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-rw-r--r--mysys/mf_iocache.c1886
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diff --git a/mysys/mf_iocache.c b/mysys/mf_iocache.c
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+++ b/mysys/mf_iocache.c
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+/*
+ Copyright (c) 2000, 2011, Oracle and/or its affiliates
+ Copyright (c) 2010, 2021, MariaDB
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; version 2 of the License.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA */
+
+/*
+ Cashing of files with only does (sequential) read or writes of fixed-
+ length records. A read isn't allowed to go over file-length. A read is ok
+ if it ends at file-length and next read can try to read after file-length
+ (and get a EOF-error).
+ Possibly use of asyncronic io.
+ macros for read and writes for faster io.
+ Used instead of FILE when reading or writing whole files.
+ One can change info->pos_in_file to a higher value to skip bytes in file if
+ also info->read_pos is set to info->read_end.
+ If called through open_cached_file(), then the temporary file will
+ only be created if a write exeeds the file buffer or if one calls
+ my_b_flush_io_cache().
+
+ If one uses SEQ_READ_APPEND, then two buffers are allocated, one for
+ reading and another for writing. Reads are first done from disk and
+ then done from the write buffer. This is an efficient way to read
+ from a log file when one is writing to it at the same time.
+ For this to work, the file has to be opened in append mode!
+ Note that when one uses SEQ_READ_APPEND, one MUST write using
+ my_b_append ! This is needed because we need to lock the mutex
+ every time we access the write buffer.
+
+TODO:
+ When one SEQ_READ_APPEND and we are reading and writing at the same time,
+ each time the write buffer gets full and it's written to disk, we will
+ always do a disk read to read a part of the buffer from disk to the
+ read buffer.
+ This should be fixed so that when we do a my_b_flush_io_cache() and
+ we have been reading the write buffer, we should transfer the rest of the
+ write buffer to the read buffer before we start to reuse it.
+*/
+
+#include "mysys_priv.h"
+#include <m_string.h>
+#include <errno.h>
+#include "mysql/psi/mysql_file.h"
+
+PSI_file_key key_file_io_cache;
+
+#define lock_append_buffer(info) \
+ mysql_mutex_lock(&(info)->append_buffer_lock)
+#define unlock_append_buffer(info) \
+ mysql_mutex_unlock(&(info)->append_buffer_lock)
+
+#define IO_ROUND_UP(X) (((X)+IO_SIZE-1) & ~(IO_SIZE-1))
+#define IO_ROUND_DN(X) ( (X) & ~(IO_SIZE-1))
+
+static int _my_b_cache_read(IO_CACHE *info, uchar *Buffer, size_t Count);
+static int _my_b_cache_read_r(IO_CACHE *info, uchar *Buffer, size_t Count);
+static int _my_b_seq_read(IO_CACHE *info, uchar *Buffer, size_t Count);
+static int _my_b_cache_write(IO_CACHE *info, const uchar *Buffer, size_t Count);
+static int _my_b_cache_write_r(IO_CACHE *info, const uchar *Buffer, size_t Count);
+
+int (*_my_b_encr_read)(IO_CACHE *info,uchar *Buffer,size_t Count)= 0;
+int (*_my_b_encr_write)(IO_CACHE *info,const uchar *Buffer,size_t Count)= 0;
+
+
+
+static void
+init_functions(IO_CACHE* info)
+{
+ enum cache_type type= info->type;
+ info->read_function = 0; /* Force a core if used */
+ info->write_function = 0; /* Force a core if used */
+ switch (type) {
+ case READ_NET:
+ /*
+ Must be initialized by the caller. The problem is that
+ _my_b_net_read has to be defined in sql directory because of
+ the dependency on THD, and therefore cannot be visible to
+ programs that link against mysys but know nothing about THD, such
+ as myisamchk
+ */
+ DBUG_ASSERT(!(info->myflags & MY_ENCRYPT));
+ break;
+ case SEQ_READ_APPEND:
+ info->read_function = _my_b_seq_read;
+ DBUG_ASSERT(!(info->myflags & MY_ENCRYPT));
+ break;
+ case READ_CACHE:
+ if (info->myflags & MY_ENCRYPT)
+ {
+ DBUG_ASSERT(info->share == 0);
+ info->read_function = _my_b_encr_read;
+ break;
+ }
+ /* fall through */
+ case WRITE_CACHE:
+ if (info->myflags & MY_ENCRYPT)
+ {
+ info->write_function = _my_b_encr_write;
+ break;
+ }
+ /* fall through */
+ case READ_FIFO:
+ DBUG_ASSERT(!(info->myflags & MY_ENCRYPT));
+ info->read_function = info->share ? _my_b_cache_read_r : _my_b_cache_read;
+ info->write_function = info->share ? _my_b_cache_write_r : _my_b_cache_write;
+ break;
+ case TYPE_NOT_SET:
+ DBUG_ASSERT(0);
+ break;
+ }
+ if (type == READ_CACHE || type == WRITE_CACHE || type == SEQ_READ_APPEND)
+ info->myflags|= MY_FULL_IO;
+ else
+ info->myflags&= ~MY_FULL_IO;
+}
+
+
+/*
+ Initialize an IO_CACHE object
+
+ SYNOPSOS
+ init_io_cache_ext()
+ info cache handler to initialize
+ file File that should be associated to to the handler
+ If == -1 then real_open_cached_file()
+ will be called when it's time to open file.
+ cachesize Size of buffer to allocate for read/write
+ If == 0 then use my_default_record_cache_size
+ type Type of cache
+ seek_offset Where cache should start reading/writing
+ use_async_io Set to 1 of we should use async_io (if available)
+ cache_myflags Bitmap of different flags
+ MY_WME | MY_FAE | MY_NABP | MY_FNABP |
+ MY_DONT_CHECK_FILESIZE
+ file_key Instrumented file key for temporary cache file
+
+ RETURN
+ 0 ok
+ # error
+*/
+
+int init_io_cache_ext(IO_CACHE *info, File file, size_t cachesize,
+ enum cache_type type, my_off_t seek_offset,
+ pbool use_async_io, myf cache_myflags,
+ PSI_file_key file_key __attribute__((unused)))
+{
+ size_t min_cache;
+ my_off_t pos;
+ my_off_t end_of_file= ~(my_off_t) 0;
+ DBUG_ENTER("init_io_cache_ext");
+ DBUG_PRINT("enter",("cache:%p type: %d pos: %llu",
+ info, (int) type, (ulonglong) seek_offset));
+
+ info->file= file;
+ info->type= TYPE_NOT_SET; /* Don't set it until mutex are created */
+ info->pos_in_file= seek_offset;
+ info->alloced_buffer = 0;
+ info->buffer=0;
+ info->seek_not_done= 0;
+ info->next_file_user= NULL;
+
+ if (file >= 0)
+ {
+ DBUG_ASSERT(!(cache_myflags & MY_ENCRYPT));
+ pos= mysql_file_tell(file, MYF(0));
+ if ((pos == (my_off_t) -1) && (my_errno == ESPIPE))
+ {
+ /*
+ This kind of object doesn't support seek() or tell(). Don't set a
+ seek_not_done that will make us again try to seek() later and fail.
+
+ Additionally, if we're supposed to start somewhere other than the
+ the beginning of whatever this file is, then somebody made a bad
+ assumption.
+ */
+ DBUG_ASSERT(seek_offset == 0);
+ }
+ else
+ info->seek_not_done= MY_TEST(seek_offset != pos);
+ }
+ else
+ if (type == WRITE_CACHE && _my_b_encr_read)
+ {
+ cache_myflags|= MY_ENCRYPT;
+ DBUG_ASSERT(seek_offset == 0);
+ }
+
+ info->disk_writes= 0;
+ info->share=0;
+
+ if (!cachesize && !(cachesize= my_default_record_cache_size))
+ DBUG_RETURN(1); /* No cache requested */
+ min_cache=use_async_io ? IO_SIZE*4 : IO_SIZE*2;
+ if (type == READ_CACHE || type == SEQ_READ_APPEND)
+ { /* Assume file isn't growing */
+ DBUG_ASSERT(!(cache_myflags & MY_ENCRYPT));
+ if (!(cache_myflags & MY_DONT_CHECK_FILESIZE))
+ {
+ /* Calculate end of file to avoid allocating oversized buffers */
+ end_of_file= mysql_file_seek(file, 0L, MY_SEEK_END, MYF(0));
+ /* Need to reset seek_not_done now that we just did a seek. */
+ info->seek_not_done= end_of_file == seek_offset ? 0 : 1;
+ if (end_of_file < seek_offset)
+ end_of_file=seek_offset;
+ /* Trim cache size if the file is very small */
+ if ((my_off_t) cachesize > end_of_file-seek_offset+IO_SIZE*2-1)
+ {
+ cachesize= (size_t) (end_of_file-seek_offset)+IO_SIZE*2-1;
+ use_async_io=0; /* No need to use async */
+ }
+ }
+ }
+ cache_myflags &= ~MY_DONT_CHECK_FILESIZE;
+ if (type != READ_NET)
+ {
+ /* Retry allocating memory in smaller blocks until we get one */
+ cachesize= ((cachesize + min_cache-1) & ~(min_cache-1));
+ for (;;)
+ {
+ size_t buffer_block;
+ /*
+ Unset MY_WAIT_IF_FULL bit if it is set, to prevent conflict with
+ MY_ZEROFILL.
+ */
+ myf flags= (myf) (cache_myflags & ~(MY_WME | MY_WAIT_IF_FULL));
+
+ if (cachesize < min_cache)
+ cachesize = min_cache;
+ buffer_block= cachesize;
+ if (type == SEQ_READ_APPEND)
+ buffer_block *= 2;
+ else if (cache_myflags & MY_ENCRYPT)
+ buffer_block= 2*(buffer_block + MY_AES_BLOCK_SIZE) + sizeof(IO_CACHE_CRYPT);
+ if (cachesize == min_cache)
+ flags|= (myf) MY_WME;
+
+ if ((info->buffer= (uchar*) my_malloc(key_memory_IO_CACHE, buffer_block, flags)) != 0)
+ {
+ if (type == SEQ_READ_APPEND)
+ info->write_buffer= info->buffer + cachesize;
+ else
+ info->write_buffer= info->buffer;
+ info->alloced_buffer= buffer_block;
+ break; /* Enough memory found */
+ }
+ if (cachesize == min_cache)
+ DBUG_RETURN(2); /* Can't alloc cache */
+ /* Try with less memory */
+ cachesize= (cachesize*3/4 & ~(min_cache-1));
+ }
+ }
+
+ DBUG_PRINT("info",("init_io_cache_ext: cachesize = %lu", (ulong) cachesize));
+ info->read_length=info->buffer_length=cachesize;
+ info->myflags=cache_myflags & ~(MY_NABP | MY_FNABP);
+ info->request_pos= info->read_pos= info->write_pos = info->buffer;
+ if (type == SEQ_READ_APPEND)
+ {
+ info->append_read_pos = info->write_pos = info->write_buffer;
+ info->write_end = info->write_buffer + info->buffer_length;
+ mysql_mutex_init(key_IO_CACHE_append_buffer_lock,
+ &info->append_buffer_lock, MY_MUTEX_INIT_FAST);
+ }
+#if defined(SAFE_MUTEX)
+ else
+ {
+ /* Clear mutex so that safe_mutex will notice that it's not initialized */
+ bzero((char*) &info->append_buffer_lock, sizeof(info->append_buffer_lock));
+ }
+#endif
+
+ if (type == WRITE_CACHE)
+ info->write_end=
+ info->buffer+info->buffer_length- (seek_offset & (IO_SIZE-1));
+ else
+ info->read_end=info->buffer; /* Nothing in cache */
+
+ /* End_of_file may be changed by user later */
+ info->end_of_file= end_of_file;
+ info->error=0;
+ info->type= type;
+ init_functions(info);
+ DBUG_RETURN(0);
+}
+
+int init_io_cache(IO_CACHE *info, File file, size_t cachesize,
+ enum cache_type type, my_off_t seek_offset,
+ my_bool use_async_io, myf cache_myflags)
+{
+ return init_io_cache_ext(info, file, cachesize, type, seek_offset,
+ use_async_io, cache_myflags, key_file_io_cache);
+}
+
+/*
+ Initialize the slave IO_CACHE to read the same file (and data)
+ as master does.
+
+ One can create multiple slaves from a single master. Every slave and master
+ will have independent file positions.
+
+ The master must be a non-shared READ_CACHE.
+ It is assumed that no more reads are done after a master and/or a slave
+ has been freed (this limitation can be easily lifted).
+*/
+
+int init_slave_io_cache(IO_CACHE *master, IO_CACHE *slave)
+{
+ uchar *slave_buf;
+ DBUG_ASSERT(master->type == READ_CACHE);
+ DBUG_ASSERT(!master->share);
+ DBUG_ASSERT(master->alloced_buffer);
+
+ if (!(slave_buf= (uchar*)my_malloc(PSI_INSTRUMENT_ME, master->alloced_buffer, MYF(0))))
+ {
+ return 1;
+ }
+ memcpy(slave, master, sizeof(IO_CACHE));
+ slave->buffer= slave_buf;
+
+ memcpy(slave->buffer, master->buffer, master->alloced_buffer);
+ slave->read_pos= slave->buffer + (master->read_pos - master->buffer);
+ slave->read_end= slave->buffer + (master->read_end - master->buffer);
+
+ if (master->next_file_user)
+ {
+ IO_CACHE *p;
+ for (p= master->next_file_user;
+ p->next_file_user !=master;
+ p= p->next_file_user)
+ {}
+
+ p->next_file_user= slave;
+ slave->next_file_user= master;
+ }
+ else
+ {
+ slave->next_file_user= master;
+ master->next_file_user= slave;
+ }
+ return 0;
+}
+
+
+void end_slave_io_cache(IO_CACHE *cache)
+{
+ /* Remove the cache from the next_file_user circular linked list. */
+ if (cache->next_file_user != cache)
+ {
+ IO_CACHE *p= cache->next_file_user;
+ while (p->next_file_user != cache)
+ p= p->next_file_user;
+ p->next_file_user= cache->next_file_user;
+
+ }
+ my_free(cache->buffer);
+}
+
+/*
+ Seek a read io cache to a given offset
+*/
+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_end -
+ cache->buffer);
+
+ if (needed_offset >= cached_data_start &&
+ needed_offset < cached_data_end)
+ {
+ /*
+ The offset we're seeking to is in the buffer.
+ Move buffer's read position accordingly
+ */
+ cache->read_pos= cache->buffer + (needed_offset - cached_data_start);
+ }
+ else
+ {
+ if (needed_offset > cache->end_of_file)
+ needed_offset= cache->end_of_file;
+ /*
+ 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.
+ TODO(cvicentiu, spetrunia) properly implement aligned seeks for
+ efficiency.
+ */
+ cache->seek_not_done= 1;
+ 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;
+ }
+}
+
+
+/*
+ Use this to reset cache to re-start reading or to change the type
+ between READ_CACHE <-> WRITE_CACHE
+ If we are doing a reinit of a cache where we have the start of the file
+ in the cache, we are reusing this memory without flushing it to disk.
+*/
+
+my_bool reinit_io_cache(IO_CACHE *info, enum cache_type type,
+ my_off_t seek_offset,
+ my_bool use_async_io __attribute__((unused)),
+ my_bool clear_cache)
+{
+ DBUG_ENTER("reinit_io_cache");
+ DBUG_PRINT("enter",("cache:%p type: %d seek_offset: %llu clear_cache: %d",
+ info, type, (ulonglong) seek_offset,
+ (int) clear_cache));
+
+ DBUG_ASSERT(type == READ_CACHE || type == WRITE_CACHE);
+ DBUG_ASSERT(info->type == READ_CACHE || info->type == WRITE_CACHE);
+
+ /* If the whole file is in memory, avoid flushing to disk */
+ if (! clear_cache &&
+ seek_offset >= info->pos_in_file &&
+ seek_offset <= my_b_tell(info))
+ {
+ /* Reuse current buffer without flushing it to disk */
+ uchar *pos;
+ if (info->type == WRITE_CACHE && type == READ_CACHE)
+ {
+ info->read_end=info->write_pos;
+ info->end_of_file=my_b_tell(info);
+ /*
+ Trigger a new seek only if we have a valid
+ file handle.
+ */
+ info->seek_not_done= (info->file != -1);
+ }
+ else if (type == WRITE_CACHE)
+ {
+ if (info->type == READ_CACHE)
+ {
+ info->write_end=info->write_buffer+info->buffer_length;
+ info->seek_not_done=1;
+ }
+ info->end_of_file = ~(my_off_t) 0;
+ }
+ pos=info->request_pos+(seek_offset-info->pos_in_file);
+ if (type == WRITE_CACHE)
+ info->write_pos=pos;
+ else
+ info->read_pos= pos;
+ }
+ else
+ {
+ /*
+ If we change from WRITE_CACHE to READ_CACHE, assume that everything
+ after the current positions should be ignored. In other cases we
+ update end_of_file as it may have changed since last init.
+ */
+ if (type == READ_CACHE)
+ {
+ if (info->type == WRITE_CACHE)
+ info->end_of_file= my_b_tell(info);
+ else
+ {
+ if (!(info->myflags & MY_ENCRYPT))
+ info->end_of_file= mysql_file_seek(info->file, 0L,
+ MY_SEEK_END, MYF(0));
+ }
+ }
+ /* flush cache if we want to reuse it */
+ if (!clear_cache && my_b_flush_io_cache(info,1))
+ DBUG_RETURN(1);
+ info->pos_in_file=seek_offset;
+ /* Better to do always do a seek */
+ info->seek_not_done=1;
+ info->request_pos=info->read_pos=info->write_pos=info->buffer;
+ if (type == READ_CACHE)
+ {
+ info->read_end=info->buffer; /* Nothing in cache */
+ }
+ else
+ {
+ if (info->myflags & MY_ENCRYPT)
+ {
+ info->write_end = info->write_buffer + info->buffer_length;
+ if (seek_offset && info->file != -1)
+ {
+ info->read_end= info->buffer;
+ _my_b_encr_read(info, 0, 0); /* prefill the buffer */
+ info->write_pos= info->read_pos;
+ info->seek_not_done=1;
+ }
+ }
+ else
+ {
+ info->write_end=(info->buffer + info->buffer_length -
+ (seek_offset & (IO_SIZE-1)));
+ }
+ info->end_of_file= ~(my_off_t) 0;
+ }
+ }
+ info->type=type;
+ info->error=0;
+ init_functions(info);
+ DBUG_RETURN(0);
+} /* reinit_io_cache */
+
+
+int _my_b_read(IO_CACHE *info, uchar *Buffer, size_t Count)
+{
+ size_t left_length;
+ int res;
+
+ /* If the buffer is not empty yet, copy what is available. */
+ if ((left_length= (size_t) (info->read_end - info->read_pos)))
+ {
+ DBUG_ASSERT(Count > left_length);
+ memcpy(Buffer, info->read_pos, left_length);
+ Buffer+=left_length;
+ Count-=left_length;
+ }
+ res= info->read_function(info, Buffer, Count);
+ if (res && info->error >= 0)
+ info->error+= (int)left_length; /* update number or read bytes */
+ return res;
+}
+
+int _my_b_write(IO_CACHE *info, const uchar *Buffer, size_t Count)
+{
+ size_t rest_length;
+ int res;
+
+ /* Always use my_b_flush_io_cache() to flush write_buffer! */
+ DBUG_ASSERT(Buffer != info->write_buffer);
+
+ if (info->pos_in_file + info->buffer_length > info->end_of_file)
+ {
+ my_errno=errno=EFBIG;
+ return info->error = -1;
+ }
+
+ rest_length= (size_t) (info->write_end - info->write_pos);
+ DBUG_ASSERT(Count >= rest_length);
+ memcpy(info->write_pos, Buffer, (size_t) rest_length);
+ Buffer+=rest_length;
+ Count-=rest_length;
+ info->write_pos+=rest_length;
+
+ if (my_b_flush_io_cache(info, 1))
+ return 1;
+
+ if (Count)
+ {
+ my_off_t old_pos_in_file= info->pos_in_file;
+ res= info->write_function(info, Buffer, Count);
+ Count-= (size_t) (info->pos_in_file - old_pos_in_file);
+ Buffer+= info->pos_in_file - old_pos_in_file;
+ }
+ else
+ res= 0;
+
+ if (!res && Count)
+ {
+ memcpy(info->write_pos, Buffer, Count);
+ info->write_pos+= Count;
+ }
+ return res;
+}
+
+/*
+ Read buffered.
+
+ SYNOPSIS
+ _my_b_cache_read()
+ info IO_CACHE pointer
+ Buffer Buffer to retrieve count bytes from file
+ Count Number of bytes to read into Buffer
+
+ NOTE
+ This function is only called from the my_b_read() macro when there
+ isn't enough characters in the buffer to satisfy the request.
+
+ WARNING
+
+ When changing this function, be careful with handling file offsets
+ (end-of_file, pos_in_file). Do not cast them to possibly smaller
+ types than my_off_t unless you can be sure that their value fits.
+ Same applies to differences of file offsets.
+
+ When changing this function, check _my_b_cache_read_r(). It might need the
+ same change.
+
+ RETURN
+ 0 we succeeded in reading all data
+ 1 Error: couldn't read requested characters. In this case:
+ If info->error == -1, we got a read error.
+ Otherwise info->error contains the number of bytes in Buffer.
+*/
+
+int _my_b_cache_read(IO_CACHE *info, uchar *Buffer, size_t Count)
+{
+ size_t length= 0, diff_length, left_length= 0, max_length;
+ my_off_t pos_in_file;
+ DBUG_ENTER("_my_b_cache_read");
+
+ /* pos_in_file always point on where info->buffer was read */
+ pos_in_file=info->pos_in_file+ (size_t) (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)
+ {
+ if ((mysql_file_seek(info->file, pos_in_file, MY_SEEK_SET, MYF(0))
+ != MY_FILEPOS_ERROR))
+ {
+ /* No error, reset seek_not_done flag. */
+ info->seek_not_done= 0;
+
+ if (info->next_file_user)
+ {
+ IO_CACHE *c;
+ for (c= info->next_file_user;
+ c!= info;
+ c= c->next_file_user)
+ {
+ c->seek_not_done= 1;
+ }
+ }
+ }
+ else
+ {
+ /*
+ If the seek failed and the error number is ESPIPE, it is because
+ info->file is a pipe or socket or FIFO. We never should have tried
+ to seek on that. See Bugs#25807 and #22828 for more info.
+ */
+ DBUG_ASSERT(my_errno != ESPIPE);
+ info->error= -1;
+ DBUG_RETURN(1);
+ }
+ }
+
+ /*
+ Calculate, how much we are within a IO_SIZE block. Ideally this
+ should be zero.
+ */
+ diff_length= (size_t) (pos_in_file & (IO_SIZE-1));
+
+ /*
+ If more than a block plus the rest of the current block is wanted,
+ we do read directly, without filling the buffer.
+ */
+ if (Count >= (size_t) (IO_SIZE+(IO_SIZE-diff_length)))
+ { /* Fill first intern buffer */
+ size_t read_length;
+ if (info->end_of_file <= pos_in_file)
+ {
+ /* End of file. Return, what we did copy from the buffer. */
+ info->error= (int) left_length;
+ info->seek_not_done=1;
+ DBUG_RETURN(1);
+ }
+ /*
+ Crop the wanted count to a multiple of IO_SIZE and subtract,
+ what we did already read from a block. That way, the read will
+ end aligned with a block.
+ */
+ length= IO_ROUND_DN(Count) - diff_length;
+ if ((read_length= mysql_file_read(info->file,Buffer, length, info->myflags))
+ != length)
+ {
+ /*
+ If we didn't get, what we wanted, we either return -1 for a read
+ error, or (it's end of file), how much we got in total.
+ */
+ info->error= (read_length == (size_t) -1 ? -1 :
+ (int) (read_length+left_length));
+ info->seek_not_done=1;
+ DBUG_RETURN(1);
+ }
+ Count-=length;
+ Buffer+=length;
+ pos_in_file+=length;
+ left_length+=length;
+ diff_length=0;
+ }
+
+ /*
+ At this point, we want less than one and a partial block.
+ We will read a full cache, minus the number of bytes, we are
+ within a block already. So we will reach new alignment.
+ */
+ max_length= info->read_length-diff_length;
+ /* We will not read past end of file. */
+ if (info->type != READ_FIFO &&
+ max_length > (info->end_of_file - pos_in_file))
+ max_length= (size_t) (info->end_of_file - pos_in_file);
+ /*
+ If there is nothing left to read,
+ we either are done, or we failed to fulfill the request.
+ Otherwise, we read max_length into the cache.
+ */
+ if (!max_length)
+ {
+ if (Count)
+ {
+ /* We couldn't fulfil the request. Return, how much we got. */
+ info->error= (int) left_length;
+ DBUG_RETURN(1);
+ }
+ else
+ {
+ info->error= 0;
+ if (length == 0) /* nothing was read */
+ DBUG_RETURN(0); /* EOF */
+
+ length= 0; /* non-zero size read was done */
+ }
+ }
+ else
+ {
+ if (info->next_file_user)
+ {
+ IO_CACHE *c;
+ for (c= info->next_file_user;
+ c!= info;
+ c= c->next_file_user)
+ {
+ c->seek_not_done= 1;
+ }
+ }
+ if ((length= mysql_file_read(info->file,info->buffer, max_length,
+ info->myflags)) < Count ||
+ length == (size_t) -1)
+ {
+ /*
+ We got an read error, or less than requested (end of file).
+ If not a read error, copy, what we got.
+ */
+ if (length != (size_t) -1)
+ memcpy(Buffer, info->buffer, length);
+ info->pos_in_file= pos_in_file;
+ /* For a read error, return -1, otherwise, what we got in total. */
+ info->error= length == (size_t) -1 ? -1 : (int) (length+left_length);
+ info->read_pos=info->read_end=info->buffer;
+ info->seek_not_done=1;
+ DBUG_RETURN(1);
+ }
+ }
+ /*
+ Count is the remaining number of bytes requested.
+ length is the amount of data in the cache.
+ Read Count bytes from the cache.
+ */
+ info->read_pos=info->buffer+Count;
+ info->read_end=info->buffer+length;
+ info->pos_in_file=pos_in_file;
+ if (Count)
+ memcpy(Buffer, info->buffer, Count);
+ DBUG_RETURN(0);
+}
+
+
+/*
+ Prepare IO_CACHE for shared use.
+
+ SYNOPSIS
+ init_io_cache_share()
+ read_cache A read cache. This will be copied for
+ every thread after setup.
+ cshare The share.
+ write_cache If non-NULL a write cache that is to be
+ synchronized with the read caches.
+ num_threads Number of threads sharing the cache
+ including the write thread if any.
+
+ DESCRIPTION
+
+ The shared cache is used so: One IO_CACHE is initialized with
+ init_io_cache(). This includes the allocation of a buffer. Then a
+ share is allocated and init_io_cache_share() is called with the io
+ cache and the share. Then the io cache is copied for each thread. So
+ every thread has its own copy of IO_CACHE. But the allocated buffer
+ is shared because cache->buffer is the same for all caches.
+
+ One thread reads data from the file into the buffer. All threads
+ read from the buffer, but every thread maintains its own set of
+ pointers into the buffer. When all threads have used up the buffer
+ contents, one of the threads reads the next block of data into the
+ buffer. To accomplish this, each thread enters the cache lock before
+ accessing the buffer. They wait in lock_io_cache() until all threads
+ joined the lock. The last thread entering the lock is in charge of
+ reading from file to buffer. It wakes all threads when done.
+
+ Synchronizing a write cache to the read caches works so: Whenever
+ the write buffer needs a flush, the write thread enters the lock and
+ waits for all other threads to enter the lock too. They do this when
+ they have used up the read buffer. When all threads are in the lock,
+ the write thread copies the write buffer to the read buffer and
+ wakes all threads.
+
+ share->running_threads is the number of threads not being in the
+ cache lock. When entering lock_io_cache() the number is decreased.
+ When the thread that fills the buffer enters unlock_io_cache() the
+ number is reset to the number of threads. The condition
+ running_threads == 0 means that all threads are in the lock. Bumping
+ up the number to the full count is non-intuitive. But increasing the
+ number by one for each thread that leaves the lock could lead to a
+ solo run of one thread. The last thread to join a lock reads from
+ file to buffer, wakes the other threads, processes the data in the
+ cache and enters the lock again. If no other thread left the lock
+ meanwhile, it would think it's the last one again and read the next
+ block...
+
+ The share has copies of 'error', 'buffer', 'read_end', and
+ 'pos_in_file' from the thread that filled the buffer. We may not be
+ able to access this information directly from its cache because the
+ thread may be removed from the share before the variables could be
+ copied by all other threads. Or, if a write buffer is synchronized,
+ it would change its 'pos_in_file' after waking the other threads,
+ possibly before they could copy its value.
+
+ However, the 'buffer' variable in the share is for a synchronized
+ write cache. It needs to know where to put the data. Otherwise it
+ would need access to the read cache of one of the threads that is
+ not yet removed from the share.
+
+ RETURN
+ void
+*/
+
+void init_io_cache_share(IO_CACHE *read_cache, IO_CACHE_SHARE *cshare,
+ IO_CACHE *write_cache, uint num_threads)
+{
+ DBUG_ENTER("init_io_cache_share");
+ DBUG_PRINT("io_cache_share", ("read_cache: %p share: %p "
+ "write_cache: %p threads: %u",
+ read_cache, cshare,
+ write_cache, num_threads));
+
+ DBUG_ASSERT(num_threads > 1);
+ DBUG_ASSERT(read_cache->type == READ_CACHE);
+ DBUG_ASSERT(!write_cache || (write_cache->type == WRITE_CACHE));
+
+ mysql_mutex_init(key_IO_CACHE_SHARE_mutex,
+ &cshare->mutex, MY_MUTEX_INIT_FAST);
+ mysql_cond_init(key_IO_CACHE_SHARE_cond, &cshare->cond, 0);
+ mysql_cond_init(key_IO_CACHE_SHARE_cond_writer, &cshare->cond_writer, 0);
+
+ cshare->running_threads= num_threads;
+ cshare->total_threads= num_threads;
+ cshare->error= 0; /* Initialize. */
+ cshare->buffer= read_cache->buffer;
+ cshare->read_end= NULL; /* See function comment of lock_io_cache(). */
+ cshare->pos_in_file= 0; /* See function comment of lock_io_cache(). */
+ cshare->source_cache= write_cache; /* Can be NULL. */
+
+ read_cache->share= cshare;
+ read_cache->read_function= _my_b_cache_read_r;
+
+ if (write_cache)
+ {
+ write_cache->share= cshare;
+ write_cache->write_function= _my_b_cache_write_r;
+ }
+
+ DBUG_VOID_RETURN;
+}
+
+
+/*
+ Remove a thread from shared access to IO_CACHE.
+
+ SYNOPSIS
+ remove_io_thread()
+ cache The IO_CACHE to be removed from the share.
+
+ NOTE
+
+ Every thread must do that on exit for not to deadlock other threads.
+
+ The last thread destroys the pthread resources.
+
+ A writer flushes its cache first.
+
+ RETURN
+ void
+*/
+
+void remove_io_thread(IO_CACHE *cache)
+{
+ IO_CACHE_SHARE *cshare= cache->share;
+ uint total;
+ DBUG_ENTER("remove_io_thread");
+
+ /* If the writer goes, it needs to flush the write cache. */
+ if (cache == cshare->source_cache)
+ flush_io_cache(cache);
+
+ mysql_mutex_lock(&cshare->mutex);
+ DBUG_PRINT("io_cache_share", ("%s: %p",
+ (cache == cshare->source_cache) ?
+ "writer" : "reader", cache));
+
+ /* Remove from share. */
+ total= --cshare->total_threads;
+ DBUG_PRINT("io_cache_share", ("remaining threads: %u", total));
+
+ /* Detach from share. */
+ cache->share= NULL;
+
+ /* If the writer goes, let the readers know. */
+ if (cache == cshare->source_cache)
+ {
+ DBUG_PRINT("io_cache_share", ("writer leaves"));
+ cshare->source_cache= NULL;
+ }
+
+ /* If all threads are waiting for me to join the lock, wake them. */
+ if (!--cshare->running_threads)
+ {
+ DBUG_PRINT("io_cache_share", ("the last running thread leaves, wake all"));
+ mysql_cond_signal(&cshare->cond_writer);
+ mysql_cond_broadcast(&cshare->cond);
+ }
+
+ mysql_mutex_unlock(&cshare->mutex);
+
+ if (!total)
+ {
+ DBUG_PRINT("io_cache_share", ("last thread removed, destroy share"));
+ mysql_cond_destroy (&cshare->cond_writer);
+ mysql_cond_destroy (&cshare->cond);
+ mysql_mutex_destroy(&cshare->mutex);
+ }
+
+ DBUG_VOID_RETURN;
+}
+
+
+/*
+ Lock IO cache and wait for all other threads to join.
+
+ SYNOPSIS
+ lock_io_cache()
+ cache The cache of the thread entering the lock.
+ pos File position of the block to read.
+ Unused for the write thread.
+
+ DESCRIPTION
+
+ Wait for all threads to finish with the current buffer. We want
+ all threads to proceed in concert. The last thread to join
+ lock_io_cache() will read the block from file and all threads start
+ to use it. Then they will join again for reading the next block.
+
+ The waiting threads detect a fresh buffer by comparing
+ cshare->pos_in_file with the position they want to process next.
+ Since the first block may start at position 0, we take
+ cshare->read_end as an additional condition. This variable is
+ initialized to NULL and will be set after a block of data is written
+ to the buffer.
+
+ RETURN
+ 1 OK, lock in place, go ahead and read.
+ 0 OK, unlocked, another thread did the read.
+*/
+
+static int lock_io_cache(IO_CACHE *cache, my_off_t pos)
+{
+ IO_CACHE_SHARE *cshare= cache->share;
+ DBUG_ENTER("lock_io_cache");
+
+ /* Enter the lock. */
+ mysql_mutex_lock(&cshare->mutex);
+ cshare->running_threads--;
+ DBUG_PRINT("io_cache_share", ("%s: %p pos: %lu running: %u",
+ (cache == cshare->source_cache) ?
+ "writer" : "reader", cache, (ulong) pos,
+ cshare->running_threads));
+
+ if (cshare->source_cache)
+ {
+ /* A write cache is synchronized to the read caches. */
+
+ if (cache == cshare->source_cache)
+ {
+ /* The writer waits until all readers are here. */
+ while (cshare->running_threads)
+ {
+ DBUG_PRINT("io_cache_share", ("writer waits in lock"));
+ mysql_cond_wait(&cshare->cond_writer, &cshare->mutex);
+ }
+ DBUG_PRINT("io_cache_share", ("writer awoke, going to copy"));
+
+ /* Stay locked. Leave the lock later by unlock_io_cache(). */
+ DBUG_RETURN(1);
+ }
+
+ /* The last thread wakes the writer. */
+ if (!cshare->running_threads)
+ {
+ DBUG_PRINT("io_cache_share", ("waking writer"));
+ mysql_cond_signal(&cshare->cond_writer);
+ }
+
+ /*
+ Readers wait until the data is copied from the writer. Another
+ reason to stop waiting is the removal of the write thread. If this
+ happens, we leave the lock with old data in the buffer.
+ */
+ while ((!cshare->read_end || (cshare->pos_in_file < pos)) &&
+ cshare->source_cache)
+ {
+ DBUG_PRINT("io_cache_share", ("reader waits in lock"));
+ mysql_cond_wait(&cshare->cond, &cshare->mutex);
+ }
+
+ /*
+ If the writer was removed from the share while this thread was
+ asleep, we need to simulate an EOF condition. The writer cannot
+ reset the share variables as they might still be in use by readers
+ of the last block. When we awake here then because the last
+ joining thread signalled us. If the writer is not the last, it
+ will not signal. So it is safe to clear the buffer here.
+ */
+ if (!cshare->read_end || (cshare->pos_in_file < pos))
+ {
+ DBUG_PRINT("io_cache_share", ("reader found writer removed. EOF"));
+ cshare->read_end= cshare->buffer; /* Empty buffer. */
+ cshare->error= 0; /* EOF is not an error. */
+ }
+ }
+ else
+ {
+ /*
+ There are read caches only. The last thread arriving in
+ lock_io_cache() continues with a locked cache and reads the block.
+ */
+ if (!cshare->running_threads)
+ {
+ DBUG_PRINT("io_cache_share", ("last thread joined, going to read"));
+ /* Stay locked. Leave the lock later by unlock_io_cache(). */
+ DBUG_RETURN(1);
+ }
+
+ /*
+ All other threads wait until the requested block is read by the
+ last thread arriving. Another reason to stop waiting is the
+ removal of a thread. If this leads to all threads being in the
+ lock, we have to continue also. The first of the awaken threads
+ will then do the read.
+ */
+ while ((!cshare->read_end || (cshare->pos_in_file < pos)) &&
+ cshare->running_threads)
+ {
+ DBUG_PRINT("io_cache_share", ("reader waits in lock"));
+ mysql_cond_wait(&cshare->cond, &cshare->mutex);
+ }
+
+ /* If the block is not yet read, continue with a locked cache and read. */
+ if (!cshare->read_end || (cshare->pos_in_file < pos))
+ {
+ DBUG_PRINT("io_cache_share", ("reader awoke, going to read"));
+ /* Stay locked. Leave the lock later by unlock_io_cache(). */
+ DBUG_RETURN(1);
+ }
+
+ /* Another thread did read the block already. */
+ }
+ DBUG_PRINT("io_cache_share", ("reader awoke, going to process %u bytes",
+ (uint) (cshare->read_end ? (size_t)
+ (cshare->read_end - cshare->buffer) :
+ 0)));
+
+ /*
+ Leave the lock. Do not call unlock_io_cache() later. The thread that
+ filled the buffer did this and marked all threads as running.
+ */
+ mysql_mutex_unlock(&cshare->mutex);
+ DBUG_RETURN(0);
+}
+
+
+/*
+ Unlock IO cache.
+
+ SYNOPSIS
+ unlock_io_cache()
+ cache The cache of the thread leaving the lock.
+
+ NOTE
+ This is called by the thread that filled the buffer. It marks all
+ threads as running and awakes them. This must not be done by any
+ other thread.
+
+ Do not signal cond_writer. Either there is no writer or the writer
+ is the only one who can call this function.
+
+ The reason for resetting running_threads to total_threads before
+ waking all other threads is that it could be possible that this
+ thread is so fast with processing the buffer that it enters the lock
+ before even one other thread has left it. If every awoken thread
+ would increase running_threads by one, this thread could think that
+ he is again the last to join and would not wait for the other
+ threads to process the data.
+
+ RETURN
+ void
+*/
+
+static void unlock_io_cache(IO_CACHE *cache)
+{
+ IO_CACHE_SHARE *cshare= cache->share;
+ DBUG_ENTER("unlock_io_cache");
+ DBUG_PRINT("io_cache_share", ("%s: %p pos: %lu running: %u",
+ (cache == cshare->source_cache) ?
+ "writer" : "reader",
+ cache, (ulong) cshare->pos_in_file,
+ cshare->total_threads));
+
+ cshare->running_threads= cshare->total_threads;
+ mysql_cond_broadcast(&cshare->cond);
+ mysql_mutex_unlock(&cshare->mutex);
+ DBUG_VOID_RETURN;
+}
+
+
+/*
+ Read from IO_CACHE when it is shared between several threads.
+
+ SYNOPSIS
+ _my_b_cache_read_r()
+ cache IO_CACHE pointer
+ Buffer Buffer to retrieve count bytes from file
+ Count Number of bytes to read into Buffer
+
+ NOTE
+ This function is only called from the my_b_read() macro when there
+ isn't enough characters in the buffer to satisfy the request.
+
+ IMPLEMENTATION
+
+ It works as follows: when a thread tries to read from a file (that
+ is, after using all the data from the (shared) buffer), it just
+ hangs on lock_io_cache(), waiting for other threads. When the very
+ last thread attempts a read, lock_io_cache() returns 1, the thread
+ does actual IO and unlock_io_cache(), which signals all the waiting
+ threads that data is in the buffer.
+
+ WARNING
+
+ When changing this function, be careful with handling file offsets
+ (end-of_file, pos_in_file). Do not cast them to possibly smaller
+ types than my_off_t unless you can be sure that their value fits.
+ Same applies to differences of file offsets. (Bug #11527)
+
+ When changing this function, check _my_b_cache_read(). It might need the
+ same change.
+
+ RETURN
+ 0 we succeeded in reading all data
+ 1 Error: can't read requested characters
+*/
+
+static int _my_b_cache_read_r(IO_CACHE *cache, uchar *Buffer, size_t Count)
+{
+ my_off_t pos_in_file;
+ size_t length, diff_length, left_length= 0;
+ IO_CACHE_SHARE *cshare= cache->share;
+ DBUG_ENTER("_my_b_cache_read_r");
+ DBUG_ASSERT(!(cache->myflags & MY_ENCRYPT));
+
+ while (Count)
+ {
+ size_t cnt, len;
+
+ pos_in_file= cache->pos_in_file + (cache->read_end - cache->buffer);
+ diff_length= (size_t) (pos_in_file & (IO_SIZE-1));
+ length=IO_ROUND_UP(Count+diff_length)-diff_length;
+ length= ((length <= cache->read_length) ?
+ length + IO_ROUND_DN(cache->read_length - length) :
+ length - IO_ROUND_UP(length - cache->read_length));
+ if (cache->type != READ_FIFO &&
+ (length > (cache->end_of_file - pos_in_file)))
+ length= (size_t) (cache->end_of_file - pos_in_file);
+ if (length == 0)
+ {
+ cache->error= (int) left_length;
+ DBUG_RETURN(1);
+ }
+ if (lock_io_cache(cache, pos_in_file))
+ {
+ /* With a synchronized write/read cache we won't come here... */
+ DBUG_ASSERT(!cshare->source_cache);
+ /*
+ ... unless the writer has gone before this thread entered the
+ lock. Simulate EOF in this case. It can be distinguished by
+ cache->file.
+ */
+ if (cache->file < 0)
+ len= 0;
+ else
+ {
+ /*
+ 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 (mysql_file_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= mysql_file_read(cache->file, cache->buffer, length, cache->myflags);
+ }
+ DBUG_PRINT("io_cache_share", ("read %lu bytes", (ulong) len));
+
+ cache->read_end= cache->buffer + (len == (size_t) -1 ? 0 : len);
+ cache->error= (len == length ? 0 : (int) len);
+ cache->pos_in_file= pos_in_file;
+
+ /* Copy important values to the share. */
+ cshare->error= cache->error;
+ cshare->read_end= cache->read_end;
+ cshare->pos_in_file= pos_in_file;
+
+ /* Mark all threads as running and wake them. */
+ unlock_io_cache(cache);
+ }
+ else
+ {
+ /*
+ With a synchronized write/read cache readers always come here.
+ Copy important values from the share.
+ */
+ cache->error= cshare->error;
+ cache->read_end= cshare->read_end;
+ cache->pos_in_file= cshare->pos_in_file;
+
+ len= ((cache->error == -1) ? (size_t) -1 :
+ (size_t) (cache->read_end - cache->buffer));
+ }
+ cache->read_pos= cache->buffer;
+ cache->seek_not_done= 0;
+ if (len == 0 || len == (size_t) -1)
+ {
+ DBUG_PRINT("io_cache_share", ("reader error. len %lu left %lu",
+ (ulong) len, (ulong) left_length));
+ cache->error= (int) left_length;
+ DBUG_RETURN(1);
+ }
+ cnt= (len > Count) ? Count : len;
+ if (cnt)
+ memcpy(Buffer, cache->read_pos, cnt);
+ Count -= cnt;
+ Buffer+= cnt;
+ left_length+= cnt;
+ cache->read_pos+= cnt;
+ }
+ DBUG_RETURN(0);
+}
+
+
+/*
+ Copy data from write cache to read cache.
+
+ SYNOPSIS
+ copy_to_read_buffer()
+ write_cache The write cache.
+ write_buffer The source of data, mostly the cache buffer.
+ write_length The number of bytes to copy.
+
+ NOTE
+ The write thread will wait for all read threads to join the cache
+ lock. Then it copies the data over and wakes the read threads.
+
+ RETURN
+ void
+*/
+
+static void copy_to_read_buffer(IO_CACHE *write_cache,
+ const uchar *write_buffer, my_off_t pos_in_file)
+{
+ size_t write_length= (size_t) (write_cache->pos_in_file - pos_in_file);
+ IO_CACHE_SHARE *cshare= write_cache->share;
+
+ DBUG_ASSERT(cshare->source_cache == write_cache);
+ /*
+ write_length is usually less or equal to buffer_length.
+ It can be bigger if _my_b_cache_write_r() is called with a big length.
+ */
+ while (write_length)
+ {
+ size_t copy_length= MY_MIN(write_length, write_cache->buffer_length);
+ int __attribute__((unused)) rc;
+
+ rc= lock_io_cache(write_cache, pos_in_file);
+ /* The writing thread does always have the lock when it awakes. */
+ DBUG_ASSERT(rc);
+
+ memcpy(cshare->buffer, write_buffer, copy_length);
+
+ cshare->error= 0;
+ cshare->read_end= cshare->buffer + copy_length;
+ cshare->pos_in_file= pos_in_file;
+
+ /* Mark all threads as running and wake them. */
+ unlock_io_cache(write_cache);
+
+ write_buffer+= copy_length;
+ write_length-= copy_length;
+ }
+}
+
+
+/*
+ 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
+*/
+
+static int _my_b_seq_read(IO_CACHE *info, uchar *Buffer, size_t Count)
+{
+ size_t length, diff_length, save_count, max_length;
+ my_off_t pos_in_file;
+ save_count=Count;
+
+ lock_append_buffer(info);
+
+ /* pos_in_file always point on where info->buffer was read */
+ if ((pos_in_file=info->pos_in_file +
+ (size_t) (info->read_end - info->buffer)) >= info->end_of_file)
+ goto read_append_buffer;
+
+ /*
+ With read-append cache we must always do a seek before we read,
+ because the write could have moved the file pointer astray
+ */
+ if (mysql_file_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= (size_t) (pos_in_file & (IO_SIZE-1));
+
+ /* now the second stage begins - read from file descriptor */
+ if (Count >= (size_t) (IO_SIZE+(IO_SIZE-diff_length)))
+ {
+ /* Fill first intern buffer */
+ size_t read_length;
+
+ length= IO_ROUND_DN(Count) - diff_length;
+ if ((read_length= mysql_file_read(info->file,Buffer, length,
+ info->myflags)) == (size_t) -1)
+ {
+ info->error= -1;
+ unlock_append_buffer(info);
+ return 1;
+ }
+ Count-=read_length;
+ Buffer+=read_length;
+ pos_in_file+=read_length;
+
+ if (read_length != length)
+ {
+ /*
+ We only got part of data; Read the rest of the data from the
+ write buffer
+ */
+ goto read_append_buffer;
+ }
+ diff_length=0;
+ }
+
+ max_length= info->read_length-diff_length;
+ if (max_length > (info->end_of_file - pos_in_file))
+ max_length= (size_t) (info->end_of_file - pos_in_file);
+ if (!max_length)
+ {
+ if (Count)
+ goto read_append_buffer;
+ length=0; /* Didn't read any more chars */
+ }
+ else
+ {
+ length= mysql_file_read(info->file,info->buffer, max_length, info->myflags);
+ if (length == (size_t) -1)
+ {
+ info->error= -1;
+ unlock_append_buffer(info);
+ return 1;
+ }
+ if (length < Count)
+ {
+ memcpy(Buffer, info->buffer, length);
+ Count -= length;
+ Buffer += length;
+
+ /*
+ added the line below to make
+ DBUG_ASSERT(pos_in_file==info->end_of_file) pass.
+ otherwise this does not appear to be needed
+ */
+ pos_in_file += length;
+ goto read_append_buffer;
+ }
+ }
+ unlock_append_buffer(info);
+ info->read_pos=info->buffer+Count;
+ info->read_end=info->buffer+length;
+ info->pos_in_file=pos_in_file;
+ memcpy(Buffer,info->buffer,(size_t) Count);
+ return 0;
+
+read_append_buffer:
+
+ /*
+ Read data from the current write buffer.
+ Count should never be == 0 here (The code will work even if count is 0)
+ */
+
+ {
+ /* First copy the data to Count */
+ size_t len_in_buff = (size_t) (info->write_pos - info->append_read_pos);
+ size_t copy_len;
+ size_t transfer_len;
+
+ DBUG_ASSERT(info->append_read_pos <= info->write_pos);
+ copy_len=MY_MIN(Count, len_in_buff);
+ memcpy(Buffer, info->append_read_pos, copy_len);
+ info->append_read_pos += copy_len;
+ Count -= copy_len;
+ if (Count)
+ info->error= (int) (save_count - Count);
+
+ /* Fill read buffer with data from write buffer */
+ memcpy(info->buffer, info->append_read_pos,
+ (size_t) (transfer_len=len_in_buff - copy_len));
+ info->read_pos= info->buffer;
+ info->read_end= info->buffer+transfer_len;
+ info->append_read_pos=info->write_pos;
+ info->pos_in_file=pos_in_file+copy_len;
+ info->end_of_file+=len_in_buff;
+ }
+ unlock_append_buffer(info);
+ return Count ? 1 : 0;
+}
+
+
+/* Read one byte when buffer is empty */
+
+int _my_b_get(IO_CACHE *info)
+{
+ uchar buff;
+ if ((*(info)->read_function)(info,&buff,1))
+ return my_b_EOF;
+ return (int) (uchar) buff;
+}
+
+/*
+ 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_cache_write(IO_CACHE *info, const uchar *Buffer, size_t Count)
+{
+ if (Buffer != info->write_buffer)
+ {
+ Count= IO_ROUND_DN(Count);
+ if (!Count)
+ return 0;
+ }
+
+ if (info->seek_not_done)
+ {
+ /*
+ 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 (mysql_file_seek(info->file, info->pos_in_file, MY_SEEK_SET,
+ MYF(info->myflags & MY_WME)) == MY_FILEPOS_ERROR)
+ {
+ info->error= -1;
+ return 1;
+ }
+ info->seek_not_done=0;
+ }
+ if (mysql_file_write(info->file, Buffer, Count, info->myflags | MY_NABP))
+ return info->error= -1;
+
+ info->pos_in_file+= Count;
+ return 0;
+}
+
+
+/*
+ In case of a shared I/O cache with a writer we normally do direct
+ write cache to read cache copy. Simulate this here by direct
+ caller buffer to read cache copy. Do it after the write so that
+ the cache readers actions on the flushed part can go in parallel
+ with the write of the extra stuff. copy_to_read_buffer()
+ synchronizes writer and readers so that after this call the
+ readers can act on the extra stuff while the writer can go ahead
+ and prepare the next output. copy_to_read_buffer() relies on
+ info->pos_in_file.
+*/
+static int _my_b_cache_write_r(IO_CACHE *info, const uchar *Buffer, size_t Count)
+{
+ my_off_t old_pos_in_file= info->pos_in_file;
+ int res= _my_b_cache_write(info, Buffer, Count);
+ if (res)
+ return res;
+
+ DBUG_ASSERT(!(info->myflags & MY_ENCRYPT));
+ DBUG_ASSERT(info->share);
+ copy_to_read_buffer(info, Buffer, old_pos_in_file);
+
+ return 0;
+}
+
+
+/*
+ Append a block to the write buffer.
+ This is done with the buffer locked to ensure that we don't read from
+ the write buffer before we are ready with it.
+*/
+
+int my_b_append(IO_CACHE *info, const uchar *Buffer, size_t Count)
+{
+ size_t rest_length,length;
+
+ MEM_CHECK_DEFINED(Buffer, Count);
+
+ /*
+ Assert that we cannot come here with a shared cache. If we do one
+ day, we might need to add a call to copy_to_read_buffer().
+ */
+ DBUG_ASSERT(!info->share);
+ DBUG_ASSERT(!(info->myflags & MY_ENCRYPT));
+
+ lock_append_buffer(info);
+ rest_length= (size_t) (info->write_end - info->write_pos);
+ if (Count <= rest_length)
+ goto end;
+ memcpy(info->write_pos, Buffer, rest_length);
+ Buffer+=rest_length;
+ Count-=rest_length;
+ info->write_pos+=rest_length;
+ if (my_b_flush_io_cache(info,0))
+ {
+ unlock_append_buffer(info);
+ return 1;
+ }
+ if (Count >= IO_SIZE)
+ { /* Fill first intern buffer */
+ length= IO_ROUND_DN(Count);
+ if (mysql_file_write(info->file,Buffer, length, info->myflags | MY_NABP))
+ {
+ unlock_append_buffer(info);
+ return info->error= -1;
+ }
+ Count-=length;
+ Buffer+=length;
+ info->end_of_file+=length;
+ }
+
+end:
+ memcpy(info->write_pos,Buffer,(size_t) Count);
+ info->write_pos+=Count;
+ unlock_append_buffer(info);
+ return 0;
+}
+
+
+int my_b_safe_write(IO_CACHE *info, const uchar *Buffer, size_t Count)
+{
+ /*
+ Sasha: We are not writing this with the ? operator to avoid hitting
+ a possible compiler bug. At least gcc 2.95 cannot deal with
+ several layers of ternary operators that evaluated comma(,) operator
+ expressions inside - I do have a test case if somebody wants it
+ */
+ if (info->type == SEQ_READ_APPEND)
+ return my_b_append(info, Buffer, Count);
+ return my_b_write(info, Buffer, Count);
+}
+
+
+/*
+ Write a block to disk where part of the data may be inside the record
+ buffer. As all write calls to the data goes through the cache,
+ we will never get a seek over the end of the buffer
+*/
+
+int my_block_write(IO_CACHE *info, const uchar *Buffer, size_t Count,
+ my_off_t pos)
+{
+ size_t length;
+ int error=0;
+
+ /*
+ Assert that we cannot come here with a shared cache. If we do one
+ day, we might need to add a call to copy_to_read_buffer().
+ */
+ DBUG_ASSERT(!info->share);
+ DBUG_ASSERT(!(info->myflags & MY_ENCRYPT));
+
+ if (pos < info->pos_in_file)
+ {
+ /* Of no overlap, write everything without buffering */
+ if (pos + Count <= info->pos_in_file)
+ return (int)mysql_file_pwrite(info->file, Buffer, Count, pos,
+ info->myflags | MY_NABP);
+ /* Write the part of the block that is before buffer */
+ length= (uint) (info->pos_in_file - pos);
+ if (mysql_file_pwrite(info->file, Buffer, length, pos, info->myflags | MY_NABP))
+ info->error= error= -1;
+ Buffer+=length;
+ pos+= length;
+ Count-= length;
+ }
+
+ /* Check if we want to write inside the used part of the buffer.*/
+ length= (size_t) (info->write_end - info->buffer);
+ if (pos < info->pos_in_file + length)
+ {
+ size_t offset= (size_t) (pos - info->pos_in_file);
+ length-=offset;
+ if (length > Count)
+ length=Count;
+ memcpy(info->buffer+offset, Buffer, length);
+ Buffer+=length;
+ Count-= length;
+ /* Fix length of buffer if the new data was larger */
+ if (info->buffer+length > info->write_pos)
+ info->write_pos=info->buffer+length;
+ if (!Count)
+ return (error);
+ }
+ /* Write at the end of the current buffer; This is the normal case */
+ if (_my_b_write(info, Buffer, Count))
+ error= -1;
+ return error;
+}
+
+
+ /* Flush write cache */
+
+#define LOCK_APPEND_BUFFER if (need_append_buffer_lock) \
+ lock_append_buffer(info);
+#define UNLOCK_APPEND_BUFFER if (need_append_buffer_lock) \
+ unlock_append_buffer(info);
+
+int my_b_flush_io_cache(IO_CACHE *info, int need_append_buffer_lock)
+{
+ size_t length;
+ my_bool append_cache= (info->type == SEQ_READ_APPEND);
+ DBUG_ENTER("my_b_flush_io_cache");
+ DBUG_PRINT("enter", ("cache: %p", info));
+
+ if (!append_cache)
+ need_append_buffer_lock= 0;
+
+ if (info->type == WRITE_CACHE || append_cache)
+ {
+ if (info->file == -1)
+ {
+ if (real_open_cached_file(info))
+ DBUG_RETURN((info->error= -1));
+ }
+ LOCK_APPEND_BUFFER;
+
+ if ((length=(size_t) (info->write_pos - info->write_buffer)))
+ {
+ if (append_cache)
+ {
+ if (mysql_file_write(info->file, info->write_buffer, length,
+ info->myflags | MY_NABP))
+ {
+ info->error= -1;
+ DBUG_RETURN(-1);
+ }
+ info->end_of_file+= info->write_pos - info->append_read_pos;
+ info->append_read_pos= info->write_buffer;
+ DBUG_ASSERT(info->end_of_file == mysql_file_tell(info->file, MYF(0)));
+ }
+ else
+ {
+ int res= info->write_function(info, info->write_buffer, length);
+ if (res)
+ DBUG_RETURN(res);
+
+ set_if_bigger(info->end_of_file, info->pos_in_file);
+ }
+ info->write_end= (info->write_buffer + info->buffer_length -
+ ((info->pos_in_file + length) & (IO_SIZE - 1)));
+ info->write_pos= info->write_buffer;
+ ++info->disk_writes;
+ UNLOCK_APPEND_BUFFER;
+ DBUG_RETURN(info->error);
+ }
+ }
+ UNLOCK_APPEND_BUFFER;
+ DBUG_RETURN(0);
+}
+
+/*
+ Free an IO_CACHE object
+
+ SYNOPSOS
+ end_io_cache()
+ info IO_CACHE Handle to free
+
+ NOTES
+ It's currently safe to call this if one has called init_io_cache()
+ on the 'info' object, even if init_io_cache() failed.
+ This function is also safe to call twice with the same handle.
+ Note that info->file is not reset as the caller may still use ut for my_close()
+
+ RETURN
+ 0 ok
+ # Error
+*/
+
+int end_io_cache(IO_CACHE *info)
+{
+ int error=0;
+ DBUG_ENTER("end_io_cache");
+ DBUG_PRINT("enter",("cache: %p", info));
+
+ /*
+ Every thread must call remove_io_thread(). The last one destroys
+ the share elements.
+ */
+ DBUG_ASSERT(!info->share || !info->share->total_threads);
+
+ if (info->alloced_buffer)
+ {
+ info->alloced_buffer=0;
+ if (info->file != -1) /* File doesn't exist */
+ error= my_b_flush_io_cache(info,1);
+ my_free(info->buffer);
+ info->buffer=info->read_pos=(uchar*) 0;
+ }
+ if (info->type == SEQ_READ_APPEND)
+ {
+ /* Destroy allocated mutex */
+ mysql_mutex_destroy(&info->append_buffer_lock);
+ }
+ info->share= 0;
+ info->type= TYPE_NOT_SET; /* Ensure that flush_io_cache() does nothing */
+ info->write_end= 0; /* Ensure that my_b_write() fails */
+ info->write_function= 0; /* my_b_write will crash if used */
+ DBUG_RETURN(error);
+} /* end_io_cache */
+
+
+/**********************************************************************
+ Testing of MF_IOCACHE
+**********************************************************************/
+
+#ifdef MAIN
+
+#include <my_dir.h>
+
+void die(const char* fmt, ...)
+{
+ va_list va_args;
+ va_start(va_args,fmt);
+ fprintf(stderr,"Error:");
+ vfprintf(stderr, fmt,va_args);
+ fprintf(stderr,", errno=%d\n", errno);
+ va_end(va_args);
+ exit(1);
+}
+
+int open_file(const char* fname, IO_CACHE* info, int cache_size)
+{
+ int fd;
+ if ((fd=my_open(fname,O_CREAT | O_RDWR,MYF(MY_WME))) < 0)
+ die("Could not open %s", fname);
+ if (init_io_cache(info, fd, cache_size, SEQ_READ_APPEND, 0,0,MYF(MY_WME)))
+ die("failed in init_io_cache()");
+ return fd;
+}
+
+void close_file(IO_CACHE* info)
+{
+ end_io_cache(info);
+ my_close(info->file, MYF(MY_WME));
+}
+
+int main(int argc, char** argv)
+{
+ IO_CACHE sra_cache; /* SEQ_READ_APPEND */
+ MY_STAT status;
+ const char* fname="/tmp/iocache.test";
+ int cache_size=16384;
+ char llstr_buf[22];
+ int max_block,total_bytes=0;
+ int i,num_loops=100,error=0;
+ char *p;
+ char* block, *block_end;
+ MY_INIT(argv[0]);
+ max_block = cache_size*3;
+ if (!(block=(char*)my_malloc(max_block,MYF(MY_WME))))
+ die("Not enough memory to allocate test block");
+ block_end = block + max_block;
+ for (p = block,i=0; p < block_end;i++)
+ {
+ *p++ = (char)i;
+ }
+ if (my_stat(fname,&status, MYF(0)) &&
+ my_delete(fname,MYF(MY_WME)))
+ {
+ die("Delete of %s failed, aborting", fname);
+ }
+ open_file(fname,&sra_cache, cache_size);
+ for (i = 0; i < num_loops; i++)
+ {
+ char buf[4];
+ int block_size = abs(rand() % max_block);
+ int4store(buf, block_size);
+ if (my_b_append(&sra_cache,buf,4) ||
+ my_b_append(&sra_cache, block, block_size))
+ die("write failed");
+ total_bytes += 4+block_size;
+ }
+ close_file(&sra_cache);
+ my_free(block);
+ if (!my_stat(fname,&status,MYF(MY_WME)))
+ die("%s failed to stat, but I had just closed it,\
+ wonder how that happened");
+ printf("Final size of %s is %s, wrote %d bytes\n",fname,
+ llstr(status.st_size,llstr_buf),
+ total_bytes);
+ my_delete(fname, MYF(MY_WME));
+ /* check correctness of tests */
+ if (total_bytes != status.st_size)
+ {
+ fprintf(stderr,"Not the same number of bytes actually in file as bytes \
+supposedly written\n");
+ error=1;
+ }
+ exit(error);
+ return 0;
+}
+#endif