typedef struct st_thr_lock_info
{
    my_thread_id thread_id;
    mysql_cond_t *suspend;
} THR_LOCK_INFO;

typedef struct st_thr_lock_data {
    THR_LOCK_INFO *owner;
    struct st_thr_lock_data *next,**prev;
    struct st_thr_lock *lock;
    mysql_cond_t *cond;
    enum thr_lock_type type;
    void *status_param;			/* Param to status functions */
    void *debug_print_param;
    struct PSI_table *m_psi;
} THR_LOCK_DATA;

struct st_lock_list {
    THR_LOCK_DATA *data,**last;
};

typedef struct st_thr_lock {
    LIST list;
    mysql_mutex_t mutex;
    struct st_lock_list read_wait;
    struct st_lock_list read;
    struct st_lock_list write_wait;
    struct st_lock_list write;
    ulong write_lock_count; /* incremented for write locks and reset on read locks */ 
    uint read_no_write_count;
    void (*get_status)(void*, int);	/* When one gets a lock */
    void (*copy_status)(void*,void*);
    void (*update_status)(void*); 	/* Before release of write */
    void (*restore_status)(void*);      /* Before release of read */
    my_bool (*check_status)(void *);
} THR_LOCK;

enum thr_lock_type {
    TL_IGNORE=-1,
    TL_UNLOCK,			/* UNLOCK ANY LOCK */
    /*
       Parser only! At open_tables() becomes TL_READ or
       TL_READ_NO_INSERT depending on the binary log format
       (SBR/RBR) and on the table category (log table).
       Used for tables that are read by statements which
       modify tables.
       */
    TL_READ_DEFAULT,
    TL_READ,			/* Read lock */
    TL_READ_WITH_SHARED_LOCKS,
    /* High prior. than TL_WRITE. Allow concurrent insert */
    TL_READ_HIGH_PRIORITY,
    /* READ, Don't allow concurrent insert */
    TL_READ_NO_INSERT,
    /* 
       Write lock, but allow other threads to read / write.
       Used by BDB tables in MySQL to mark that someone is
       reading/writing to the table.
       */
    TL_WRITE_ALLOW_WRITE,
    /*
       parser only! Late bound low_priority_flag.
       At open_tables() becomes thd->insert_lock_default.
       */
    TL_WRITE_CONCURRENT_DEFAULT,
    /*
       WRITE lock used by concurrent insert. Will allow
       READ, if one could use concurrent insert on table.
       */
    TL_WRITE_CONCURRENT_INSERT,
    /* 
       parser only! Late bound low_priority flag. 
       At open_tables() becomes thd->update_lock_default.
       */
    TL_WRITE_DEFAULT,
    /* WRITE lock that has lower priority than TL_READ */
    TL_WRITE_LOW_PRIORITY,
    /* Normal WRITE lock */
    TL_WRITE,
    /* Abort new lock request with an error */
    TL_WRITE_ONLY
};