diff options
Diffstat (limited to 'db2/include/mp.h')
| -rw-r--r-- | db2/include/mp.h | 41 |
1 files changed, 22 insertions, 19 deletions
diff --git a/db2/include/mp.h b/db2/include/mp.h index 3b71774..f68f42b 100644 --- a/db2/include/mp.h +++ b/db2/include/mp.h @@ -4,7 +4,7 @@ * Copyright (c) 1996, 1997 * Sleepycat Software. All rights reserved. * - * @(#)mp.h 10.16 (Sleepycat) 9/23/97 + * @(#)mp.h 10.19 (Sleepycat) 10/25/97 */ struct __bh; typedef struct __bh BH; @@ -22,30 +22,36 @@ struct __mpoolfile; typedef struct __mpoolfile MPOOLFILE; #define DB_CACHESIZE_DEF (128 * 1024) #define DB_CACHESIZE_MIN ( 20 * 1024) -/* Macro to return per-process address, offsets. */ -#define ADDR(base, offset) ((void *)((u_int8_t *)((base)->addr) + offset)) -#define OFFSET(base, p) ((u_int8_t *)(p) - (u_int8_t *)(base)->addr) - #define INVALID 0 /* Invalid shared memory offset. */ #define TEMPORARY "<tmp>" /* Temporary file name. */ /* - * There are two kinds of locks in the mpool code. The first is the region - * lock, used to serialize modifications to all data structures. The second - * is a per-buffer header lock. The locking order is as follows: + * There are three ways we do locking in the mpool code: + * + * Locking a handle mutex to provide concurrency for DB_THREAD operations. + * Locking the region mutex to provide mutual exclusion while reading and + * writing structures in the shared region. + * Locking buffer header mutexes during I/O. + * + * The first will not be further described here. We use the shared mpool + * region lock to provide mutual exclusion while reading/modifying all of + * the data structures, including the buffer headers. We use a per-buffer + * header lock to wait on buffer I/O. The order of locking is as follows: * - * Process searching for a buffer: + * Searching for a buffer: * Acquire the region lock. * Find the buffer header. * Increment the reference count (guarantee the buffer stays). - * If the BH_LOCKED flag is set: + * If the BH_LOCKED flag is set (I/O is going on): * Release the region lock. + * Request the buffer lock. + * The I/O will complete... * Acquire the buffer lock. * Release the buffer lock. * Acquire the region lock. * Return the buffer. * - * Process reading/writing a buffer: + * Reading/writing a buffer: * Acquire the region lock. * Find/create the buffer header. * If reading, increment the reference count (guarantee the buffer stays). @@ -69,8 +75,7 @@ struct __mpoolfile; typedef struct __mpoolfile MPOOLFILE; #define LOCKHANDLE(dbmp, mutexp) \ if (F_ISSET(dbmp, MP_LOCKHANDLE)) \ - (void)__db_mutex_lock(mutexp, (dbmp)->fd, \ - (dbmp)->dbenv == NULL ? NULL : (dbmp)->dbenv->db_yield) + (void)__db_mutex_lock(mutexp, (dbmp)->fd) #define UNLOCKHANDLE(dbmp, mutexp) \ if (F_ISSET(dbmp, MP_LOCKHANDLE)) \ (void)__db_mutex_unlock(mutexp, (dbmp)->fd) @@ -78,8 +83,7 @@ struct __mpoolfile; typedef struct __mpoolfile MPOOLFILE; #define LOCKREGION(dbmp) \ if (F_ISSET(dbmp, MP_LOCKREGION)) \ (void)__db_mutex_lock(&((RLAYOUT *)(dbmp)->mp)->lock, \ - (dbmp)->fd, \ - (dbmp)->dbenv == NULL ? NULL : (dbmp)->dbenv->db_yield) + (dbmp)->fd) #define UNLOCKREGION(dbmp) \ if (F_ISSET(dbmp, MP_LOCKREGION)) \ (void)__db_mutex_unlock(&((RLAYOUT *)(dbmp)->mp)->lock, \ @@ -87,8 +91,7 @@ struct __mpoolfile; typedef struct __mpoolfile MPOOLFILE; #define LOCKBUFFER(dbmp, bhp) \ if (F_ISSET(dbmp, MP_LOCKREGION)) \ - (void)__db_mutex_lock(&(bhp)->mutex, (dbmp)->fd, \ - (dbmp)->dbenv == NULL ? NULL : (dbmp)->dbenv->db_yield) + (void)__db_mutex_lock(&(bhp)->mutex, (dbmp)->fd) #define UNLOCKBUFFER(dbmp, bhp) \ if (F_ISSET(dbmp, MP_LOCKREGION)) \ (void)__db_mutex_unlock(&(bhp)->mutex, (dbmp)->fd) @@ -250,8 +253,8 @@ struct __bh { #define BH_WRITE 0x020 /* Page scheduled for writing. */ u_int16_t flags; - SH_TAILQ_ENTRY q; /* LRU list of bucket headers. */ - SH_TAILQ_ENTRY mq; /* MPOOLFILE list of bucket headers. */ + SH_TAILQ_ENTRY q; /* LRU queue. */ + SH_TAILQ_ENTRY hq; /* MPOOL hash bucket queue. */ db_pgno_t pgno; /* Underlying MPOOLFILE page number. */ size_t mf_offset; /* Associated MPOOLFILE offset. */ |