compressed pages from the buffer pool.

Makefile.am: Add buf0buddy.h, buf0buddy.ic.

buf/Makefile.am: Add buf0buddy.c.

Introduce the constants BUF_BUDDY_LOW and BUF_BUDDY_SIZES.

buf_pool_t: Add zip_mutex and the lists zip_clean and zip_free[].

buf_page_get_mutex(): Return &buf_pool->zip_mutex instead of NULL.

buf_buddy_get_offset(), buf_buddy_get(), buf_buddy_get_slot(),
buf_buddy_alloc_free(), buf_buddy_alloc_free_low(): New functions.

and document the possible list memberships.

buf_LRU_block_remove_hashed_page() changes the state of the block.
This error was introduced in r1090.

to free_or_flush_list.  The list node pointers can be shared, because a
block can never be belong to both lists at the same time.

as the field will be read without mutex protection in buf_page_io_complete().

(state == BUF_BLOCK_ZIP_PAGE).  Make use of buf_page_in_file()
and buf_page_get_mutex().

buf_block_get_newest_modification(): Rename to
buf_page_get_newest_modification().

Add m_nonempty for facilitating the test in page_zip_alloc().  This
reduces the combined size of the bit-fields to 32 bits.  Thus,
sizeof(page_zip_des_t) == 2 machine words on 32-bit and wider systems.

LRU_position and possibly freed_page_clock.  All these fields are
protected by buf_pool->mutex rather than buf_page_get_mutex().

buf_page_set_accessed(): Add a mutex_own() assertion.

on a NULL pointer.  This error was introduced in r1082.

of the buffer pool from buf_block_t to buf_page_t.  Replace some buf_block_t*
parameters with buf_page_t*.  Add accessor functions.

decompression from page_zip_des_t to buf_page_t, because the fields
needed in compression are modified without holding the block mutex.
All writes to bit-fields sharing a machine word must be protected
by the same mutex or rw-lock.

buf_block_buf_fix_inc_func() to eliminate an #ifdef in every invocation.

to ut_uint64_align_down() and ut_uint64_align_up(), to reflect the rename
of ib_ulonglong to ib_uint64_t in r1085.

64 bits.  "long long" might be longer than 64 bits on some systems.

buf_block_t.  Move the fields "hash" and "file_page_was_freed" from
buf_block_t to buf_page_t.

buf_page_in_file(): New function, for checking block state in assertions.

was broken in r1066.

of the fields "freed_page_clock" and "old".

buf_page_t and page_zip_des_t.

storage size from 16 to 3 bits.

page_zip_get_size(), page_zip_set_size(): New functions.

Replace direct references to page_zip_des_t:size with calls to
buf_block_get_zip_size(), page_zip_get_size(), and page_zip_set_size().

for log sequence numbers, to replace dulint.

buf_block_get_state().

buf_block_init(), buf_page_init_for_backup_restore(): Assign
block->page.zip.state after invoking page_zip_des_init(&block->page).

introduced in r1057 are of the int type.

which should have been replaced in r1057.

threshold.

and uncompressed buffer pool pages.

buf_block_t: Replace page_zip, space, and offset with buf_page_t page.
Replace some integers with bit-fields.

enum buf_block_state: Rename to buf_page_state.  Add BUF_BLOCK_ZIP_PAGE.

page_zip_des_t: Add the field "state".  Make the integer fields bit-fields.

page_zip_copy(): Document which fields are copied.

buf_block_state_valid(): New macro for replacing the magic_n check

BUF_BLOCK_READY_FOR_USE to BUF_BLOCK_NOT_USED.

buf_block_get_space(), buf_block_get_page_no():
Remove ut_ad(block->buf_fix_count > 0), because since r1052
these functions are also used in low-level code.

buf_block_set_state(): New function.  Also checks the state transitions.

buf_block_set_file_page(): New function.

and block->space with buf_block_get_state(block), buf_block_get_page_no(block),
and buf_block_get_space(block).

enum buf_block_state: Replaces the #define'd buf_block_t.state values.

buf_block_get_state(): New function.

buf_block_get_frame(): Add __attribute__((const)).

buf0buf.ic: Remove the extern declaration of buf_dbg_counter.
It was declared static in buf0buf.c in r1025.

ha0ha.c: #include "btr0sea.h" #ifdef UNIV_SYNC_DEBUG.  Assertions on
btr_search_latch were added in r1041.

buf_pool_page_hash_rebuild(): New function.

hash index, because it might occupy the chunk we would like to free.

TODO: In btr_search_check_free_space_in_heap(), release the block if
btr_search_latch is not immediately available.

buf_pool_shrink(): Split from buf_pool_resize().

btr_search_disabled: New variable, similar to srv_use_adaptive_hash_indexes
that was removed earlier.

btr_search_disable(): New function: disable and purge the adaptive hash index.

btr_search_enable(): New function: enable the adaptive hash index.

ha_clear(): New function: Empty a hash table and free the memory heaps.

function to ha_node_set_data_func().  In this way, the #ifdef in the
callers can be removed.

SHOW MUTEX STATUS in non-debug builds.  (Bug #24386)

assume that non-file pages are free.  After trying to free or flush
file pages, do not proceed to buf_chunk_free(), because the calls will
temporarily release buf_pool->mutex.  Do not flush if there are non-free
blocks, because it would not achieve anything.