eliminate some local variables, and add branching hints.

to tables.

dict_mem_table_add_col(): Add the parameter "heap" for temporary memory
allocation.  Allow it and "name" to be NULL.  These parameters are NULL
when creating dummy indexes.

dict_add_col_name(): Remove calls to ut_malloc() and ut_free().

dict_table_get_col_name(): Allow table->col_names to be NULL.

dict_table_add_system_columns(), dict_table_add_to_cache():
Add the parameter "heap".

page_zip_set_alloc(): New function, to configure zlib to use a memory heap.

btr_store_big_rec_extern_fields(): Reduce memLevel, so that a heap of
256 kilobytes will suffice.  Use page_zip_set_alloc().

btr_copy_externally_stored_field_prefix_low(): Use page_zip_set_alloc().

page_zip_compress(), page_zip_decompress(): Use page_zip_set_alloc().

of HASH_DELETE().

HASH_ASSERT_VALID(), HASH_INVALIDATE(): New macros, used in HASH_DELETE()
and HASH_SEARCH().

buf_page_init_low(): Add HASH_INVALIDATE(bpage, hash);

buf_page_init(): Call buf_page_init_low() before HASH_INSERT(), so that
bpage->hash will not be invalidated.

for extra validation in UNIV_DEBUG builds.

block->page.buf_fix_count.  This mistake was made in r1255.
When access to the block is requested by some other thread,
buf_fix_count can be incremented during the execution of
buf_zip_decompress().

Replace some while loops with do..while or for loops.

lock_move_rec_list_start(): Replace 2 with PAGE_HEAP_NO_USER_LOW.

initialize all the fields of the control block.

buf_block_init_low(), buf_page_init_low(): New functions, used in
buf_page_init_for_backup_restore(), buf_page_init(), and
buf_page_init_for_read().

Declare some local variables in narrower scope.

lock_move_rec_list_start(): Check for orphan locks #ifdef UNIV_DEBUG

orphaned locks outside the "for" loop.  This mistake was made in r1252.

and implement UNIV_DEBUG diagnostics for orphaned locks.

inside #ifdef UNIV_DEBUG_LOCK_VALIDATE.

lock_rec_validate_page(): Assert that page_find_rec_with_heap_no()
returns non-NULL.

lock_rec_get_nth_bit(), lock_rec_set_nth_bit(), lock_rec_reset_nth_bit(),
lock_rec_copy(): Simplify the code.

buf_buddy_relocate_block(): New function, split from buf_buddy_relocate().
Return FALSE when buf_page_can_relocate() returns FALSE.

Fix some formatting in buf_buddy_free_low() and buf_page_init_for_read().

uncompressed page frames.

buf_page_get_zip(), buf_page_release_zip(): New functions, used
by btr_copy_zblob_prefix().

btr_copy_zblob_prefix(): Do not call inflateEnd().

buf_LRU_free_block(): Do not allocate the control block when
a compressed-only page is being freed.

buf_validate(): Note that buf_pool->zip_clean may contain blocks
with io_fix == BUF_IO_READ.

compressed page also when freeing an unmodified uncompressed page.

btr_blob_free(): New function to commit a mini-transaction and to free
an uncompressed BLOB block, or the entire block.

btr_store_big_rec_extern_fields(): Replace the existing code with
btr_blob_free().  The old code may have contained a race condition.

btr_free_externally_stored_field(): Completely free the buffer blocks
allocated for the freed BLOB.

buf_page_get_gen().  This saves one mutex operation per block request.

buf_page_get_gen(), various macros and functions: Add parameter zip_size.

btr_node_ptr_get_child(): Add parameter index.

fil_space_get_latch(): Add optional output parameter zip_size.

fil_space_get_zip_size(): Return 0 for space id==0, because the
system tablespace is never compressed.

fsp_header_init(): Remove the parameter zip_size.

ibuf_free_excess_pages(): Remove the parameter zip_size.

trx_rseg_t, trx_undo_t: Add field zip_size.

xdes_lst_get_next(): Remove, unused.

Split the code to subroutines.

btr_copy_blob_prefix(): New function: copy the prefix of the externally
stored part of an uncompressed BLOB.

btr_copy_zblob_prefix(): New function: copy the prefix of the externally
stored part of a compressed BLOB.

btr_blob_get_part_len(), btr_blob_get_next_page_no(): Add const qualifier
to the parameter.

that also exists in uncompressed form in the buffer pool, pass the
compressed frame to fil_io() instead of the uncompressed one when
not using the doublewrite buffer.

page checksum of compressed-only blocks.  Pass the compressed page frame
to fil_io() when needed.

page_zip_calc_checksum(): Skip also FIL_PAGE_LSN and FIL_PAGE_FILE_FLUSH_LSN.

buf_flush_init_for_writing(): Expect page to be non-NULL.

and to be flushed to disk.

buf_LRU_free_block(): Enable the freeing of uncompressed pages of
compressed tablespaces.

trx_doublewrite->buf_block_arr[]: Change the type from buf_block_t*
to buf_page_t*.

buf_flush_ready_for_flush(): Add debug assertion.

buf_flush_buffered_writes(), buf_flush_try_page(): Support blocks of type
BUF_BLOCK_ZIP_DIRTY.

buf_flush_post_to_doublewrite_buf(), buf_flush_write_block_low():
Change the type of the parameter from buf_block_t* to buf_page_t*.

buf_flush_init_for_writing(): Allow page to be NULL if page_zip_ is non-NULL.

compressed page) is not protected by block_mutex.  Before releasing
buf_pool->mutex, we can simply assign b->io_fix.  After reacquiring
buf_pool->mutex, we also have to acquire buf_pool->zip_mutex.

of a block, do not release buf_pool->mutex between the time the old control
block is removed from buf_pool->page_hash and the new control block is
added to it.  Prevent operations on the compressed-only block while calling
btr_search_drop_page_hash_index() or page_zip_calc_checksum().

buf_LRU_invalidate_tablespace(): Revert the change done in r1223.
buf_pool->zip_mutex will have been released by
buf_LRU_block_remove_hashed_page() when it returns BUF_BLOCK_ZIP_FREE.

acquired by the caller.

buf_LRU_invalidate_tablespace(): Do not leak buf_pool->zip_mutex when
rescanning the LRU list.

of a dirty block, relocate the control blocks on buf_pool->flush_list
instead of calling buf_flush_insert_into_flush_list().

invoking buf_buddy_alloc().  An IO-fixed block must also be x-latched
when block->mutex and buf_pool->mutex are released.

buf_page_create(): Protect the block during buf_buddy_alloc() by
IO-fixing and X-latching it.

should have been added in r1218.

buf_zip_decompress().  This will prevent btr_cur_search_to_nth_level()
from accessing a half-decompressed leaf page.  Internal B-tree nodes
(non-leaf pages) in B-tree searches are only protected by the tree
latch (index->lock) and by buffer-fixing.

page frame to save memory.

compressed page, copy the contents from the uncompressed page if necessary.

and update the comments.

buf_pool->page_hash and buf_pool->LRU before releasing buf_pool->mutex.

buf_page_init_for_read(), buf_page_create(): Allocate the compressed
page after the block has been added to the buffer pool.  Document the
reason for this.

when calling btr_search_drop_page_hash_index() and uninitialized after that.

buf_page_init(): Declare block->frame valid only in the system tablespace.

trx_sysf_create(): Declare the rest of the page valid, although it is
uninitialized.

buf_buddy_relocate(): Document that src may have been split and some of
it may be in buf_pool->zip_free[j] for some j<i, thus mach_read_from_4()
may be reading from free memory.  Check buffer pages only for addressability,
not for being completely initialized.  Ensure that block descriptors are
completely initialized.

buf_buddy_remove_from_free(): Check prev->state and next->state in
UNIV_DEBUG && UNIV_DEBUG_VALGRIND builds.

buf_buddy_free_low(): Flag the entire block valid prior to invoking
buf_buddy_remove_from_free() in order to avoid a Valgrind warning about
the debug assertion on bpage->state.  Remove the Valgrind check for
buddy being completely allocated.  If it has been split to smaller blocks,
some of those blocks may be free.