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bbolt
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Intermediate commit.

pull/34/head
Ben Johnson 2014-01-21 14:37:55 -07:00
parent 153372abd4
commit bce3e667df
9 changed files with 505 additions and 559 deletions
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34
README.md
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@ -1,4 +1,38 @@
bolt
====
## Overview
A low-level key/value database for Go.
## API
### DB
### Creating a database
```
db := DB()
err := db.Open("/path/to/db", 0666)
...
err := db.Close()
```
### Creating a bucket
* Cursor
```
DB
Bucket
Transaction / RWTransaction
Cursor / RWCursor
page
meta
branchNode
leafNode
```

79
branch_node.go
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@ -10,86 +10,7 @@ const (
dupNode = 0x04
)
// branchNode represents a node on a branch page.
type branchNode struct {
pgno uint32
flags uint16
keySize uint16
data uintptr // Pointer to the beginning of the data.
}
// key returns a byte slice that of the key data.
func (n *branchNode) key() []byte {
return (*[MaxKeySize]byte)(unsafe.Pointer(&n.data))[:n.keySize]
}
func (n *branchNode) size() int {
return 0 // TODO: offsetof(MDB_node, mn_data)
}
// TODO: #define INDXSIZE(k) (NODESIZE + ((k) == NULL ? 0 : (k)->mv_size))
// TODO: #define LEAFSIZE(k, d) (NODESIZE + (k)->mv_size + (d)->mv_size)
// TODO: #define NODEPTR(p, i) ((MDB_node *)((char *)(p) + (p)->mp_ptrs[i]))
// TODO: #define NODEKEY(node) (void *)((node)->mn_data)
// TODO: #define NODEDATA(node) (void *)((char *)(node)->mn_data + (node)->mn_ksize)
// TODO: #define NODEPGNO(node) ((node)->mn_lo | ((pgno_t) (node)->mn_hi << 16) | (PGNO_TOPWORD ? ((pgno_t) (node)->mn_flags << PGNO_TOPWORD) : 0))
// TODO: #define SETPGNO(node,pgno) do { (node)->mn_lo = (pgno) & 0xffff; (node)->mn_hi = (pgno) >> 16; if (PGNO_TOPWORD) (node)->mn_flags = (pgno) >> PGNO_TOPWORD; } while(0)
// TODO: #define NODEDSZ(node) ((node)->mn_lo | ((unsigned)(node)->mn_hi << 16))
// TODO: #define SETDSZ(node,size) do { (node)->mn_lo = (size) & 0xffff; (node)->mn_hi = (size) >> 16;} while(0)
// TODO: #define NODEKSZ(node) ((node)->mn_ksize)
// TODO: #define LEAF2KEY(p, i, ks) ((char *)(p) + PAGEHDRSZ + ((i)*(ks)))
// TODO: #define MDB_GET_KEY(node, keyptr) { if ((keyptr) != NULL) { (keyptr)->mv_size = NODEKSZ(node); (keyptr)->mv_data = NODEKEY(node); } }
// TODO: #define MDB_GET_KEY2(node, key) { key.mv_size = NODEKSZ(node); key.mv_data = NODEKEY(node); }
// Compact the main page after deleting a node on a subpage.
// @param[in] mp The main page to operate on.
// @param[in] indx The index of the subpage on the main page.
func (n *node) shrink(index int) {
/*
MDB_node *node;
MDB_page *sp, *xp;
char *base;
int nsize, delta;
indx_t i, numkeys, ptr;
node = NODEPTR(mp, indx);
sp = (MDB_page *)NODEDATA(node);
delta = SIZELEFT(sp);
xp = (MDB_page *)((char *)sp + delta);
// shift subpage upward
if (IS_LEAF2(sp)) {
nsize = NUMKEYS(sp) * sp->mp_pad;
if (nsize & 1)
return; // do not make the node uneven-sized
memmove(METADATA(xp), METADATA(sp), nsize);
} else {
int i;
numkeys = NUMKEYS(sp);
for (i=numkeys-1; i>=0; i--)
xp->mp_ptrs[i] = sp->mp_ptrs[i] - delta;
}
xp->mp_upper = sp->mp_lower;
xp->mp_lower = sp->mp_lower;
xp->mp_flags = sp->mp_flags;
xp->mp_pad = sp->mp_pad;
COPY_PGNO(xp->mp_pgno, mp->mp_pgno);
nsize = NODEDSZ(node) - delta;
SETDSZ(node, nsize);
// shift lower nodes upward
ptr = mp->mp_ptrs[indx];
numkeys = NUMKEYS(mp);
for (i = 0; i < numkeys; i++) {
if (mp->mp_ptrs[i] <= ptr)
mp->mp_ptrs[i] += delta;
}
base = (char *)mp + mp->mp_upper;
memmove(base + delta, base, ptr - mp->mp_upper + NODESIZE + NODEKSZ(node));
mp->mp_upper += delta;
*/
}

1
bucket.go
View File

@ -29,4 +29,3 @@ type bucket struct {
entries uint64
root pgno
}

40
cursor.go
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@ -5,31 +5,19 @@ package bolt
const (
c_initialized = 0x01 /**< cursor has been initialized and is valid */
c_eof = 0x02 /**< No more data */
c_sub = 0x04 /**< Cursor is a sub-cursor */
c_del = 0x08 /**< last op was a cursor_del */
c_splitting = 0x20 /**< Cursor is in page_split */
c_untrack = 0x40 /**< Un-track cursor when closing */
)
// TODO: #define MDB_NOSPILL 0x8000 /** Do not spill pages to disk if txn is getting full, may fail instead */
/*
type Cursor interface {
First() error
FirstDup() error
Get() ([]byte, []byte, error)
GetRange() ([]byte, []byte, error)
Current() ([]byte, []byte, error)
Last()
LastDup()
Last() error
Next() ([]byte, []byte, error)
NextDup() ([]byte, []byte, error)
NextNoDup() ([]byte, []byte, error)
Prev() ([]byte, []byte, error)
PrevDup() ([]byte, []byte, error)
PrevNoDup() ([]byte, []byte, error)
Set() ([]byte, []byte, error)
SetRange() ([]byte, []byte, error)
Current() ([]byte, []byte, error)
Get([]byte) ([]byte, error)
}
*/
@ -37,10 +25,8 @@ type Cursor struct {
flags int
next *Cursor
backup *Cursor
subcursor *Cursor
transaction *Transaction
bucket *Bucket
subbucket *Bucket
top int
pages []*page
indices []int /* the index of the node for the page at the same level */
@ -53,12 +39,6 @@ func (c *Cursor) Get(key []byte) ([]byte, error) {
int exact = 0;
int (*mfunc)(MDB_cursor *mc, MDB_val *key, MDB_val *data);
if (mc == NULL)
return EINVAL;
if (mc->mc_txn->mt_flags & MDB_TXN_ERROR)
return MDB_BAD_TXN;
switch (op) {
case MDB_GET_CURRENT:
if (!(mc->mc_flags & C_INITIALIZED)) {
@ -222,14 +202,14 @@ func (c *Cursor) page(key []byte, flags int) (*page, error) {
if (flags & ps_first) != 0 {
index = 0
} else if (flags & ps_last) != 0 {
index = indx(p.numkeys()) - 1;
index = indx(p.numkeys()) - 1
} else {
node, i, exact := p.find(key, c.transaction.db.pageSize);
node, i, exact := p.find(key, c.transaction.db.pageSize)
if exact {
c.indices[c.top] = i
}
if node == nil {
index = indx(p.numkeys()) - 1;
index = indx(p.numkeys()) - 1
} else {
index = indx(c.indices[c.top])
if !exact {
@ -279,8 +259,8 @@ func (c *Cursor) push(p *page) {
c.top = len(c.pages) - 1
}
// page retrieves the last page on the page stack.
func (c *Cursor) page() *page {
// currentPage retrieves the last page on the page stack.
func (c *Cursor) currentPage() *page {
top := len(c.pages)
if top > 0 {
return c.pages[top]
@ -306,7 +286,6 @@ func (c *Cursor) currentLeafNode() *node {
return nil
}
// //
// //
// //
@ -642,9 +621,6 @@ func (c *Cursor) page_touch() int {
return 0
}
// Search for the lowest key under the current branch page.
// This just bypasses a NUMKEYS check in the current page
// before calling mdb_page_search_root(), because the callers

16
leaf_node.go → node.go
View File

@ -4,14 +4,26 @@ import (
"unsafe"
)
// leafNode represents a node on a leaf page.
type leafNode struct {
// node represents a node on a page.
type node struct {
flags uint16
keySize uint16
}
// leafNode represents a node on a leaf page.
type leafNode struct {
node
dataSize uint32
data uintptr // Pointer to the beginning of the data.
}
// branchNode represents a node on a branch page.
type branchNode struct {
node
pgno uint32
data uintptr // Pointer to the beginning of the data.
}
// key returns a byte slice that of the key data.
func (n *leafNode) key() []byte {
return (*[MaxKeySize]byte)(unsafe.Pointer(&n.data))[:n.keySize]

5
page.go
View File

@ -21,7 +21,6 @@ const (
p_overflow = 0x04
p_meta = 0x08
p_dirty = 0x10 /**< dirty page, also set for #P_SUBP pages */
p_sub = 0x40
p_keep = 0x8000 /**< leave this page alone during spill */
p_invalid = ^pgno(0)
@ -124,13 +123,13 @@ func (p *page) find(key []byte, pageSize int) (*node, int, bool) {
// Perform a binary search to find the correct node.
var i, rc int
for ; low <= high; {
for low <= high {
i = (low + high) / 2
node = p.node(indx(i))
rc = bytes.Compare(key, node.key())
if rc == 0 {
break;
break
} else if rc > 0 {
low = i + 1
} else {

7
rwcursor.go
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@ -1,5 +1,12 @@
package bolt
/*
type RWCursor interface {
Put([]byte, []byte) (error)
Delete([]byte) (error)
}
*/
// RWCursor represents a cursor that can read and write data for a bucket.
type RWCursor struct {
Cursor

2
rwtransaction.go
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@ -4,6 +4,4 @@ package bolt
// Only one read/write transaction can be active for a DB at a time.
type RWTransaction struct {
Transaction
pagestate pagestate
}