not_done) - { /* File touched, do seek */ - VOID(my_seek(info->file,pos_in_file,MY_SEEK_SET,MYF(0))); + { + if (my_seek(info->file,pos_in_file,MY_SEEK_SET,MYF(0)) + == MY_FILEPOS_ERROR) + { + info->error= -1; + DBUG_RETURN(1); + } info->seek_not_done=0; } + diff_length=(uint) (pos_in_file & (IO_SIZE-1)); if (Count >= (uint) (IO_SIZE+(IO_SIZE-diff_length))) { /* Fill first intern buffer */ @@ -633,8 +646,22 @@ int _my_b_read_r(register IO_CACHE *info, byte *Buffer, uint Count) if (lock_io_cache(info, pos_in_file)) { info->share->active=info; - if (info->seek_not_done) /* File touched, do seek */ - VOID(my_seek(info->file,pos_in_file,MY_SEEK_SET,MYF(0))); + /* + Whenever a function which operates on IO_CACHE flushes/writes + some part of the IO_CACHE to disk it will set the property + "seek_not_done" to indicate this to other functions operating + on the IO_CACHE. + */ + if (info->seek_not_done) + { + if (my_seek(info->file,pos_in_file,MY_SEEK_SET,MYF(0)) + == MY_FILEPOS_ERROR) + { + info->error= -1; + unlock_io_cache(info); + DBUG_RETURN(1); + } + } len=(int)my_read(info->file,info->buffer, length, info->myflags); info->read_end=info->buffer + (len == -1 ? 0 : len); info->error=(len == (int)length ? 0 : len); @@ -668,11 +695,16 @@ int _my_b_read_r(register IO_CACHE *info, byte *Buffer, uint Count) /* - Do sequential read from the SEQ_READ_APPEND cache - we do this in three stages: + Do sequential read from the SEQ_READ_APPEND cache. + + We do this in three stages: - first read from info->buffer - then if there are still data to read, try the file descriptor - afterwards, if there are still data to read, try append buffer + + RETURNS + 0 Success + 1 Failed to read */ int _my_b_seq_read(register IO_CACHE *info, byte *Buffer, uint Count) @@ -700,7 +732,13 @@ int _my_b_seq_read(register IO_CACHE *info, byte *Buffer, uint Count) With read-append cache we must always do a seek before we read, because the write could have moved the file pointer astray */ - VOID(my_seek(info->file,pos_in_file,MY_SEEK_SET,MYF(0))); + if (my_seek(info->file,pos_in_file,MY_SEEK_SET,MYF(0)) + == MY_FILEPOS_ERROR) + { + info->error= -1; + unlock_append_buffer(info); + return (1); + } info->seek_not_done=0; diff_length=(uint) (pos_in_file & (IO_SIZE-1)); @@ -816,6 +854,21 @@ read_append_buffer: #ifdef HAVE_AIOWAIT +/* + Read from the IO_CACHE into a buffer and feed asynchronously + from disk when needed. + + SYNOPSIS + _my_b_async_read() + info IO_CACHE pointer + Buffer Buffer to retrieve count bytes from file + Count Number of bytes to read into Buffer + + RETURN VALUE + -1 An error has occurred; my_errno is set. + 0 Success + 1 An error has occurred; IO_CACHE to error state. +*/ int _my_b_async_read(register IO_CACHE *info, byte *Buffer, uint Count) { uint length,read_length,diff_length,left_length,use_length,org_Count; @@ -906,13 +959,20 @@ int _my_b_async_read(register IO_CACHE *info, byte *Buffer, uint Count) info->error=(int) (read_length+left_length); return 1; } - VOID(my_seek(info->file,next_pos_in_file,MY_SEEK_SET,MYF(0))); + + if (my_seek(info->file,next_pos_in_file,MY_SEEK_SET,MYF(0)) + == MY_FILEPOS_ERROR) + { + info->error= -1; + return (1); + } + read_length=IO_SIZE*2- (uint) (next_pos_in_file & (IO_SIZE-1)); if (Count < read_length) { /* Small block, read to cache */ if ((read_length=my_read(info->file,info->request_pos, read_length, info->myflags)) == (uint) -1) - return info->error= -1; + return info->error= -1; use_length=min(Count,read_length); memcpy(Buffer,info->request_pos,(size_t) use_length); info->read_pos=info->request_pos+Count; @@ -999,7 +1059,15 @@ int _my_b_get(IO_CACHE *info) return (int) (uchar) buff; } - /* Returns != 0 if error on write */ +/* + Write a byte buffer to IO_CACHE and flush to disk + if IO_CACHE is full. + + RETURN VALUE + 1 On error on write + 0 On success + -1 On error; my_errno contains error code. +*/ int _my_b_write(register IO_CACHE *info, const byte *Buffer, uint Count) { @@ -1022,8 +1090,18 @@ int _my_b_write(register IO_CACHE *info, const byte *Buffer, uint Count) { /* Fill first intern buffer */ length=Count & (uint) ~(IO_SIZE-1); if (info->seek_not_done) - { /* File touched, do seek */ - VOID(my_seek(info->file,info->pos_in_file,MY_SEEK_SET,MYF(0))); + { + /* + Whenever a function which operates on IO_CACHE flushes/writes + some part of the IO_CACHE to disk it will set the property + "seek_not_done" to indicate this to other functions operating + on the IO_CACHE. + */ + if (my_seek(info->file,info->pos_in_file,MY_SEEK_SET,MYF(0))) + { + info->error= -1; + return (1); + } info->seek_not_done=0; } if (my_write(info->file,Buffer,(uint) length,info->myflags | MY_NABP)) |