vendor: Add github.com/cznic/lldb and friends (new recursive dependency)

2016-09-13 21:57:19 +02:00
parent ca755ec9e0
commit 81d19a00aa
26 changed files with 8156 additions and 0 deletions
--- a/vendor/github.com/cznic/lldb/xact.go
+++ b/vendor/github.com/cznic/lldb/xact.go
@@ -0,0 +1,616 @@
+// Copyright 2014 The lldb Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Structural transactions.
+
+package lldb
+
+//DONE+ TransactionalMemoryFiler
+//	----
+//	Use NewRollbackFiler(myMemFiler, ...)
+
+/*
+
+bfBits: 3
+BenchmarkRollbackFiler	20000000	       102 ns/op	   9.73 MB/s
+
+bfBits: 4
+BenchmarkRollbackFiler	50000000	        55.7 ns/op	  17.95 MB/s
+
+bfBits: 5
+BenchmarkRollbackFiler	100000000	        32.2 ns/op	  31.06 MB/s
+
+bfBits: 6
+BenchmarkRollbackFiler	100000000	        20.6 ns/op	  48.46 MB/s
+
+bfBits: 7
+BenchmarkRollbackFiler	100000000	        15.1 ns/op	  66.12 MB/s
+
+bfBits: 8
+BenchmarkRollbackFiler	100000000	        10.5 ns/op	  95.66 MB/s
+
+bfBits: 9
+BenchmarkRollbackFiler	200000000	         8.02 ns/op	 124.74 MB/s
+
+bfBits: 10
+BenchmarkRollbackFiler	200000000	         9.25 ns/op	 108.09 MB/s
+
+bfBits: 11
+BenchmarkRollbackFiler	100000000	        11.7 ns/op	  85.47 MB/s
+
+bfBits: 12
+BenchmarkRollbackFiler	100000000	        17.2 ns/op	  57.99 MB/s
+
+bfBits: 13
+BenchmarkRollbackFiler	100000000	        32.7 ns/op	  30.58 MB/s
+
+bfBits: 14
+BenchmarkRollbackFiler	50000000	        39.6 ns/op	  25.27 MB/s
+
+*/
+
+import (
+	"fmt"
+	"io"
+	"sync"
+
+	"github.com/cznic/fileutil"
+	"github.com/cznic/internal/buffer"
+	"github.com/cznic/mathutil"
+)
+
+var (
+	_ Filer = &bitFiler{}      // Ensure bitFiler is a Filer.
+	_ Filer = &RollbackFiler{} // ditto
+)
+
+const (
+	bfBits = 12
+	bfSize = 1 << bfBits
+	bfMask = bfSize - 1
+)
+
+type (
+	bitPage struct {
+		prev, next *bitPage
+		pdata      *[]byte
+		data       []byte
+		dirty      bool
+	}
+
+	bitFilerMap map[int64]*bitPage
+
+	bitFiler struct {
+		parent Filer
+		m      bitFilerMap
+		size   int64
+	}
+)
+
+func newBitFiler(parent Filer) (f *bitFiler, err error) {
+	sz, err := parent.Size()
+	if err != nil {
+		return
+	}
+
+	return &bitFiler{parent: parent, m: bitFilerMap{}, size: sz}, nil
+}
+
+func (f *bitFiler) BeginUpdate() error { panic("internal error") }
+func (f *bitFiler) EndUpdate() error   { panic("internal error") }
+func (f *bitFiler) Rollback() error    { panic("internal error") }
+func (f *bitFiler) Sync() error        { panic("internal error") }
+
+func (f *bitFiler) Close() (err error)   { return }
+func (f *bitFiler) Name() string         { return fmt.Sprintf("%p.bitfiler", f) }
+func (f *bitFiler) Size() (int64, error) { return f.size, nil }
+
+func (f *bitFiler) free() {
+	for _, pg := range f.m {
+		buffer.Put(pg.pdata)
+	}
+}
+
+func (f *bitFiler) PunchHole(off, size int64) (err error) {
+	first := off >> bfBits
+	if off&bfMask != 0 {
+		first++
+	}
+	off += size - 1
+	last := off >> bfBits
+	if off&bfMask != 0 {
+		last--
+	}
+	if limit := f.size >> bfBits; last > limit {
+		last = limit
+	}
+	for pgI := first; pgI <= last; pgI++ {
+		pg := &bitPage{}
+		pg.pdata = buffer.CGet(bfSize)
+		pg.data = *pg.pdata
+		pg.dirty = true
+		f.m[pgI] = pg
+	}
+	return
+}
+
+func (f *bitFiler) ReadAt(b []byte, off int64) (n int, err error) {
+	avail := f.size - off
+	pgI := off >> bfBits
+	pgO := int(off & bfMask)
+	rem := len(b)
+	if int64(rem) >= avail {
+		rem = int(avail)
+		err = io.EOF
+	}
+	for rem != 0 && avail > 0 {
+		pg := f.m[pgI]
+		if pg == nil {
+			pg = &bitPage{}
+			pg.pdata = buffer.CGet(bfSize)
+			pg.data = *pg.pdata
+			if f.parent != nil {
+				_, err = f.parent.ReadAt(pg.data, off&^bfMask)
+				if err != nil && !fileutil.IsEOF(err) {
+					return
+				}
+
+				err = nil
+			}
+			f.m[pgI] = pg
+		}
+		nc := copy(b[:mathutil.Min(rem, bfSize)], pg.data[pgO:])
+		pgI++
+		pgO = 0
+		rem -= nc
+		n += nc
+		b = b[nc:]
+		off += int64(nc)
+	}
+	return
+}
+
+func (f *bitFiler) Truncate(size int64) (err error) {
+	switch {
+	case size < 0:
+		return &ErrINVAL{"Truncate size", size}
+	case size == 0:
+		f.m = bitFilerMap{}
+		f.size = 0
+		return
+	}
+
+	first := size >> bfBits
+	if size&bfMask != 0 {
+		first++
+	}
+	last := f.size >> bfBits
+	if f.size&bfMask != 0 {
+		last++
+	}
+	for ; first < last; first++ {
+		if bp, ok := f.m[first]; ok {
+			buffer.Put(bp.pdata)
+		}
+		delete(f.m, first)
+	}
+
+	f.size = size
+	return
+}
+
+func (f *bitFiler) WriteAt(b []byte, off int64) (n int, err error) {
+	off0 := off
+	pgI := off >> bfBits
+	pgO := int(off & bfMask)
+	n = len(b)
+	rem := n
+	var nc int
+	for rem != 0 {
+		pg := f.m[pgI]
+		if pg == nil {
+			pg = &bitPage{}
+			pg.pdata = buffer.CGet(bfSize)
+			pg.data = *pg.pdata
+			if f.parent != nil {
+				_, err = f.parent.ReadAt(pg.data, off&^bfMask)
+				if err != nil && !fileutil.IsEOF(err) {
+					return
+				}
+
+				err = nil
+			}
+			f.m[pgI] = pg
+		}
+		nc = copy(pg.data[pgO:], b)
+		pgI++
+		pg.dirty = true
+		pgO = 0
+		rem -= nc
+		b = b[nc:]
+		off += int64(nc)
+	}
+	f.size = mathutil.MaxInt64(f.size, off0+int64(n))
+	return
+}
+
+func (f *bitFiler) link() {
+	for pgI, pg := range f.m {
+		nx, ok := f.m[pgI+1]
+		if !ok || !nx.dirty {
+			continue
+		}
+
+		nx.prev, pg.next = pg, nx
+	}
+}
+
+func (f *bitFiler) dumpDirty(w io.WriterAt) (nwr int, err error) {
+	f.link()
+	for pgI, pg := range f.m {
+		if !pg.dirty {
+			continue
+		}
+
+		for pg.prev != nil && pg.prev.dirty {
+			pg = pg.prev
+			pgI--
+		}
+
+		for pg != nil && pg.dirty {
+			if _, err := w.WriteAt(pg.data, pgI<<bfBits); err != nil {
+				return 0, err
+			}
+
+			nwr++
+			pg.dirty = false
+			pg = pg.next
+			pgI++
+		}
+	}
+	return
+}
+
+// RollbackFiler is a Filer implementing structural transaction handling.
+// Structural transactions should be small and short lived because all non
+// committed data are held in memory until committed or discarded by a
+// Rollback.
+//
+// While using RollbackFiler, every intended update of the wrapped Filler, by
+// WriteAt, Truncate or PunchHole, _must_ be made within a transaction.
+// Attempts to do it outside of a transaction will return ErrPERM. OTOH,
+// invoking ReadAt outside of a transaction is not a problem.
+//
+// No nested transactions: All updates within a transaction are held in memory.
+// On a matching EndUpdate the updates held in memory are actually written to
+// the wrapped Filer.
+//
+// Nested transactions: Correct data will be seen from RollbackFiler when any
+// level of a nested transaction is rollbacked. The actual writing to the
+// wrapped Filer happens only when the outer most transaction nesting level is
+// closed.
+//
+// Invoking Rollback is an alternative to EndUpdate. It discards all changes
+// made at the current transaction level and returns the "state" (possibly not
+// yet persisted) of the Filer to what it was before the corresponding
+// BeginUpdate.
+//
+// During an open transaction, all reads (using ReadAt) are "dirty" reads,
+// seeing the uncommitted changes made to the Filer's data.
+//
+// Lldb databases should be based upon a RollbackFiler.
+//
+// With a wrapped MemFiler one gets transactional memory. With, for example a
+// wrapped disk based SimpleFileFiler it protects against at least some HW
+// errors - if Rollback is properly invoked on such failures and/or if there's
+// some WAL or 2PC or whatever other safe mechanism based recovery procedure
+// used by the client.
+//
+// The "real" writes to the wrapped Filer (or WAL instead) go through the
+// writerAt supplied to NewRollbackFiler.
+//
+// List of functions/methods which are recommended to be wrapped in a
+// BeginUpdate/EndUpdate structural transaction:
+//
+// 	Allocator.Alloc
+// 	Allocator.Free
+// 	Allocator.Realloc
+//
+//	CreateBTree
+// 	RemoveBTree
+// 	BTree.Clear
+// 	BTree.Delete
+// 	BTree.DeleteAny
+// 	BTree.Clear
+// 	BTree.Extract
+// 	BTree.Get (it can mutate the DB)
+// 	BTree.Put
+// 	BTree.Set
+//
+// NOTE: RollbackFiler is a generic solution intended to wrap Filers provided
+// by this package which do not implement any of the transactional methods.
+// RollbackFiler thus _does not_ invoke any of the transactional methods of its
+// wrapped Filer.
+//
+// RollbackFiler is safe for concurrent use by multiple goroutines.
+type RollbackFiler struct {
+	mu           sync.RWMutex
+	inCallback   bool
+	inCallbackMu sync.RWMutex
+	bitFiler     *bitFiler
+	checkpoint   func(int64) error
+	closed       bool
+	f            Filer
+	parent       Filer
+	tlevel       int // transaction nesting level, 0 == not in transaction
+	writerAt     io.WriterAt
+
+	// afterRollback, if not nil, is called after performing Rollback
+	// without errros.
+	afterRollback func() error
+}
+
+// NewRollbackFiler returns a RollbackFiler wrapping f.
+//
+// The checkpoint parameter
+//
+// The checkpoint function is called after closing (by EndUpdate) the upper
+// most level open transaction if all calls of writerAt were successful and the
+// DB (or eg. a WAL) is thus now in a consistent state (virtually, in the ideal
+// world with no write caches, no HW failures, no process crashes, ...).
+//
+// NOTE: In, for example, a 2PC it is necessary to reflect also the sz
+// parameter as the new file size (as in the parameter to Truncate). All
+// changes were successfully written already by writerAt before invoking
+// checkpoint.
+//
+// The writerAt parameter
+//
+// The writerAt interface is used to commit the updates of the wrapped Filer.
+// If any invocation of writerAt fails then a non nil error will be returned
+// from EndUpdate and checkpoint will _not_ ne called.  Neither is necessary to
+// call Rollback. The rule of thumb: The [structural] transaction [level] is
+// closed by invoking exactly once one of EndUpdate _or_ Rollback.
+//
+// It is presumed that writerAt uses WAL or 2PC or whatever other safe
+// mechanism to physically commit the updates.
+//
+// Updates performed by invocations of writerAt are byte-precise, but not
+// necessarily maximum possible length precise. IOW, for example an update
+// crossing page boundaries may be performed by more than one writerAt
+// invocation.  No offset sorting is performed.  This may change if it proves
+// to be a problem. Such change would be considered backward compatible.
+//
+// NOTE: Using RollbackFiler, but failing to ever invoke a matching "closing"
+// EndUpdate after an "opening" BeginUpdate means neither writerAt or
+// checkpoint will ever get called - with all the possible data loss
+// consequences.
+func NewRollbackFiler(f Filer, checkpoint func(sz int64) error, writerAt io.WriterAt) (r *RollbackFiler, err error) {
+	if f == nil || checkpoint == nil || writerAt == nil {
+		return nil, &ErrINVAL{Src: "lldb.NewRollbackFiler, nil argument"}
+	}
+
+	return &RollbackFiler{
+		checkpoint: checkpoint,
+		f:          f,
+		writerAt:   writerAt,
+	}, nil
+}
+
+// Implements Filer.
+func (r *RollbackFiler) BeginUpdate() (err error) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	parent := r.f
+	if r.tlevel != 0 {
+		parent = r.bitFiler
+	}
+	r.bitFiler, err = newBitFiler(parent)
+	if err != nil {
+		return
+	}
+
+	r.tlevel++
+	return
+}
+
+// Implements Filer.
+//
+// Close will return an error if not invoked at nesting level 0.  However, to
+// allow emergency closing from eg. a signal handler; if Close is invoked
+// within an open transaction(s), it rollbacks any non committed open
+// transactions and performs the Close operation.
+//
+// IOW: Regardless of the transaction nesting level the Close is always
+// performed but any uncommitted transaction data are lost.
+func (r *RollbackFiler) Close() (err error) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	if r.closed {
+		return &ErrPERM{r.f.Name() + ": Already closed"}
+	}
+
+	r.closed = true
+	if err = r.f.Close(); err != nil {
+		return
+	}
+
+	if r.tlevel != 0 {
+		err = &ErrPERM{r.f.Name() + ": Close inside an open transaction"}
+	}
+
+	if r.bitFiler != nil {
+		r.bitFiler.free()
+		r.bitFiler = nil
+	}
+
+	return
+}
+
+// Implements Filer.
+func (r *RollbackFiler) EndUpdate() (err error) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	if r.tlevel == 0 {
+		return &ErrPERM{r.f.Name() + " : EndUpdate outside of a transaction"}
+	}
+
+	sz, err := r.size() // Cannot call .Size() -> deadlock
+	if err != nil {
+		return
+	}
+
+	r.tlevel--
+	bf := r.bitFiler
+	parent := bf.parent
+	w := r.writerAt
+	if r.tlevel != 0 {
+		w = parent
+	}
+	nwr, err := bf.dumpDirty(w)
+	if err != nil {
+		return
+	}
+
+	switch {
+	case r.tlevel == 0:
+		defer func() {
+			r.bitFiler.free()
+			r.bitFiler = nil
+		}()
+
+		if nwr == 0 {
+			return
+		}
+
+		return r.checkpoint(sz)
+	default:
+		r.bitFiler.free()
+		r.bitFiler = parent.(*bitFiler)
+		sz, _ := bf.Size() // bitFiler.Size() never returns err != nil
+		return parent.Truncate(sz)
+	}
+}
+
+// Implements Filer.
+func (r *RollbackFiler) Name() string {
+	r.mu.RLock()
+	defer r.mu.RUnlock()
+
+	return r.f.Name()
+}
+
+// Implements Filer.
+func (r *RollbackFiler) PunchHole(off, size int64) error {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	if r.tlevel == 0 {
+		return &ErrPERM{r.f.Name() + ": PunchHole outside of a transaction"}
+	}
+
+	if off < 0 {
+		return &ErrINVAL{r.f.Name() + ": PunchHole off", off}
+	}
+
+	if size < 0 || off+size > r.bitFiler.size {
+		return &ErrINVAL{r.f.Name() + ": PunchHole size", size}
+	}
+
+	return r.bitFiler.PunchHole(off, size)
+}
+
+// Implements Filer.
+func (r *RollbackFiler) ReadAt(b []byte, off int64) (n int, err error) {
+	r.inCallbackMu.RLock()
+	defer r.inCallbackMu.RUnlock()
+	if !r.inCallback {
+		r.mu.RLock()
+		defer r.mu.RUnlock()
+	}
+	if r.tlevel == 0 {
+		return r.f.ReadAt(b, off)
+	}
+
+	return r.bitFiler.ReadAt(b, off)
+}
+
+// Implements Filer.
+func (r *RollbackFiler) Rollback() (err error) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	if r.tlevel == 0 {
+		return &ErrPERM{r.f.Name() + ": Rollback outside of a transaction"}
+	}
+
+	if r.tlevel > 1 {
+		r.bitFiler.free()
+		r.bitFiler = r.bitFiler.parent.(*bitFiler)
+	}
+	r.tlevel--
+	if f := r.afterRollback; f != nil {
+		r.inCallbackMu.Lock()
+		r.inCallback = true
+		r.inCallbackMu.Unlock()
+		defer func() {
+			r.inCallbackMu.Lock()
+			r.inCallback = false
+			r.inCallbackMu.Unlock()
+		}()
+		return f()
+	}
+	return
+}
+
+func (r *RollbackFiler) size() (sz int64, err error) {
+	if r.tlevel == 0 {
+		return r.f.Size()
+	}
+
+	return r.bitFiler.Size()
+}
+
+// Implements Filer.
+func (r *RollbackFiler) Size() (sz int64, err error) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	return r.size()
+}
+
+// Implements Filer.
+func (r *RollbackFiler) Sync() error {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	return r.f.Sync()
+}
+
+// Implements Filer.
+func (r *RollbackFiler) Truncate(size int64) error {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	if r.tlevel == 0 {
+		return &ErrPERM{r.f.Name() + ": Truncate outside of a transaction"}
+	}
+
+	return r.bitFiler.Truncate(size)
+}
+
+// Implements Filer.
+func (r *RollbackFiler) WriteAt(b []byte, off int64) (n int, err error) {
+	r.mu.Lock()
+	defer r.mu.Unlock()
+
+	if r.tlevel == 0 {
+		return 0, &ErrPERM{r.f.Name() + ": WriteAt outside of a transaction"}
+	}
+
+	return r.bitFiler.WriteAt(b, off)
+}