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Diffstat (limited to 'db2/include/lock.h')
| -rw-r--r-- | db2/include/lock.h | 194 |
1 files changed, 194 insertions, 0 deletions
diff --git a/db2/include/lock.h b/db2/include/lock.h new file mode 100644 index 0000000000..18d29e8740 --- /dev/null +++ b/db2/include/lock.h @@ -0,0 +1,194 @@ +/*- + * See the file LICENSE for redistribution information. + * + * Copyright (c) 1996, 1997 + * Sleepycat Software. All rights reserved. + * + * @(#)lock.h 10.7 (Sleepycat) 7/29/97 + */ + +typedef struct __db_lockobj DB_LOCKOBJ; + +#define DB_DEFAULT_LOCK_FILE "__db_lock.share" +#define DB_LOCK_DEFAULT_N 5000 +#define DB_LOCK_MAXID 0x7fffffff + +/* + * The lock region consists of: + * The DB_LOCKREGION structure (sizeof(DB_LOCKREGION)). + * The conflict matrix of nmodes * nmodes bytes (nmodes * nmodes). + * The hash table for object lookup (hashsize * sizeof(DB_OBJ *)). + * The locks themselves (maxlocks * sizeof(struct __db_lock). + * The objects being locked (maxlocks * sizeof(DB_OBJ)). + * String space to represent the DBTs that are the objects being locked. + */ +struct __db_lockregion { + RLAYOUT hdr; /* Shared region header. */ + u_int32_t magic; /* lock magic number */ + u_int32_t version; /* version number */ + u_int32_t id; /* unique id generator */ + u_int32_t need_dd; /* flag for deadlock detector */ + u_int32_t detect; /* run dd on every conflict */ + SH_TAILQ_HEAD(lock_header) free_locks; /* free lock header */ + SH_TAILQ_HEAD(obj_header) free_objs; /* free obj header */ + u_int32_t maxlocks; /* maximum number of locks in table */ + u_int32_t table_size; /* size of hash table */ + u_int32_t nmodes; /* number of lock modes */ + u_int32_t numobjs; /* number of objects */ + u_int32_t nlockers; /* number of lockers */ + size_t increment; /* how much to grow region */ + size_t hash_off; /* offset of hash table */ + size_t mem_off; /* offset of memory region */ + size_t mem_bytes; /* number of bytes in memory region */ + u_int32_t nconflicts; /* number of lock conflicts */ + u_int32_t nrequests; /* number of lock gets */ + u_int32_t nreleases; /* number of lock puts */ + u_int32_t ndeadlocks; /* number of deadlocks */ +}; + +/* Macros to lock/unlock the region. */ +#define LOCK_LOCKREGION(lt) \ + (void)__db_mutex_lock(&(lt)->region->hdr.lock,(lt)->fd, \ + (lt)->dbenv == NULL ? NULL : (lt)->dbenv->db_yield) +#define UNLOCK_LOCKREGION(lt) \ + (void)__db_mutex_unlock(&(lt)->region->hdr.lock, (lt)->fd) + +/* + * Since we will be keeping DBTs in shared memory, we need the equivalent + * of a DBT that will work in shared memory. + */ +typedef struct __sh_dbt { + u_int32_t size; + ssize_t off; +} SH_DBT; + +#define SH_DBT_PTR(p) ((void *)(((u_int8_t *)(p)) + (p)->off)) + +/* + * The lock table is the per-process cookie returned from a lock_open call. + */ +struct __db_lockobj { + SH_DBT lockobj; /* Identifies object locked. */ + SH_TAILQ_ENTRY links; /* Links for free list. */ + union { + SH_TAILQ_HEAD(_wait) _waiters; /* List of waiting locks. */ + u_int32_t _dd_id; /* Deadlock detector id. */ + } wlinks; + union { + SH_LIST_HEAD(_held) _heldby; /* Locks held by this locker. */ + SH_TAILQ_HEAD(_hold) _holders; /* List of held locks. */ + } dlinks; +#define DB_LOCK_OBJTYPE 1 +#define DB_LOCK_LOCKER 2 + u_int8_t type; /* Real object or locker id. */ +}; + + +#define dd_id wlinks._dd_id +#define waiters wlinks._waiters +#define holders dlinks._holders +#define heldby dlinks._heldby + +struct __db_locktab { + DB_ENV *dbenv; /* Environment. */ + int fd; /* mapped file descriptor */ + DB_LOCKREGION *region; /* address of shared memory region */ + DB_HASHTAB *hashtab; /* Beginning of hash table. */ + size_t reg_size; /* last known size of lock region */ + void *mem; /* Beginning of string space. */ + u_int8_t *conflicts; /* Pointer to conflict matrix. */ +}; + +/* Test for conflicts. */ +#define CONFLICTS(T, HELD, WANTED) \ + T->conflicts[HELD * T->region->nmodes + WANTED] + +/* + * Status of a lock. + */ +typedef enum { + DB_LSTAT_ABORTED, /* Lock belongs to an aborted txn. */ + DB_LSTAT_ERR, /* Lock is bad. */ + DB_LSTAT_FREE, /* Lock is unallocated. */ + DB_LSTAT_HELD, /* Lock is currently held. */ + DB_LSTAT_NOGRANT, /* Lock was not granted. */ + DB_LSTAT_PENDING, /* Lock was waiting and has been + * promoted; waiting for the owner + * to run and upgrade it to held. */ + DB_LSTAT_WAITING /* Lock is on the wait queue. */ +} db_status_t; + +/* + * Resources in the lock region. Used to indicate which resource + * is running low when we need to grow the region. + */ +typedef enum { + DB_LOCK_MEM, DB_LOCK_OBJ, DB_LOCK_LOCK +} db_resource_t; + +struct __db_lock { + /* + * Wait on mutex to wait on lock. You reference your own mutex with + * ID 0 and others reference your mutex with ID 1. + */ + db_mutex_t mutex; + + u_int32_t holder; /* Who holds this lock. */ + SH_TAILQ_ENTRY links; /* Free or holder/waiter list. */ + SH_LIST_ENTRY locker_links; /* List of locks held by a locker. */ + u_int32_t refcount; /* Reference count the lock. */ + db_lockmode_t mode; /* What sort of lock. */ + ssize_t obj; /* Relative offset of object struct. */ + db_status_t status; /* Status of this lock. */ +}; + +/* + * We cannot return pointers to the user (else we cannot easily grow regions), + * so we return offsets in the region. These must be converted to and from + * regular pointers. Always use the macros below. + */ +#define OFFSET_TO_LOCK(lt, off) \ + ((struct __db_lock *)((u_int8_t *)((lt)->region) + (off))) +#define LOCK_TO_OFFSET(lt, lock) \ + ((size_t)((u_int8_t *)(lock) - (u_int8_t *)lt->region)) +#define OFFSET_TO_OBJ(lt, off) \ + ((DB_LOCKOBJ *)((u_int8_t *)((lt)->region) + (off))) +#define OBJ_TO_OFFSET(lt, obj) \ + ((size_t)((u_int8_t *)(obj) - (u_int8_t *)lt->region)) + +/* + * The lock header contains the region structure and the conflict matrix. + * Aligned to a large boundary because we don't know what the underlying + * type of the hash table elements are. + */ +#define LOCK_HASH_ALIGN 8 +#define LOCK_HEADER_SIZE(M) \ + ((size_t)(sizeof(DB_LOCKREGION) + ALIGN((M * M), LOCK_HASH_ALIGN))) + +/* + * For the full region, we need to add the locks, the objects, the hash table + * and the string space (which is 16 bytes per lock). + */ +#define STRING_SIZE(N) (16 * N) + +#define LOCK_REGION_SIZE(M, N, H) \ + (ALIGN(LOCK_HEADER_SIZE(M) + \ + (H) * sizeof(DB_HASHTAB), MUTEX_ALIGNMENT) + \ + (N) * ALIGN(sizeof(struct __db_lock), MUTEX_ALIGNMENT) + \ + ALIGN((N) * sizeof(DB_LOCKOBJ), sizeof(size_t)) + \ + ALIGN(STRING_SIZE(N), sizeof(size_t))) + +#ifdef DEBUG +#define LOCK_DEBUG_LOCKERS 0x0001 +#define LOCK_DEBUG_LOCK 0x0002 +#define LOCK_DEBUG_OBJ 0x0004 +#define LOCK_DEBUG_CONF 0x0008 +#define LOCK_DEBUG_MEM 0x0010 +#define LOCK_DEBUG_BUCKET 0x0020 +#define LOCK_DEBUG_OBJECTS 0x0040 +#define LOCK_DEBUG_ALL 0xFFFF + +#define LOCK_DEBUG_NOMUTEX 0x0100 +#endif + +#include "lock_ext.h" |