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db_int.h

/*-
 * See the file LICENSE for redistribution information.
 *
 * Copyright (c) 1996, 1997, 1998
 *    Sleepycat Software.  All rights reserved.
 *
 *    @(#)db_int.h.src  10.62 (Sleepycat) 5/23/98
 */

#ifndef _DB_INTERNAL_H_
#define     _DB_INTERNAL_H_

#include <db.h>                     /* Standard DB include file. */
#include "queue.h"

/*******************************************************
 * General purpose constants and macros.
 *******************************************************/
#define     UINT16_T_MAX          0xffff  /* Maximum 16 bit unsigned. */
#define     UINT32_T_MAX      0xffffffff  /* Maximum 32 bit unsigned. */

#define     DB_MIN_PGSIZE     0x000200    /* Minimum page size. */
#define     DB_MAX_PGSIZE     0x010000    /* Maximum page size. */

#define     DB_MINCACHE 10          /* Minimum cached pages */

#define     MEGABYTE    1048576

/*
 * If we are unable to determine the underlying filesystem block size, use
 * 8K on the grounds that most OS's use less than 8K as their VM page size.
 */
#define     DB_DEF_IOSIZE     (8 * 1024)

/*
 * Aligning items to particular sizes or in pages or memory.  ALIGNP is a
 * separate macro, as we've had to cast the pointer to different integral
 * types on different architectures.
 *
 * We cast pointers into unsigned longs when manipulating them because C89
 * guarantees that u_long is the largest available integral type and further,
 * to never generate overflows.  However, neither C89 or C9X  requires that
 * any integer type be large enough to hold a pointer, although C9X created
 * the intptr_t type, which is guaranteed to hold a pointer but may or may
 * not exist.  At some point in the future, we should test for intptr_t and
 * use it where available.
 */
#undef      ALIGNTYPE
#define     ALIGNTYPE         u_long
#undef      ALIGNP
#define     ALIGNP(value, bound)    ALIGN((ALIGNTYPE)value, bound)
#undef      ALIGN
#define     ALIGN(value, bound)     (((value) + (bound) - 1) & ~((bound) - 1))

/*
 * There are several on-page structures that are declared to have a number of
 * fields followed by a variable length array of items.  The structure size
 * without including the variable length array or the address of the first of
 * those elements can be found using SSZ.
 *
 * This macro can also be used to find the offset of a structure element in a
 * structure.  This is used in various places to copy structure elements from
 * unaligned memory references, e.g., pointers into a packed page.
 *
 * There are two versions because compilers object if you take the address of
 * an array.
 */
#undef      SSZ
#define SSZ(name, field)      ((int)&(((name *)0)->field))

#undef      SSZA
#define SSZA(name, field)     ((int)&(((name *)0)->field[0]))

/* Macros to return per-process address, offsets based on shared regions. */
#define     R_ADDR(base, offset)    ((void *)((u_int8_t *)((base)->addr) + offset))
#define     R_OFFSET(base, p) ((u_int8_t *)(p) - (u_int8_t *)(base)->addr)

/* Free and free-string macros that overwrite memory. */
#ifdef DIAGNOSTIC
#undef      FREE
#define     FREE(p, len) {                                        \
      memset(p, 0xff, len);                                 \
      __db_free(p);                                         \
}
#undef      FREES
#define     FREES(p) {                                      \
      FREE(p, strlen(p));                                   \
}
#else
#undef      FREE
#define     FREE(p, len) {                                        \
      __db_free(p);                                         \
}
#undef      FREES
#define     FREES(p) {                                      \
      __db_free(p);                                         \
}
#endif

/* Structure used to print flag values. */
typedef struct __fn {
      u_int32_t mask;               /* Flag value. */
      const char *name;       /* Flag name. */
} FN;

/* Set, clear and test flags. */
#define     F_SET(p, f) (p)->flags |= (f)
#define     F_CLR(p, f) (p)->flags &= ~(f)
#define     F_ISSET(p, f)     ((p)->flags & (f))
#define     LF_SET(f)   (flags |= (f))
#define     LF_CLR(f)   (flags &= ~(f))
#define     LF_ISSET(f) (flags & (f))

/* Display separator string. */
#undef      DB_LINE
#define     DB_LINE "=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-="

/* Global variables. */
typedef struct __db_globals {
      int db_mutexlocks;            /* DB_MUTEXLOCKS */
      int db_region_anon;           /* DB_REGION_ANON, DB_REGION_NAME */
      int db_region_init;           /* DB_REGION_INIT */
      int db_tsl_spins;       /* DB_TSL_SPINS */
      int db_pageyield;       /* DB_PAGEYIELD */
} DB_GLOBALS;
extern      DB_GLOBALS  __db_global_values;
#define     DB_GLOBAL(v)      __db_global_values.v

/* Unused, or not-used-yet variable.  "Shut that bloody compiler up!" */
#define     COMPQUIET(n, v)   (n) = (v)

/*
 * Win16 needs specific syntax on callback functions.  Nobody else cares.
 */
#ifndef     DB_CALLBACK
#define     DB_CALLBACK /* Nothing. */
#endif

/*******************************************************
 * Files.
 *******************************************************/
 /*
  * We use 1024 as the maximum path length.  It's too hard to figure out what
  * the real path length is, as it was traditionally stored in <sys/param.h>,
  * and that file isn't always available.
  */
#undef      MAXPATHLEN
#define     MAXPATHLEN  1024

#define     PATH_DOT    "."   /* Current working directory. */
#define     PATH_SEPARATOR    "/"   /* Path separator character. */

/*******************************************************
 * Mutex support.
 *******************************************************/
typedef unsigned char tsl_t;



/*
 * !!!
 * Various systems require different alignments for mutexes (the worst we've
 * seen so far is 16-bytes on some HP architectures).  The mutex (tsl_t) must
 * be first in the db_mutex_t structure, which must itself be first in the
 * region.  This ensures the alignment is as returned by mmap(2), which should
 * be sufficient.  All other mutex users must ensure proper alignment locally.
 */
#define     MUTEX_ALIGNMENT   1

/*
 * The offset of a mutex in memory.
 *
 * !!!
 * Not an off_t, so backing file offsets MUST be less than 4Gb.  See the
 * off field of the db_mutex_t as well.
 */
#define     MUTEX_LOCK_OFFSET(a, b) ((u_int32_t)((u_int8_t *)b - (u_int8_t *)a))

typedef struct _db_mutex_t {
#ifdef HAVE_SPINLOCKS
      tsl_t   tsl_resource;         /* Resource test and set. */
#ifdef DIAGNOSTIC
      u_int32_t pid;                /* Lock holder: 0 or process pid. */
#endif
#else
      u_int32_t off;                /* Backing file offset. */
      u_int32_t pid;                /* Lock holder: 0 or process pid. */
#endif
      u_int32_t spins;        /* Spins before block. */
      u_int32_t mutex_set_wait;     /* Granted after wait. */
      u_int32_t mutex_set_nowait;   /* Granted without waiting. */
} db_mutex_t;

#include "mutex_ext.h"

/*******************************************************
 * Access methods.
 *******************************************************/
/* Lock/unlock a DB thread. */
#define     DB_THREAD_LOCK(dbp)                                   \
      if (F_ISSET(dbp, DB_AM_THREAD))                             \
          (void)__db_mutex_lock((db_mutex_t *)(dbp)->mutexp, -1);
#define     DB_THREAD_UNLOCK(dbp)                                 \
      if (F_ISSET(dbp, DB_AM_THREAD))                             \
          (void)__db_mutex_unlock((db_mutex_t *)(dbp)->mutexp, -1);

/* Btree/recno local statistics structure. */
struct __db_bt_lstat;   typedef struct __db_bt_lstat DB_BTREE_LSTAT;
struct __db_bt_lstat {
      u_int32_t bt_freed;           /* Pages freed for reuse. */
      u_int32_t bt_pfxsaved;        /* Bytes saved by prefix compression. */
      u_int32_t bt_split;           /* Total number of splits. */
      u_int32_t bt_rootsplit;       /* Root page splits. */
      u_int32_t bt_fastsplit;       /* Fast splits. */
      u_int32_t bt_added;           /* Items added. */
      u_int32_t bt_deleted;         /* Items deleted. */
      u_int32_t bt_get;       /* Items retrieved. */
      u_int32_t bt_cache_hit;       /* Hits in fast-insert code. */
      u_int32_t bt_cache_miss;      /* Misses in fast-insert code. */
};

/*******************************************************
 * Environment.
 *******************************************************/
/* Type passed to __db_appname(). */
typedef enum {
      DB_APP_NONE=0,                /* No type (region). */
      DB_APP_DATA,                  /* Data file. */
      DB_APP_LOG,             /* Log file. */
      DB_APP_TMP              /* Temporary file. */
} APPNAME;

/*******************************************************
 * Shared memory regions.
 *******************************************************/
/*
 * The shared memory regions share an initial structure so that the general
 * region code can handle races between the region being deleted and other
 * processes waiting on the region mutex.
 *
 * !!!
 * Note, the mutex must be the first entry in the region; see comment above.
 */
typedef struct _rlayout {
      db_mutex_t lock;        /* Region mutex. */
#define     DB_REGIONMAGIC    0x120897
      u_int32_t  valid;       /* Valid magic number. */
      u_int32_t  refcnt;            /* Region reference count. */
      size_t         size;          /* Region length. */
      int      majver;        /* Major version number. */
      int      minver;        /* Minor version number. */
      int      patch;         /* Patch version number. */
#define     INVALID_SEGID     -1
      int      segid;         /* shmget(2) ID, or Win16 segment ID. */

#define     REGION_ANONYMOUS  0x01  /* Region is/should be in anon mem. */
      u_int32_t  flags;
} RLAYOUT;

/*
 * DB creates all regions on 4K boundaries out of sheer paranoia, so that
 * we don't make the underlying VM unhappy.
 */
#define     DB_VMPAGESIZE     (4 * 1024)
#define     DB_ROUNDOFF(i) {                                \
      (i) += DB_VMPAGESIZE - 1;                             \
      (i) -= (i) % DB_VMPAGESIZE;                           \
}

/*
 * The interface to region attach is nasty, there is a lot of complex stuff
 * going on, which has to be retained between create/attach and detach.  The
 * REGINFO structure keeps track of it.
 */
struct __db_reginfo;    typedef struct __db_reginfo REGINFO;
struct __db_reginfo {
                              /* Arguments. */
      DB_ENV         *dbenv;        /* Region naming info. */
      APPNAME         appname;            /* Region naming info. */
      char     *path;         /* Region naming info. */
      const char *file;       /* Region naming info. */
      int       mode;         /* Region mode, if a file. */
      size_t          size;         /* Region size. */
      u_int32_t   dbflags;          /* Region file open flags, if a file. */

                              /* Results. */
      char     *name;         /* Region name. */
      void     *addr;         /* Region address. */
      int       fd;                 /* Fcntl(2) locking file descriptor.
                                 NB: this is only valid if a regular
                                 file is backing the shared region,
                                 and mmap(2) is being used to map it
                                 into our address space. */
      int       segid;        /* shmget(2) ID, or Win16 segment ID. */

                              /* Shared flags. */
/*                      0x0001      COMMON MASK with RLAYOUT structure. */
#define     REGION_CANGROW          0x0002      /* Can grow. */
#define     REGION_CREATED          0x0004      /* Created. */
#define     REGION_HOLDINGSYS 0x0008      /* Holding system resources. */
#define     REGION_LASTDETACH 0x0010      /* Delete on last detach. */
#define     REGION_MALLOC           0x0020      /* Created in malloc'd memory. */
#define     REGION_PRIVATE          0x0040      /* Private to thread/process. */
#define     REGION_REMOVED          0x0080      /* Already deleted. */
#define     REGION_SIZEDEF          0x0100      /* Use default region size if exists. */
      u_int32_t   flags;
};

/*******************************************************
 * Mpool.
 *******************************************************/
/*
 * File types for DB access methods.  Negative numbers are reserved to DB.
 */
#define     DB_FTYPE_BTREE          -1    /* Btree. */
#define     DB_FTYPE_HASH           -2    /* Hash. */

/* Structure used as the DB pgin/pgout pgcookie. */
typedef struct __dbpginfo {
      size_t      db_pagesize;            /* Underlying page size. */
      int   needswap;         /* If swapping required. */
} DB_PGINFO;

/*******************************************************
 * Log.
 *******************************************************/
/* Initialize an LSN to 'zero'. */
#define     ZERO_LSN(LSN) {                                       \
      (LSN).file = 0;                                       \
      (LSN).offset = 0;                               \
}

/* Return 1 if LSN is a 'zero' lsn, otherwise return 0. */
#define     IS_ZERO_LSN(LSN)  ((LSN).file == 0)

/* Test if we need to log a change. */
#define     DB_LOGGING(dbp)                                       \
      (F_ISSET(dbp, DB_AM_LOGGING) && !F_ISSET(dbp, DB_AM_RECOVER))

#ifdef DIAGNOSTIC
/*
 * Debugging macro to log operations.
 *    If DEBUG_WOP is defined, log operations that modify the database.
 *    If DEBUG_ROP is defined, log operations that read the database.
 *
 * D dbp
 * T txn
 * O operation (string)
 * K key
 * A data
 * F flags
 */
#define     LOG_OP(D, T, O, K, A, F) {                            \
      DB_LSN _lsn;                                          \
      DBT _op;                                        \
      if (DB_LOGGING((D))) {                                \
            memset(&_op, 0, sizeof(_op));                   \
            _op.data = O;                                   \
            _op.size = strlen(O) + 1;                       \
            (void)__db_debug_log((D)->dbenv->lg_info,       \
                T, &_lsn, 0, &_op, (D)->log_fileid, K, A, F);     \
      }                                               \
}
#ifdef DEBUG_ROP
#define     DEBUG_LREAD(D, T, O, K, A, F) LOG_OP(D, T, O, K, A, F)
#else
#define     DEBUG_LREAD(D, T, O, K, A, F)
#endif
#ifdef DEBUG_WOP
#define     DEBUG_LWRITE(D, T, O, K, A, F)      LOG_OP(D, T, O, K, A, F)
#else
#define     DEBUG_LWRITE(D, T, O, K, A, F)
#endif
#else
#define     DEBUG_LREAD(D, T, O, K, A, F)
#define     DEBUG_LWRITE(D, T, O, K, A, F)
#endif /* DIAGNOSTIC */

/*******************************************************
 * Transactions and recovery.
 *******************************************************/
/*
 * Out of band value for a lock.  The locks are returned to callers as offsets
 * into the lock regions.  Since the RLAYOUT structure begins all regions, an
 * offset of 0 is guaranteed not to be a valid lock.
 */
#define     LOCK_INVALID      0

/* The structure allocated for every transaction. */
struct __db_txn {
      DB_TXNMGR   *mgrp;            /* Pointer to transaction manager. */
      DB_TXN            *parent;    /* Pointer to transaction's parent. */
      DB_LSN            last_lsn;   /* Lsn of last log write. */
      u_int32_t   txnid;            /* Unique transaction id. */
      size_t            off;        /* Detail structure within region. */
      TAILQ_ENTRY(__db_txn) links;
};

#include "os_func.h"
#include "os_ext.h"

#endif /* !_DB_INTERNAL_H_ */

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