mirror of https://github.com/etcd-io/bbolt.git
102 lines
2.3 KiB
Go
102 lines
2.3 KiB
Go
package bolt
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import (
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"unsafe"
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)
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const maxPageSize = 0x8000
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const minKeyCount = 2
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var _page page
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const pageHeaderSize = int(unsafe.Offsetof(_page.ptr))
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const minPageKeys = 2
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const fillThreshold = 250 // 25%
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const (
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p_branch = 0x01
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p_leaf = 0x02
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p_overflow = 0x04
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p_meta = 0x08
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p_dirty = 0x10 /**< dirty page, also set for #P_SUBP pages */
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p_sub = 0x40
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p_keep = 0x8000 /**< leave this page alone during spill */
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p_invalid = ^pgno(0)
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)
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// maxCommitPages is the maximum number of pages to commit in one writev() call.
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const maxCommitPages = 64
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/* max bytes to write in one call */
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const maxWriteByteCount uint = 0x80000000 // TODO: #define MAX_WRITE 0x80000000U >> (sizeof(ssize_t) == 4))
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// TODO:
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// #if defined(IOV_MAX) && IOV_MAX < MDB_COMMIT_PAGES
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// #undef MDB_COMMIT_PAGES
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// #define MDB_COMMIT_PAGES IOV_MAX
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// #endif
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// TODO: #define MDB_PS_MODIFY 1
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// TODO: #define MDB_PS_ROOTONLY 2
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// TODO: #define MDB_PS_FIRST 4
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// TODO: #define MDB_PS_LAST 8
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// TODO: #define MDB_SPLIT_REPLACE MDB_APPENDDUP /**< newkey is not new */
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type pgno uint64
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type txnid uint64
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type indx uint16
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type page struct {
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id pgno
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flags int
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lower indx
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upper indx
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overflow int
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ptr int
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}
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type pageState struct {
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head int /**< Reclaimed freeDB pages, or NULL before use */
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last int /**< ID of last used record, or 0 if !mf_pghead */
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}
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// meta returns a pointer to the metadata section of the page.
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func (p *page) meta() (*meta, error) {
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// Exit if page is not a meta page.
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if (p.flags & p_meta) == 0 {
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return nil, InvalidMetaPageError
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}
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// Cast the meta section and validate before returning.
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m := (*meta)(unsafe.Pointer(&p.ptr))
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if err := m.validate(); err != nil {
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return nil, err
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}
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return m, nil
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}
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// initMeta initializes a page as a new meta page.
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func (p *page) initMeta(pageSize int) {
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p.flags = p_meta
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m := (*meta)(unsafe.Pointer(&p.ptr))
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m.magic = magic
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m.version = version
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m.free.pad = uint32(pageSize)
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m.pgno = 1
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m.free.root = p_invalid
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m.main.root = p_invalid
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}
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// nodeCount returns the number of nodes on the page.
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func (p *page) nodeCount() int {
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return 0 // (p.header.lower - unsafe.Sizeof(p.header) >> 1
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}
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// remainingSize returns the number of bytes left in the page.
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func (p *page) remainingSize() int {
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return int(p.upper - p.lower)
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}
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