[VOL-2235] Mocks and interfaces for rw-core
This update consists of mocks that are used by the rw-core
during unit testing. It also includes interfaces used for unit
tests.
Change-Id: I20ca1455c358113c3aa897acc6355e0ddbc614b7
diff --git a/vendor/go.etcd.io/bbolt/tx.go b/vendor/go.etcd.io/bbolt/tx.go
new file mode 100644
index 0000000..2df7688
--- /dev/null
+++ b/vendor/go.etcd.io/bbolt/tx.go
@@ -0,0 +1,726 @@
+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
+}