diff options
Diffstat (limited to 'mysys/mf_iocache.c')
| -rw-r--r-- | mysys/mf_iocache.c | 108 |
1 files changed, 95 insertions, 13 deletions
diff --git a/mysys/mf_iocache.c b/mysys/mf_iocache.c index b1cf940d70d..249eaf48ad2 100644 --- a/mysys/mf_iocache.c +++ b/mysys/mf_iocache.c @@ -332,7 +332,11 @@ my_bool reinit_io_cache(IO_CACHE *info, enum cache_type type, { info->read_end=info->write_pos; info->end_of_file=my_b_tell(info); - info->seek_not_done=1; + /* + Trigger a new seek only if we have a valid + file handle. + */ + info->seek_not_done= (info->file != -1); } else if (type == WRITE_CACHE) { @@ -441,11 +445,24 @@ 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 */ @@ -946,8 +963,22 @@ int _my_b_read_r(register IO_CACHE *cache, byte *Buffer, uint Count) len= 0; else { - if (cache->seek_not_done) /* File touched, do seek */ - VOID(my_seek(cache->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 (cache->seek_not_done) + { + if (my_seek(cache->file, pos_in_file, MY_SEEK_SET, MYF(0)) + == MY_FILEPOS_ERROR) + { + cache->error= -1; + unlock_io_cache(cache); + DBUG_RETURN(1); + } + } len= (int) my_read(cache->file, cache->buffer, length, cache->myflags); } DBUG_PRINT("io_cache_share", ("read %d bytes", len)); @@ -1049,11 +1080,16 @@ static void copy_to_read_buffer(IO_CACHE *write_cache, /* - 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) @@ -1081,7 +1117,13 @@ 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)); @@ -1197,6 +1239,21 @@ 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; @@ -1287,13 +1344,20 @@ 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; @@ -1380,7 +1444,15 @@ 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) { @@ -1404,8 +1476,18 @@ 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)) |