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mariadb/storage/innobase/sync/sync0arr.c
aivanov@mysql.com d33b523271 Applied innodb-5.1-ss269 snapshot. 
Fixed BUGS:
  #3300: "UPDATE statement with no index column in where condition locks
    all rows"
    Implement semi-consistent read to reduce lock conflicts at the cost
    of breaking serializability.
    ha_innobase::unlock_row(): reset the "did semi consistent read" flag
    ha_innobase::was_semi_consistent_read(),
    ha_innobase::try_semi_consistent_read(): new methods
    row_prebuilt_t, row_create_prebuilt(): add field row_read_type for
    keeping track of semi-consistent reads
    row_vers_build_for_semi_consistent_read(),
    row_sel_build_committed_vers_for_mysql(): new functions
    row_search_for_mysql(): implement semi-consistent reads

  #9802: "Foreign key checks disallow alter table".
    Added test cases.

  #12456: "Cursor shows incorrect data - DML does not affect,
    probably caching"
    This patch implements a high-granularity read view to be used with
    cursors. In this high-granularity consistent read view modifications 
    done by the creating transaction after the cursor is created or 
   future transactions are not visible. But those modifications that 
   transaction did before the cursor was created are visible.

  #12701: "Support >4GB buffer pool and log files on 64-bit Windows"
    Do not call os_file_create_tmpfile() at runtime. Instead, create all
    tempfiles at startup and guard access to them with mutexes.

  #13778: "If FOREIGN_KEY_CHECKS=0, one can create inconsistent FOREIGN KEYs".
    When FOREIGN_KEY_CHECKS=0 we still need to check that datatypes between
    foreign key references are compatible.

  #14189: "VARBINARY and BINARY variables: trailing space ignored with InnoDB"
    innobase_init(): Assert that
    DATA_MYSQL_BINARY_CHARSET_COLL == my_charset_bin.number.
    dtype_get_pad_char(): Do not pad VARBINARY or BINARY columns.
    row_ins_cascade_calc_update_vec(): Refuse ON UPDATE CASCADE when trying
    to change the length of a VARBINARY column that refers to or is referenced
    by a BINARY column. BINARY columns are no longer padded on comparison,
    and thus they cannot be padded on storage either.

  #14747: "Race condition can cause btr_search_drop_page_hash_index() to crash"
    Note that buf_block_t::index should be protected by btr_search_latch
    or an s-latch or x-latch on the index page.
    btr_search_drop_page_hash_index(): Read block->index while holding
    btr_search_latch and use the cached value in the loop.  Remove some
    redundant assertions.

  #15108: "mysqld crashes when innodb_log_file_size is set > 4G"

  #15308: "Problem of Order with Enum Column in Primary Key"

  #15550: "mysqld crashes in printing a FOREIGN KEY error in InnoDB"
    row_ins_foreign_report_add_err(): When printing the parent record,
    use the index in the parent table rather than the index in the child table.

  #15653: "Slow inserts to InnoDB if many thousands of .ibd files"
    Keep track on unflushed modifications to file spaces.  When there are tens
    of thousands of file spaces, flushing all files in fil_flush_file_spaces()
    would be very slow.
    fil_flush_file_spaces(): Only flush unflushed file spaces.
    fil_space_t, fil_system_t: Add a list of unflushed spaces.

  #15991: "innodb-file-per-table + symlink database + rename = cr"
   os_file_handle_error(): Map the error codes EXDEV, ENOTDIR, and EISDIR
   to the new code OS_FILE_PATH_ERROR. Treat this code as OS_FILE_PATH_ERROR.
   This fixes the crash on RENAME TABLE when the .ibd file is a symbolic link
   to a different file system.

  #16157: "InnoDB crashes when main location settings are empty"
    This patch is from Heikki.

  #16298: "InnoDB segfaults in INSERTs in upgrade of 4.0 -> 5.0 tables
    with VARCHAR BINARY"
    dict_load_columns(): Set the charset-collation code
    DATA_MYSQL_BINARY_CHARSET_COLL for those binary string columns
    that lack a charset-collation code, i.e., the tables were created
    with an older version of MySQL/InnoDB than 4.1.2.

  #16229: "MySQL/InnoDB uses full explicit table locks in trigger processing"
    Take a InnoDB table lock only if user has explicitly requested a table
    lock. Added some additional comments to store_lock() and external_lock().

  #16387: "InnoDB crash when dropping a foreign key <table>_ibfk_0"
    Do not mistake TABLENAME_ibfk_0 for auto-generated id.
    dict_table_get_highest_foreign_id(): Ignore foreign constraint
    identifiers starting with the pattern TABLENAME_ibfk_0.

  #16582: "InnoDB: Error in an adaptive hash index pointer to page"
    Account for a race condition when dropping the adaptive hash index
    for a B-tree page.
    btr_search_drop_page_hash_index(): Retry the operation if a hash index
    with different parameters was built meanwhile.  Add diagnostics for the
    case that hash node pointers to the page remain.
    btr_search_info_update_hash(), btr_search_info_update_slow():
    Document the parameter "info" as in/out.

  #16814: "SHOW INNODB STATUS format error in LATEST FOREIGN KEY ERROR
    section"
    Add a missing newline to the LAST FOREIGN KEY ERROR section in SHOW
    INNODB STATUS output.
    dict_foreign_error_report(): Always print a newline after invoking
    dict_print_info_on_foreign_key_in_create_format().

  #16827: "Better InnoDB error message if ibdata files omitted from my.cnf"

  #17126: "CHECK TABLE on InnoDB causes a short hang during check of adaptive
    hash"
    CHECK TABLE blocking other queries, by releasing the btr_search_latch
    periodically during the adaptive hash table validation.

  #17405: "Valgrind: conditional jump or move depends on unititialised values"
    buf_block_init(): Reset magic_n, buf_fix_count and io_fix to avoid
    testing uninitialized variables.
2006-03-10 19:22:21 +03:00

1097 lines
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/******************************************************
The wait array used in synchronization primitives
(c) 1995 Innobase Oy
Created 9/5/1995 Heikki Tuuri
*******************************************************/
#include "sync0arr.h"
#ifdef UNIV_NONINL
#include "sync0arr.ic"
#endif
#include "sync0sync.h"
#include "sync0rw.h"
#include "os0sync.h"
#include "os0file.h"
#include "srv0srv.h"
/*
WAIT ARRAY
==========
The wait array consists of cells each of which has an
an operating system event object created for it. The threads
waiting for a mutex, for example, can reserve a cell
in the array and suspend themselves to wait for the event
to become signaled. When using the wait array, remember to make
sure that some thread holding the synchronization object
will eventually know that there is a waiter in the array and
signal the object, to prevent infinite wait.
Why we chose to implement a wait array? First, to make
mutexes fast, we had to code our own implementation of them,
which only in usually uncommon cases resorts to using
slow operating system primitives. Then we had the choice of
assigning a unique OS event for each mutex, which would
be simpler, or using a global wait array. In some operating systems,
the global wait array solution is more efficient and flexible,
because we can do with a very small number of OS events,
say 200. In NT 3.51, allocating events seems to be a quadratic
algorithm, because 10 000 events are created fast, but
100 000 events takes a couple of minutes to create.
*/
/* A cell where an individual thread may wait suspended
until a resource is released. The suspending is implemented
using an operating system event semaphore. */
struct sync_cell_struct {
/* State of the cell. SC_WAKING_UP means
sync_array_struct->n_reserved has been decremented, but the thread
in this cell has not waken up yet. When it does, it will set the
state to SC_FREE. Note that this is done without the protection of
any mutex. */
enum { SC_FREE, SC_RESERVED, SC_WAKING_UP } state;
void* wait_object; /* pointer to the object the
thread is waiting for; this is not
reseted to NULL when a cell is
freed. */
mutex_t* old_wait_mutex; /* the latest wait mutex in cell */
rw_lock_t* old_wait_rw_lock;/* the latest wait rw-lock in cell */
ulint request_type; /* lock type requested on the
object */
const char* file; /* in debug version file where
requested */
ulint line; /* in debug version line where
requested */
os_thread_id_t thread; /* thread id of this waiting
thread */
ibool waiting; /* TRUE if the thread has already
called sync_array_event_wait
on this cell */
ibool event_set; /* TRUE if the event is set */
os_event_t event; /* operating system event
semaphore handle */
time_t reservation_time;/* time when the thread reserved
the wait cell */
};
struct sync_array_struct {
ulint n_reserved; /* number of currently reserved
cells in the wait array */
ulint n_cells; /* number of cells in the
wait array */
sync_cell_t* array; /* pointer to wait array */
ulint protection; /* this flag tells which
mutex protects the data */
mutex_t mutex; /* possible database mutex
protecting this data structure */
os_mutex_t os_mutex; /* Possible operating system mutex
protecting the data structure.
As this data structure is used in
constructing the database mutex,
to prevent infinite recursion
in implementation, we fall back to
an OS mutex. */
ulint sg_count; /* count of how many times an
object has been signalled */
ulint res_count; /* count of cell reservations
since creation of the array */
};
#ifdef UNIV_SYNC_DEBUG
/**********************************************************************
This function is called only in the debug version. Detects a deadlock
of one or more threads because of waits of semaphores. */
static
ibool
sync_array_detect_deadlock(
/*=======================*/
/* out: TRUE if deadlock detected */
sync_array_t* arr, /* in: wait array; NOTE! the caller must
own the mutex to array */
sync_cell_t* start, /* in: cell where recursive search started */
sync_cell_t* cell, /* in: cell to search */
ulint depth); /* in: recursion depth */
#endif /* UNIV_SYNC_DEBUG */
/*********************************************************************
Gets the nth cell in array. */
static
sync_cell_t*
sync_array_get_nth_cell(
/*====================*/
/* out: cell */
sync_array_t* arr, /* in: sync array */
ulint n) /* in: index */
{
ut_a(arr);
ut_a(n < arr->n_cells);
return(arr->array + n);
}
/**********************************************************************
Reserves the mutex semaphore protecting a sync array. */
static
void
sync_array_enter(
/*=============*/
sync_array_t* arr) /* in: sync wait array */
{
ulint protection;
protection = arr->protection;
if (protection == SYNC_ARRAY_OS_MUTEX) {
os_mutex_enter(arr->os_mutex);
} else if (protection == SYNC_ARRAY_MUTEX) {
mutex_enter(&(arr->mutex));
} else {
ut_error;
}
}
/**********************************************************************
Releases the mutex semaphore protecting a sync array. */
static
void
sync_array_exit(
/*============*/
sync_array_t* arr) /* in: sync wait array */
{
ulint protection;
protection = arr->protection;
if (protection == SYNC_ARRAY_OS_MUTEX) {
os_mutex_exit(arr->os_mutex);
} else if (protection == SYNC_ARRAY_MUTEX) {
mutex_exit(&(arr->mutex));
} else {
ut_error;
}
}
/***********************************************************************
Creates a synchronization wait array. It is protected by a mutex
which is automatically reserved when the functions operating on it
are called. */
sync_array_t*
sync_array_create(
/*==============*/
/* out, own: created wait array */
ulint n_cells, /* in: number of cells in the array
to create */
ulint protection) /* in: either SYNC_ARRAY_OS_MUTEX or
SYNC_ARRAY_MUTEX: determines the type
of mutex protecting the data structure */
{
sync_array_t* arr;
sync_cell_t* cell_array;
sync_cell_t* cell;
ulint i;
ut_a(n_cells > 0);
/* Allocate memory for the data structures */
arr = ut_malloc(sizeof(sync_array_t));
cell_array = ut_malloc(sizeof(sync_cell_t) * n_cells);
arr->n_cells = n_cells;
arr->n_reserved = 0;
arr->array = cell_array;
arr->protection = protection;
arr->sg_count = 0;
arr->res_count = 0;
/* Then create the mutex to protect the wait array complex */
if (protection == SYNC_ARRAY_OS_MUTEX) {
arr->os_mutex = os_mutex_create(NULL);
} else if (protection == SYNC_ARRAY_MUTEX) {
mutex_create(&(arr->mutex));
mutex_set_level(&(arr->mutex), SYNC_NO_ORDER_CHECK);
} else {
ut_error;
}
for (i = 0; i < n_cells; i++) {
cell = sync_array_get_nth_cell(arr, i);
cell->state = SC_FREE;
cell->wait_object = NULL;
/* Create an operating system event semaphore with no name */
cell->event = os_event_create(NULL);
cell->event_set = FALSE; /* it is created in reset state */
}
return(arr);
}
/**********************************************************************
Frees the resources in a wait array. */
void
sync_array_free(
/*============*/
sync_array_t* arr) /* in, own: sync wait array */
{
ulint i;
sync_cell_t* cell;
ulint protection;
ut_a(arr->n_reserved == 0);
sync_array_validate(arr);
for (i = 0; i < arr->n_cells; i++) {
cell = sync_array_get_nth_cell(arr, i);
os_event_free(cell->event);
}
protection = arr->protection;
/* Release the mutex protecting the wait array complex */
if (protection == SYNC_ARRAY_OS_MUTEX) {
os_mutex_free(arr->os_mutex);
} else if (protection == SYNC_ARRAY_MUTEX) {
mutex_free(&(arr->mutex));
} else {
ut_error;
}
ut_free(arr->array);
ut_free(arr);
}
/************************************************************************
Validates the integrity of the wait array. Checks
that the number of reserved cells equals the count variable. */
void
sync_array_validate(
/*================*/
sync_array_t* arr) /* in: sync wait array */
{
ulint i;
sync_cell_t* cell;
ulint count = 0;
sync_array_enter(arr);
for (i = 0; i < arr->n_cells; i++) {
cell = sync_array_get_nth_cell(arr, i);
if (cell->state == SC_RESERVED) {
count++;
}
}
ut_a(count == arr->n_reserved);
sync_array_exit(arr);
}
/**********************************************************************
Reserves a wait array cell for waiting for an object.
The event of the cell is reset to nonsignalled state. */
void
sync_array_reserve_cell(
/*====================*/
sync_array_t* arr, /* in: wait array */
void* object, /* in: pointer to the object to wait for */
ulint type, /* in: lock request type */
const char* file, /* in: file where requested */
ulint line, /* in: line where requested */
ulint* index) /* out: index of the reserved cell */
{
sync_cell_t* cell;
ulint i;
ut_a(object);
ut_a(index);
sync_array_enter(arr);
arr->res_count++;
/* Reserve a new cell. */
for (i = 0; i < arr->n_cells; i++) {
cell = sync_array_get_nth_cell(arr, i);
if (cell->state == SC_FREE) {
/* We do not check cell->event_set because it is
set outside the protection of the sync array mutex
and we had a bug regarding it, and since resetting
an event when it is not needed does no harm it is
safer always to do it. */
cell->event_set = FALSE;
os_event_reset(cell->event);
cell->state = SC_RESERVED;
cell->reservation_time = time(NULL);
cell->thread = os_thread_get_curr_id();
cell->wait_object = object;
if (type == SYNC_MUTEX) {
cell->old_wait_mutex = object;
} else {
cell->old_wait_rw_lock = object;
}
cell->request_type = type;
cell->waiting = FALSE;
cell->file = file;
cell->line = line;
arr->n_reserved++;
*index = i;
sync_array_exit(arr);
return;
}
}
ut_error; /* No free cell found */
return;
}
/**********************************************************************
Frees the cell. Note that we don't have any mutex reserved when calling
this. */
static
void
sync_array_free_cell(
/*=================*/
sync_array_t* arr, /* in: wait array */
ulint index) /* in: index of the cell in array */
{
sync_cell_t* cell;
cell = sync_array_get_nth_cell(arr, index);
ut_a(cell->state == SC_WAKING_UP);
ut_a(cell->wait_object != NULL);
cell->state = SC_FREE;
}
/**********************************************************************
Frees the cell safely by reserving the sync array mutex and decrementing
n_reserved if necessary. Should only be called from mutex_spin_wait. */
void
sync_array_free_cell_protected(
/*===========================*/
sync_array_t* arr, /* in: wait array */
ulint index) /* in: index of the cell in array */
{
sync_cell_t* cell;
sync_array_enter(arr);
cell = sync_array_get_nth_cell(arr, index);
ut_a(cell->state != SC_FREE);
ut_a(cell->wait_object != NULL);
/* We only need to decrement n_reserved if it has not already been
done by sync_array_signal_object. */
if (cell->state == SC_RESERVED) {
ut_a(arr->n_reserved > 0);
arr->n_reserved--;
} else if (cell->state == SC_WAKING_UP) {
/* This is tricky; if we don't wait for the event to be
signaled, signal_object can set the state of a cell to
SC_WAKING_UP, mutex_spin_wait can call this and set the
state to SC_FREE, and then signal_object gets around to
calling os_set_event for the cell but since it's already
been freed things break horribly. */
sync_array_exit(arr);
os_event_wait(cell->event);
sync_array_enter(arr);
}
cell->state = SC_FREE;
sync_array_exit(arr);
}
/**********************************************************************
This function should be called when a thread starts to wait on
a wait array cell. In the debug version this function checks
if the wait for a semaphore will result in a deadlock, in which
case prints info and asserts. */
void
sync_array_wait_event(
/*==================*/
sync_array_t* arr, /* in: wait array */
ulint index) /* in: index of the reserved cell */
{
sync_cell_t* cell;
os_event_t event;
ut_a(arr);
cell = sync_array_get_nth_cell(arr, index);
ut_a((cell->state == SC_RESERVED) || (cell->state == SC_WAKING_UP));
ut_a(cell->wait_object);
ut_a(!cell->waiting);
ut_ad(os_thread_get_curr_id() == cell->thread);
event = cell->event;
cell->waiting = TRUE;
#ifdef UNIV_SYNC_DEBUG
/* We use simple enter to the mutex below, because if
we cannot acquire it at once, mutex_enter would call
recursively sync_array routines, leading to trouble.
rw_lock_debug_mutex freezes the debug lists. */
sync_array_enter(arr);
rw_lock_debug_mutex_enter();
if (TRUE == sync_array_detect_deadlock(arr, cell, cell, 0)) {
fputs("########################################\n", stderr);
ut_error;
}
rw_lock_debug_mutex_exit();
sync_array_exit(arr);
#endif
os_event_wait(event);
sync_array_free_cell(arr, index);
}
/**********************************************************************
Reports info of a wait array cell. Note: sync_array_print_long_waits()
calls this without mutex protection. */
static
void
sync_array_cell_print(
/*==================*/
FILE* file, /* in: file where to print */
sync_cell_t* cell) /* in: sync cell */
{
mutex_t* mutex;
rw_lock_t* rwlock;
ulint type;
type = cell->request_type;
fprintf(file,
"--Thread %lu has waited at %s line %lu for %.2f seconds the semaphore:\n",
(ulong) os_thread_pf(cell->thread), cell->file,
(ulong) cell->line,
difftime(time(NULL), cell->reservation_time));
fprintf(file, "Wait array cell state %lu\n", (ulong)cell->state);
/* If the memory area pointed to by old_wait_mutex /
old_wait_rw_lock has been freed, this can crash. */
if (cell->state != SC_RESERVED) {
/* If cell has this state, then even if we are holding the sync
array mutex, the wait object may get freed meanwhile. Do not
print the wait object then. */
} else if (type == SYNC_MUTEX) {
/* We use old_wait_mutex in case the cell has already
been freed meanwhile */
mutex = cell->old_wait_mutex;
fprintf(file,
"Mutex at %p created file %s line %lu, lock var %lu\n"
#ifdef UNIV_SYNC_DEBUG
"Last time reserved in file %s line %lu, "
#endif /* UNIV_SYNC_DEBUG */
"waiters flag %lu\n",
mutex, mutex->cfile_name, (ulong) mutex->cline,
(ulong) mutex->lock_word,
#ifdef UNIV_SYNC_DEBUG
mutex->file_name, (ulong) mutex->line,
#endif /* UNIV_SYNC_DEBUG */
(ulong) mutex->waiters);
} else if (type == RW_LOCK_EX || type == RW_LOCK_SHARED) {
fputs(type == RW_LOCK_EX ? "X-lock on" : "S-lock on", file);
rwlock = cell->old_wait_rw_lock;
fprintf(file,
" RW-latch at %p created in file %s line %lu\n",
rwlock, rwlock->cfile_name,
(ulong) rwlock->cline);
if (rwlock->writer != RW_LOCK_NOT_LOCKED) {
fprintf(file,
"a writer (thread id %lu) has reserved it in mode %s",
(ulong) os_thread_pf(rwlock->writer_thread),
rwlock->writer == RW_LOCK_EX
? " exclusive\n"
: " wait exclusive\n");
}
fprintf(file,
"number of readers %lu, waiters flag %lu\n"
"Last time read locked in file %s line %lu\n"
"Last time write locked in file %s line %lu\n",
(ulong) rwlock->reader_count,
(ulong) rwlock->waiters,
rwlock->last_s_file_name,
(ulong) rwlock->last_s_line,
rwlock->last_x_file_name,
(ulong) rwlock->last_x_line);
} else {
ut_error;
}
if (cell->event_set) {
fputs("wait is ending\n", file);
}
}
#ifdef UNIV_SYNC_DEBUG
/**********************************************************************
Looks for a cell with the given thread id. */
static
sync_cell_t*
sync_array_find_thread(
/*===================*/
/* out: pointer to cell or NULL
if not found */
sync_array_t* arr, /* in: wait array */
os_thread_id_t thread) /* in: thread id */
{
ulint i;
sync_cell_t* cell;
for (i = 0; i < arr->n_cells; i++) {
cell = sync_array_get_nth_cell(arr, i);
if ((cell->state == SC_RESERVED)
&& os_thread_eq(cell->thread, thread)) {
return(cell); /* Found */
}
}
return(NULL); /* Not found */
}
/**********************************************************************
Recursion step for deadlock detection. */
static
ibool
sync_array_deadlock_step(
/*=====================*/
/* out: TRUE if deadlock detected */
sync_array_t* arr, /* in: wait array; NOTE! the caller must
own the mutex to array */
sync_cell_t* start, /* in: cell where recursive search
started */
os_thread_id_t thread, /* in: thread to look at */
ulint pass, /* in: pass value */
ulint depth) /* in: recursion depth */
{
sync_cell_t* new;
ibool ret;
depth++;
if (pass != 0) {
/* If pass != 0, then we do not know which threads are
responsible of releasing the lock, and no deadlock can
be detected. */
return(FALSE);
}
new = sync_array_find_thread(arr, thread);
if (new == start) {
/* Stop running of other threads */
ut_dbg_stop_threads = TRUE;
/* Deadlock */
fputs("########################################\n"
"DEADLOCK of threads detected!\n", stderr);
return(TRUE);
} else if (new) {
ret = sync_array_detect_deadlock(arr, start, new, depth);
if (ret) {
return(TRUE);
}
}
return(FALSE);
}
/**********************************************************************
This function is called only in the debug version. Detects a deadlock
of one or more threads because of waits of semaphores. */
static
ibool
sync_array_detect_deadlock(
/*=======================*/
/* out: TRUE if deadlock detected */
sync_array_t* arr, /* in: wait array; NOTE! the caller must
own the mutex to array */
sync_cell_t* start, /* in: cell where recursive search started */
sync_cell_t* cell, /* in: cell to search */
ulint depth) /* in: recursion depth */
{
mutex_t* mutex;
rw_lock_t* lock;
os_thread_id_t thread;
ibool ret;
rw_lock_debug_t*debug;
ut_a(arr && start && cell);
ut_ad(cell->state == SC_RESERVED);
ut_ad(cell->wait_object);
ut_ad(os_thread_get_curr_id() == start->thread);
ut_ad(depth < 100);
depth++;
if (cell->event_set || !cell->waiting) {
return(FALSE); /* No deadlock here */
}
if (cell->request_type == SYNC_MUTEX) {
mutex = cell->wait_object;
if (mutex_get_lock_word(mutex) != 0) {
thread = mutex->thread_id;
/* Note that mutex->thread_id above may be
also OS_THREAD_ID_UNDEFINED, because the
thread which held the mutex maybe has not
yet updated the value, or it has already
released the mutex: in this case no deadlock
can occur, as the wait array cannot contain
a thread with ID_UNDEFINED value. */
ret = sync_array_deadlock_step(arr, start, thread, 0,
depth);
if (ret) {
fprintf(stderr,
"Mutex %p owned by thread %lu file %s line %lu\n",
mutex,
(ulong) os_thread_pf(mutex->thread_id),
mutex->file_name, (ulong) mutex->line);
sync_array_cell_print(stderr, cell);
return(TRUE);
}
}
return(FALSE); /* No deadlock */
} else if (cell->request_type == RW_LOCK_EX) {
lock = cell->wait_object;
debug = UT_LIST_GET_FIRST(lock->debug_list);
while (debug != NULL) {
thread = debug->thread_id;
if (((debug->lock_type == RW_LOCK_EX)
&& !os_thread_eq(thread, cell->thread))
|| ((debug->lock_type == RW_LOCK_WAIT_EX)
&& !os_thread_eq(thread, cell->thread))
|| (debug->lock_type == RW_LOCK_SHARED)) {
/* The (wait) x-lock request can block
infinitely only if someone (can be also cell
thread) is holding s-lock, or someone
(cannot be cell thread) (wait) x-lock, and
he is blocked by start thread */
ret = sync_array_deadlock_step(arr, start,
thread, debug->pass, depth);
if (ret) {
print:
fprintf(stderr, "rw-lock %p ", lock);
sync_array_cell_print(stderr, cell);
rw_lock_debug_print(debug);
return(TRUE);
}
}
debug = UT_LIST_GET_NEXT(list, debug);
}
return(FALSE);
} else if (cell->request_type == RW_LOCK_SHARED) {
lock = cell->wait_object;
debug = UT_LIST_GET_FIRST(lock->debug_list);
while (debug != NULL) {
thread = debug->thread_id;
if ((debug->lock_type == RW_LOCK_EX)
|| (debug->lock_type == RW_LOCK_WAIT_EX)) {
/* The s-lock request can block infinitely
only if someone (can also be cell thread) is
holding (wait) x-lock, and he is blocked by
start thread */
ret = sync_array_deadlock_step(arr, start,
thread, debug->pass, depth);
if (ret) {
goto print;
}
}
debug = UT_LIST_GET_NEXT(list, debug);
}
return(FALSE);
} else {
ut_error;
}
return(TRUE); /* Execution never reaches this line: for compiler
fooling only */
}
#endif /* UNIV_SYNC_DEBUG */
/**********************************************************************
Determines if we can wake up the thread waiting for a sempahore. */
static
ibool
sync_arr_cell_can_wake_up(
/*======================*/
sync_cell_t* cell) /* in: cell to search */
{
mutex_t* mutex;
rw_lock_t* lock;
if (cell->request_type == SYNC_MUTEX) {
mutex = cell->wait_object;
if (mutex_get_lock_word(mutex) == 0) {
return(TRUE);
}
} else if (cell->request_type == RW_LOCK_EX) {
lock = cell->wait_object;
if (rw_lock_get_reader_count(lock) == 0
&& rw_lock_get_writer(lock) == RW_LOCK_NOT_LOCKED) {
return(TRUE);
}
if (rw_lock_get_reader_count(lock) == 0
&& rw_lock_get_writer(lock) == RW_LOCK_WAIT_EX
&& os_thread_eq(lock->writer_thread, cell->thread)) {
return(TRUE);
}
} else if (cell->request_type == RW_LOCK_SHARED) {
lock = cell->wait_object;
if (rw_lock_get_writer(lock) == RW_LOCK_NOT_LOCKED) {
return(TRUE);
}
}
return(FALSE);
}
/**************************************************************************
Looks for the cells in the wait array which refer to the wait object
specified, and sets their corresponding events to the signaled state. In this
way releases the threads waiting for the object to contend for the object.
It is possible that no such cell is found, in which case does nothing. */
void
sync_array_signal_object(
/*=====================*/
sync_array_t* arr, /* in: wait array */
void* object) /* in: wait object */
{
sync_cell_t* cell;
ulint count;
ulint i;
ulint res_count;
/* We store the addresses of cells we need to signal and signal
them only after we have released the sync array's mutex (for
performance reasons). cell_count is the number of such cells, and
cell_ptr points to the first one. If there are less than
UT_ARR_SIZE(cells) of them, cell_ptr == &cells[0], otherwise
cell_ptr points to malloc'd memory that we must free. */
sync_cell_t* cells[100];
sync_cell_t** cell_ptr = &cells[0];
ulint cell_count = 0;
ulint cell_max_count = UT_ARR_SIZE(cells);
ut_a(100 == cell_max_count);
sync_array_enter(arr);
arr->sg_count++;
i = 0;
count = 0;
/* We need to store this to a local variable because it is modified
inside the loop */
res_count = arr->n_reserved;
while (count < res_count) {
cell = sync_array_get_nth_cell(arr, i);
if (cell->state == SC_RESERVED) {
count++;
if (cell->wait_object == object) {
cell->state = SC_WAKING_UP;
ut_a(arr->n_reserved > 0);
arr->n_reserved--;
if (cell_count == cell_max_count) {
sync_cell_t** old_cell_ptr = cell_ptr;
size_t old_size, new_size;
old_size = cell_max_count *
sizeof(sync_cell_t*);
cell_max_count *= 2;
new_size = cell_max_count *
sizeof(sync_cell_t*);
cell_ptr = malloc(new_size);
ut_a(cell_ptr);
memcpy(cell_ptr, old_cell_ptr,
old_size);
if (old_cell_ptr != &cells[0]) {
free(old_cell_ptr);
}
}
cell_ptr[cell_count] = cell;
cell_count++;
}
}
i++;
}
sync_array_exit(arr);
for (i = 0; i < cell_count; i++) {
cell = cell_ptr[i];
cell->event_set = TRUE;
os_event_set(cell->event);
}
if (cell_ptr != &cells[0]) {
free(cell_ptr);
}
}
/**************************************************************************
If the wakeup algorithm does not work perfectly at semaphore relases,
this function will do the waking (see the comment in mutex_exit). This
function should be called about every 1 second in the server.
Note that there's a race condition between this thread and mutex_exit
changing the lock_word and calling signal_object, so sometimes this finds
threads to wake up even when nothing has gone wrong. */
void
sync_arr_wake_threads_if_sema_free(void)
/*====================================*/
{
sync_array_t* arr = sync_primary_wait_array;
sync_cell_t* cell;
ulint count;
ulint i;
ulint res_count;
sync_array_enter(arr);
i = 0;
count = 0;
/* We need to store this to a local variable because it is modified
inside the loop */
res_count = arr->n_reserved;
while (count < res_count) {
cell = sync_array_get_nth_cell(arr, i);
if (cell->state == SC_RESERVED) {
count++;
if (sync_arr_cell_can_wake_up(cell)) {
cell->state = SC_WAKING_UP;
cell->event_set = TRUE;
os_event_set(cell->event);
ut_a(arr->n_reserved > 0);
arr->n_reserved--;
}
}
i++;
}
sync_array_exit(arr);
}
/**************************************************************************
Prints warnings of long semaphore waits to stderr. */
ibool
sync_array_print_long_waits(void)
/*=============================*/
/* out: TRUE if fatal semaphore wait threshold
was exceeded */
{
sync_cell_t* cell;
ibool old_val;
ibool noticed = FALSE;
ulint i;
ulint fatal_timeout = srv_fatal_semaphore_wait_threshold;
ibool fatal = FALSE;
for (i = 0; i < sync_primary_wait_array->n_cells; i++) {
cell = sync_array_get_nth_cell(sync_primary_wait_array, i);
if ((cell->state != SC_FREE)
&& difftime(time(NULL), cell->reservation_time) > 240) {
fputs("InnoDB: Warning: a long semaphore wait:\n",
stderr);
sync_array_cell_print(stderr, cell);
noticed = TRUE;
}
if ((cell->state != SC_FREE)
&& difftime(time(NULL), cell->reservation_time)
> fatal_timeout) {
fatal = TRUE;
}
}
if (noticed) {
fprintf(stderr,
"InnoDB: ###### Starts InnoDB Monitor for 30 secs to print diagnostic info:\n");
old_val = srv_print_innodb_monitor;
/* If some crucial semaphore is reserved, then also the InnoDB
Monitor can hang, and we do not get diagnostics. Since in
many cases an InnoDB hang is caused by a pwrite() or a pread()
call hanging inside the operating system, let us print right
now the values of pending calls of these. */
fprintf(stderr,
"InnoDB: Pending preads %lu, pwrites %lu\n", (ulong)os_file_n_pending_preads,
(ulong)os_file_n_pending_pwrites);
srv_print_innodb_monitor = TRUE;
os_event_set(srv_lock_timeout_thread_event);
os_thread_sleep(30000000);
srv_print_innodb_monitor = old_val;
fprintf(stderr,
"InnoDB: ###### Diagnostic info printed to the standard error stream\n");
}
return(fatal);
}
/**************************************************************************
Prints info of the wait array. */
static
void
sync_array_output_info(
/*===================*/
FILE* file, /* in: file where to print */
sync_array_t* arr) /* in: wait array; NOTE! caller must own the
mutex */
{
sync_cell_t* cell;
ulint i;
fprintf(file,
"OS WAIT ARRAY INFO: reservation count %ld, signal count %ld\n",
(long) arr->res_count,
(long) arr->sg_count);
for (i = 0; i < arr->n_cells; i++) {
cell = sync_array_get_nth_cell(arr, i);
if (cell->state != SC_FREE) {
sync_array_cell_print(file, cell);
}
}
}
/**************************************************************************
Prints info of the wait array. */
void
sync_array_print_info(
/*==================*/
FILE* file, /* in: file where to print */
sync_array_t* arr) /* in: wait array */
{
sync_array_enter(arr);
sync_array_output_info(file, arr);
sync_array_exit(arr);
}
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