Commit 9ac8638d authored by Howard Chu's avatar Howard Chu
Browse files

More docs

parent bed3123b
......@@ -543,17 +543,17 @@ typedef struct MDB_node {
/** Size of the node header, excluding dynamic data at the end */
#define NODESIZE offsetof(MDB_node, mn_data)
/** Size of a node in a branch page.
/** Size of a node in a branch page with a given key.
* This is just the node header plus the key, there is no data.
*/
#define INDXSIZE(k) (NODESIZE + ((k) == NULL ? 0 : (k)->mv_size))
/** Size of a node in a leaf page.
/** Size of a node in a leaf page with a given key and data.
* This is node header plus key plus data size.
*/
#define LEAFSIZE(k, d) (NODESIZE + (k)->mv_size + (d)->mv_size)
/** Address of node \i in page \p */
/** Address of node \b i in page \b p */
#define NODEPTR(p, i) ((MDB_node *)((char *)(p) + (p)->mp_ptrs[i]))
/** Address of the key for the node */
......@@ -748,6 +748,7 @@ struct MDB_env {
HANDLE me_fd; /**< The main data file */
HANDLE me_lfd; /**< The lock file */
HANDLE me_mfd; /**< just for writing the meta pages */
/** Failed to update the meta page. Probably an I/O error. */
#define MDB_FATAL_ERROR 0x80000000U
uint32_t me_flags;
uint32_t me_extrapad; /**< unused for now */
......@@ -805,8 +806,8 @@ static int mdb_read_data(MDB_txn *txn, MDB_node *leaf, MDB_val *data);
static int mdb_rebalance(MDB_cursor *mc);
static int mdb_update_key(MDB_page *mp, indx_t indx, MDB_val *key);
static int mdb_move_node(MDB_cursor *csrcrc, MDB_cursor *cdstst);
static int mdb_merge(MDB_cursor *csrcrc, MDB_cursor *cdstst);
static int mdb_move_node(MDB_cursor *csrc, MDB_cursor *cdst);
static int mdb_merge(MDB_cursor *csrc, MDB_cursor *cdst);
static int mdb_split(MDB_cursor *mc, MDB_val *newkey, MDB_val *newdata,
pgno_t newpgno);
static MDB_page *mdb_new_page(MDB_cursor *mc, uint32_t flags, int num);
......@@ -842,6 +843,7 @@ static SECURITY_ATTRIBUTES mdb_all_sa;
static int mdb_sec_inited;
#endif
/** Return the library version info. */
char *
mdb_version(int *major, int *minor, int *patch)
{
......@@ -851,7 +853,7 @@ mdb_version(int *major, int *minor, int *patch)
return MDB_VERSION_STRING;
}
/** Table of descriptions for MDB @ref error codes */
/** Table of descriptions for MDB @ref errors */
static char *const mdb_errstr[] = {
"MDB_KEYEXIST: Key/data pair already exists",
"MDB_NOTFOUND: No matching key/data pair found",
......@@ -874,6 +876,11 @@ mdb_strerror(int err)
}
#if DEBUG
/** Display a key in hexadecimal and return the address of the result.
* @param[in] key the key to display
* @param[in] buf the buffer to write into. Should always be #DKBUF.
* @return The key in hexadecimal form.
*/
static char *
mdb_dkey(MDB_val *key, char *buf)
{
......@@ -882,6 +889,9 @@ mdb_dkey(MDB_val *key, char *buf)
unsigned int i;
if (key->mv_size > MAXKEYSIZE)
return "MAXKEYSIZE";
/* may want to make this a dynamic check: if the key is mostly
* printable characters, print it as-is instead of converting to hex.
*/
#if 1
for (i=0; i<key->mv_size; i++)
ptr += sprintf(ptr, "%02x", *c++);
......@@ -898,6 +908,15 @@ mdb_cmp(MDB_txn *txn, MDB_dbi dbi, const MDB_val *a, const MDB_val *b)
return txn->mt_dbxs[dbi].md_cmp(a, b);
}
/** Compare two data items according to a particular database.
* This returns a comparison as if the two items were data items of
* a sorted duplicates #MDB_DUPSORT database.
* @param[in] txn A transaction handle returned by #mdb_txn_begin()
* @param[in] dbi A database handle returned by #mdb_open()
* @param[in] a The first item to compare
* @param[in] b The second item to compare
* @return < 0 if a < b, 0 if a == b, > 0 if a > b
*/
int
mdb_dcmp(MDB_txn *txn, MDB_dbi dbi, const MDB_val *a, const MDB_val *b)
{
......@@ -907,7 +926,15 @@ mdb_dcmp(MDB_txn *txn, MDB_dbi dbi, const MDB_val *a, const MDB_val *b)
return EINVAL; /* too bad you can't distinguish this from a valid result */
}
/* Allocate new page(s) for writing */
/** Allocate pages for writing.
* If there are free pages available from older transactions, they
* will be re-used first. Otherwise a new page will be allocated.
* @param[in] mc cursor A cursor handle identifying the transaction and
* database for which we are allocating.
* @param[in] num the number of pages to allocate.
* @return Address of the allocated page(s). Requests for multiple pages
* will always be satisfied by a single contiguous chunk of memory.
*/
static MDB_page *
mdb_alloc_page(MDB_cursor *mc, int num)
{
......@@ -1025,7 +1052,9 @@ mdb_alloc_page(MDB_cursor *mc, int num)
return np;
}
/* Touch a page: make it dirty and re-insert into tree with updated pgno.
/** Touch a page: make it dirty and re-insert into tree with updated pgno.
* @param[in] mc cursor pointing to the page to be touched
* @return 0 on success, non-zero on failure.
*/
static int
mdb_touch(MDB_cursor *mc)
......@@ -1047,7 +1076,9 @@ mdb_touch(MDB_cursor *mc)
mp->mp_flags |= P_DIRTY;
mc->mc_pg[mc->mc_top] = mp;
/* Update the page number to new touched page. */
/** If this page has a parent, update the parent to point to
* this new page.
*/
if (mc->mc_top)
SETPGNO(NODEPTR(mc->mc_pg[mc->mc_top-1], mc->mc_ki[mc->mc_top-1]), mp->mp_pgno);
}
......@@ -1068,6 +1099,12 @@ mdb_env_sync(MDB_env *env, int force)
static inline void
mdb_txn_reset0(MDB_txn *txn);
/** Common code for #mdb_txn_begin() and #mdb_txn_renew().
* @param[in] txn the transaction handle to initialize
* @return 0 on success, non-zero on failure. This can only
* fail for read-only transactions, and then only if the
* reader table is full.
*/
static inline int
mdb_txn_renew0(MDB_txn *txn)
{
......@@ -1181,6 +1218,9 @@ mdb_txn_begin(MDB_env *env, unsigned int flags, MDB_txn **ret)
return rc;
}
/** Common code for #mdb_txn_reset() and #mdb_txn_abort().
* @param[in] txn the transaction handle to reset
*/
static inline void
mdb_txn_reset0(MDB_txn *txn)
{
......@@ -1213,6 +1253,7 @@ mdb_txn_reset0(MDB_txn *txn)
env->me_txn = NULL;
for (i=2; i<env->me_numdbs; i++)
env->me_dbxs[i].md_dirty = 0;
/* The writer mutex was locked in mdb_txn_begin. */
UNLOCK_MUTEX_W(env);
}
}
......@@ -1510,6 +1551,12 @@ done:
return MDB_SUCCESS;
}
/** Read the environment parameters of a DB environment before
* mapping it into memory.
* @param[in] env the environment handle
* @param[out] meta address of where to store the meta information
* @return 0 on success, non-zero on failure.
*/
static int
mdb_env_read_header(MDB_env *env, MDB_meta *meta)
{
......@@ -1560,6 +1607,11 @@ mdb_env_read_header(MDB_env *env, MDB_meta *meta)
return 0;
}
/** Write the environment parameters of a freshly created DB environment.
* @param[in] env the environment handle
* @param[out] meta address of where to store the meta information
* @return 0 on success, non-zero on failure.
*/
static int
mdb_env_init_meta(MDB_env *env, MDB_meta *meta)
{
......@@ -1610,6 +1662,10 @@ mdb_env_init_meta(MDB_env *env, MDB_meta *meta)
return rc;
}
/** Update the environment info to commit a transaction.
* @param[in] txn the transaction that's being committed
* @return 0 on success, non-zero on failure.
*/
static int
mdb_env_write_meta(MDB_txn *txn)
{
......@@ -1690,6 +1746,11 @@ mdb_env_write_meta(MDB_txn *txn)
return MDB_SUCCESS;
}
/** Check both meta pages to see which one is newer.
* @param[in] env the environment handle
* @param[out] which address of where to store the meta toggle ID
* @return 0 on success, non-zero on failure.
*/
static int
mdb_env_read_meta(MDB_env *env, int *which)
{
......@@ -1759,6 +1820,8 @@ mdb_env_get_maxreaders(MDB_env *env, int *readers)
return MDB_SUCCESS;
}
/** Further setup required for opening an MDB environment
*/
static int
mdb_env_open2(MDB_env *env, unsigned int flags)
{
......@@ -4493,6 +4556,10 @@ mdb_put(MDB_txn *txn, MDB_dbi dbi,
int
mdb_env_set_flags(MDB_env *env, unsigned int flag, int onoff)
{
/** Only a subset of the @ref mdb_env flags can be changed
* at runtime. Changing other flags requires closing the environment
* and re-opening it with the new flags.
*/
#define CHANGEABLE (MDB_NOSYNC)
if ((flag & CHANGEABLE) != flag)
return EINVAL;
......
......@@ -151,7 +151,12 @@ typedef void (MDB_rel_func)(void *newptr, void *oldptr, size_t size);
#define MDB_REVERSEKEY 0x02
/** use sorted duplicates */
#define MDB_DUPSORT 0x04
/** numeric keys in native byte order */
/** numeric keys in native byte order.
* @note The keys size must actually be equal to
* sizeof(int) or sizeof(long) otherwise there will be
* alignment issues. On some processors, accessing misaligned
* data will cause a SIGBUS.
*/
#define MDB_INTEGERKEY 0x08
/** with #MDB_DUPSORT, sorted dup items have fixed size */
#define MDB_DUPFIXED 0x10
......
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