~drizzle-trunk/drizzle/development : revision 481.2.1

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/* - mode: c; c-basic-offset: 2; indent-tabs-mode: nil; -*-

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* vim:expandtab:shiftwidth=2:tabstop=2:smarttab:

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*

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*

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* This program is free software; you can redistribute it and/or modify

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* it under the terms of the GNU General Public License as published by

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* the Free Software Foundation; either version 2 of the License, or

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* (at your option) any later version.

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*

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* This program is distributed in the hope that it will be useful,

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* but WITHOUT ANY WARRANTY; without even the implied warranty of

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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

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* GNU General Public License for more details.

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*

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* You should have received a copy of the GNU General Public License

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* along with this program; if not, write to the Free Software

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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA

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*/

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#ifndef mysys_iocache_h

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#define mysys_iocache_h

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struct st_io_cache;

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typedef int (*IO_CACHE_CALLBACK)(struct st_io_cache*);

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typedef struct st_io_cache_share

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{

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pthread_mutex_t mutex; /* To sync on reads into buffer. */

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pthread_cond_t cond; /* To wait for signals. */

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pthread_cond_t cond_writer; /* For a synchronized writer. */

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/* Offset in file corresponding to the first byte of buffer. */

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my_off_t pos_in_file;

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/* If a synchronized write cache is the source of the data. */

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struct st_io_cache *source_cache;

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unsigned char *buffer; /* The read buffer. */

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unsigned char *read_end; /* Behind last valid byte of buffer. */

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int running_threads; /* threads not in lock. */

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int total_threads; /* threads sharing the cache. */

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int error; /* Last error. */

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#ifdef NOT_YET_IMPLEMENTED

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/* whether the structure should be free'd */

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bool alloced;

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#endif

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} IO_CACHE_SHARE;

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typedef struct st_io_cache /* Used when cacheing files */

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{

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/* Offset in file corresponding to the first byte of unsigned char* buffer. */

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my_off_t pos_in_file;

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/*

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The offset of end of file for READ_CACHE and WRITE_CACHE.

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For SEQ_READ_APPEND it the maximum of the actual end of file and

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the position represented by read_end.

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*/

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my_off_t end_of_file;

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/* Points to current read position in the buffer */

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unsigned char *read_pos;

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/* the non-inclusive boundary in the buffer for the currently valid read */

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unsigned char *read_end;

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unsigned char *buffer; /* The read buffer */

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/* Used in ASYNC_IO */

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unsigned char *request_pos;

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/* Only used in WRITE caches and in SEQ_READ_APPEND to buffer writes */

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unsigned char *write_buffer;

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/*

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Only used in SEQ_READ_APPEND, and points to the current read position

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in the write buffer. Note that reads in SEQ_READ_APPEND caches can

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happen from both read buffer (unsigned char* buffer) and write buffer

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(unsigned char* write_buffer).

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*/

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unsigned char *append_read_pos;

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/* Points to current write position in the write buffer */

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unsigned char *write_pos;

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/* The non-inclusive boundary of the valid write area */

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unsigned char *write_end;

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/*

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Current_pos and current_end are convenience variables used by

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my_b_tell() and other routines that need to know the current offset

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current_pos points to &write_pos, and current_end to &write_end in a

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WRITE_CACHE, and &read_pos and &read_end respectively otherwise

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*/

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unsigned char **current_pos, **current_end;

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/*

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The lock is for append buffer used in SEQ_READ_APPEND cache

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need mutex copying from append buffer to read buffer.

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*/

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pthread_mutex_t append_buffer_lock;

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/*

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The following is used when several threads are reading the

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same file in parallel. They are synchronized on disk

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accesses reading the cached part of the file asynchronously.

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It should be set to NULL to disable the feature. Only

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READ_CACHE mode is supported.

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*/

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IO_CACHE_SHARE *share;

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/*

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A caller will use my_b_read() macro to read from the cache

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if the data is already in cache, it will be simply copied with

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memcpy() and internal variables will be accordinging updated with

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no functions invoked. However, if the data is not fully in the cache,

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my_b_read() will call read_function to fetch the data. read_function

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must never be invoked directly.

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*/

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int (*read_function)(struct st_io_cache *,unsigned char *,size_t);

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/*

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Same idea as in the case of read_function, except my_b_write() needs to

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be replaced with my_b_append() for a SEQ_READ_APPEND cache

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*/

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int (*write_function)(struct st_io_cache *,const unsigned char *,size_t);

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/*

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Specifies the type of the cache. Depending on the type of the cache

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certain operations might not be available and yield unpredicatable

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results. Details to be documented later

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*/

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enum cache_type type;

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/*

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Callbacks when the actual read I/O happens. These were added and

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are currently used for binary logging of LOAD DATA INFILE - when a

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block is read from the file, we create a block create/append event, and

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when IO_CACHE is closed, we create an end event. These functions could,

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of course be used for other things

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*/

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IO_CACHE_CALLBACK pre_read;

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IO_CACHE_CALLBACK post_read;

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IO_CACHE_CALLBACK pre_close;

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/*

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Counts the number of times, when we were forced to use disk. We use it to

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increase the binlog_cache_disk_use status variable.

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*/

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uint32_t disk_writes;

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void* arg; /* for use by pre/post_read */

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char *file_name; /* if used with 'open_cached_file' */

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char *dir,*prefix;

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File file; /* file descriptor */

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/*

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seek_not_done is set by my_b_seek() to inform the upcoming read/write

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operation that a seek needs to be preformed prior to the actual I/O

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error is 0 if the cache operation was successful, -1 if there was a

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"hard" error, and the actual number of I/O-ed bytes if the read/write was

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partial.

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*/

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int seek_not_done,error;

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/* buffer_length is memory size allocated for buffer or write_buffer */

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size_t buffer_length;

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/* read_length is the same as buffer_length except when we use async io */

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size_t read_length;

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myf myflags; /* Flags used to my_read/my_write */

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/*

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alloced_buffer is 1 if the buffer was allocated by init_io_cache() and

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0 if it was supplied by the user.

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Currently READ_NET is the only one that will use a buffer allocated

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somewhere else

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*/

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bool alloced_buffer;

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#ifdef HAVE_AIOWAIT

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/*

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As inidicated by ifdef, this is for async I/O, which is not currently

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used (because it's not reliable on all systems)

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*/

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uint32_t inited;

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my_off_t aio_read_pos;

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my_aio_result aio_result;

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#endif

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} IO_CACHE;

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/* tell write offset in the SEQ_APPEND cache */

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int my_b_copy_to_file(IO_CACHE *cache, FILE *file);

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my_off_t my_b_append_tell(IO_CACHE* info);

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my_off_t my_b_safe_tell(IO_CACHE* info); /* picks the correct tell() */

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extern int init_io_cache(IO_CACHE *info,File file,size_t cachesize,

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enum cache_type type,my_off_t seek_offset,

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bool use_async_io, myf cache_myflags);

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extern bool reinit_io_cache(IO_CACHE *info,enum cache_type type,

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my_off_t seek_offset,bool use_async_io,

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bool clear_cache);

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extern void setup_io_cache(IO_CACHE* info);

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extern int _my_b_read(IO_CACHE *info,unsigned char *Buffer,size_t Count);

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extern int _my_b_read_r(IO_CACHE *info,unsigned char *Buffer,size_t Count);

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extern void init_io_cache_share(IO_CACHE *read_cache, IO_CACHE_SHARE *cshare,

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IO_CACHE *write_cache, uint32_t num_threads);

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extern void remove_io_thread(IO_CACHE *info);

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extern int _my_b_seq_read(IO_CACHE *info,unsigned char *Buffer,size_t Count);

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extern int _my_b_net_read(IO_CACHE *info,unsigned char *Buffer,size_t Count);

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extern int _my_b_get(IO_CACHE *info);

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extern int _my_b_async_read(IO_CACHE *info,unsigned char *Buffer,size_t Count);

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extern int _my_b_write(IO_CACHE *info,const unsigned char *Buffer,

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size_t Count);

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extern int my_b_append(IO_CACHE *info,const unsigned char *Buffer,

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size_t Count);

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extern int my_b_safe_write(IO_CACHE *info,const unsigned char *Buffer,

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size_t Count);

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extern int my_block_write(IO_CACHE *info, const unsigned char *Buffer,

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size_t Count, my_off_t pos);

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extern int my_b_flush_io_cache(IO_CACHE *info, int need_append_buffer_lock);

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#define flush_io_cache(info) my_b_flush_io_cache((info),1)

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extern int end_io_cache(IO_CACHE *info);

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extern size_t my_b_fill(IO_CACHE *info);

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extern void my_b_seek(IO_CACHE *info,my_off_t pos);

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extern size_t my_b_gets(IO_CACHE *info, char *to, size_t max_length);

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extern my_off_t my_b_filelength(IO_CACHE *info);

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extern size_t my_b_printf(IO_CACHE *info, const char* fmt, ...);

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extern size_t my_b_vprintf(IO_CACHE *info, const char* fmt, va_list ap);

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extern bool open_cached_file(IO_CACHE *cache,const char *dir,

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const char *prefix, size_t cache_size,

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myf cache_myflags);

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extern bool real_open_cached_file(IO_CACHE *cache);

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extern void close_cached_file(IO_CACHE *cache);

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#endif