~drizzle-trunk/drizzle/development

/******************************************************

The database server main program

NOTE: SQL Server 7 uses something which the documentation

calls user mode scheduled threads (UMS threads). One such

thread is usually allocated per processor. Win32

documentation does not know any UMS threads, which suggests

that the concept is internal to SQL Server 7. It may mean that

SQL Server 7 does all the scheduling of threads itself, even

in i/o waits. We should maybe modify InnoDB to use the same

technique, because thread switches within NT may be too slow.

SQL Server 7 also mentions fibers, which are cooperatively

scheduled threads. They can boost performance by 5 %,

according to the Delaney and Soukup's book.

Windows 2000 will have something called thread pooling

(see msdn website), which we could possibly use.

Another possibility could be to use some very fast user space

thread library. This might confuse NT though.

(c) 1995 Innobase Oy

Created 10/8/1995 Heikki Tuuri

*******************************************************/

/* Dummy comment */

#include "srv0srv.h"

#include "ut0mem.h"

#include "os0proc.h"

#include "mem0mem.h"

#include "mem0pool.h"

#include "sync0sync.h"

#include "thr0loc.h"

#include "que0que.h"

#include "srv0que.h"

#include "log0recv.h"

#include "pars0pars.h"

#include "usr0sess.h"

#include "lock0lock.h"

#include "trx0purge.h"

#include "ibuf0ibuf.h"

#include "buf0flu.h"

#include "btr0sea.h"

#include "dict0load.h"

#include "dict0boot.h"

#include "srv0start.h"

#include "row0mysql.h"

#include "ha_prototypes.h"

/* This is set to TRUE if the MySQL user has set it in MySQL; currently

affects only FOREIGN KEY definition parsing */

ibool	srv_lower_case_table_names	= FALSE;

/* The following counter is incremented whenever there is some user activity

in the server */

ulint	srv_activity_count	= 0;

/* The following is the maximum allowed duration of a lock wait. */

ulint	srv_fatal_semaphore_wait_threshold = 600;

/* How much data manipulation language (DML) statements need to be delayed,

in microseconds, in order to reduce the lagging of the purge thread. */

ulint	srv_dml_needed_delay = 0;

ibool	srv_lock_timeout_and_monitor_active = FALSE;

ibool	srv_error_monitor_active = FALSE;

const char*	srv_main_thread_op_info = "";

/* Prefix used by MySQL to indicate pre-5.1 table name encoding */

const char	srv_mysql50_table_name_prefix[9] = "#mysql50#";

/* Server parameters which are read from the initfile */

/* The following three are dir paths which are catenated before file

names, where the file name itself may also contain a path */

char*	srv_data_home	= NULL;

#ifdef UNIV_LOG_ARCHIVE

char*	srv_arch_dir	= NULL;

#endif /* UNIV_LOG_ARCHIVE */

ibool	srv_file_per_table = FALSE;	/* store to its own file each table

					created by an user; data dictionary

					tables are in the system tablespace

					0 */

ibool	srv_locks_unsafe_for_binlog = FALSE;	/* Place locks to

						records only i.e. do

						not use next-key

						locking except on

						duplicate key checking

						and foreign key

						checking */

ulint	srv_n_data_files = 0;

char**	srv_data_file_names = NULL;

ulint*	srv_data_file_sizes = NULL;	/* size in database pages */

ibool	srv_auto_extend_last_data_file	= FALSE; /* if TRUE, then we

						 auto-extend the last data

						 file */

ulint	srv_last_file_size_max	= 0;		 /* if != 0, this tells

						 the max size auto-extending

						 may increase the last data

						 file size */

ulong	srv_auto_extend_increment = 8;		 /* If the last data file is

						 auto-extended, we add this

						 many pages to it at a time */

ulint*	srv_data_file_is_raw_partition = NULL;

/* If the following is TRUE we do not allow inserts etc. This protects

the user from forgetting the 'newraw' keyword to my.cnf */

ibool	srv_created_new_raw	= FALSE;

char**	srv_log_group_home_dirs = NULL;

ulint	srv_n_log_groups	= ULINT_MAX;

ulint	srv_n_log_files		= ULINT_MAX;

ulint	srv_log_file_size	= ULINT_MAX;	/* size in database pages */

ulint	srv_log_buffer_size	= ULINT_MAX;	/* size in database pages */

ulong	srv_flush_log_at_trx_commit = 1;

byte	srv_latin1_ordering[256]	/* The sort order table of the latin1

					character set. The following table is

					the MySQL order as of Feb 10th, 2002 */

= {

  0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07

, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F

, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17

, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F

, 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27

, 0x28, 0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F

, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37

, 0x38, 0x39, 0x3A, 0x3B, 0x3C, 0x3D, 0x3E, 0x3F

, 0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47

, 0x48, 0x49, 0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x4F

, 0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57

, 0x58, 0x59, 0x5A, 0x5B, 0x5C, 0x5D, 0x5E, 0x5F

, 0x60, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47

, 0x48, 0x49, 0x4A, 0x4B, 0x4C, 0x4D, 0x4E, 0x4F

, 0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57

, 0x58, 0x59, 0x5A, 0x7B, 0x7C, 0x7D, 0x7E, 0x7F

, 0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87

, 0x88, 0x89, 0x8A, 0x8B, 0x8C, 0x8D, 0x8E, 0x8F

, 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97

, 0x98, 0x99, 0x9A, 0x9B, 0x9C, 0x9D, 0x9E, 0x9F

, 0xA0, 0xA1, 0xA2, 0xA3, 0xA4, 0xA5, 0xA6, 0xA7

, 0xA8, 0xA9, 0xAA, 0xAB, 0xAC, 0xAD, 0xAE, 0xAF

, 0xB0, 0xB1, 0xB2, 0xB3, 0xB4, 0xB5, 0xB6, 0xB7

, 0xB8, 0xB9, 0xBA, 0xBB, 0xBC, 0xBD, 0xBE, 0xBF

, 0x41, 0x41, 0x41, 0x41, 0x5C, 0x5B, 0x5C, 0x43

, 0x45, 0x45, 0x45, 0x45, 0x49, 0x49, 0x49, 0x49

, 0x44, 0x4E, 0x4F, 0x4F, 0x4F, 0x4F, 0x5D, 0xD7

, 0xD8, 0x55, 0x55, 0x55, 0x59, 0x59, 0xDE, 0xDF

, 0x41, 0x41, 0x41, 0x41, 0x5C, 0x5B, 0x5C, 0x43

, 0x45, 0x45, 0x45, 0x45, 0x49, 0x49, 0x49, 0x49

, 0x44, 0x4E, 0x4F, 0x4F, 0x4F, 0x4F, 0x5D, 0xF7

, 0xD8, 0x55, 0x55, 0x55, 0x59, 0x59, 0xDE, 0xFF

};

ulint	srv_pool_size		= ULINT_MAX;	/* size in pages; MySQL inits

						this to size in kilobytes but

						we normalize this to pages in

						srv_boot() */

ulint	srv_awe_window_size	= 0;		/* size in pages; MySQL inits

						this to bytes, but we

						normalize it to pages in

						srv_boot() */

ulint	srv_mem_pool_size	= ULINT_MAX;	/* size in bytes */

ulint	srv_lock_table_size	= ULINT_MAX;

ulint	srv_n_file_io_threads	= ULINT_MAX;

#ifdef UNIV_LOG_ARCHIVE

ibool	srv_log_archive_on	= FALSE;

ibool	srv_archive_recovery	= 0;

dulint	srv_archive_recovery_limit_lsn;

#endif /* UNIV_LOG_ARCHIVE */

ulint	srv_lock_wait_timeout	= 1024 * 1024 * 1024;

/* This parameter is used to throttle the number of insert buffers that are

merged in a batch. By increasing this parameter on a faster disk you can

possibly reduce the number of I/O operations performed to complete the

merge operation. The value of this parameter is used as is by the

background loop when the system is idle (low load), on a busy system

the parameter is scaled down by a factor of 4, this is to avoid putting

a heavier load on the I/O sub system. */

ulong	srv_insert_buffer_batch_size = 20;

char*	srv_file_flush_method_str = NULL;

ulint	srv_unix_file_flush_method = SRV_UNIX_FSYNC;

ulint	srv_win_file_flush_method = SRV_WIN_IO_UNBUFFERED;

ulint	srv_max_n_open_files	  = 300;

/* The InnoDB main thread tries to keep the ratio of modified pages

in the buffer pool to all database pages in the buffer pool smaller than

the following number. But it is not guaranteed that the value stays below

that during a time of heavy update/insert activity. */

ulong	srv_max_buf_pool_modified_pct	= 90;

/* variable counts amount of data read in total (in bytes) */

ulint srv_data_read = 0;

/* here we count the amount of data written in total (in bytes) */

ulint srv_data_written = 0;

/* the number of the log write requests done */

ulint srv_log_write_requests = 0;

/* the number of physical writes to the log performed */

ulint srv_log_writes = 0;

/* amount of data written to the log files in bytes */

ulint srv_os_log_written = 0;

/* amount of writes being done to the log files */

ulint srv_os_log_pending_writes = 0;

/* we increase this counter, when there we don't have enough space in the

log buffer and have to flush it */

ulint srv_log_waits = 0;

/* this variable counts the amount of times, when the doublewrite buffer

was flushed */

ulint srv_dblwr_writes = 0;

/* here we store the number of pages that have been flushed to the

doublewrite buffer */

ulint srv_dblwr_pages_written = 0;

/* in this variable we store the number of write requests issued */

ulint srv_buf_pool_write_requests = 0;

/* here we store the number of times when we had to wait for a free page

in the buffer pool. It happens when the buffer pool is full and we need

to make a flush, in order to be able to read or create a page. */

ulint srv_buf_pool_wait_free = 0;

/* variable to count the number of pages that were written from buffer

pool to the disk */

ulint srv_buf_pool_flushed = 0;

/* variable to count the number of buffer pool reads that led to the

reading of a disk page */

ulint srv_buf_pool_reads = 0;

/* variable to count the number of sequential read-aheads */

ulint srv_read_ahead_seq = 0;

/* variable to count the number of random read-aheads */

ulint srv_read_ahead_rnd = 0;

/* structure to pass status variables to MySQL */

export_struc export_vars;

/* If the following is != 0 we do not allow inserts etc. This protects

the user from forgetting the innodb_force_recovery keyword to my.cnf */

ulint	srv_force_recovery	= 0;

/*-----------------------*/

/* We are prepared for a situation that we have this many threads waiting for

a semaphore inside InnoDB. innobase_start_or_create_for_mysql() sets the

value. */

ulint	srv_max_n_threads	= 0;

/* The following controls how many threads we let inside InnoDB concurrently:

threads waiting for locks are not counted into the number because otherwise

we could get a deadlock. MySQL creates a thread for each user session, and

semaphore contention and convoy problems can occur withput this restriction.

Value 10 should be good if there are less than 4 processors + 4 disks in the

computer. Bigger computers need bigger values. Value 0 will disable the

concurrency check. */

ulong	srv_thread_concurrency	= 0;

ulong	srv_commit_concurrency	= 0;

os_fast_mutex_t	srv_conc_mutex;		/* this mutex protects srv_conc data

					structures */

lint	srv_conc_n_threads	= 0;	/* number of OS threads currently

					inside InnoDB; it is not an error

					if this drops temporarily below zero

					because we do not demand that every

					thread increments this, but a thread

					waiting for a lock decrements this

					temporarily */

ulint	srv_conc_n_waiting_threads = 0;	/* number of OS threads waiting in the

					FIFO for a permission to enter InnoDB

					*/

typedef struct srv_conc_slot_struct	srv_conc_slot_t;

struct srv_conc_slot_struct{

	os_event_t			event;		/* event to wait */

	ibool				reserved;	/* TRUE if slot

							reserved */

	ibool				wait_ended;	/* TRUE when another

							thread has already set

							the event and the

							thread in this slot is

							free to proceed; but

							reserved may still be

							TRUE at that point */

	UT_LIST_NODE_T(srv_conc_slot_t)	srv_conc_queue;	/* queue node */

};

UT_LIST_BASE_NODE_T(srv_conc_slot_t)	srv_conc_queue;	/* queue of threads

							waiting to get in */

srv_conc_slot_t* srv_conc_slots;			/* array of wait

							slots */

/* Number of times a thread is allowed to enter InnoDB within the same

SQL query after it has once got the ticket at srv_conc_enter_innodb */

#define SRV_FREE_TICKETS_TO_ENTER srv_n_free_tickets_to_enter

#define SRV_THREAD_SLEEP_DELAY srv_thread_sleep_delay

/*-----------------------*/

/* If the following is set to 1 then we do not run purge and insert buffer

merge to completion before shutdown. If it is set to 2, do not even flush the

buffer pool to data files at the shutdown: we effectively 'crash'

InnoDB (but lose no committed transactions). */

ulint	srv_fast_shutdown	= 0;

/* Generate a innodb_status.<pid> file */

ibool	srv_innodb_status	= FALSE;

ibool	srv_stats_on_metadata	= TRUE;

ibool	srv_use_doublewrite_buf	= TRUE;

ibool	srv_use_checksums = TRUE;

ibool	srv_set_thread_priorities = TRUE;

int	srv_query_thread_priority = 0;

/* TRUE if the Address Windowing Extensions of Windows are used; then we must

disable adaptive hash indexes */

ibool	srv_use_awe			= FALSE;

ibool	srv_use_adaptive_hash_indexes	= TRUE;

/*-------------------------------------------*/

ulong	srv_n_spin_wait_rounds	= 20;

ulong	srv_n_free_tickets_to_enter = 500;

ulong	srv_thread_sleep_delay = 10000;

ulint	srv_spin_wait_delay	= 5;

ibool	srv_priority_boost	= TRUE;

ibool	srv_print_thread_releases	= FALSE;

ibool	srv_print_lock_waits		= FALSE;

ibool	srv_print_buf_io		= FALSE;

ibool	srv_print_log_io		= FALSE;

ibool	srv_print_latch_waits		= FALSE;

ulint		srv_n_rows_inserted		= 0;

ulint		srv_n_rows_updated		= 0;

ulint		srv_n_rows_deleted		= 0;

ulint		srv_n_rows_read			= 0;

#ifndef UNIV_HOTBACKUP

static ulint	srv_n_rows_inserted_old		= 0;

static ulint	srv_n_rows_updated_old		= 0;

static ulint	srv_n_rows_deleted_old		= 0;

static ulint	srv_n_rows_read_old		= 0;

#endif /* !UNIV_HOTBACKUP */

ulint		srv_n_lock_wait_count		= 0;

ulint		srv_n_lock_wait_current_count	= 0;

ib_longlong	srv_n_lock_wait_time		= 0;

ulint		srv_n_lock_max_wait_time	= 0;

/*

  Set the following to 0 if you want InnoDB to write messages on

  stderr on startup/shutdown

*/

ibool	srv_print_verbose_log		= TRUE;

ibool	srv_print_innodb_monitor	= FALSE;

ibool	srv_print_innodb_lock_monitor	= FALSE;

ibool	srv_print_innodb_tablespace_monitor = FALSE;

ibool	srv_print_innodb_table_monitor = FALSE;

/* Array of English strings describing the current state of an

i/o handler thread */

const char* srv_io_thread_op_info[SRV_MAX_N_IO_THREADS];

const char* srv_io_thread_function[SRV_MAX_N_IO_THREADS];

time_t	srv_last_monitor_time;

mutex_t	srv_innodb_monitor_mutex;

/* Mutex for locking srv_monitor_file */

mutex_t	srv_monitor_file_mutex;

/* Temporary file for innodb monitor output */

FILE*	srv_monitor_file;

/* Mutex for locking srv_dict_tmpfile.

This mutex has a very high rank; threads reserving it should not

be holding any InnoDB latches. */

mutex_t	srv_dict_tmpfile_mutex;

/* Temporary file for output from the data dictionary */

FILE*	srv_dict_tmpfile;

/* Mutex for locking srv_misc_tmpfile.

This mutex has a very low rank; threads reserving it should not

acquire any further latches or sleep before releasing this one. */

mutex_t	srv_misc_tmpfile_mutex;

/* Temporary file for miscellanous diagnostic output */

FILE*	srv_misc_tmpfile;

ulint	srv_main_thread_process_no	= 0;

ulint	srv_main_thread_id		= 0;

/*

	IMPLEMENTATION OF THE SERVER MAIN PROGRAM

	=========================================

There is the following analogue between this database

server and an operating system kernel:

DB concept			equivalent OS concept

----------			---------------------

transaction		--	process;

query thread		--	thread;

lock			--	semaphore;

transaction set to

the rollback state	--	kill signal delivered to a process;

kernel			--	kernel;

query thread execution:

(a) without kernel mutex

reserved		--	process executing in user mode;

(b) with kernel mutex reserved

			--	process executing in kernel mode;

The server is controlled by a master thread which runs at

a priority higher than normal, that is, higher than user threads.

It sleeps most of the time, and wakes up, say, every 300 milliseconds,

to check whether there is anything happening in the server which

requires intervention of the master thread. Such situations may be,

for example, when flushing of dirty blocks is needed in the buffer

pool or old version of database rows have to be cleaned away.

The threads which we call user threads serve the queries of

the clients and input from the console of the server.

They run at normal priority. The server may have several

communications endpoints. A dedicated set of user threads waits

at each of these endpoints ready to receive a client request.

Each request is taken by a single user thread, which then starts

processing and, when the result is ready, sends it to the client

and returns to wait at the same endpoint the thread started from.

So, we do not have dedicated communication threads listening at

the endpoints and dealing the jobs to dedicated worker threads.

Our architecture saves one thread swithch per request, compared

to the solution with dedicated communication threads

which amounts to 15 microseconds on 100 MHz Pentium

running NT. If the client

is communicating over a network, this saving is negligible, but

if the client resides in the same machine, maybe in an SMP machine

on a different processor from the server thread, the saving

can be important as the threads can communicate over shared

memory with an overhead of a few microseconds.

We may later implement a dedicated communication thread solution

for those endpoints which communicate over a network.

Our solution with user threads has two problems: for each endpoint

there has to be a number of listening threads. If there are many

communication endpoints, it may be difficult to set the right number

of concurrent threads in the system, as many of the threads

may always be waiting at less busy endpoints. Another problem

is queuing of the messages, as the server internally does not

offer any queue for jobs.

Another group of user threads is intended for splitting the

queries and processing them in parallel. Let us call these

parallel communication threads. These threads are waiting for

parallelized tasks, suspended on event semaphores.

A single user thread waits for input from the console,

like a command to shut the database.

Utility threads are a different group of threads which takes

care of the buffer pool flushing and other, mainly background

operations, in the server.

Some of these utility threads always run at a lower than normal

priority, so that they are always in background. Some of them

may dynamically boost their priority by the pri_adjust function,

even to higher than normal priority, if their task becomes urgent.

The running of utilities is controlled by high- and low-water marks

of urgency. The urgency may be measured by the number of dirty blocks

in the buffer pool, in the case of the flush thread, for example.

When the high-water mark is exceeded, an utility starts running, until

the urgency drops under the low-water mark. Then the utility thread

suspend itself to wait for an event. The master thread is

responsible of signaling this event when the utility thread is

again needed.

For each individual type of utility, some threads always remain

at lower than normal priority. This is because pri_adjust is implemented

so that the threads at normal or higher priority control their

share of running time by calling sleep. Thus, if the load of the

system sudenly drops, these threads cannot necessarily utilize

the system fully. The background priority threads make up for this,

starting to run when the load drops.

When there is no activity in the system, also the master thread

suspends itself to wait for an event making

the server totally silent. The responsibility to signal this

event is on the user thread which again receives a message

from a client.

There is still one complication in our server design. If a

background utility thread obtains a resource (e.g., mutex) needed by a user

thread, and there is also some other user activity in the system,

the user thread may have to wait indefinitely long for the

resource, as the OS does not schedule a background thread if

there is some other runnable user thread. This problem is called

priority inversion in real-time programming.

One solution to the priority inversion problem would be to

keep record of which thread owns which resource and

in the above case boost the priority of the background thread

so that it will be scheduled and it can release the resource.

This solution is called priority inheritance in real-time programming.

A drawback of this solution is that the overhead of acquiring a mutex

increases slightly, maybe 0.2 microseconds on a 100 MHz Pentium, because

the thread has to call os_thread_get_curr_id.

This may be compared to 0.5 microsecond overhead for a mutex lock-unlock

pair. Note that the thread

cannot store the information in the resource, say mutex, itself,

because competing threads could wipe out the information if it is

stored before acquiring the mutex, and if it stored afterwards,

the information is outdated for the time of one machine instruction,

at least. (To be precise, the information could be stored to

lock_word in mutex if the machine supports atomic swap.)

The above solution with priority inheritance may become actual in the

future, but at the moment we plan to implement a more coarse solution,

which could be called a global priority inheritance. If a thread

has to wait for a long time, say 300 milliseconds, for a resource,

we just guess that it may be waiting for a resource owned by a background

thread, and boost the the priority of all runnable background threads

to the normal level. The background threads then themselves adjust

their fixed priority back to background after releasing all resources

they had (or, at some fixed points in their program code).

What is the performance of the global priority inheritance solution?

We may weigh the length of the wait time 300 milliseconds, during

which the system processes some other thread

to the cost of boosting the priority of each runnable background

thread, rescheduling it, and lowering the priority again.

On 100 MHz Pentium + NT this overhead may be of the order 100

microseconds per thread. So, if the number of runnable background

threads is not very big, say < 100, the cost is tolerable.

Utility threads probably will access resources used by

user threads not very often, so collisions of user threads

to preempted utility threads should not happen very often.

The thread table contains

information of the current status of each thread existing in the system,

and also the event semaphores used in suspending the master thread

and utility and parallel communication threads when they have nothing to do.

The thread table can be seen as an analogue to the process table

in a traditional Unix implementation.

The thread table is also used in the global priority inheritance

scheme. This brings in one additional complication: threads accessing

the thread table must have at least normal fixed priority,

because the priority inheritance solution does not work if a background

thread is preempted while possessing the mutex protecting the thread table.

So, if a thread accesses the thread table, its priority has to be

boosted at least to normal. This priority requirement can be seen similar to

the privileged mode used when processing the kernel calls in traditional

Unix.*/

/* Thread slot in the thread table */

struct srv_slot_struct{

	os_thread_id_t	id;		/* thread id */

	os_thread_t	handle;		/* thread handle */

	ulint		type;		/* thread type: user, utility etc. */

	ibool		in_use;		/* TRUE if this slot is in use */

	ibool		suspended;	/* TRUE if the thread is waiting

					for the event of this slot */

	ib_time_t	suspend_time;	/* time when the thread was

					suspended */

	os_event_t	event;		/* event used in suspending the

					thread when it has nothing to do */

	que_thr_t*	thr;		/* suspended query thread (only

					used for MySQL threads) */

};

/* Table for MySQL threads where they will be suspended to wait for locks */

srv_slot_t*	srv_mysql_table = NULL;

os_event_t	srv_lock_timeout_thread_event;

srv_sys_t*	srv_sys	= NULL;

byte		srv_pad1[64];	/* padding to prevent other memory update

				hotspots from residing on the same memory

				cache line */

mutex_t*	kernel_mutex_temp;/* mutex protecting the server, trx structs,

				query threads, and lock table */

byte		srv_pad2[64];	/* padding to prevent other memory update

				hotspots from residing on the same memory

				cache line */

/* The following three values measure the urgency of the jobs of

buffer, version, and insert threads. They may vary from 0 - 1000.

The server mutex protects all these variables. The low-water values

tell that the server can acquiesce the utility when the value

drops below this low-water mark. */

ulint	srv_meter[SRV_MASTER + 1];

ulint	srv_meter_low_water[SRV_MASTER + 1];

ulint	srv_meter_high_water[SRV_MASTER + 1];

ulint	srv_meter_high_water2[SRV_MASTER + 1];

ulint	srv_meter_foreground[SRV_MASTER + 1];

/* The following values give info about the activity going on in

the database. They are protected by the server mutex. The arrays

are indexed by the type of the thread. */

ulint	srv_n_threads_active[SRV_MASTER + 1];

ulint	srv_n_threads[SRV_MASTER + 1];

/*************************************************************************

Sets the info describing an i/o thread current state. */

void

srv_set_io_thread_op_info(

/*======================*/

	ulint		i,	/* in: the 'segment' of the i/o thread */

	const char*	str)	/* in: constant char string describing the

				state */

{

	ut_a(i < SRV_MAX_N_IO_THREADS);

	srv_io_thread_op_info[i] = str;

}

/*************************************************************************

Accessor function to get pointer to n'th slot in the server thread

table. */

static

srv_slot_t*

srv_table_get_nth_slot(

/*===================*/

				/* out: pointer to the slot */

	ulint	index)		/* in: index of the slot */

{

	ut_a(index < OS_THREAD_MAX_N);

	return(srv_sys->threads + index);

}

#ifndef UNIV_HOTBACKUP

/*************************************************************************

Gets the number of threads in the system. */

ulint

srv_get_n_threads(void)

/*===================*/

{

	ulint	i;

	ulint	n_threads	= 0;

	mutex_enter(&kernel_mutex);

	for (i = SRV_COM; i < SRV_MASTER + 1; i++) {

		n_threads += srv_n_threads[i];

	}

	mutex_exit(&kernel_mutex);

	return(n_threads);

}

/*************************************************************************

Reserves a slot in the thread table for the current thread. Also creates the

thread local storage struct for the current thread. NOTE! The server mutex

has to be reserved by the caller! */

static

ulint

srv_table_reserve_slot(

/*===================*/

			/* out: reserved slot index */

	ulint	type)	/* in: type of the thread: one of SRV_COM, ... */

{

	srv_slot_t*	slot;

	ulint		i;

	ut_a(type > 0);

	ut_a(type <= SRV_MASTER);

	i = 0;

	slot = srv_table_get_nth_slot(i);

	while (slot->in_use) {

		i++;

		slot = srv_table_get_nth_slot(i);

	}

	ut_a(slot->in_use == FALSE);

	slot->in_use = TRUE;

	slot->suspended = FALSE;

	slot->id = os_thread_get_curr_id();

	slot->handle = os_thread_get_curr();

	slot->type = type;

	thr_local_create();

	thr_local_set_slot_no(os_thread_get_curr_id(), i);

	return(i);

}

/*************************************************************************

Suspends the calling thread to wait for the event in its thread slot.

NOTE! The server mutex has to be reserved by the caller! */

static

os_event_t

srv_suspend_thread(void)

/*====================*/

			/* out: event for the calling thread to wait */

{

	srv_slot_t*	slot;

	os_event_t	event;

	ulint		slot_no;

	ulint		type;

	ut_ad(mutex_own(&kernel_mutex));

	slot_no = thr_local_get_slot_no(os_thread_get_curr_id());

	if (srv_print_thread_releases) {

		fprintf(stderr,

			"Suspending thread %lu to slot %lu meter %lu\n",

			(ulong) os_thread_get_curr_id(), (ulong) slot_no,

			(ulong) srv_meter[SRV_RECOVERY]);

	}

	slot = srv_table_get_nth_slot(slot_no);

	type = slot->type;

	ut_ad(type >= SRV_WORKER);

	ut_ad(type <= SRV_MASTER);

	event = slot->event;

	slot->suspended = TRUE;

	ut_ad(srv_n_threads_active[type] > 0);

	srv_n_threads_active[type]--;

	os_event_reset(event);

	return(event);

}

#endif /* !UNIV_HOTBACKUP */

/*************************************************************************

Releases threads of the type given from suspension in the thread table.

NOTE! The server mutex has to be reserved by the caller! */

ulint

srv_release_threads(

/*================*/

			/* out: number of threads released: this may be

			< n if not enough threads were suspended at the

			moment */

	ulint	type,	/* in: thread type */

	ulint	n)	/* in: number of threads to release */

{

	srv_slot_t*	slot;

	ulint		i;

	ulint		count	= 0;

	ut_ad(type >= SRV_WORKER);

	ut_ad(type <= SRV_MASTER);

	ut_ad(n > 0);

	ut_ad(mutex_own(&kernel_mutex));

	for (i = 0; i < OS_THREAD_MAX_N; i++) {

		slot = srv_table_get_nth_slot(i);

		if (slot->in_use && slot->type == type && slot->suspended) {

			slot->suspended = FALSE;

			srv_n_threads_active[type]++;

			os_event_set(slot->event);

			if (srv_print_thread_releases) {

				fprintf(stderr,

					"Releasing thread %lu type %lu"

					" from slot %lu meter %lu\n",

					(ulong) slot->id, (ulong) type,

					(ulong) i,

					(ulong) srv_meter[SRV_RECOVERY]);

			}

			count++;

			if (count == n) {

				break;

			}

		}

	}

	return(count);

}

/*************************************************************************

Returns the calling thread type. */

ulint

srv_get_thread_type(void)

/*=====================*/

			/* out: SRV_COM, ... */

{

	ulint		slot_no;

	srv_slot_t*	slot;

	ulint		type;

	mutex_enter(&kernel_mutex);

	slot_no = thr_local_get_slot_no(os_thread_get_curr_id());

	slot = srv_table_get_nth_slot(slot_no);

	type = slot->type;

	ut_ad(type >= SRV_WORKER);

	ut_ad(type <= SRV_MASTER);

	mutex_exit(&kernel_mutex);

	return(type);

}

/*************************************************************************

Initializes the server. */

void

srv_init(void)

/*==========*/

{

	srv_conc_slot_t*	conc_slot;

	srv_slot_t*		slot;

	dict_table_t*		table;

	ulint			i;

	srv_sys = mem_alloc(sizeof(srv_sys_t));

	kernel_mutex_temp = mem_alloc(sizeof(mutex_t));

	mutex_create(&kernel_mutex, SYNC_KERNEL);

	mutex_create(&srv_innodb_monitor_mutex, SYNC_NO_ORDER_CHECK);

	srv_sys->threads = mem_alloc(OS_THREAD_MAX_N * sizeof(srv_slot_t));

	for (i = 0; i < OS_THREAD_MAX_N; i++) {

		slot = srv_table_get_nth_slot(i);

		slot->in_use = FALSE;

		slot->type=0;	/* Avoid purify errors */

		slot->event = os_event_create(NULL);

		ut_a(slot->event);

	}

	srv_mysql_table = mem_alloc(OS_THREAD_MAX_N * sizeof(srv_slot_t));

	for (i = 0; i < OS_THREAD_MAX_N; i++) {

		slot = srv_mysql_table + i;

		slot->in_use = FALSE;

		slot->type = 0;

		slot->event = os_event_create(NULL);

		ut_a(slot->event);

	}

	srv_lock_timeout_thread_event = os_event_create(NULL);

	for (i = 0; i < SRV_MASTER + 1; i++) {

		srv_n_threads_active[i] = 0;

		srv_n_threads[i] = 0;

		srv_meter[i] = 30;

		srv_meter_low_water[i] = 50;

		srv_meter_high_water[i] = 100;

		srv_meter_high_water2[i] = 200;

		srv_meter_foreground[i] = 250;

	}

	UT_LIST_INIT(srv_sys->tasks);

	/* create dummy table and index for old-style infimum and supremum */

	table = dict_mem_table_create("SYS_DUMMY1",

				      DICT_HDR_SPACE, 1, 0);