diff options
Diffstat (limited to 'vendor/github.com/etcd-io/bbolt/tx.go')
-rw-r--r-- | vendor/github.com/etcd-io/bbolt/tx.go | 726 |
1 files changed, 0 insertions, 726 deletions
diff --git a/vendor/github.com/etcd-io/bbolt/tx.go b/vendor/github.com/etcd-io/bbolt/tx.go deleted file mode 100644 index 2df7688c2..000000000 --- a/vendor/github.com/etcd-io/bbolt/tx.go +++ /dev/null @@ -1,726 +0,0 @@ -package bbolt - -import ( - "fmt" - "io" - "os" - "sort" - "strings" - "time" - "unsafe" -) - -// txid represents the internal transaction identifier. -type txid uint64 - -// Tx represents a read-only or read/write transaction on the database. -// Read-only transactions can be used for retrieving values for keys and creating cursors. -// Read/write transactions can create and remove buckets and create and remove keys. -// -// IMPORTANT: You must commit or rollback transactions when you are done with -// them. Pages can not be reclaimed by the writer until no more transactions -// are using them. A long running read transaction can cause the database to -// quickly grow. -type Tx struct { - writable bool - managed bool - db *DB - meta *meta - root Bucket - pages map[pgid]*page - stats TxStats - commitHandlers []func() - - // WriteFlag specifies the flag for write-related methods like WriteTo(). - // Tx opens the database file with the specified flag to copy the data. - // - // By default, the flag is unset, which works well for mostly in-memory - // workloads. For databases that are much larger than available RAM, - // set the flag to syscall.O_DIRECT to avoid trashing the page cache. - WriteFlag int -} - -// init initializes the transaction. -func (tx *Tx) init(db *DB) { - tx.db = db - tx.pages = nil - - // Copy the meta page since it can be changed by the writer. - tx.meta = &meta{} - db.meta().copy(tx.meta) - - // Copy over the root bucket. - tx.root = newBucket(tx) - tx.root.bucket = &bucket{} - *tx.root.bucket = tx.meta.root - - // Increment the transaction id and add a page cache for writable transactions. - if tx.writable { - tx.pages = make(map[pgid]*page) - tx.meta.txid += txid(1) - } -} - -// ID returns the transaction id. -func (tx *Tx) ID() int { - return int(tx.meta.txid) -} - -// DB returns a reference to the database that created the transaction. -func (tx *Tx) DB() *DB { - return tx.db -} - -// Size returns current database size in bytes as seen by this transaction. -func (tx *Tx) Size() int64 { - return int64(tx.meta.pgid) * int64(tx.db.pageSize) -} - -// Writable returns whether the transaction can perform write operations. -func (tx *Tx) Writable() bool { - return tx.writable -} - -// Cursor creates a cursor associated with the root bucket. -// All items in the cursor will return a nil value because all root bucket keys point to buckets. -// The cursor is only valid as long as the transaction is open. -// Do not use a cursor after the transaction is closed. -func (tx *Tx) Cursor() *Cursor { - return tx.root.Cursor() -} - -// Stats retrieves a copy of the current transaction statistics. -func (tx *Tx) Stats() TxStats { - return tx.stats -} - -// Bucket retrieves a bucket by name. -// Returns nil if the bucket does not exist. -// The bucket instance is only valid for the lifetime of the transaction. -func (tx *Tx) Bucket(name []byte) *Bucket { - return tx.root.Bucket(name) -} - -// CreateBucket creates a new bucket. -// Returns an error if the bucket already exists, if the bucket name is blank, or if the bucket name is too long. -// The bucket instance is only valid for the lifetime of the transaction. -func (tx *Tx) CreateBucket(name []byte) (*Bucket, error) { - return tx.root.CreateBucket(name) -} - -// CreateBucketIfNotExists creates a new bucket if it doesn't already exist. -// Returns an error if the bucket name is blank, or if the bucket name is too long. -// The bucket instance is only valid for the lifetime of the transaction. -func (tx *Tx) CreateBucketIfNotExists(name []byte) (*Bucket, error) { - return tx.root.CreateBucketIfNotExists(name) -} - -// DeleteBucket deletes a bucket. -// Returns an error if the bucket cannot be found or if the key represents a non-bucket value. -func (tx *Tx) DeleteBucket(name []byte) error { - return tx.root.DeleteBucket(name) -} - -// ForEach executes a function for each bucket in the root. -// If the provided function returns an error then the iteration is stopped and -// the error is returned to the caller. -func (tx *Tx) ForEach(fn func(name []byte, b *Bucket) error) error { - return tx.root.ForEach(func(k, v []byte) error { - return fn(k, tx.root.Bucket(k)) - }) -} - -// OnCommit adds a handler function to be executed after the transaction successfully commits. -func (tx *Tx) OnCommit(fn func()) { - tx.commitHandlers = append(tx.commitHandlers, fn) -} - -// Commit writes all changes to disk and updates the meta page. -// Returns an error if a disk write error occurs, or if Commit is -// called on a read-only transaction. -func (tx *Tx) Commit() error { - _assert(!tx.managed, "managed tx commit not allowed") - if tx.db == nil { - return ErrTxClosed - } else if !tx.writable { - return ErrTxNotWritable - } - - // TODO(benbjohnson): Use vectorized I/O to write out dirty pages. - - // Rebalance nodes which have had deletions. - var startTime = time.Now() - tx.root.rebalance() - if tx.stats.Rebalance > 0 { - tx.stats.RebalanceTime += time.Since(startTime) - } - - // spill data onto dirty pages. - startTime = time.Now() - if err := tx.root.spill(); err != nil { - tx.rollback() - return err - } - tx.stats.SpillTime += time.Since(startTime) - - // Free the old root bucket. - tx.meta.root.root = tx.root.root - - // Free the old freelist because commit writes out a fresh freelist. - if tx.meta.freelist != pgidNoFreelist { - tx.db.freelist.free(tx.meta.txid, tx.db.page(tx.meta.freelist)) - } - - if !tx.db.NoFreelistSync { - err := tx.commitFreelist() - if err != nil { - return err - } - } else { - tx.meta.freelist = pgidNoFreelist - } - - // Write dirty pages to disk. - startTime = time.Now() - if err := tx.write(); err != nil { - tx.rollback() - return err - } - - // If strict mode is enabled then perform a consistency check. - // Only the first consistency error is reported in the panic. - if tx.db.StrictMode { - ch := tx.Check() - var errs []string - for { - err, ok := <-ch - if !ok { - break - } - errs = append(errs, err.Error()) - } - if len(errs) > 0 { - panic("check fail: " + strings.Join(errs, "\n")) - } - } - - // Write meta to disk. - if err := tx.writeMeta(); err != nil { - tx.rollback() - return err - } - tx.stats.WriteTime += time.Since(startTime) - - // Finalize the transaction. - tx.close() - - // Execute commit handlers now that the locks have been removed. - for _, fn := range tx.commitHandlers { - fn() - } - - return nil -} - -func (tx *Tx) commitFreelist() error { - // Allocate new pages for the new free list. This will overestimate - // the size of the freelist but not underestimate the size (which would be bad). - opgid := tx.meta.pgid - p, err := tx.allocate((tx.db.freelist.size() / tx.db.pageSize) + 1) - if err != nil { - tx.rollback() - return err - } - if err := tx.db.freelist.write(p); err != nil { - tx.rollback() - return err - } - tx.meta.freelist = p.id - // If the high water mark has moved up then attempt to grow the database. - if tx.meta.pgid > opgid { - if err := tx.db.grow(int(tx.meta.pgid+1) * tx.db.pageSize); err != nil { - tx.rollback() - return err - } - } - - return nil -} - -// Rollback closes the transaction and ignores all previous updates. Read-only -// transactions must be rolled back and not committed. -func (tx *Tx) Rollback() error { - _assert(!tx.managed, "managed tx rollback not allowed") - if tx.db == nil { - return ErrTxClosed - } - tx.nonPhysicalRollback() - return nil -} - -// nonPhysicalRollback is called when user calls Rollback directly, in this case we do not need to reload the free pages from disk. -func (tx *Tx) nonPhysicalRollback() { - if tx.db == nil { - return - } - if tx.writable { - tx.db.freelist.rollback(tx.meta.txid) - } - tx.close() -} - -// rollback needs to reload the free pages from disk in case some system error happens like fsync error. -func (tx *Tx) rollback() { - if tx.db == nil { - return - } - if tx.writable { - tx.db.freelist.rollback(tx.meta.txid) - if !tx.db.hasSyncedFreelist() { - // Reconstruct free page list by scanning the DB to get the whole free page list. - // Note: scaning the whole db is heavy if your db size is large in NoSyncFreeList mode. - tx.db.freelist.noSyncReload(tx.db.freepages()) - } else { - // Read free page list from freelist page. - tx.db.freelist.reload(tx.db.page(tx.db.meta().freelist)) - } - } - tx.close() -} - -func (tx *Tx) close() { - if tx.db == nil { - return - } - if tx.writable { - // Grab freelist stats. - var freelistFreeN = tx.db.freelist.free_count() - var freelistPendingN = tx.db.freelist.pending_count() - var freelistAlloc = tx.db.freelist.size() - - // Remove transaction ref & writer lock. - tx.db.rwtx = nil - tx.db.rwlock.Unlock() - - // Merge statistics. - tx.db.statlock.Lock() - tx.db.stats.FreePageN = freelistFreeN - tx.db.stats.PendingPageN = freelistPendingN - tx.db.stats.FreeAlloc = (freelistFreeN + freelistPendingN) * tx.db.pageSize - tx.db.stats.FreelistInuse = freelistAlloc - tx.db.stats.TxStats.add(&tx.stats) - tx.db.statlock.Unlock() - } else { - tx.db.removeTx(tx) - } - - // Clear all references. - tx.db = nil - tx.meta = nil - tx.root = Bucket{tx: tx} - tx.pages = nil -} - -// Copy writes the entire database to a writer. -// This function exists for backwards compatibility. -// -// Deprecated; Use WriteTo() instead. -func (tx *Tx) Copy(w io.Writer) error { - _, err := tx.WriteTo(w) - return err -} - -// WriteTo writes the entire database to a writer. -// If err == nil then exactly tx.Size() bytes will be written into the writer. -func (tx *Tx) WriteTo(w io.Writer) (n int64, err error) { - // Attempt to open reader with WriteFlag - f, err := tx.db.openFile(tx.db.path, os.O_RDONLY|tx.WriteFlag, 0) - if err != nil { - return 0, err - } - defer func() { - if cerr := f.Close(); err == nil { - err = cerr - } - }() - - // Generate a meta page. We use the same page data for both meta pages. - buf := make([]byte, tx.db.pageSize) - page := (*page)(unsafe.Pointer(&buf[0])) - page.flags = metaPageFlag - *page.meta() = *tx.meta - - // Write meta 0. - page.id = 0 - page.meta().checksum = page.meta().sum64() - nn, err := w.Write(buf) - n += int64(nn) - if err != nil { - return n, fmt.Errorf("meta 0 copy: %s", err) - } - - // Write meta 1 with a lower transaction id. - page.id = 1 - page.meta().txid -= 1 - page.meta().checksum = page.meta().sum64() - nn, err = w.Write(buf) - n += int64(nn) - if err != nil { - return n, fmt.Errorf("meta 1 copy: %s", err) - } - - // Move past the meta pages in the file. - if _, err := f.Seek(int64(tx.db.pageSize*2), io.SeekStart); err != nil { - return n, fmt.Errorf("seek: %s", err) - } - - // Copy data pages. - wn, err := io.CopyN(w, f, tx.Size()-int64(tx.db.pageSize*2)) - n += wn - if err != nil { - return n, err - } - - return n, nil -} - -// CopyFile copies the entire database to file at the given path. -// A reader transaction is maintained during the copy so it is safe to continue -// using the database while a copy is in progress. -func (tx *Tx) CopyFile(path string, mode os.FileMode) error { - f, err := tx.db.openFile(path, os.O_RDWR|os.O_CREATE|os.O_TRUNC, mode) - if err != nil { - return err - } - - err = tx.Copy(f) - if err != nil { - _ = f.Close() - return err - } - return f.Close() -} - -// Check performs several consistency checks on the database for this transaction. -// An error is returned if any inconsistency is found. -// -// It can be safely run concurrently on a writable transaction. However, this -// incurs a high cost for large databases and databases with a lot of subbuckets -// because of caching. This overhead can be removed if running on a read-only -// transaction, however, it is not safe to execute other writer transactions at -// the same time. -func (tx *Tx) Check() <-chan error { - ch := make(chan error) - go tx.check(ch) - return ch -} - -func (tx *Tx) check(ch chan error) { - // Force loading free list if opened in ReadOnly mode. - tx.db.loadFreelist() - - // Check if any pages are double freed. - freed := make(map[pgid]bool) - all := make([]pgid, tx.db.freelist.count()) - tx.db.freelist.copyall(all) - for _, id := range all { - if freed[id] { - ch <- fmt.Errorf("page %d: already freed", id) - } - freed[id] = true - } - - // Track every reachable page. - reachable := make(map[pgid]*page) - reachable[0] = tx.page(0) // meta0 - reachable[1] = tx.page(1) // meta1 - if tx.meta.freelist != pgidNoFreelist { - for i := uint32(0); i <= tx.page(tx.meta.freelist).overflow; i++ { - reachable[tx.meta.freelist+pgid(i)] = tx.page(tx.meta.freelist) - } - } - - // Recursively check buckets. - tx.checkBucket(&tx.root, reachable, freed, ch) - - // Ensure all pages below high water mark are either reachable or freed. - for i := pgid(0); i < tx.meta.pgid; i++ { - _, isReachable := reachable[i] - if !isReachable && !freed[i] { - ch <- fmt.Errorf("page %d: unreachable unfreed", int(i)) - } - } - - // Close the channel to signal completion. - close(ch) -} - -func (tx *Tx) checkBucket(b *Bucket, reachable map[pgid]*page, freed map[pgid]bool, ch chan error) { - // Ignore inline buckets. - if b.root == 0 { - return - } - - // Check every page used by this bucket. - b.tx.forEachPage(b.root, 0, func(p *page, _ int) { - if p.id > tx.meta.pgid { - ch <- fmt.Errorf("page %d: out of bounds: %d", int(p.id), int(b.tx.meta.pgid)) - } - - // Ensure each page is only referenced once. - for i := pgid(0); i <= pgid(p.overflow); i++ { - var id = p.id + i - if _, ok := reachable[id]; ok { - ch <- fmt.Errorf("page %d: multiple references", int(id)) - } - reachable[id] = p - } - - // We should only encounter un-freed leaf and branch pages. - if freed[p.id] { - ch <- fmt.Errorf("page %d: reachable freed", int(p.id)) - } else if (p.flags&branchPageFlag) == 0 && (p.flags&leafPageFlag) == 0 { - ch <- fmt.Errorf("page %d: invalid type: %s", int(p.id), p.typ()) - } - }) - - // Check each bucket within this bucket. - _ = b.ForEach(func(k, v []byte) error { - if child := b.Bucket(k); child != nil { - tx.checkBucket(child, reachable, freed, ch) - } - return nil - }) -} - -// allocate returns a contiguous block of memory starting at a given page. -func (tx *Tx) allocate(count int) (*page, error) { - p, err := tx.db.allocate(tx.meta.txid, count) - if err != nil { - return nil, err - } - - // Save to our page cache. - tx.pages[p.id] = p - - // Update statistics. - tx.stats.PageCount += count - tx.stats.PageAlloc += count * tx.db.pageSize - - return p, nil -} - -// write writes any dirty pages to disk. -func (tx *Tx) write() error { - // Sort pages by id. - pages := make(pages, 0, len(tx.pages)) - for _, p := range tx.pages { - pages = append(pages, p) - } - // Clear out page cache early. - tx.pages = make(map[pgid]*page) - sort.Sort(pages) - - // Write pages to disk in order. - for _, p := range pages { - size := (int(p.overflow) + 1) * tx.db.pageSize - offset := int64(p.id) * int64(tx.db.pageSize) - - // Write out page in "max allocation" sized chunks. - ptr := (*[maxAllocSize]byte)(unsafe.Pointer(p)) - for { - // Limit our write to our max allocation size. - sz := size - if sz > maxAllocSize-1 { - sz = maxAllocSize - 1 - } - - // Write chunk to disk. - buf := ptr[:sz] - if _, err := tx.db.ops.writeAt(buf, offset); err != nil { - return err - } - - // Update statistics. - tx.stats.Write++ - - // Exit inner for loop if we've written all the chunks. - size -= sz - if size == 0 { - break - } - - // Otherwise move offset forward and move pointer to next chunk. - offset += int64(sz) - ptr = (*[maxAllocSize]byte)(unsafe.Pointer(&ptr[sz])) - } - } - - // Ignore file sync if flag is set on DB. - if !tx.db.NoSync || IgnoreNoSync { - if err := fdatasync(tx.db); err != nil { - return err - } - } - - // Put small pages back to page pool. - for _, p := range pages { - // Ignore page sizes over 1 page. - // These are allocated using make() instead of the page pool. - if int(p.overflow) != 0 { - continue - } - - buf := (*[maxAllocSize]byte)(unsafe.Pointer(p))[:tx.db.pageSize] - - // See https://go.googlesource.com/go/+/f03c9202c43e0abb130669852082117ca50aa9b1 - for i := range buf { - buf[i] = 0 - } - tx.db.pagePool.Put(buf) - } - - return nil -} - -// writeMeta writes the meta to the disk. -func (tx *Tx) writeMeta() error { - // Create a temporary buffer for the meta page. - buf := make([]byte, tx.db.pageSize) - p := tx.db.pageInBuffer(buf, 0) - tx.meta.write(p) - - // Write the meta page to file. - if _, err := tx.db.ops.writeAt(buf, int64(p.id)*int64(tx.db.pageSize)); err != nil { - return err - } - if !tx.db.NoSync || IgnoreNoSync { - if err := fdatasync(tx.db); err != nil { - return err - } - } - - // Update statistics. - tx.stats.Write++ - - return nil -} - -// page returns a reference to the page with a given id. -// If page has been written to then a temporary buffered page is returned. -func (tx *Tx) page(id pgid) *page { - // Check the dirty pages first. - if tx.pages != nil { - if p, ok := tx.pages[id]; ok { - return p - } - } - - // Otherwise return directly from the mmap. - return tx.db.page(id) -} - -// forEachPage iterates over every page within a given page and executes a function. -func (tx *Tx) forEachPage(pgid pgid, depth int, fn func(*page, int)) { - p := tx.page(pgid) - - // Execute function. - fn(p, depth) - - // Recursively loop over children. - if (p.flags & branchPageFlag) != 0 { - for i := 0; i < int(p.count); i++ { - elem := p.branchPageElement(uint16(i)) - tx.forEachPage(elem.pgid, depth+1, fn) - } - } -} - -// Page returns page information for a given page number. -// This is only safe for concurrent use when used by a writable transaction. -func (tx *Tx) Page(id int) (*PageInfo, error) { - if tx.db == nil { - return nil, ErrTxClosed - } else if pgid(id) >= tx.meta.pgid { - return nil, nil - } - - // Build the page info. - p := tx.db.page(pgid(id)) - info := &PageInfo{ - ID: id, - Count: int(p.count), - OverflowCount: int(p.overflow), - } - - // Determine the type (or if it's free). - if tx.db.freelist.freed(pgid(id)) { - info.Type = "free" - } else { - info.Type = p.typ() - } - - return info, nil -} - -// TxStats represents statistics about the actions performed by the transaction. -type TxStats struct { - // Page statistics. - PageCount int // number of page allocations - PageAlloc int // total bytes allocated - - // Cursor statistics. - CursorCount int // number of cursors created - - // Node statistics - NodeCount int // number of node allocations - NodeDeref int // number of node dereferences - - // Rebalance statistics. - Rebalance int // number of node rebalances - RebalanceTime time.Duration // total time spent rebalancing - - // Split/Spill statistics. - Split int // number of nodes split - Spill int // number of nodes spilled - SpillTime time.Duration // total time spent spilling - - // Write statistics. - Write int // number of writes performed - WriteTime time.Duration // total time spent writing to disk -} - -func (s *TxStats) add(other *TxStats) { - s.PageCount += other.PageCount - s.PageAlloc += other.PageAlloc - s.CursorCount += other.CursorCount - s.NodeCount += other.NodeCount - s.NodeDeref += other.NodeDeref - s.Rebalance += other.Rebalance - s.RebalanceTime += other.RebalanceTime - s.Split += other.Split - s.Spill += other.Spill - s.SpillTime += other.SpillTime - s.Write += other.Write - s.WriteTime += other.WriteTime -} - -// Sub calculates and returns the difference between two sets of transaction stats. -// This is useful when obtaining stats at two different points and time and -// you need the performance counters that occurred within that time span. -func (s *TxStats) Sub(other *TxStats) TxStats { - var diff TxStats - diff.PageCount = s.PageCount - other.PageCount - diff.PageAlloc = s.PageAlloc - other.PageAlloc - diff.CursorCount = s.CursorCount - other.CursorCount - diff.NodeCount = s.NodeCount - other.NodeCount - diff.NodeDeref = s.NodeDeref - other.NodeDeref - diff.Rebalance = s.Rebalance - other.Rebalance - diff.RebalanceTime = s.RebalanceTime - other.RebalanceTime - diff.Split = s.Split - other.Split - diff.Spill = s.Spill - other.Spill - diff.SpillTime = s.SpillTime - other.SpillTime - diff.Write = s.Write - other.Write - diff.WriteTime = s.WriteTime - other.WriteTime - return diff -} |